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How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims?
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The marketing script in triathlon bikes has been consistent for over a decade. Every bike brand checks similar boxes:

1. Tease a new release.

2. Release with accompanying "data" published in "white paper" to establish an argument for technical merit: "Best in wind tunnel/real world/etc."

3. Sponsor pro athlete and hope for results.

4. If results happen, attribute them by association to the bike, but never directly.

Here is my inquiry:

Does this language still inspire you to make a new bike purchase?

If you answered "Yes", Stop here and set down your pencil.

If you answered "No", please explain your answer briefly and suggest an alternative to this marketing script.

Tom Demerly
The Tri Shop.com
Last edited by: Tom Demerly: Oct 15, 15 9:49
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Tom Demerly wrote:
The marketing script in triathlon bikes has been consistent for over a decade. Every bike brand checks similar boxes:

1. Tease a new release.

2. Release with accompanying "data" published in "white paper" to establish an argument for technical merit: "Best in wind tunnel/real world/etc."

3. Sponsor pro athlete and hope for results.

4. If results happen, attribute them by association to the bike, but never directly.

Here is my inquiry:

Does this language still inspire you to make a new bike purchase.

If you answered "Yes", Stop here and set down your pencil.

If you answered "No", please explain your answer briefly and suggest an alternative to this marketing script.

No.

I honestly don't really trust any "data", because all of the "data" and white papers are lacking in details. The only way I would trust it is if there is a standard methodology, properly validated so that it is agreed as representative of the real world, summary results are presented and complete datasets are available for download and independent analysis, with annotations for why any particular data point should be excluded from the analysis. Everyone follows that protocol, with independent observers confirming that the protocol has been followed.

Until then, I'll choose my bike by geometry, visual appeal, and colour.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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Thank you Jason. Appreciated Sir.

I think your answer may speak for the other 63 people who looked at this thread but didn't answer.

Tom Demerly
The Tri Shop.com
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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No.

There are too many variables the setup for me to trust the comparisons. I admit I haven't read all of the white papers (I've scanned a few), but the marketing materials I've seen don't include any error bars or provide the detail in setup or methodology. I'd be very interested to know how the claimed margin of difference compared to those error bars.

I'd like to see some independent third parties conduct wind tunnel tests with the exact same methodology and wind tunnel. I'd also like to see those tests done in various different setups (rider position, bottle setups, wheels). All with the level of uncertainty explicit.



-Andrew
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Nope.

For the same reason you don't trust the politician when they say something self-serving, you don't trust a bike company with their wind tunnel data. I don't entirely think they fudge the data, but they almost certainly pick wind tunnel settings and tests that will be most favourable to their frame and unfavourable to the competition's.

Similarly, you can't really trust most magazines' tests since they're usually accepting cash for ads, and the sometimes-unsaid proposition there is "we buy five digits worth of ads, you say nice things about our bike".

Actually-independent owners that aren't trying to sell ads or pageviews can be trustworthy since they don't have conflicts of interest (other than not wanting to tank the resale value of their frame), but it's going to be rare that you can get enough bike owners together at a windtunnel and put on a good test. And even if you do put on a good test, you may just inadvertently pick test parameters that favour one frame over another, so you may get a false ranking anyway.

Basically, I'm utterly nihilistic when it comes to comparing frames. Way too many parameters to fiddle with and far too many huge conflicts of interest behind any data release.

This isn't unique to cycling: compliant car reviewers get access to nice vehicles, positive game reviewers get pre-release access and betas, journalists that uncritically parrot "anonymous government sources" are granted more access to future scoops. Disseminating accurate, unbiased information is a hard problem to solve in any industry when there's so many people with lots of interest in muddying the waters.

My favourite source of data is the kona top 10. You can't say "top 10 at kona = fastest equipment" since most equipment in the kona top 10 will be chosen by the sponsors, not the athlete. But you can say "this stuff is good enough that it didn't sabotage their race". Anything ridden to a top-10 finish may or may not be the fastest, but it's definitely good enough.

STAC Zero Trainer - Zero noise, zero tire contact, zero moving parts. Suffer in Silence starting fall 2016
Last edited by: AHare: Oct 15, 15 10:12
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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No. I also didn't think that Air Jordans would make me jump like Mike. Everytime I think about trading in my old QR and getting a new superbike, I just remind myself that Mark Allen and Dave Scott could beat me on a unicycle.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Verify your sources. And corroborate the data from other sources. That's the key.

A bike maker releasing some wind tunnel data which makes their frame look better than competitor's should be viewed with skepticism of course, for two reasons: that's a single data point, and there's conflict of interest that may skew the data in their favor if for no other reason than the fact the test isn't blind.

If an independent entity were to test that frame, then the data should be viewed as more trustworthy (the single data point, again, is of concern as it may or may not be accurate). When several entities run frames through wind tunnels and come up with similar numbers for a given frame, then we can begin to trust both the credibility and accuracy of that data.

That's hard to do, lacking standardized testing methods as it's been pointed out.

Great example of good data is Shiv vs P5. Several bike makers have tested their bikes against those two and in their (independent) testing the P5 was a little faster at lower yaw angles and Shiv at higher yaw angles.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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No, because i'm not sure that the lab demonstrated gains are not outweighed by other variables on the day, and I'm even less convinced that there's as much separating brands as they'd have us believe in that frame style, design and geometry appear to be gravitating to a "mean"
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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I'm pretty sure the large majority of ST will say no but as large as ST is it's a small fraction of the tri world where I think this really does work.

1. The tease is exciting. The amount of chatter over the Cervelo 140.6 days annoucement among friends is ridiculous.
2. The whitepaper could be completely fabricated (who knows it might even be) but the majority don't know or simply don't care.
3. Define results. If you simply mean fastest bike split and <insert race here> it is happening and,
4. When it happens you can be sure it is attributed partially to the bike. Case in point http://www.slowtwitch.com/...k_Twelsiek_5422.html with no mention of his pedestrian run.


Rodney
TrainingPeaks | Altra Running | RAD Roller
http://www.goinglong.ca
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Cervelo is 2nd in every other manufacturer's data, I'd say that it's a 100% stone cold credible lock that Cervelo bikes are fast.


Tom Demerly wrote:
The marketing script in triathlon bikes has been consistent for over a decade. Every bike brand checks similar boxes:

1. Tease a new release.

2. Release with accompanying "data" published in "white paper" to establish an argument for technical merit: "Best in wind tunnel/real world/etc."

3. Sponsor pro athlete and hope for results.

4. If results happen, attribute them by association to the bike, but never directly.

Here is my inquiry:

Does this language still inspire you to make a new bike purchase?

If you answered "Yes", Stop here and set down your pencil.

If you answered "No", please explain your answer briefly and suggest an alternative to this marketing script.

Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.â€
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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For me the benchmark is the old carbon P3. Once you've got something more aero than that, which is pretty common nowadays, then training is where you ought to focus your efforts. If all these super bikes really make the claimed 10 minute IM difference we would see times well under 8 hours for Hawaii. Just read Hutchinson's 'Faster' book to see a full expose of the aero-myth. There is a lot more than just aero to concentrate on too. For a small number of people a custom fit will result in a more balanced ride, for others a more comfortable frame will enable them to ride in an aero position for longer (fit being equal), some like something different and are willing to pay to stand out of the crowd or subsidise a small manufacturer, for others the convenience of an S&S frame would be worth the expense considering they like to race in far flung places.

SteveMc
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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No. It boils down to the engine. At the MOP level, that stuff is going to "buy" me a very small amount of time on a 140.6 and even smaller time on a 70.3, in which it will have a very poor cost/benefit for me to leverage it out on purchasing a big money (assuming that the new bikes are all big money) bike.

That, and the fact that I think the "data" is always framed to benefit the bike that they are trying to sell. Marketing 101 stuff....nothing new.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [SteveMc] [ In reply to ]
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I have read the book and totally agree. I am more of the issue than what I am sitting on.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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No. I consider it necessary but not sufficient.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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There are certain bike frames that can be eliminated from your choices based on tunnel data. In the past the Ordu, the Argon 18 for example were pretty bad. When you see the superbike charts the data is all close enough imo. If a person sheds a shiv for a P5 there is not way to measure the delta, if there is any. From a 2004 QR to an IA, that is measurable.

To answer your question, the decision to buy which bike is made by what the LBS says, what people can get deal on, and then just random bs that we will never know. No company has any advantage on marketing.

Dave Scott and Mark Allen would be doing Kona in 3:55 if you added up the incremental advantages claimed over the years :)
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Very little, but I give them the benefit of the doubt that they have found some particular yaw angle or set of circumstances where they have made gains. In fairness probably the most fantastic claim I saw was related to the new Specialized Venge where they claimed about a time savings of 5 minutes over 40km versus their previous model. I may be glossing over some facts with my memory here but CyclingTips did some field testing and found that it held up in practice. I never would have expected this, but I would like to see more affirmation of aerodynamic claims on the road.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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No.

A significant part of the problem is that some big manufacturers have "peed in the pool". There have been many of the "white papers" that would do things like compare a road bike to a tri-bike, but use riders in different positions, clothes, helmets, etc., across the tests of bikes. So was the result, the bike, or the other factors? That is just a simple example. All that type of paper tells me is that the vendor is trying to make me think the bike is bette than it is, and I should not trust them. At this point, there is only one vendor who I generally trust.

2015 USAT Long Course National Champion (M50-54)
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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No.
There have been enough discussions on this forum about how individual the aerodynamics are between person to person when testing in wind tunnels with regard to different helmets, positions, skinsuits, shaving of legs, etc, not even getting into the myriad options for hydration and spares locations, that once you put a rider on a bike all claims of "best" aerodynamics are just best guesses. If other pieces of equipment can test differently on different people because the interaction between moving air and a solid object is complex with minor variances having relatively large consequences then is it not also likely that different body shapes, pedaling form (knees in vs out), foot angle etc. also affect the overall aeroness of a particular bike and may interact with different frames in positive or negative ways. If this is true (I'm sure some smarter people will let me know if I'm way off on this) then with all the current frames being "relatively" close you may as well choose the one you like the best and makes you feel faster.

Anyway that's what I tell myself - it must be the engine that makes me go fast when I race my slow and outdated Shiv.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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I trust them about as much as I trust ads for penis enlargement pills.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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I tend to listen to the proclamations of companies such as Trek, Cervelo, and Specialized (in that order) because I feel they have earned it. Everyone else I tend to take with a huge grain of salt. I'll look at their whitepaper and their data but I'm constantly looking for holes in it. When it comes to pro endorsements, I tend to mostly disregard them except for someone like Gomez swimming in a Roka wetsuit. If he's wearing that suit I know, at the very least, it's not slowing him down.

Alternative marketing script? Sheesh, that's tough. All I can say is that if you're going to put out data make sure it's good data with a solid methodology behind it.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [dgran] [ In reply to ]
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The five minutes claim from specialized was comparing a rider on the bias whilst wearing an evade and skinsuit etc vs a rider on regular roadie clothing and a non-aero helmet whilst riding a Tarmac

So there are a tonne of factors contributing to that 5:00 difference
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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The problem with standardised tests is that you get designs that perform well in standardised tests. Cough cough... VW.


In answer to the question: no, but I still love reading a 'white paper'. Bikes are having a lot of money spent on their development now, so it's nice to read a narrative on the process, even if it is easily distorted.

I've never found sponsorship to be a good indicator of how a particular product will work for me.

I can't think of an alternative to the white paper as noted above. If aero is the measure of performance then any test is very limited in scope.

Developing aero, fit and other fun stuff at Red is Faster
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [SkippyKitten] [ In reply to ]
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that's why i added that the standard protocol would be "properly validated as representative of the real world".

standardised tests, properly set up, allow for good, meaningful comparison across time and space. You can take a result from one day, in one tunnel, and compare it to a result from another day, in another tunnel. Right now, you can't. Not very well, in any case.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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Good luck with designing a 'real world' test that doesn't lead to designs optimised to perform well in that test.

Developing aero, fit and other fun stuff at Red is Faster
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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tease is irrelevant, unless the timing is right when i am considering a purchase.
as i think someone else said, whitepapers/test data etc and pro rider performances are necessary but not sufficient.
i like to see that they have done some reasonable testing and found that their bike is at least comparable to known top performers (at least given some not completely unrealistic parameters). whether its the "fastest" or not is insignificant, it just has to be thereabouts. P5 and shiv are great comparisons as they have been well tested and show known patterns across yaw range which helps validate test results. any supposedly aero bike release that does not include some form of tunnel test data makes you wonder whether they didn't do any testing or do they just not want to tell anyone the results.
if you're not willing/able to front up with some cash and persuade a top pro to ride your bike then i have to question your commitment and/or product. i don't believe that a top pro becomes so because of what they ride

so that establishes a possible contender. from there the decision comes down to aspects like fit, looks, storage etc integration, local shop support, brand trust...

fwiw on this basis i recently bought a trek speed concept:
- nice white paper showing aero results with P5 and shiv displaying expected behaviour, SC results similar to P5
- surprisingly few top pros so i guess that doesn't really mean to much to me
- white paper also addresses fit, storage
- i like the looks
- a good local shop
- brand i trust

i don't really think its practical to expect everyone's tests to be exactly the same, there are just too many variables and any standard is subject to gaming. i hate setting of specific targets that encourage people to meet the test rather than the real goal. everyone design a bike to meet what you think is important and then feel free to test against that basis. as long as its not too far from reality (and accompanied by explanations to allow readers to judge that) all good. it would be nice if we could get closer to an agreed standard though and that would not mean testing at 50km/h!

in summary, no that language does not really inspire me. however it does help and i don't really see much in the way of alternatives
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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I pay attention to the big announcements and white papers.

I value independent testing and analysis more. The bottom line for me is that if I am dropping the amount of money it takes to get a high end tri bike, I am going to use (and critically evaluate) every bit of information I can get my hands on.

If I can't get some credible data about the bike, or the major components like wheels I will not consider making a purchase. I also won't consider buying if that data indicates the bike is significantly slower in the wind tunnel.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [ In reply to ]
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No.

For me, the purchase of a bike is based on expected durability, quality, and price of the bike. For me, triathlon is a hobby and it's important to maintain perspective of this. It's a hobby that is very expensive, and only supports a selfish 'need' and my triathlon results are not gonna pay for my son's college education.

I'm kind of like how aerospace selects materials, going by proven reliability over minor technical performance benefits (typically). I bought a P2 after the model was already on the market for several years and had proven its value. I still ride it today, 6 years later, so that means it has shown to be a reliable purchase. And if all goes well, it will easily last me another 6 years. My road bike is a Merckx that celebrated its 10th year this year. I'm hoping it will last another 10.

It's the same for components, I am not looking for the most complicated latest designed brake X or cable Y or electronic this or mechanical that. I'm using shimano components ranging from 105 to Dura-Ace depending on what came with the bike when I bought it. I don't replace Dura-Ace with Dura-Ace. I replace Dura-Ace with ultegra or 105.

I consider myself a strong biker and that to me confirms there's no need for a faster top of the line bike. I am usually in the top 2-3 fastest bikers in local races. My IM MD bike split last year was 4:45. Not trying to brag but the point is that a bike such as my 2009 P2 still has plenty of potential and i don't see how a faster bike would make a dramatic difference. If I want a dramatic difference I should start by eating less junk and swimming more. :-)

So to answer the question about marketing... I want proven reliability. Mechanical performance. Why this bike will be fast AND will last a lifetime. Why it is stiff and not too stiff. Why it's comfortable. Why I will love this bike for the next 10 years without feeling like I'm using something that belongs in a museum.


_____________________
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Hmmm... Looks like a lot of no votes yet just try to launch a new, state of the art performance wheel like Dished Wheels, without the data and you'll get skewered.

Does data only count for wheels but not for frames?

I tend to view it the opposite way. Assuming a proper fit is "possible" on various bikes, then the data does matter regardless of my fit because I can have an equally bad, or good fit, so the variable left is the bike.

Of course, in the real world of budgets, it also comes down to the speed / cost ratio.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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The only tunnel data I feel like I can trust is from Zipp and Cervelo since so many tests have been done against these two brands and the data is pretty much the same from test to test. I like reading the Tech Papers but I want to see data and have it backed up by independent sources.

Make Inside Out Sports your next online tri shop! http://www.insideoutsports.com/
Last edited by: BryanD: Oct 15, 15 20:52
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [BryanD] [ In reply to ]
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The thing that boggles me about always trying to sell bikes in the same way is the "blank space".

The blank space is everything left over to sell a bike. Everything left besides bicycle aerodynamics.

Things like:

  • Appearance (more important than most of us are willing to admit).
  • Weight.
  • Warranty.
  • Frame stiffness (Note here: one highly credible brand has a unique feature that makes their bikes stiffer, but none of their P.O.P. displays mention it.)
  • Component specification. (I dare someone to run an ad that says, "Best value in a Dura-Ace equipped triathlon bike).
  • Fit. (Everyone acknowledges the importance of bike fit. No manufacturer actively uses it as a selling tool in their marketing.)
  • History.
  • Construction technique.
  • Durability.
  • Ride quality.
  • Comfort.
  • Ease of maintenance (honorable mention to Quintana Roo for their "Ease of Packing" campaign for their very good PR bikes).
  • Mise en scene (the cache' of the brand, an analogue that is more important than most consumers are willing to admit since some of it is subconscious.)

It took less than 2 minutes to list 13 new conversations bike companies could be having with their customers instead of the same one they are all having.


It's like being in a room full of people shouting. And someone needs to whisper to truly be heard.

Tom Demerly
The Tri Shop.com
Last edited by: Tom Demerly: Oct 15, 15 21:51
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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this is purely from a technical stand point, (and assuming manf. dont fudge data, I think they dont!)
YES and NO..

YES - Because, Wind tunnel data can be credible if bikes are tested with same protocol. For ex: if test data come out of A2 wind tunnel from different manufacturers, we can rely on data, as A2 typically has a standard test protocol, use same tare/model mount setup etc. Also there are a lot of independent bike aero test comparisons by publishers out there which can be credible.

NO - because, if they are coming out of different wind tunnels, then there is no apple to apple comparison (wind tunnel size/blockage differences etc.).

Adi Prabakar
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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To be fair, Cannonade are trying to go down that route with the Slice.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Idk but I think there are other cheaper ways to get faster for way less money
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Not a lot.

For me, I pay more attention to what comes out of the testing done by Jim at Ero and Brian Stover in the tunnel. Try and pay attention to trends and the things that generally test well.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Goobdog] [ In reply to ]
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Goobdog wrote:
Hmmm... Looks like a lot of no votes yet just try to launch a new, state of the art performance wheel like Dished Wheels, without the data and you'll get skewered.

Does data only count for wheels but not for frames?

I tend to view it the opposite way. Assuming a proper fit is "possible" on various bikes, then the data does matter regardless of my fit because I can have an equally bad, or good fit, so the variable left is the bike.

Of course, in the real world of budgets, it also comes down to the speed / cost ratio.

The criticism of OISHEO had nothing to do with lack of data (well, very little anyway), and everything to do with the claims he was making and the fact that he was flat out lying, along with stealing Flo's website.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [SteveMc] [ In reply to ]
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SteveMc makes a good point, and there should be two brands with honorable mentions here:

1. Cannondale has maintained a good conversation about bike weight and ride quality on their tri bike.

2. Quintana Roo has discussed the mechanical simplicity of their PR bikes for bike packing and maintenance.

Interestingly, one other non-aerodynamic major (very major) triathlon/aero bike brand has a key feature unique to them that I will suggest does provide a tangible benefit across the entire performance envelope. But they never talk about it.


I've always thought that's odd, but then again, that's just me.

Tom Demerly
The Tri Shop.com
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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But you've also never thought that wind tunnel data was applicable in the real world. Or at least that was the case in the past and a source of a lot of arguments/discussions in the forums. I'm guessing you are no longer working for FELT, so you are free to continue back down that road again?

Aerodynamics are really only one part of the puzzle, and they are real and measurable. I've spent a lot of time in the tunnel with Brian and at the track with Jim doing our AeroCamps as well as doing independent testing. I can tell you for a fact that the gains we have seen are realized on the race course.

I'm also a big proponent of a proper fit. Stiffness is a red herring. Lightness is also secondary to aero.

The process is get a proper fit then find the most aerodynamic frame that works for your fit and your riding style. A frame from FELT, Scott, Cervelo, or Trek will all fit the bill nearly equally but fit differently. Cervelo is a low yaw bike and the others perform better outside of 7.5 degrees. If you are slower or racing at Kona the other bikes will perform better aerodynamically.

Beyond that, it is color and what you LBS happens to carry.



Heath Dotson
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [GreenPlease] [ In reply to ]
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GreenPlease wrote:
I tend to listen to the proclamations of companies such as Trek, Cervelo, and Specialized (in that order) because I feel they have earned it. Everyone else I tend to take with a huge grain of salt. I'll look at their whitepaper and their data but I'm constantly looking for holes in it. When it comes to pro endorsements, I tend to mostly disregard them except for someone like Gomez swimming in a Roka wetsuit. If he's wearing that suit I know, at the very least, it's not slowing him down.

Alternative marketing script? Sheesh, that's tough. All I can say is that if you're going to put out data make sure it's good data with a solid methodology behind it.

I agree with your comment. I would add that the Giant marketing is interesting. The drag graph they published pretty much showed that most people would be better off with a Speedconcept or a P5 because they are clearly faster in the 0-5 degree range.

The alternative marketing angle I would appreciate would be "Don't buy are bike if you you match this set of parameters", but that isn't going to happen.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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I've always taken the trust but verify. You look at enough of them and know a P5 has to be the fastest at 0 yaw. I suppose someone else is gonig to beat it, someday? but the best ones show the P5 doing what it does best, and ideally you see the p5, the speed concept, and some others that have been baseline bikes frequently, and in the right relationship, with the manufacturer's bike slotted in where it belongs.

While it won't be the only thing that I buy a bike off of, a lack of such data would stop me cold from buying a bike.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Tom Demerly wrote:

2. Quintana Roo has discussed the mechanical simplicity of their PR bikes for bike packing and maintenance.

In line with what I said before, this would be a big factor in getting a bike because simple bike packing and maintenance means better reliability and in the end, better performance. It also helps mentally when you know you can fix a problem and won't be stuck on the road or not able to use your bike while you're waiting for replacement parts.

For me, QR would definitely be an serious option if it weren't that their PRSix is so expensive (which no longer makes it an option).


_____________________
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [jackmott] [ In reply to ]
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jackmott wrote:
well I guess you are lucky you find airfoils visually appealing

Doesn't everyone?
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [chaparral] [ In reply to ]
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chaparral wrote:
jackmott wrote:
well I guess you are lucky you find airfoils visually appealing

Doesn't everyone?

strangely, no



Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [jackmott] [ In reply to ]
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My tastes run towards "simpler and cleaner is better".

When someone comes out with something in general terms, it looks like it makes sense, I'll say "that looks like its reasonable". So if tririg says that their brake is faster than a sidepull Dura Ace, I believe that. Where I roll my eyes is when specific numbers start getting attached, when someone claims a detectable difference without showing the variability in the measurements. That's where I stop caring.

It is when someone claims one thing, and you have no idea if their claim is real or noise, then that's an issue. I haven't bothered to look at white papers in a long time, because when I did, there was no way to reasonably discern signal from noise. So I've given up.

Swimming Workout of the Day:

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2020 National Masters Champion - M50-54 - 50m Butterfly
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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Well you can always look at the totality of white papers and notice trends.
Like Cervelo still wins in other people's white papers, heh

The nice thing is now almost all of the major brands have good stuff. You can't go very wrong. So shopping by looks ins't likely to screw you anymore anyway.


JasoninHalifax wrote:
It is when someone claims one thing, and you have no idea if their claim is real or noise, then that's an issue. I haven't bothered to look at white papers in a long time, because when I did, there was no way to reasonably discern signal from noise. So I've given up.



Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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There are some very important things in the white papers beyond the wind tunnel models. The first is the testing protocol. If one company tests with bottles and the other does not, it is good to see the difference and gives the consumer valuable data. They also will detail things like the size and aero-bar configuration, this can explain difference in results between different tests. This sort of information can explain why one bike ends up on top in one test and another is on top of another test.

The second aspect is it shows the design process. Take the speedconcept for example, both the whitepaper are pretty great. The first one showed their process for developing their tube shapes. They started in CFD just looking at individual tube shapes, then took a bunch of those tube shapes to the windtunnel. Then they went back and then compared the wind tunnel to the CFD and were able to correlate their CFD process to the windtunnel. Only then did they start designing the bike as a whole in CFD, then went back to the windtunnel to test some of the CFD models. Then went back again to correlate their CFD. This sort of methodical process of building up knowledge from a base and confirming bit by bit, is not guaranteed to result in a fast bike, but there is a very good chance a fast bike will be the result. This sell to me the results in the windtunnel, because clearly they did the right things leading up to final product. Similar thing for the 2nd speed concept white paper. This one had lots of information about what yaw riders actually see. There is lots of good detail information in there how they get good yaw data, like making sure their measurements were not affected by the frame behind the measurement devices. They actually put their bike and rig in a wind tunnel to make sure it worked correctly. Then they used that actual yaw data to determine what yaw to optimize the frame for.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [jackmott] [ In reply to ]
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True, but that's not really what Demerly was asking in his OP.

I can look at the totality and say "OK, a P2 or P3 is going to be pretty good"

Or I can look at something like a PlanetX Exocet 2, which has no white paper that I'm aware of, but say "that looks pretty similar to the P2", and I can route the rear brake cable more cleanly, so it probably isn't terrible.

i.e. I can make claims in pretty general terms, but not precise claims.

What I am not comfortable doing is saying that the P2 is going to be 2 watts less drag at 25 mph than the ShivTT, or whatever highly accurate claim is being made.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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No.

It's actually not complicated, if you look at it without getting bogged down in the hype/details.


Here is the question that every triathlete should be asking regarding how fast their bike will be:

"Will it make me measurably faster on the race course?"

Wind tunnels do a good job in teasing out theoretical tiny gains with small aerodynamic changes, but all the science and hype is moot if there is no reliably measurable effect in the real world, on a real outdoor race course.

To date, there is NO bike manufacturer that will lay claim to even saying you will be measurably +20 seconds faster outdoors with their superior aerodynamic bike. And believe me, if any manufacturer had good data showing this type of effect reliably outdoors, you'd be seeing it in their ads, since they'd be the only ones good enough to pull it off.

To all those folks who say, 'well the wind tunnel gives the cleanest results which should directly translate to faster outdoor times", it's all totally meaningless if the 'noise' from outdoor practice dwarfs the speed gains.

It sounds like 'duh' common sense, but to say it again explicity - if you cannot reliably measure a speed benefit outdoors in the same race conditions that serves as what this hardware is meant to be used for, it's not making you any faster even if the wind tunnel results says you should theoretically be faster.

Now if the wind tunnel results were an excellent proxy for outdoor results (meaning there's good evidence showing that the small advantages in a wind tunnel translate to well to measurable outdoor results), I'd be more inclined to believe the data, but to date, there is not once single bike manufacturer, even ones with millions of dollars of R&D, that make the claim of having an outdoor, measurable real-world difference.

Note that this doesn't mean I don't believe in aero gear. There is no doubt that aerobars vs non-aerobars (in a good position for both) will give you a real, outdoor measurable speed advantage. There's also no doubt that non-UCI positions like the full recumbent position are much faster than standard positions in flat courses. But I would make the claim that bike manufacturs resort to wind tunnel data because they are unable to provide convincing outdoor real data that their bikes are any faster than their competitor road/tribikes.

I'd be more than happy for people to prove me wrong - show me the data showing that Cervelos, or whatever bikes are faster outdoors using a convincing sample size, and I'll gladly give the thumbs up to believing their claims that their bikes truly are faster.
Last edited by: lightheir: Oct 16, 15 8:24
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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JasoninHalifax wrote:
True, but that's not really what Demerly was asking in his OP.

I don't really talk to Demerly.



Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:
To date, there is NO bike manufacturer that will lay claim to even saying you will be measurably +20 seconds faster outdoors with their superior aerodynamic bike. And believe me, if any manufacturer had good data showing this type of effect reliably outdoors, you'd be seeing it in their ads, since they'd be the only ones good enough to pull it off.

Cervelo, Specialized, Trek, at a minimum,I'm sure there are others, do aero testing outdoors with various "Chung on a stick" type devices.

additionally, figure 2 in the following study shows that wind tunnel measured CdA has strong predictive power for outdoor real world results:

http://www.wisil.recumbents.com/...20road%20cycling.pdf

This does not represent the only validation of wind tunnels vs real world, it was just handy.

I think the degree to which you mistrust wind tunnel testing is misplaced.



Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [jackmott] [ In reply to ]
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jackmott wrote:
JasoninHalifax wrote:
True, but that's not really what Demerly was asking in his OP.


I don't really talk to Demerly.

fair enough...

Swimming Workout of the Day:

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [jackmott] [ In reply to ]
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jackmott wrote:
Well you can always look at the totality of white papers and notice trends.
Like Cervelo still wins in other people's white papers, heh

The nice thing is now almost all of the major brands have good stuff. You can't go very wrong. So shopping by looks ins't likely to screw you anymore anyway.


JasoninHalifax wrote:

It is when someone claims one thing, and you have no idea if their claim is real or noise, then that's an issue. I haven't bothered to look at white papers in a long time, because when I did, there was no way to reasonably discern signal from noise. So I've given up.

I'm leery of Orbea's new bike tbh. I really like the direction they went with certain design decisions (e.g. standard cockpit, direct mount brakes, boss behind seat tube for storage, vertical dropouts) and it looks like a very easy bike to travel with but until I see aero data there's no way it's replacing my Speed Concept.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [jackmott] [ In reply to ]
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jackmott wrote:
lightheir wrote:

To date, there is NO bike manufacturer that will lay claim to even saying you will be measurably +20 seconds faster outdoors with their superior aerodynamic bike. And believe me, if any manufacturer had good data showing this type of effect reliably outdoors, you'd be seeing it in their ads, since they'd be the only ones good enough to pull it off.


Cervelo, Specialized, Trek, at a minimum,I'm sure there are others, do aero testing outdoors with various "Chung on a stick" type devices.

additionally, figure 2 in the following study shows that wind tunnel measured CdA has strong predictive power for outdoor real world results:

http://www.wisil.recumbents.com/...20road%20cycling.pdf

This does not represent the only validation of wind tunnels vs real world, it was just handy.

I think the degree to which you mistrust wind tunnel testing is misplaced.

Can you point me to where Cervelo or others actually show how their superior aero frames truly give an outdoor advantage? I've never seen it, but if you have it and it's legit, I'm willing to believe it.

I'm sure they DO test them outdoors, but again, I've yet to see convincing proof that shows their wind tunnel data is legit outdoors.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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I'm not aware that they have published it.
You could refer to some of Tom A's field testing on various cervelo frames. Or perhaps pick the brains of some of the people who have been to EROSport.

But unless you think Cervelo manages to find shapes that somehow work in a wind tunnel but not outside, despite the fact that in general these things work the same, I don't know why you are so suspect. Again, see figure 2 in the link.


lightheir wrote:

Can you point me to where Cervelo or others actually show how their superior aero frames truly give an outdoor advantage? I've never seen it, but if you have it and it's legit, I'm willing to believe it.

I'm sure they DO test them outdoors, but again, I've yet to see convincing proof that shows their wind tunnel data is legit outdoors.



Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [jackmott] [ In reply to ]
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jackmott wrote:
I'm not aware that they have published it.
You could refer to some of Tom A's field testing on various cervelo frames. Or perhaps pick the brains of some of the people who have been to EROSport.

But unless you think Cervelo manages to find shapes that somehow work in a wind tunnel but not outside, despite the fact that in general these things work the same, I don't know why you are so suspect. Again, see figure 2 in the link.


lightheir wrote:


Can you point me to where Cervelo or others actually show how their superior aero frames truly give an outdoor advantage? I've never seen it, but if you have it and it's legit, I'm willing to believe it.

I'm sure they DO test them outdoors, but again, I've yet to see convincing proof that shows their wind tunnel data is legit outdoors.

I am absolutely suspect!

Seriously, if you had good, reliable data showing that your wind tunnel effects are measurable and reproducible outdoors, why would you choose to hide it?

This type of surrogate-testing as-proxy is a well-known method in the biological sciences of trying to indirectly 'prove' something even if really doesn't work. For example, your drug might not cure diabetes humans, but you could get a lot of excitement from investors and even science publications by showing that it cures diabetes in mice or other surrogates. It's interesting stuff, no doubt, but still a far cry from saying it works in the circumstance that you are trying to prove, which is humans (or outdoors, in bikes case.)
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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http://cms.trekbikes.com/...adone_whitepaper.pdf

starts with CFD-tunnel correlations, gets into velodrome testing on pages 15-16, and finishes up with lots of multi-rider field testing on pages 34-38

Carl Matson
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [jackmott] [ In reply to ]
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jackmott wrote:
But unless you think Cervelo manages to find shapes that somehow work in a wind tunnel but not outside, despite the fact that in general these things work the same, I don't know why you are so suspect.
He thinks bike companies are like Volkswagen.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Carl] [ In reply to ]
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Carl wrote:
http://cms.trekbikes.com/...adone_whitepaper.pdf

starts with CFD-tunnel correlations, gets into velodrome testing on pages 15-16, and finishes up with lots of multi-rider field testing on pages 34-38

Aerostick!
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Carl] [ In reply to ]
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This is the part of the thread where I humbly illustrate that this thread has:

1. Reverted once again to the endless, circular argument about the aerodynamic merits of bikes.

2. Potentially illustrated that selling the same thing the same way probably doesn't sell anything that wasn't already going to be bought.

Here's what I mean, and some of you already know this:

The sport has grown in participation. Lots of new triathletes. Very few are contributors or readers on the Slowtwitch.com forum. It's a new demographic. The industry is still selling to the old demographic. It appears afraid to even try to sell to the new demographic with a fresh approach.

Examples in other industries:

Coca-Cola raised brand awareness with their beverage by putting peoples' names on the cans.

Apple introduced computers with metal bodies, different looking and functioning retail outlets and cross-device connectivity.

Casio made an inexpensive digital watch focused not on time keeping accuracy or fashion appearance but on durability, the G-Shock.

Ford popularized a vehicle category started by International Harvester called the "Sport Utility", something people never realized they wanted.

Dan Empfield marketed a new bike category by changing the orientation of the riders' pelvis to the bottom bracket and other geometric changes.

And here's my point: There is untaped opportunity here.

What is the average bike speed of most people doing Ironman? I'm not talking about the top 15%. What does that customer really find useful?

And finally, why isn't the industry marketing to that segment?

Tom Demerly
The Tri Shop.com
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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This is the part of the thread where I humbly illustrate that you have an axe to grind.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Good points, I think.

Most of our tri fit clients aren't regulars on ST, and a surprising number don't even know about this site. ERO, along with a few other companies (Louis Garneau, PowerTap, Profile Design), are going to partake in a project over the next few weeks where we take an "average" triathlete and see just how "ERO" we can make her. She's a mom, never much of an athlete, she'll never likely sniff a podium, but she very much represents the majority of newer triathletes. She recently borrowed a power meter, and noted she was using more watts to go slower than her friends. I thought it was pretty cool that she noticed, and it re-enforced in me that position, aerodynamics, equipment choice, proper training, etc. are important for everyone, not just the pointy end of the sword. Virtually everyone, no matter how "fast" they may be, cares about getting the most out of themselves. I do see the industry going after them, but perhaps there's a better way.

As for credibility of aero test claims? Well, I've posted on that many times now; testing one frame vs another is silly. Heath is right, find your position, and then get the bike that allows you attain it. Frames are far down the list of importance if you're looking strictly at aero drag. Weight - who cares? We're beyond weight at this point.

Jim Manton / ERO Sports
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Carl] [ In reply to ]
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Carl wrote:
http://cms.trekbikes.com/...adone_whitepaper.pdf

starts with CFD-tunnel correlations, gets into velodrome testing on pages 15-16, and finishes up with lots of multi-rider field testing on pages 34-38



And of critical note in that document - the only time they compare other bike manufacturer designs to their bike is in the wind tunnel and velodrome.

ALL of the outdoor testing in that document is not against other bikes - it's just additional testing on their own frame with different yaw angles, etc. They specifically AVOID showing any data of testing various other bike frames against theirs outdoors. Even if the data was imperfect (due to varying wind, rider consistency, etc.), I still would want to see how big (more likely how small/irrelevant) the measurable difference are outdoors.

I definitely am ok with both the wind tunnel and velodrome data in terms of how they test between frames/companies, but I'm definitely still not sold on how measurable these effects are between frames in outdoor settings.

This isn't a trivial issue - we triathletes race bikes exclusively outdoors and not in a velodrome, so if we're going to buy into how effective their highly researched frames are, they should have data that reflects it in the outdoor conditions. If the outdoor variables are big enough to render all their engineering to the level of background noise in terms of speed gains, the conclusion drawn should be 'insignificant' between different frames in real-world OUTDOOR practice.
Last edited by: lightheir: Oct 16, 15 10:33
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [jackmott] [ In reply to ]
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jackmott wrote:
figure 2 in the following study shows that wind tunnel measured CdA has strong predictive power for outdoor real world results:

http://www.wisil.recumbents.com/...20road%20cycling.pdf

This does not represent the only validation of wind tunnels vs real world, it was just handy.

It may not be the only, but it was the first. (BTW, you can find a cleaner copy here: https://www.academia.edu/...mech_1998_14_276-291)

The irony is that the stimulus for the study was the frustration that Jim had with "aero deniers" like lightheir. Now here we are almost 20 y later, and they still exist!
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:
If the outdoor variables are big enough to render all their engineering to the level of background noise in terms of speed gains, the conclusion drawn should be 'insignificant' between different frames in real-world OUTDOOR practice.

Apparently you've never heard the saying, "absence of evidence is not evidence of absence?"

Regardless, at least in the right hands field testing can be quite precise:

http://www.trainingandracingwithapowermeter.com/...aerodynamicists.html

and is sufficient to detect the difference between, e.g., aero frames:

http://www.trainingandracingwithapowermeter.com/...-p2t-or-javelin.html

http://www.trainingandracingwithapowermeter.com/...-p3c-or-cervelo.html
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [jackmott] [ In reply to ]
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jackmott wrote:
JasoninHalifax wrote:
True, but that's not really what Demerly was asking in his OP.

I don't really talk to Demerly.

Yeah, but would you talk to his wife?
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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JasoninHalifax wrote:
When someone comes out with something in general terms, it looks like it makes sense, I'll say "that looks like its reasonable". So if tririg says that their brake is faster than a sidepull Dura Ace, I believe that. Where I roll my eyes is when specific numbers start getting attached, when someone claims a detectable difference without showing the variability in the measurements.

Variability estimates, did you say?

http://www.tririg.com/...omega_whitepaper.pdf

(BTW, think if I posted this to ResearchGate.net as a work-in-progress everyone would assume it is a peer-reviewed paper? Based on recent events, I bet most people would.)
Last edited by: Andrew Coggan: Oct 16, 15 10:48
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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without letting this go too much further into rabbit-hole/hijack territory...

lightheir wrote:
And of critical note in that document - the only time they compare other bike manufacturer designs to their bike is in the wind tunnel and velodrome.

ALL of the outdoor testing in that document is not against other bikes - it's just additional testing on their own frame with different yaw angles, etc. They specifically AVOID showing any data of testing various other bike frames against theirs outdoors.

not because there's something to hide, but because it wasn't the purpose of the testing. the point was to establish relevance of aero data even in drafting situations, period...not to establish whether or not one frame performed better than another in a given drafting situation. seemed like a prudent thing to investigate, since there's a chunk of the road market in particular which gets hung up on "but it all goes away in the real world when you're drafting"...conveniently forgetting that in the real world you're still moving through air.

<steps back into black helicopter>

Carl Matson
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
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Anything with slight bias I don't give much credibility to but I don't think its that far off either. It would be nice if there was a all powerful independent wind tunnel tester that did yearly reviews on the major products and published it. I realize that's probably not going to happen as the financial requirement even with companies cooperation has to be much more than any return would provide.

For example, who's to say when testing the cable excess on the derailleurs and brakes is longer? The type of handlebars used is important, bar tape, etc. There are all kinds of ways to slightly fudge data.

Personally, I like to see how the equipment stands as a single item (i.e. the frame) and not a full setup. For tri bikes with integrated setups it can't be done but with road bikes most of us chuck the handlebars and wheels after getting a bike so testing products stock means nothing for some of us.
Last edited by: furiousferret: Oct 16, 15 11:04
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Carl] [ In reply to ]
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Carl wrote:
without letting this go too much further into rabbit-hole/hijack territory...

lightheir wrote:
And of critical note in that document - the only time they compare other bike manufacturer designs to their bike is in the wind tunnel and velodrome.

ALL of the outdoor testing in that document is not against other bikes - it's just additional testing on their own frame with different yaw angles, etc. They specifically AVOID showing any data of testing various other bike frames against theirs outdoors.


not because there's something to hide, but because it wasn't the purpose of the testing. the point was to establish relevance of aero data even in drafting situations, period...not to establish whether or not one frame performed better than another in a given drafting situation. seemed like a prudent thing to investigate, since there's a chunk of the road market in particular which gets hung up on "but it all goes away in the real world when you're drafting"...conveniently forgetting that in the real world you're still moving through air.

<steps back into black helicopter>

It actually very might go away in the real world. If the external variable forces are enough to render the small gains of the aero frame immeasurable, those vaunted wind tunnel gains are in fact 'gone' on race day. It is critically important to interpret the magnitude of the speed gain relative to the expected variability of 'real world situations.'

This would be analogous to having a blood pressure drug, that in the lab, with humans, absolutely lowers blood pressure by 1mm HG in the lab, but has no measurable effect on BP out of the lab, due to the variability of human physiology/BP which makes a 1mmHG difference clinically useless. There is no clinician that would say that this was an effective hypertension drug worth prescribing to reduce real clinical hypertension, despite the rock-solid data that it really does lower blood pressure (by a measly 1 mmHG.)
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:
If the external variable forces are enough to render the small gains of the aero frame immeasurable, those vaunted wind tunnel gains are in fact 'gone' on race day

Logic isn't your strong suit, now is it?

lightheir wrote:
This would be analogous to having a blood pressure drug, that in the lab, with humans, absolutely lowers blood pressure by 1mm HG in the lab, but has no measurable effect on BP out of the lab, due to the variability of human physiology/BP which makes a 1mmHG difference clinically useless. There is no clinician that would say that this was an effective hypertension drug worth prescribing to reduce real clinical hypertension, despite the rock-solid data that it really does lower blood pressure (by a measly 1 mmHG.)

1 mmHg is 1 mmHg, regardless of the variability of the measurements.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
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Andrew Coggan wrote:
lightheir wrote:
If the outdoor variables are big enough to render all their engineering to the level of background noise in terms of speed gains, the conclusion drawn should be 'insignificant' between different frames in real-world OUTDOOR practice.


Apparently you've never heard the saying, "absence of evidence is not evidence of absence?"

Regardless, at least in the right hands field testing can be quite precise:

http://www.trainingandracingwithapowermeter.com/...aerodynamicists.html

and is sufficient to detect the difference between, e.g., aero frames:

http://www.trainingandracingwithapowermeter.com/...-p2t-or-javelin.html

http://www.trainingandracingwithapowermeter.com/...-p3c-or-cervelo.html


The testing you do in the javelin/cervelo links is the kind of data that bike manufacturers SHOULD be providing. I would love to see more frames tested in this manner, outside of the wind tunnel.

Given your extensive expertise in this area, and your research that such OUTDOOR testing should not be difficult in practice and also should yield highly precise results (both premises I absolutely agree with), then what do you think the reason is why bike manufacturers never show A/B comparison OUTDOOR data versus other bikes, if their frame is in fact, superior?

This situation would be akin to multiple hypertension medication manufacturer saying they have a great drug with great effects, but not one of them providing a single clinical trial outside of highly controlled lab conditions to prove it. If the medication (or frame) is really so effective - why can't they show it works in the real world or in real conditions if it's not so hard to test it?
Last edited by: lightheir: Oct 16, 15 11:24
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
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Anyone sell any bikes yet?

Tom Demerly
The Tri Shop.com
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [RChung] [ In reply to ]
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RChung wrote:
This is the part of the thread where I humbly illustrate that you have an axe to grind.

That was my point, which he of course ignored.



Heath Dotson
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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I've no idea where you are going with this. I don't sell bikes so don't know the mindset that you're alluding to, nor the current bike that has the elusive 'mojo'.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
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Andrew Coggan wrote:
lightheir wrote:
If the external variable forces are enough to render the small gains of the aero frame immeasurable, those vaunted wind tunnel gains are in fact 'gone' on race day


Logic isn't your strong suit, now is it?

lightheir wrote:
This would be analogous to having a blood pressure drug, that in the lab, with humans, absolutely lowers blood pressure by 1mm HG in the lab, but has no measurable effect on BP out of the lab, due to the variability of human physiology/BP which makes a 1mmHG difference clinically useless. There is no clinician that would say that this was an effective hypertension drug worth prescribing to reduce real clinical hypertension, despite the rock-solid data that it really does lower blood pressure (by a measly 1 mmHG.)


1 mmHg is 1 mmHg, regardless of the variability of the measurements.


I will, add, Dr. Coggan, it's not encouraging when you respond to a very reasonable claim I've made with a 'ad-hominem' attack about my logic or lack of, which completely avoids addressing the situations I've presented.

You're not hurting my feelings, as I have enough academic credentials to feel good about my logic, but it certainly undercuts the message you are trying to get across, nor does it refute what I have said.

And 1mmHg is 1mmHG is true, but I still stand by my point that such a small magnitude difference needs to be considered before changing practices to incorporate this drug before other more effective means. In fact, you should probably make the argument with this data that you should completely ignore this drug, and spend your time on all the other more highly effective means of treating hypertension - an analagous approach would be a coach advising someone to ignore the gains of aero vs nonaero bike frames and focus on rider position and aerobars instead.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:
Given your extensive expertise in this area, and your research that such OUTDOOR testing should not be difficult in practice and also should yield highly precise results (both premises I absolutely agree with), then what do you think the reason is why bike manufacturers never show A/B comparison OUTDOOR data versus other bikes, if their frame is in fact, superior?

Because wind tunnel testing offers numerous advantages over testing outdoors - after all, that's why wind tunnels were invented in the 1st place.

Of course, now that CFD has been extensively developed and validated, it has started to become the "go to" instead of wind tunnel testing, for essentially the same reasons that wind tunnel testing supplanted testing outdoors (e.g., of airplanes).
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
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Andrew Coggan wrote:
lightheir wrote:

Given your extensive expertise in this area, and your research that such OUTDOOR testing should not be difficult in practice and also should yield highly precise results (both premises I absolutely agree with), then what do you think the reason is why bike manufacturers never show A/B comparison OUTDOOR data versus other bikes, if their frame is in fact, superior?


Because wind tunnel testing offers numerous advantages over testing outdoors - after all, that's why wind tunnels were invented in the 1st place.

Of course, now that CFD has been extensively developed and validated, it has started to become the "go to" instead of wind tunnel testing, for essentially the same reasons that wind tunnel testing supplanted testing outdoors (e.g., of airplanes).


The gold standard, though still should be outdoor results, if you are racing outdoors. Saying wind tunnels are advantageous does not change this - I can tests blood pressure medications in highly controlled laboratory conditions with highly controlled subjects, using parameters that have shown excellent correlation to how the med should function in the real-world, but until I actual provide that real-world testing data and results, it's all theoretical.

This is a core concept in Phase1-Phase4 clinical trials. No matter how well the drug performs in the lab or in selected controlled human subjects, you cannot skip the gold standard testing of actually showing the results after you give the drug to a range of people in the real world, if you wish to claim that your lab results hold up in actual practice.

I'm also ok with using 'next-best surrogate test' (like CFD) if real-world testing is too cost-prohibitive (jet engine testing) or difficult. But as you yourself show with your own studies, this is eminently NOT the case in outdoor bicycle frame speed testing, even if it's not absolutely perfect.
Last edited by: lightheir: Oct 16, 15 11:52
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Yeah Tom, you're right on.
What the bike industry desperately needs is a respite from empiricism. All hail the return of "Laterally stiff yet vertically compliant!" and "This one comes in red!"

Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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The problem with testing outdoors is that outdoors is a far more variable environment than indoors. You cannot control wind velocity, wind direction, temperature, humidity, ground slope, etc, etc. You are stuck at testing at whatever yaw angle is present as riding. You have variation in rider postition (however slight), road surface.

Each of those things introduces error. So if you want a true picture, then you really need to do the testing in a controlled environment, which means a wind tunnel, indoors.

My beef is really that there are no actual industry standards for conducting such testing. Everyone comes up with their own.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:
If the outdoor variables are big enough to render all their engineering to the level of background noise in terms of speed gains, the conclusion drawn should be 'insignificant' between different frames in real-world OUTDOOR practice.

Maybe think about it this way. Lets say you lose 2lbs of weight. Then you say, well I lost 2lbs of weight so I should climb 1.5% faster. You go and do some climbs at the same power and it turns out you were slower. Does that mean that losing weight does not help climbing? No, it just means that the weight was overwhelmed by all the other things. Like maybe you had two full waterbottles this time or were wearing heavier clothing. Or you did not poop before your ride.

BUT the important thing is that DID climb 1.5% faster than you would have if you did not lose that weight. This does not mean that losing 2 lbs is insignificant. It is faster, just that it is hard to discern without strict control.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
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Andrew Coggan wrote:
JasoninHalifax wrote:

When someone comes out with something in general terms, it looks like it makes sense, I'll say "that looks like its reasonable". So if tririg says that their brake is faster than a sidepull Dura Ace, I believe that. Where I roll my eyes is when specific numbers start getting attached, when someone claims a detectable difference without showing the variability in the measurements.


Variability estimates, did you say?

http://www.tririg.com/...omega_whitepaper.pdf

(BTW, think if I posted this to ResearchGate.net as a work-in-progress everyone would assume it is a peer-reviewed paper? Based on recent events, I bet most people would.)

That's what I would like to see (based on a cursory scan, anyway. I haven't spent a lot of time looking at it). But both of us know that the white papers released by the vast majority of manufacturers don't go into anywhere near that level of detail.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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JasoninHalifax wrote:
The problem with testing outdoors is that outdoors is a far more variable environment than indoors. You cannot control wind velocity, wind direction, temperature, humidity, ground slope, etc, etc. You are stuck at testing at whatever yaw angle is present as riding. You have variation in rider postition (however slight), road surface.

Each of those things introduces error. So if you want a true picture, then you really need to do the testing in a controlled environment, which means a wind tunnel, indoors.

My beef is really that there are no actual industry standards for conducting such testing. Everyone comes up with their own.

Actually, as per the links Andrew Coggan put up above, despite those difference you claim, you can still get very precise, and reproducible results, fairly simply.

And truth is, if racing outdoors does in fact involve conditions so variable that it masks all the wind tunnel effects, then you've proven my point completely.

Even an imperfect test would be highly, highly useful: take 5 riders who can each reliably output 200 watts for 10 minutes or so, wait for a near-ideal day with no wind, and have them ride outdoors on many bikes on a flat road . This is exactly what Dr. Coggan did in his links above (he just used himself). He included wind measurements in his studies, but tried to minimize them.

Then plot out the results, including the standard deviation to show variability. If you can't tease out a reliable advantage of one bike frame in such conditions, I'd definitely assert that you will be hard pressed to show the same advantage come race day with even more variable conditions on a variable course and without ideal wind conditions. It doesn't matter even if your wind tunnel says you should be +5 minutes per hour theoretically - if it doesn't pan out in racelike conditions, it doesn't pan out.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
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You could make an analogy with 'real healthcare' and RCTs. RCTs are mightily useful, even though it's nice to see pragmatic trials in between large RCTs and healthcare in practice.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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that's my point. a near ideal day with no wind does not actually have no wind. the temperature varies from hour to hour. the wind at one point of the course will be different than a another point on the course. etc etc.... you can try to minimize those things, but you cannot eliminate them.

It's the same reason that we don't generally use open water swim times as being indicative of how fast someone is. We can use relative placing, when everyone is swimming the same course at the same time, but not absolute time. Even in something like the TdF, early starters in a TT are sometimes at an advantage over late starters, sometimes at a disadvantage, depending on how conditions change.

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Last edited by: JasoninHalifax: Oct 16, 15 12:14
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [chaparral] [ In reply to ]
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chaparral wrote:
lightheir wrote:
If the outdoor variables are big enough to render all their engineering to the level of background noise in terms of speed gains, the conclusion drawn should be 'insignificant' between different frames in real-world OUTDOOR practice.


Maybe think about it this way. Lets say you lose 2lbs of weight. Then you say, well I lost 2lbs of weight so I should climb 1.5% faster. You go and do some climbs at the same power and it turns out you were slower. Does that mean that losing weight does not help climbing? No, it just means that the weight was overwhelmed by all the other things. Like maybe you had two full waterbottles this time or were wearing heavier clothing. Or you did not poop before your ride.

BUT the important thing is that DID climb 1.5% faster than you would have if you did not lose that weight. This does not mean that losing 2 lbs is insignificant. It is faster, just that it is hard to discern without strict control.

In response:

Yes, you are right - you have to try and reasonably control influencing factors before drawing a conclusion. BUT In your case, the rider is not controlling waterbottles, temp, wind, etc. so of course they will likely draw an incorrect conclusion. Odds are certain that if the rider did control for weight, temp, etc., he'd find a meaningful results, (as has been shown by real-world riders elsewhere in real-world conditions.)

Point is that Andrew Coggan himself showed in his links above that you can very easily design a bike expriment OUTDOORS where you do control for the influencing factors (wind, weight, course), and get very precise, and reliable data. It is a total fallacy that outdoor testing of bike frames is so complex that you can't get the data - he got it already, and pretty easily.

The problem is when you take controlling variables to too far an extreme, and rely strictly on these artificial situations to draw final conclusions. That is a common error that you shouldn't fall for. The artificial environments should be used as a tool to help you work faster toward the final product/goal, but once you're there, you still have to validate the final product by the gold standard. Or else doctors would be giving us medications that worked in a lab rat but was never tested in humans for efficacy, in an extreme case.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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JasoninHalifax wrote:
that's my point. a near ideal day with no wind does not actually have no wind. the temperature varies from hour to hour. etc etc.... you can try to minimize those things, but you cannot eliminate them.

And my point is that you should not be dissuaded by the pursuit of utter perfection.

You can minimize the outdoor factors with judicious experimental design, to a point where they are meaningfully accounted for or eliminated. Even if you can't eliminate the wind, you can measure the wind speed and limit your data analysis to runs where the wind is either the same or almost gone.

Coggan's experiment does exactly this, and as I said in my posts above, that's EXACTLY what the bike manufacturers should be showing doing and showing us their data with.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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So Tom you posed the question and now have a number of responses. Do you draw a conclusion as to what Bike manufacturers should do to market bikes from this in-put or from your own thoughts?

Dan Kennison

facebook: @triPremierBike
http://www.PremierBike.com
http://www.PositionOneSports.com
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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zero
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [dkennison] [ In reply to ]
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I think my thesis, not only from this, but from prior thought on the topic would look like this:

The current triathlon bike product mix emphasizes aerodynamic performance. This is a common competitive theme across different brands. It is the singular and predominant basis for comparison used for differentiation.

The aero thesis is relevant for a segment of the consumership. But only a segment. And it ignores a sizable and growing segment. It is not a universal sales case that speaks to the entire consumership.

I will suggest the entry of a significant number of new, and less performance-oriented, athletes into the sport may support the sales case for other feature sets. These may include economy, comfort, safety, ease of use. This product set, let's call it the "Multi-Sport Bike", a catch-all for a bike using aerobars but with a higher head tube, comfort oriented saddle and other comfort/convenience features, would provide a natural segue-way into specific aerodynamic triathlon bikes as we are accustomed to seeing.

While the Kona Bike Count has been the de-facto metric for taking a census of what people are buying, I'll suggest it may be decreasing in relevance to the middle 60% triathlete. If a Kona style Bike Count were tabulated across a larger number of smaller triathlons, local and regional level races, we may see different distributions of bike types; more road bikes with aerobars, even hybrids. That's because there are more new athletes at these events, and much less at Kona.

So- the industry is forgetting this group. This first year athlete who wants to "try a triathlon" and spend about $1500 on a non-intimidating looking bike they can acclimate to quickly. Right now, it's up to the retailer to sell them a comfort, high head tube road bike and bolt some aerobars on it. That isn't a great solution, but it's all we really have.

This is an opportunity for a new category. The "Multi-Sport" category.

A few years ago we saw the introduction of the "fat bike", the off-road MTB with very wide balloon tires. I don't see too much utility for this category, probably since I am not an active MTB rider, but the category has gained some sales traction. Retailers were apparently willing to sell a new category and some consumers were willing to buy it. E-bikes are another new category. Same with wider tire road bikes or dirt-road bikes. Newish categories morphed from other existing categories. Let's do that with road and tri, merging them into "Multi-Sport", the bike you buy for entry level group rides and triathlons. It has component spec and geometry that is specific to that use- the multi-tool aggregation of the two categories.

Now that we have our new category, it's time to sell it. The marketing language can be entirely different, including the key themes of comfort, convenience, ease of use, economy. The stratification of the product relative to the current triathlon bike is progressive; you buy the Multi-Sport bike first, then you graduate to a triathlon bike. You may also need a road bike if you decide to do the local fast group ride.

There is a down side to this; do we really need another bike category? The rank n' file consumership has a difficult enough time understanding the current assortment. That said, it may be a way to sell more bikes, not just different bikes. A consumer who may have only bought one bike during a five-year span has now bought two bikes.

This is just one case- one idea.

Here is a different one: Let's talk about Dimond Bikes.

Dimond has a huge opportunity here. They own the fastest bike split at Kona. Not Cervelo, not Trek, not Specialized, not Felt- Dimond. A little, brand new start-up company with a decidedly unconventional looking bike relative to the rest of the competitive set.

So, we have a different story to tell. Dimond bikes are likely pretty aerodynamic. I don't know for sure. But they may also offer an additional sales feature entirely absent from the rest of the competitive set. They are a beam bike. They have different ride characteristics. Could it be that part of the reason they are faster is that they do have different ride characteristics? What if there is some measurable physiological benefit from having the rider sit at the end of a beam as opposed to on top of a nearly vertical seat tube? If every major and some minor brands can argue a case that their bike is the most aerodynamic, when all of them except one are wrong, then it isn't much of a task (relatively speaking) to construct an argument that beam bikes are measurably faster. And, since Dimond is really the only beam bike widely available (isn't there another that looks like the bat-bike?) then it becomes the "desired outlier". It becomes the De Soto two-piece wetsuit of the bike world.

Tom Demerly
The Tri Shop.com
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Thank you for your thoughts. I think you have some very interesting ideas.

Dan Kennison

facebook: @triPremierBike
http://www.PremierBike.com
http://www.PositionOneSports.com
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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JasoninHalifax wrote:
both of us know that the white papers released by the vast majority of manufacturers don't go into anywhere near that level of detail.

"Obsessive-compulsive behavior: it's not a character flaw, it's a way of life." - Dr. Jim Martin
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:
Point is that Andrew Coggan himself showed in his links above that you can very easily design a bike expriment OUTDOORS where you do control for the influencing factors (wind, weight, course), and get very precise, and reliable data. It is a total fallacy that outdoor testing of bike frames is so complex that you can't get the data - he got it already, and pretty easily.

Easy for you to say it was easy - you're not the one getting up at 4:30 a.m. and then often freezing their arse off in order to test on the handful of days all year (usually in the fall) when wind speeds are absolutely minimal.

But forget my discomfort, and just how much time it takes to make just a handful of comparisons - at the end of the day, the results only reflect what happens at/near 0 deg of yaw.

IOW, it's just like testing on an indoor velodrome, 'cept those folks* don't have to freeze to death and can test pretty much whenever they want.

OTOH, with wind tunnel testing not only can you make measurements regardless of the weather outside, you can test at varying yaw angles, and you can collect a lot of data in a relatively short period of time. (This is why my wife and I flew w/ our infant son to Texas A&M back in the spring of 2007, rather than relying on field tests.)

*Actually, I've also done both outdoor and indoor velodrome testing.
Last edited by: Andrew Coggan: Oct 16, 15 14:23
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
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I'd still consider that easy to measure, by 'science experiment' standards. Hard by casual messing around standards, but easy by scientist standards!

(Go make a transgenic mouse before the CRISPR era - that's a lot harder and resource intensive - I'd gladly stand outside at 4:30AM in the dead of winter for weeks on end if that was the main obstacle to make something like that.)

I do find the velodrome (indoors or out) testing more useful than the wind tunnel testing, but I still consider the gold standard to be testing on-road. An outdoor velodrome would be pretty good in my book - I'd prefer that way over wind tunnel testing in terms of generating and claiming meaningful differences.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Tom Demerly wrote:
, a catch-all for a bike using aerobars but with a higher head tube, comfort oriented saddle and other comfort/convenience features, would provide a natural segue-way into specific aerodynamic triathlon bikes as we are accustomed to seeing.



I think you have the saddle bit wrong. The more serious and performance-oriented the cyclist, the more seriously they take saddle comfort. They might find the most comfortable saddle then pick the version with carbon rails, etc, but generally the more hours you spend in the saddle, the more seriously you take saddle comfort. Same with shoes. With saddle, shoes, and chamois comfort==performance.

While newbies often just take the OEM saddle or the one that looks cool, experienced cyclists are downright religious fundamentalists about a saddle they've found that works for them.
Last edited by: trail: Oct 16, 15 14:34
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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"Dimond bikes are likely pretty aerodynamic. I don't know for sure. But they may also offer an additional sales feature entirely absent from the rest of the competitive set"

The best feature is the detachable beam that makes traveling with it a breeze and without airline fees due to compact travel size. I would own one but for the ITU rules that disallow it.

"(isn't there another that looks like the bat-bike?)"

Yes, it's a Falco. I owned one until I found out (the hard way) that's it's not ITU legal and it totally sucked to travel with.
Last edited by: Xing triathlete: Oct 16, 15 15:30
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [RChung] [ In reply to ]
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RChung wrote:
This is the part of the thread where I humbly illustrate that you have an axe to grind.

Well his first venture at selling bikes didn't work... So maybe he's trying to figure out what people want this time. Actually getting stuff they ordered would be a start...
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Grant.Reuter] [ In reply to ]
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And besides the bike record in Kona is held by Kuota...not Dimond. Ultimately this thread (as many others) stems from a very poor understanding of statistics.
Akin to the 'it's cold in my backyard, therefore there is no global warming'.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Grant.Reuter] [ In reply to ]
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Fastest bike splits in Kona:

Stadler: 4.18.23
Lieto: 4.18.31

Can't remember either of them on a Dimond. Just that both are super solid cyclists.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:
Andrew Coggan wrote:
lightheir wrote:

Given your extensive expertise in this area, and your research that such OUTDOOR testing should not be difficult in practice and also should yield highly precise results (both premises I absolutely agree with), then what do you think the reason is why bike manufacturers never show A/B comparison OUTDOOR data versus other bikes, if their frame is in fact, superior?


Because wind tunnel testing offers numerous advantages over testing outdoors - after all, that's why wind tunnels were invented in the 1st place.

Of course, now that CFD has been extensively developed and validated, it has started to become the "go to" instead of wind tunnel testing, for essentially the same reasons that wind tunnel testing supplanted testing outdoors (e.g., of airplanes).


The gold standard, though still should be outdoor results, if you are racing outdoors. Saying wind tunnels are advantageous does not change this - I can tests blood pressure medications in highly controlled laboratory conditions with highly controlled subjects, using parameters that have shown excellent correlation to how the med should function in the real-world, but until I actual provide that real-world testing data and results, it's all theoretical.

This is a core concept in Phase1-Phase4 clinical trials. No matter how well the drug performs in the lab or in selected controlled human subjects, you cannot skip the gold standard testing of actually showing the results after you give the drug to a range of people in the real world, if you wish to claim that your lab results hold up in actual practice.

I'm also ok with using 'next-best surrogate test' (like CFD) if real-world testing is too cost-prohibitive (jet engine testing) or difficult. But as you yourself show with your own studies, this is eminently NOT the case in outdoor bicycle frame speed testing, even if it's not absolutely perfect.

Here's some outdoor results for you...wasn't that hard to find...you really should get out more ;-)
http://www.bikeradar.com/...-aero-is-aero-19273/

http://bikeblather.blogspot.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Francois] [ In reply to ]
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They ain't even second :)

Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Tom Demerly wrote:

And here's my point: There is untaped opportunity here.

Ummm...I think these guys have that covered: http://www.kinesiotaping.com

http://bikeblather.blogspot.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
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Tom A. wrote:
lightheir wrote:
Andrew Coggan wrote:
lightheir wrote:

Given your extensive expertise in this area, and your research that such OUTDOOR testing should not be difficult in practice and also should yield highly precise results (both premises I absolutely agree with), then what do you think the reason is why bike manufacturers never show A/B comparison OUTDOOR data versus other bikes, if their frame is in fact, superior?


Because wind tunnel testing offers numerous advantages over testing outdoors - after all, that's why wind tunnels were invented in the 1st place.

Of course, now that CFD has been extensively developed and validated, it has started to become the "go to" instead of wind tunnel testing, for essentially the same reasons that wind tunnel testing supplanted testing outdoors (e.g., of airplanes).


The gold standard, though still should be outdoor results, if you are racing outdoors. Saying wind tunnels are advantageous does not change this - I can tests blood pressure medications in highly controlled laboratory conditions with highly controlled subjects, using parameters that have shown excellent correlation to how the med should function in the real-world, but until I actual provide that real-world testing data and results, it's all theoretical.

This is a core concept in Phase1-Phase4 clinical trials. No matter how well the drug performs in the lab or in selected controlled human subjects, you cannot skip the gold standard testing of actually showing the results after you give the drug to a range of people in the real world, if you wish to claim that your lab results hold up in actual practice.

I'm also ok with using 'next-best surrogate test' (like CFD) if real-world testing is too cost-prohibitive (jet engine testing) or difficult. But as you yourself show with your own studies, this is eminently NOT the case in outdoor bicycle frame speed testing, even if it's not absolutely perfect.


Here's some outdoor results for you...wasn't that hard to find...you really should get out more ;-)
http://www.bikeradar.com/...-aero-is-aero-19273/


I'm well aware of that study.

You guys keep trying to oversimplify the issue - this study is a good one, but only compares aerobars or aero position to the nonaero position.

It is NOT comparing similar-class bike frames, like Cervelo TT bike vs Specialized TT bike vs Kestrel TT bike outdoors, which is what we're discussing here when we're discussing wind tunnel claims.

But that 'study' is a good one - get the rider outdoors, and test him repeatedly on various types of gear, and the results, while not surprising, are good in my book - get down in those aerobars, and you can definitely measure a speed difference OUTDOORS.

I'm asking for bike companies to do the same type of trials on a similar course. Compare their bike frame to other bike frames in the same class outdoors, similarly as this 'ministudy' did. I'm happy to change my tune if you 'think I should get out more' provided you provide me to the link(s) of such outdoor comparisons.
Last edited by: lightheir: Oct 16, 15 17:08
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
Quote | Reply
lightheir wrote:
Carl wrote:
without letting this go too much further into rabbit-hole/hijack territory...

lightheir wrote:
And of critical note in that document - the only time they compare other bike manufacturer designs to their bike is in the wind tunnel and velodrome.

ALL of the outdoor testing in that document is not against other bikes - it's just additional testing on their own frame with different yaw angles, etc. They specifically AVOID showing any data of testing various other bike frames against theirs outdoors.


not because there's something to hide, but because it wasn't the purpose of the testing. the point was to establish relevance of aero data even in drafting situations, period...not to establish whether or not one frame performed better than another in a given drafting situation. seemed like a prudent thing to investigate, since there's a chunk of the road market in particular which gets hung up on "but it all goes away in the real world when you're drafting"...conveniently forgetting that in the real world you're still moving through air.

<steps back into black helicopter>

It actually very might go away in the real world. If the external variable forces are enough to render the small gains of the aero frame immeasurable, those vaunted wind tunnel gains are in fact 'gone' on race day. It is critically important to interpret the magnitude of the speed gain relative to the expected variability of 'real world situations.'

This would be analogous to having a blood pressure drug, that in the lab, with humans, absolutely lowers blood pressure by 1mm HG in the lab, but has no measurable effect on BP out of the lab, due to the variability of human physiology/BP which makes a 1mmHG difference clinically useless. There is no clinician that would say that this was an effective hypertension drug worth prescribing to reduce real clinical hypertension, despite the rock-solid data that it really does lower blood pressure (by a measly 1 mmHG.)

They're NOT "gone on race day"...they're still there, it's just that unmeasured variables are making it difficult to compare results from separate runs. If you measure those variables and account for them, the differences stand.


http://bikeblather.blogspot.com/
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
Quote | Reply
Tom A. wrote:
lightheir wrote:
Carl wrote:
without letting this go too much further into rabbit-hole/hijack territory...

lightheir wrote:
And of critical note in that document - the only time they compare other bike manufacturer designs to their bike is in the wind tunnel and velodrome.

ALL of the outdoor testing in that document is not against other bikes - it's just additional testing on their own frame with different yaw angles, etc. They specifically AVOID showing any data of testing various other bike frames against theirs outdoors.


not because there's something to hide, but because it wasn't the purpose of the testing. the point was to establish relevance of aero data even in drafting situations, period...not to establish whether or not one frame performed better than another in a given drafting situation. seemed like a prudent thing to investigate, since there's a chunk of the road market in particular which gets hung up on "but it all goes away in the real world when you're drafting"...conveniently forgetting that in the real world you're still moving through air.

<steps back into black helicopter>


It actually very might go away in the real world. If the external variable forces are enough to render the small gains of the aero frame immeasurable, those vaunted wind tunnel gains are in fact 'gone' on race day. It is critically important to interpret the magnitude of the speed gain relative to the expected variability of 'real world situations.'

This would be analogous to having a blood pressure drug, that in the lab, with humans, absolutely lowers blood pressure by 1mm HG in the lab, but has no measurable effect on BP out of the lab, due to the variability of human physiology/BP which makes a 1mmHG difference clinically useless. There is no clinician that would say that this was an effective hypertension drug worth prescribing to reduce real clinical hypertension, despite the rock-solid data that it really does lower blood pressure (by a measly 1 mmHG.)


They're NOT "gone on race day"...they're still there, it's just that unmeasured variables are making it difficult to compare results from separate runs. If you measure those variables and account for them, the differences stand.


And again, if I just simplified everything to 'it's there, you just can't detect it', I would right now be a billionaire several times over by investing in blood pressure and other medications that lower your BP by <1mmHG (clinically insignicant), but saying 'just because you can't measure it, it's still there so you should take this.'

Fortunately for the general public, the FDA folks are smart enough to know that doing this would be a bunch of bull.

I still stand by that if you can't even reliably measure the speed gain outdoors with a reasonable trial (like the article you link to above), you better seriously question whether you're gaining any advantage with it while racing, and seriously consider not spending any more time/energy looking at that variable compared to the other much more influential variables that DO show significant and measurable effects outdoors.
Last edited by: lightheir: Oct 16, 15 17:15
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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Why should the manufacturers test more outside?

Those studies (along with logic and physics) demonstrate that drag values obtained within a wind tunnel match extremely close to the data measured outdoors, and to a level well capable of teasing out differences between frames. The correlation is there.

However, wind tunnel testing is significantly faster, easier, and more consistent.

They aren't going to test outside just because you don't get that...that would be a waste of time and resources.

http://bikeblather.blogspot.com/
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
Quote | Reply
Except, of course, that's only what you're saying now, because it works better in your attempt to win the argument.

What you were suggesting earlier is much more along the lines of "It doesn't matter if these experimental protocols have been validated in real-world studies, unless real-world study results are shown every single time, the protocols can't be considered valid."

Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
Quote | Reply
lightheir wrote:
Tom A. wrote:
lightheir wrote:
Carl wrote:
without letting this go too much further into rabbit-hole/hijack territory...

lightheir wrote:
And of critical note in that document - the only time they compare other bike manufacturer designs to their bike is in the wind tunnel and velodrome.

ALL of the outdoor testing in that document is not against other bikes - it's just additional testing on their own frame with different yaw angles, etc. They specifically AVOID showing any data of testing various other bike frames against theirs outdoors.


not because there's something to hide, but because it wasn't the purpose of the testing. the point was to establish relevance of aero data even in drafting situations, period...not to establish whether or not one frame performed better than another in a given drafting situation. seemed like a prudent thing to investigate, since there's a chunk of the road market in particular which gets hung up on "but it all goes away in the real world when you're drafting"...conveniently forgetting that in the real world you're still moving through air.

<steps back into black helicopter>


It actually very might go away in the real world. If the external variable forces are enough to render the small gains of the aero frame immeasurable, those vaunted wind tunnel gains are in fact 'gone' on race day. It is critically important to interpret the magnitude of the speed gain relative to the expected variability of 'real world situations.'

This would be analogous to having a blood pressure drug, that in the lab, with humans, absolutely lowers blood pressure by 1mm HG in the lab, but has no measurable effect on BP out of the lab, due to the variability of human physiology/BP which makes a 1mmHG difference clinically useless. There is no clinician that would say that this was an effective hypertension drug worth prescribing to reduce real clinical hypertension, despite the rock-solid data that it really does lower blood pressure (by a measly 1 mmHG.)


They're NOT "gone on race day"...they're still there, it's just that unmeasured variables are making it difficult to compare results from separate runs. If you measure those variables and account for them, the differences stand.


And again, if I just simplified everything to 'it's there, you just can't detect it', I would right now be a billionaire several times over by investing in blood pressure and other medications that lower your BP by <1mmHG (clinically insignicant), but saying 'just because you can't measure it, it's still there so you should take this.'

Fortunately for the general public, the FDA folks are smart enough to know that doing this would be a bunch of bull.

I still stand by that if you can't even reliably measure the speed gain outdoors with a reasonable trial (like the article you link to above), you better seriously question whether you're gaining any advantage with it while racing, and seriously consider not spending any more time/energy looking at that variable compared to the other much more influential variables that DO show significant and measurable effects outdoors.

So...does that mean you don't think someone could discern (outside) the difference between...oh, let's say, a P3C and a P2K for a given rider with the same position and kit/equipment?

http://bikeblather.blogspot.com/
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
Quote | Reply
Tom A. wrote:
Why should the manufacturers test more outside?

Those studies (along with logic and physics) demonstrate that drag values obtained within a wind tunnel match extremely close to the data measured outdoors, and to a level well capable of teasing out differences between frames. The correlation is there.

However, wind tunnel testing is significantly faster, easier, and more consistent.

They aren't going to test outside just because you don't get that...that would be a waste of time and resources.

I'm saying that you cannot just choose to focus on the potentially insignificantly small effect of your aero frame, and just use idealized wind tunnel data, and then claim 'my frame is the fastest as per wind tunnel testing', when in outdoor practice, normally encountered variability can render that small measured effect irrelevant and unmeasurable.

It is absolutely NOT a waste of time and resources to test bikes outside the wind tunnel. That's something so easily done as per the article you linked to above, that it SHOULD be done, every time. Costs a HECK of a lot less than a wind tunnel, and is much closer to race situations.

We encounter this sort of 'avoid the-gold-standard test' approach all the time in biology and drug development. Companies might know full well that their drugs don't work as well as they claim in the fuzzier real world situation where real patients take the meds, but they try and pass off selected laboratory highly controlled studies with good results as surrogates measures. If someone is purposefully avoiding providing data that should otherwise easily be measured (and I consider the bikeradar 'experiment' a pretty easy one, at that), you must first ask why they would go through so much trouble to not do the easier outdoor experiment.

If bikeradar did that same trial with 5 bike frames, and couldn't measure a reliable difference, I would conclude 'no significant difference in aero advantages' for those frames, regardless of how well one of the performs in the wind tunnel. Likewise, if they showed that the Cervelo was reliably faster outdoors in those tests, but was last in the wind tunnel, I'd first make sure they weren't screwing up their methodology, but if the methods were sound, I'd go with the Cervelo as fastest.
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:
...an analagous approach would be a coach advising someone to ignore the gains of aero vs nonaero bike frames and focus on rider position and aerobars instead.

It's OK to do BOTH though, right?...is that allowed??

http://bikeblather.blogspot.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [fredly] [ In reply to ]
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fredly wrote:
Except, of course, that's only what you're saying now, because it works better in your attempt to win the argument.

What you were suggesting earlier is much more along the lines of "It doesn't matter if these experimental protocols have been validated in real-world studies, unless real-world study results are shown every single time, the protocols can't be considered valid."


No, not what I'm saying at all.

I don't think it's true at all that bike tunnel speed differences have shown to be reliably measurable outdoors. I think that's what they would LIKE you to believe, but I don't think it's true whatsoever, and the lack of data on it (contrary to the attempts above to discredit me on this belief) is pretty telling.

I think the tiny differences they're dealing with are so small that they are very likely irrelevant outdoors even with near-ideal outdoor conditions.

Not one single decent study out there comparing bike frame vs bike frame in the same class outdoors. Yet TONS of wind tunnel data as a surrogate. Even thought the wind tunnel is $$$$ and highly artificial compared to outdoors. Again, if this were prohibitively expensive to test outdoors (jet engines), ok, I'll give it a pass, but it's absolutely not the case with bike frame testing with riders.

Again, I'd be perfectly happy with doing the Bikeradar 'experiment' with multiple bike frames. I'm not asking for much, and I think it's the correct question to ask if you're looking for the fastest racing bike outside the wind tunnel.
Last edited by: lightheir: Oct 16, 15 17:32
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
Quote | Reply
Tom A. wrote:
lightheir wrote:
Tom A. wrote:
lightheir wrote:
Carl wrote:
without letting this go too much further into rabbit-hole/hijack territory...

lightheir wrote:
And of critical note in that document - the only time they compare other bike manufacturer designs to their bike is in the wind tunnel and velodrome.

ALL of the outdoor testing in that document is not against other bikes - it's just additional testing on their own frame with different yaw angles, etc. They specifically AVOID showing any data of testing various other bike frames against theirs outdoors.


not because there's something to hide, but because it wasn't the purpose of the testing. the point was to establish relevance of aero data even in drafting situations, period...not to establish whether or not one frame performed better than another in a given drafting situation. seemed like a prudent thing to investigate, since there's a chunk of the road market in particular which gets hung up on "but it all goes away in the real world when you're drafting"...conveniently forgetting that in the real world you're still moving through air.

<steps back into black helicopter>


It actually very might go away in the real world. If the external variable forces are enough to render the small gains of the aero frame immeasurable, those vaunted wind tunnel gains are in fact 'gone' on race day. It is critically important to interpret the magnitude of the speed gain relative to the expected variability of 'real world situations.'

This would be analogous to having a blood pressure drug, that in the lab, with humans, absolutely lowers blood pressure by 1mm HG in the lab, but has no measurable effect on BP out of the lab, due to the variability of human physiology/BP which makes a 1mmHG difference clinically useless. There is no clinician that would say that this was an effective hypertension drug worth prescribing to reduce real clinical hypertension, despite the rock-solid data that it really does lower blood pressure (by a measly 1 mmHG.)


They're NOT "gone on race day"...they're still there, it's just that unmeasured variables are making it difficult to compare results from separate runs. If you measure those variables and account for them, the differences stand.


And again, if I just simplified everything to 'it's there, you just can't detect it', I would right now be a billionaire several times over by investing in blood pressure and other medications that lower your BP by <1mmHG (clinically insignicant), but saying 'just because you can't measure it, it's still there so you should take this.'

Fortunately for the general public, the FDA folks are smart enough to know that doing this would be a bunch of bull.

I still stand by that if you can't even reliably measure the speed gain outdoors with a reasonable trial (like the article you link to above), you better seriously question whether you're gaining any advantage with it while racing, and seriously consider not spending any more time/energy looking at that variable compared to the other much more influential variables that DO show significant and measurable effects outdoors.



So...does that mean you don't think someone could discern (outside) the difference between...oh, let's say, a P3C and a P2K for a given rider with the same position and kit/equipment?



I would absolutely love to see Bikeradar do the exact experiment you suggest, outdoors, with P3C vs P2k with same rider and equipment.

If I had to place a bet on the outcome, I'd bet that there would be no measurable advantage, meaning you're just as well off riding the P2k compared to the p3c. But I'd love to see this done.


I would love to see the bike companies stop all the wind-tunnel marketing BS, and just do this much more straightforward experiment, and show us the data, even if it's negative (shows no measurable effect), or not.
Last edited by: lightheir: Oct 16, 15 17:30
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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Wait, let me get this straight: you're actually holding up the Bikeradar testing as some kind of gold-standard?!

Dude, you made my day. That's the single most unintentionally hilarious thing I've read in weeks.

Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [fredly] [ In reply to ]
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fredly wrote:
Wait, let me get this straight: you're actually holding up the Bikeradar testing as some kind of gold-standard?!

Dude, you made my day. That's the single most unintentionally hilarious thing I've read in weeks.


You got a better 'gold-standard' of outdoor testing bike frame vs bike frame that's been done? Please share!

Of course, the Bikeradar study would be low-bar for gold standards of testing. You or I could design a far better study in seconds, that wouldn't be that much harder to do.

Unfortunately, I'm still waiting for someone to provide a COMPLETED better study comparing bike frames outdoors, but ANY study comparing bike frames outdoors, even if it shows no measurable differences.

(I'd bet a high school kid doing this would actually get some press in cycling magazines - it would be a near-ideal summer project for an aspiring HS triathlete in science, hint hint.)
Last edited by: lightheir: Oct 16, 15 17:39
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
Quote | Reply
lightheir wrote:
Tom A. wrote:
Why should the manufacturers test more outside?

Those studies (along with logic and physics) demonstrate that drag values obtained within a wind tunnel match extremely close to the data measured outdoors, and to a level well capable of teasing out differences between frames. The correlation is there.

However, wind tunnel testing is significantly faster, easier, and more consistent.

They aren't going to test outside just because you don't get that...that would be a waste of time and resources.

I'm saying that you cannot just choose to focus on the potentially insignificantly small effect of your aero frame, and just use idealized wind tunnel data, and then claim 'my frame is the fastest as per wind tunnel testing', when in outdoor practice, normally encountered variability can render that small measured effect irrelevant and unmeasurable.

It is absolutely NOT a waste of time and resources to test bikes outside the wind tunnel. That's something so easily done as per the article you linked to above, that it SHOULD be done, every time. Costs a HECK of a lot less than a wind tunnel, and is much closer to race situations.

We encounter this sort of 'avoid the-gold-standard test' approach all the time in biology and drug development. Companies might know full well that their drugs don't work as well as they claim in the fuzzier real world situation where real patients take the meds, but they try and pass off selected laboratory highly controlled studies with good results as surrogates measures. If someone is purposefully avoiding providing data that should otherwise easily be measured (and I consider the bikeradar 'experiment' a pretty easy one, at that), you must first ask why they would go through so much trouble to not do the easier outdoor experiment.

If bikeradar did that same trial with 5 bike frames, and couldn't measure a reliable difference, I would conclude 'no significant difference in aero advantages' for those frames, regardless of how well one of the performs in the wind tunnel. Likewise, if they showed that the Cervelo was reliably faster outdoors in those tests, but was last in the wind tunnel, I'd first make sure they weren't screwing up their methodology, but if the methods were sound, I'd go with the Cervelo as fastest.

The thing is...the differences typically aren't "potentially insignificant" AND the "gold standard" in this regard IS the wind tunnel.

I fully understand what you're saying about drug development...it's just that you aren't correctly applying the analogies.

http://bikeblather.blogspot.com/
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
Quote | Reply
Tom A. wrote:
lightheir wrote:
Tom A. wrote:
Why should the manufacturers test more outside?

Those studies (along with logic and physics) demonstrate that drag values obtained within a wind tunnel match extremely close to the data measured outdoors, and to a level well capable of teasing out differences between frames. The correlation is there.

However, wind tunnel testing is significantly faster, easier, and more consistent.

They aren't going to test outside just because you don't get that...that would be a waste of time and resources.


I'm saying that you cannot just choose to focus on the potentially insignificantly small effect of your aero frame, and just use idealized wind tunnel data, and then claim 'my frame is the fastest as per wind tunnel testing', when in outdoor practice, normally encountered variability can render that small measured effect irrelevant and unmeasurable.

It is absolutely NOT a waste of time and resources to test bikes outside the wind tunnel. That's something so easily done as per the article you linked to above, that it SHOULD be done, every time. Costs a HECK of a lot less than a wind tunnel, and is much closer to race situations.

We encounter this sort of 'avoid the-gold-standard test' approach all the time in biology and drug development. Companies might know full well that their drugs don't work as well as they claim in the fuzzier real world situation where real patients take the meds, but they try and pass off selected laboratory highly controlled studies with good results as surrogates measures. If someone is purposefully avoiding providing data that should otherwise easily be measured (and I consider the bikeradar 'experiment' a pretty easy one, at that), you must first ask why they would go through so much trouble to not do the easier outdoor experiment.

If bikeradar did that same trial with 5 bike frames, and couldn't measure a reliable difference, I would conclude 'no significant difference in aero advantages' for those frames, regardless of how well one of the performs in the wind tunnel. Likewise, if they showed that the Cervelo was reliably faster outdoors in those tests, but was last in the wind tunnel, I'd first make sure they weren't screwing up their methodology, but if the methods were sound, I'd go with the Cervelo as fastest.


The thing is...the differences typically aren't "potentially insignificant" AND the "gold standard" in this regard IS the wind tunnel.

I fully understand what you're saying about drug development...it's just that you aren't correctly applying the analogies.


Then please enlighten me as to where my analogy is incorrect.

If you're trying to say that the wind tunnel IS the gold standard, then we definitely differ fundamentally on that issue. I will strongly stand by my premise that if you race outdoors, you measure outdoors.

If you race on an indoor velodrome, than indoor velodrome testing is the gold standard.

If your race in a highly controlled wind tunnel, than the wind tunnel is the gold standard.

The wind tunnel is otherwise a surrogate for the gold standard if you are racing outdoors, and should be retested outdoors unless costs or logistics make this impossible. (True for jet engines, not true for bicycles.)
Last edited by: lightheir: Oct 16, 15 17:41
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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The main problem here is that you believe that your disagreement with Tom as to what actually constitutes a "gold standard" is a matter of opinion.

It's not.

You also fundamentally don't understand why airplane development is done in CFD and wind tunnels.
You keep citing "cost."

It's not.

Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:


I would absolutely love to see Bikeradar do the exact experiment you suggest, outdoors, with P3C vs P2k with same rider and equipment.

If I had to place a bet on the outcome, I'd bet that there would be no measurable advantage, meaning you're just as well off riding the P2k compared to the p3c. But I'd love to see this done.


I would love to see the bike companies stop all the wind-tunnel marketing BS, and just do this much more straightforward experiment, and show us the data, even if it's negative (shows no measurable effect), or not.


Bike radar doesn't need to...I already did it :-)

http://bikeblather.blogspot.com/...00&max-results=5

I don't think I would call ~2.5s/km of difference "potentially insignificant". You just lost that virtual bet you made ;-)

http://bikeblather.blogspot.com/
Last edited by: Tom A.: Oct 16, 15 18:10
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [fredly] [ In reply to ]
Quote | Reply
fredly wrote:
The main problem here is that you believe that your disagreement with Tom as to what actually constitutes a "gold standard" is a matter of opinion.

It's not.

You also fundamentally don't understand why airplane development is done in CFD and wind tunnels.
You keep citing "cost."

It's not.

Then you please explain to me why if you race outdoors, why outdoor measurement shouldn't be a gold standard.
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
Quote | Reply
Tom, that's what, the third link to "real world" validation that's been put up on this thread?

People keep calling the bet and he keeps ante-ing up again.

Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
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What is this magical stuff that makes the medium you cycle in (air) different indoors and outdoors? Lightheir's argument is ridiculous.

Now, getting back to the serious stuff. Wind tunnel claims are often problematic because they depend on the testers deciding on angles and speeds to test at. These may not perfectly approximate real life. (A flat course on a "windless" day is going to give you an even worse approximation of the real distribution of yaw angles and speeds).

The only way to deal with this is with more data, which companies like Swiss Side are gathering and using. This information can be used for CFD models and for wind-tunnel testing.

http://www.swissside.com/...e-instrumented-bike/


And to answer Tom's question: Quite a lot of credibility. If it's a company I trust using a tunnel I trust and being very clear about their choices, then this will have a lot of influence over my bike choices. If Specialized say things about a bike and show us their graphs, I'll take them as trustworthy and useful.

'It never gets easier, you just get crazier.'
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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Do you happen to know what "Overfitting" is?

Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Tom Demerly wrote:

Here is a different one: Let's talk about Dimond Bikes.

Dimond has a huge opportunity here. They own the fastest bike split at Kona. Not Cervelo, not Trek, not Specialized, not Felt- Dimond. A little, brand new start-up company with a decidedly unconventional looking bike relative to the rest of the competitive set.

So, we have a different story to tell. Dimond bikes are likely pretty aerodynamic. I don't know for sure. But they may also offer an additional sales feature entirely absent from the rest of the competitive set. They are a beam bike. They have different ride characteristics. Could it be that part of the reason they are faster is that they do have different ride characteristics? What if there is some measurable physiological benefit from having the rider sit at the end of a beam as opposed to on top of a nearly vertical seat tube? If every major and some minor brands can argue a case that their bike is the most aerodynamic, when all of them except one are wrong, then it isn't much of a task (relatively speaking) to construct an argument that beam bikes are measurably faster. And, since Dimond is really the only beam bike widely available (isn't there another that looks like the bat-bike?) then it becomes the "desired outlier". It becomes the De Soto two-piece wetsuit of the bike world.

Interestingly I have a very different opinion. The fact that a rider on a Dimond bike had the fastest bike split means nothing. Except, this rider walked the marathon therefore either he had to work too hard (i.e. bike is not aero) or he simply came out with a strategy to have the fastest bike split without caring about the result of the triathlon he participated in.

Using this argument as evidence that a Dimond is fast is very weak to my opinion. Seriously, is that all you got, Dimond? I would put 100x more trust in the aerodynamic performance of a bike who's rider was 5 minutes slower on the bike but then won the race because he still had the legs to have a strong run. Because unlike what so many think, triathlon ends after the run, not after the bike.

As Rich Strauss has already said so many times: there's no such thing as a good bike followed by a bad run. And therefore, Twelsiek's run does not count as a good bike split at all.


_____________________
Don't forget to attack!
Last edited by: Cobble: Oct 16, 15 18:02
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Cobble] [ In reply to ]
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Cobble wrote:
Tom Demerly wrote:


Here is a different one: Let's talk about Dimond Bikes.

Dimond has a huge opportunity here. They own the fastest bike split at Kona. Not Cervelo, not Trek, not Specialized, not Felt- Dimond. A little, brand new start-up company with a decidedly unconventional looking bike relative to the rest of the competitive set.

So, we have a different story to tell. Dimond bikes are likely pretty aerodynamic. I don't know for sure. But they may also offer an additional sales feature entirely absent from the rest of the competitive set. They are a beam bike. They have different ride characteristics. Could it be that part of the reason they are faster is that they do have different ride characteristics? What if there is some measurable physiological benefit from having the rider sit at the end of a beam as opposed to on top of a nearly vertical seat tube? If every major and some minor brands can argue a case that their bike is the most aerodynamic, when all of them except one are wrong, then it isn't much of a task (relatively speaking) to construct an argument that beam bikes are measurably faster. And, since Dimond is really the only beam bike widely available (isn't there another that looks like the bat-bike?) then it becomes the "desired outlier". It becomes the De Soto two-piece wetsuit of the bike world.


Interestingly I have a very different opinion. The fact that a rider on a Dimond bike had the fastest bike split means nothing. Except, this rider walked the marathon therefore either he had to work too hard (i.e. bike is not aero) or he simply came out with a strategy to have the fastest bike split without caring about the result of the triathlon he participated in.

Using this argument as evidence that a Dimond is fast is very weak to my opinion. Seriously, is that all you got, Dimond? I would put 100x more trust in the aerodynamic performance of a bike who's rider was 5 minutes slower on the bike but then won the race because he still had the legs to have a strong run. Because unlike what so many think, triathlon ends after the run, not after the bike.

As Rich Strauss has already said so many times: there's no such thing as a good bike followed by a bad run. And therefore, Twelsiek's run does not count as a good bike split at all.

You guys are all missing the point that this fast bike split was done on relatively low average power (275W IIRC?)...THAT is what implies the Dimond is FAST.

http://bikeblather.blogspot.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
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Tom A. wrote:
lightheir wrote:


I would absolutely love to see Bikeradar do the exact experiment you suggest, outdoors, with P3C vs P2k with same rider and equipment.

If I had to place a bet on the outcome, I'd bet that there would be no measurable advantage, meaning you're just as well off riding the P2k compared to the p3c. But I'd love to see this done.


I would love to see the bike companies stop all the wind-tunnel marketing BS, and just do this much more straightforward experiment, and show us the data, even if it's negative (shows no measurable effect), or not.


Bike radar doesn't need to...I already did it :-)

http://bikeblather.blogspot.com/...00&max-results=5

I don't think I would call ~2.5s/km of difference "potentially insignificant". You just lost that virtual bet you made ;-)

That's exactly the kind of testing that should be reported!

Of course, we'll need more than n=1, but if the differences actually pan out reliably over many samples as your test did, that would be the best marketing for bike companies. But I'll give you a thumbs up on that one for at least doing the basic ground level of what SHOULD be reported when bike companies are claiming their bike is faster. It would greatly supplement their (cleaner) wind tunnel data.

Links to any more of such testing would be greatly welcomed, if you say it's more common than I'm claiming.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [georged] [ In reply to ]
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georged wrote:
What is this magical stuff that makes the medium you cycle in (air) different indoors and outdoors? Lightheir's argument is ridiculous.

Now, getting back to the serious stuff. Wind tunnel claims are often problematic because they depend on the testers deciding on angles and speeds to test at. These may not perfectly approximate real life. (A flat course on a "windless" day is going to give you an even worse approximation of the real distribution of yaw angles and speeds).

The only way to deal with this is with more data, which companies like Swiss Side are gathering and using. This information can be used for CFD models and for wind-tunnel testing.

http://www.swissside.com/...e-instrumented-bike/


And to answer Tom's question: Quite a lot of credibility. If it's a company I trust using a tunnel I trust and being very clear about their choices, then this will have a lot of influence over my bike choices. If Specialized say things about a bike and show us their graphs, I'll take them as trustworthy and useful.


Uhh, you just explained exactly why I'm criticizes indoor vs outdoor testing in the bolded section above. Not because of magical air, but because of the artificial situations (like fixed yaw angles) just as you describe.

I do like the idea of the swisside as you posted. It gets directly at the issue I'm complaining about, which is why the artificiality of wind tunnels is a problem if there's no outdoor corroborating data whatsoever.

I wouldn't trust bike companies at all with the hype that because their testing is the best/fastest, it must be so. An INDEPENDENT tester with no conflicts of interest, I'd be much more inclined to believe. But believe Specialized when they do their own tests and say they test the fastest so it must be so? I think you're giving them too much credit there - their marketing team would rapidly shoot down publishing any data that contradicts their claims that their bike is the best/fastest. Hence the independent testing, and preferably outdoors - like on that swisside bike you posted about.
Last edited by: lightheir: Oct 16, 15 18:28
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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So, what you're saying is that you didn't actually look at the Trek Whitepaper that Carl posted on the first page of the thread, right? The one with the whole supplementary section devoted to on-bike draft testing and comparison to wind tunnel and velodrome testing?

Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
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Tom A. wrote:
Cobble wrote:
Tom Demerly wrote:


Here is a different one: Let's talk about Dimond Bikes.

Dimond has a huge opportunity here. They own the fastest bike split at Kona. Not Cervelo, not Trek, not Specialized, not Felt- Dimond. A little, brand new start-up company with a decidedly unconventional looking bike relative to the rest of the competitive set.

So, we have a different story to tell. Dimond bikes are likely pretty aerodynamic. I don't know for sure. But they may also offer an additional sales feature entirely absent from the rest of the competitive set. They are a beam bike. They have different ride characteristics. Could it be that part of the reason they are faster is that they do have different ride characteristics? What if there is some measurable physiological benefit from having the rider sit at the end of a beam as opposed to on top of a nearly vertical seat tube? If every major and some minor brands can argue a case that their bike is the most aerodynamic, when all of them except one are wrong, then it isn't much of a task (relatively speaking) to construct an argument that beam bikes are measurably faster. And, since Dimond is really the only beam bike widely available (isn't there another that looks like the bat-bike?) then it becomes the "desired outlier". It becomes the De Soto two-piece wetsuit of the bike world.


Interestingly I have a very different opinion. The fact that a rider on a Dimond bike had the fastest bike split means nothing. Except, this rider walked the marathon therefore either he had to work too hard (i.e. bike is not aero) or he simply came out with a strategy to have the fastest bike split without caring about the result of the triathlon he participated in.

Using this argument as evidence that a Dimond is fast is very weak to my opinion. Seriously, is that all you got, Dimond? I would put 100x more trust in the aerodynamic performance of a bike who's rider was 5 minutes slower on the bike but then won the race because he still had the legs to have a strong run. Because unlike what so many think, triathlon ends after the run, not after the bike.

As Rich Strauss has already said so many times: there's no such thing as a good bike followed by a bad run. And therefore, Twelsiek's run does not count as a good bike split at all.

You guys are all missing the point that this fast bike split was done on relatively low average power (275W IIRC?)...THAT is what implies the Dimond is FAST.
But you are missing the point that the guy couldn't run if his life depended on it... at the end of the day it doesn't matter if the winner pushed 275 watts or 250 or 300. He was ahead of the number two at the finish line and that's the only thing that matters. For all I know, the Dimond evidence proves that it beats up your body so much you can't get a decent run done despite not having to use as much energy on the bike as, say, Jan Frodeno's Canyon. A bike that gives you a shitty run isn't a good bike.


_____________________
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Last edited by: Cobble: Oct 16, 15 19:42
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [fredly] [ In reply to ]
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fredly wrote:
So, what you're saying is that you didn't actually look at the Trek Whitepaper that Carl posted on the first page of the thread, right? The one with the whole supplementary section devoted to on-bike draft testing and comparison to wind tunnel and velodrome testing?

??? I did look at it. Ok, I didn't analyze it in detail, but it doesn't address my wind tunnel testing vs outdoor concerns adequately. I'm mostly fine with wind tunnel surrogating for velodrome, but that paper doesn't convince me that their wind tunnel results will be replicable and measurable in real world outdoors given all the outdoor factors that can dwarf the magnitude of their measured effect.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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That basically sounds like a "no" answer to me, as the section of the whitepaper in question is 8 pages devoted almost entirely to a description of on-road testing modalities.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [fredly] [ In reply to ]
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fredly wrote:
That basically sounds like a "no" answer to me, as the section of the whitepaper in question is 8 pages devoted almost entirely to a description of on-road testing modalities.


If this is the whitepaper you're talking about,

http://cms.trekbikes.com/pdf/owners_manuals/MY16_Madone_whitepaper.pdf


it's a perfectly nice white paper, but I'm struggling to see where they convicingly prove that wind tunnel model captures or supersedes outdoor testing.


And even if they did, I don't change my tune - if you race outdoors, you test outdoors as the gold standard. You can't measure a significant, reproducible result outdoors, you can't say your bike is testing faster outdoors.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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It's abundantly clear that you do, in fact, fail to see how this is so.

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Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [fredly] [ In reply to ]
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fredly wrote:
It's abundantly clear that you do, in fact, fail to see how this is so.

This is as close as they get - from page 4:


CFD (computational fluid dynamics) using wind tunnel data


We rigorously calibrated CFD prior to the project frame analysis so that the computational results accurately portray the outputs of experiments. Choosing the correct turbulence model, fine tuning the model parameters, and conducting extensive mesh convergence studies are essential to accurately capture the flow dynamics around a bicycle. One of the calibration results comparing the wind tunnel drag vs. CFD drag on previous Madone is shown in figure 1. In this particular example, CFD accuracy is within 3% of the wind tunnel result.



That's not at all saying that their CFD or wind tunnel data is being validated as outdoor surrogates.

There is no mention anywhere in those first 8 pages how their models were validated against outdoor testing or even subjected to such.

They do finally do a real-world drafting test at the end, but this is a drafting test, not a frame comparison, and it's only a supplemental section. There are other technical setups to measure cornering, effect of brakes, etc., but this is a completely different issue than a claim that wind tunnel testing is a better standard than outdoor testing and doesn't address this issue at all.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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OK, fine; you're right. With all the money companies like Trek are spending on testing - including on-road testing; we can all agree that they are doing on-road testing now, right? - they aren't doing exactly what you're asking for.

The question one should generally ask oneself in this type of a situation is "am I the smartest guy in the room, or do I just not know what the hell I'm talking about?"


ps - that stats terminology question you're conspicuously ignoring? It's not impertinent to an understanding of why your "Gold Standard" isn't.

Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/
Last edited by: fredly: Oct 16, 15 20:36
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [fredly] [ In reply to ]
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fredly wrote:
OK, fine; you're right. With all the money companies like Trek are spending on testing - including on-road testing; we can all agree that they are doing on-road testing now, right? - they aren't doing exactly what you're asking for.

The question one should generally ask oneself in this type of a situation is "am I the smartest guy in the room, or do I just not know what the hell I'm talking about?"

Nice try again at deflecting from the original point with more ad hominem attacks.

I never tried to say "I'm the smartest guy in the room." If you want proof, look above, where I clearly agree with Tom A's later post where he tested it himself - I'm not out to prove I'm the smartest - I'm just pointing out the truth about testing if you really want to do it right.

I'm looking at all the 'white papers' from bike companies with a skeptical eye. They've got so much money, yet they can't produce a single field test a la Tom A or Dr. Coggan where they prove their engineered bike is faster outdoors than the competition, but they're happy to claim 'we've got the fastest wind tunnel tested bike' (Cervelo, at least.)


I'm not asking them to go above and beyond reasonable testing. I'm asking for perhaps the most obvious, low-cost testing method and to post the results publicly if their bike can do what they claim. Their glaring lack of having such data is very telling - it basically demands that you should view of what they're showing in that white paper as intentional obfuscation and unnecessarily complicating the situation in an effort to avoid showing the results of the simple test - line up the bikes, line up the riders, pace 'em out at 200 watts on a windless day outdoors, and show us the results. If their wind tunnel results are really that translatable to real world, let's see it. Tom A's test is the first I've seen that actually attempts to do this, and yes, his n=1 result suggests that you SHOULD be able to have a measurable difference between frames outdoors.

And like you, I'm not naive - you and I both know that they're testing the crap out of their bikes outdoors, right now. Many, many times over. So the next obvious question, which is the crux of my entire posting on this thread - why haven't we seen it? What are they hiding?
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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Sorry dude, claiming humility while (essentially) proclaiming "everyone is doing it wrong when they don't do it the way I want it" doesn't wash, nor is it fallacious to point this out. You agreed that Tom had done the thing that you said no one had done. Congrats. Humility would be doing the research necessary to understand the implications of what Tom did, and admitting that it kills your thesis, IE: tunnel tests & CFD have been well validated as reproducible in real world conditions, aren't subject to the most confounding variables present in field testing, and are found to be consistently reproduced. This is definitional of a test standard.

You don't understand what you're asking for and the reasons you aren't seeing it, which aren't to be found in black helicopters, rather in sound experimental practice.

Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:
fredly wrote:
OK, fine; you're right. With all the money companies like Trek are spending on testing - including on-road testing; we can all agree that they are doing on-road testing now, right? - they aren't doing exactly what you're asking for.

The question one should generally ask oneself in this type of a situation is "am I the smartest guy in the room, or do I just not know what the hell I'm talking about?"

Nice try again at deflecting from the original point with more ad hominem attacks.

I never tried to say "I'm the smartest guy in the room." If you want proof, look above, where I clearly agree with Tom A's later post where he tested it himself - I'm not out to prove I'm the smartest - I'm just pointing out the truth about testing if you really want to do it right.

I'm looking at all the 'white papers' from bike companies with a skeptical eye. They've got so much money, yet they can't produce a single field test a la Tom A or Dr. Coggan where they prove their engineered bike is faster outdoors than the competition, but they're happy to claim 'we've got the fastest wind tunnel tested bike' (Cervelo, at least.)


I'm not asking them to go above and beyond reasonable testing. I'm asking for perhaps the most obvious, low-cost testing method and to post the results publicly if their bike can do what they claim. Their glaring lack of having such data is very telling - it basically demands that you should view of what they're showing in that white paper as intentional obfuscation and unnecessarily complicating the situation in an effort to avoid showing the results of the simple test - line up the bikes, line up the riders, pace 'em out at 200 watts on a windless day outdoors, and show us the results. If their wind tunnel results are really that translatable to real world, let's see it. Tom A's test is the first I've seen that actually attempts to do this, and yes, his n=1 result suggests that you SHOULD be able to have a measurable difference between frames outdoors.

And like you, I'm not naive - you and I both know that they're testing the crap out of their bikes outdoors, right now. Many, many times over. So the next obvious question, which is the crux of my entire posting on this thread - why haven't we seen it? What are they hiding?

I think you're over-selling how easy it is to do the field testing properly (as Doc C. pointed out earlier), along with how limited the results can be (basically near zero yaw...unless using bike mounted wind measuring equipment with a "street value" of ~$15k-20k). Do you think it was inexpensive for Specialized to rent the Lowes Motor Speedway?

Let's put it this way: I'm a mechanical engineer who has done field testing AND has also participated in wind tunnel tests. If I was responsible for developing a new aerodynamic bicycle frame, I know exactly where I would go for the best and most efficient testing of the development models...and that would be in a wind tunnel...hands down. Yes, field testing has a lower entry cost, but it takes a LOT of effort and time to get results comparable to what is possible in a wind tunnel.

Here's another take...if field testing was a better and easier option, why were the guys at Specialized able to make the business case for building their own facility from scratch? Someone had to look at the ROI and agree it made sense, no?

http://bikeblather.blogspot.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
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Nonsense, Tom.
They're all hiding something, and you're in on it.

Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
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Tom A. wrote:
lightheir wrote:
fredly wrote:
OK, fine; you're right. With all the money companies like Trek are spending on testing - including on-road testing; we can all agree that they are doing on-road testing now, right? - they aren't doing exactly what you're asking for.

The question one should generally ask oneself in this type of a situation is "am I the smartest guy in the room, or do I just not know what the hell I'm talking about?"


Nice try again at deflecting from the original point with more ad hominem attacks.

I never tried to say "I'm the smartest guy in the room." If you want proof, look above, where I clearly agree with Tom A's later post where he tested it himself - I'm not out to prove I'm the smartest - I'm just pointing out the truth about testing if you really want to do it right.

I'm looking at all the 'white papers' from bike companies with a skeptical eye. They've got so much money, yet they can't produce a single field test a la Tom A or Dr. Coggan where they prove their engineered bike is faster outdoors than the competition, but they're happy to claim 'we've got the fastest wind tunnel tested bike' (Cervelo, at least.)


I'm not asking them to go above and beyond reasonable testing. I'm asking for perhaps the most obvious, low-cost testing method and to post the results publicly if their bike can do what they claim. Their glaring lack of having such data is very telling - it basically demands that you should view of what they're showing in that white paper as intentional obfuscation and unnecessarily complicating the situation in an effort to avoid showing the results of the simple test - line up the bikes, line up the riders, pace 'em out at 200 watts on a windless day outdoors, and show us the results. If their wind tunnel results are really that translatable to real world, let's see it. Tom A's test is the first I've seen that actually attempts to do this, and yes, his n=1 result suggests that you SHOULD be able to have a measurable difference between frames outdoors.

And like you, I'm not naive - you and I both know that they're testing the crap out of their bikes outdoors, right now. Many, many times over. So the next obvious question, which is the crux of my entire posting on this thread - why haven't we seen it? What are they hiding?


I think you're over-selling how easy it is to do the field testing properly (as Doc C. pointed out earlier), along with how limited the results can be (basically near zero yaw...unless using bike mounted wind measuring equipment with a "street value" of ~$15k-20k). Do you think it was inexpensive for Specialized to rent the Lowes Motor Speedway?

Let's put it this way: I'm a mechanical engineer who has done field testing AND has also participated in wind tunnel tests. If I was responsible for developing a new aerodynamic bicycle frame, I know exactly where I would go for the best and most efficient testing of the development models...and that would be in a wind tunnel...hands down. Yes, field testing has a lower entry cost, but it takes a LOT of effort and time to get results comparable to what is possible in a wind tunnel.

Here's another take...if field testing was a better and easier option, why were the guys at Specialized able to make the business case for building their own facility from scratch? Someone had to look at the ROI and agree it made sense, no?

No, they built the wind tunnel because it's very good to help rapidly design and test prototypes.

You still have to test them outdoors after the prototypes are built. And no, field testing of the final prototype is very reasonable.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [fredly] [ In reply to ]
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fredly wrote:
Sorry dude, claiming humility while (essentially) proclaiming "everyone is doing it wrong when they don't do it the way I want it" doesn't wash, nor is it fallacious to point this out. You agreed that Tom had done the thing that you said no one had done. Congrats. Humility would be doing the research necessary to understand the implications of what Tom did, and admitting that it kills your thesis, IE: tunnel tests & CFD have been well validated as reproducible in real world conditions, aren't subject to the most confounding variables present in field testing, and are found to be consistently reproduced. This is definitional of a test standard.

You don't understand what you're asking for and the reasons you aren't seeing it, which aren't to be found in black helicopters, rather in sound experimental practice.

NO, I'm seeing it pretty well.

In fact, YOU are then one who apparently misread pages 1-8 of the document, contrary to what I directly posted above.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:
Tom A. wrote:
lightheir wrote:
fredly wrote:
OK, fine; you're right. With all the money companies like Trek are spending on testing - including on-road testing; we can all agree that they are doing on-road testing now, right? - they aren't doing exactly what you're asking for.

The question one should generally ask oneself in this type of a situation is "am I the smartest guy in the room, or do I just not know what the hell I'm talking about?"


Nice try again at deflecting from the original point with more ad hominem attacks.

I never tried to say "I'm the smartest guy in the room." If you want proof, look above, where I clearly agree with Tom A's later post where he tested it himself - I'm not out to prove I'm the smartest - I'm just pointing out the truth about testing if you really want to do it right.

I'm looking at all the 'white papers' from bike companies with a skeptical eye. They've got so much money, yet they can't produce a single field test a la Tom A or Dr. Coggan where they prove their engineered bike is faster outdoors than the competition, but they're happy to claim 'we've got the fastest wind tunnel tested bike' (Cervelo, at least.)


I'm not asking them to go above and beyond reasonable testing. I'm asking for perhaps the most obvious, low-cost testing method and to post the results publicly if their bike can do what they claim. Their glaring lack of having such data is very telling - it basically demands that you should view of what they're showing in that white paper as intentional obfuscation and unnecessarily complicating the situation in an effort to avoid showing the results of the simple test - line up the bikes, line up the riders, pace 'em out at 200 watts on a windless day outdoors, and show us the results. If their wind tunnel results are really that translatable to real world, let's see it. Tom A's test is the first I've seen that actually attempts to do this, and yes, his n=1 result suggests that you SHOULD be able to have a measurable difference between frames outdoors.

And like you, I'm not naive - you and I both know that they're testing the crap out of their bikes outdoors, right now. Many, many times over. So the next obvious question, which is the crux of my entire posting on this thread - why haven't we seen it? What are they hiding?


I think you're over-selling how easy it is to do the field testing properly (as Doc C. pointed out earlier), along with how limited the results can be (basically near zero yaw...unless using bike mounted wind measuring equipment with a "street value" of ~$15k-20k). Do you think it was inexpensive for Specialized to rent the Lowes Motor Speedway?

Let's put it this way: I'm a mechanical engineer who has done field testing AND has also participated in wind tunnel tests. If I was responsible for developing a new aerodynamic bicycle frame, I know exactly where I would go for the best and most efficient testing of the development models...and that would be in a wind tunnel...hands down. Yes, field testing has a lower entry cost, but it takes a LOT of effort and time to get results comparable to what is possible in a wind tunnel.

Here's another take...if field testing was a better and easier option, why were the guys at Specialized able to make the business case for building their own facility from scratch? Someone had to look at the ROI and agree it made sense, no?

No, they built the wind tunnel because it's very good to help rapidly design and test prototypes.

You still have to test them outdoors after the prototypes are built. And no, field testing of the final prototype is very reasonable.

Except test after test after test (ad infinitum) has shown that the wind tunnel results tell you as much, if not more, about real world performance than the most elaborate field testing. It's been proven redundant.

http://bikeblather.blogspot.com/
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
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Well then we definitely disagree here. If we're dealing with differences so small that they're so difficult to reliably measure outdoors in racing conditions, I absolutely want outdoor data, even if it is 'redundant.'

From the lack of bike companies providing such data, I strongly suspect it's not going to just say the same thing they found in the wind tunnel. I'd be happy to be proven wrong!
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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The part that you seem to be missing is that outdoor testing is actually less applicable to real world riding than the wind tunnel, because of the limitations of what can be tested outdoors.

The problem as it stands is that people can't compare 2 different tests in any meaningful manner.

Think of it this way. The wind tunnel is a fancy ruler. I should be able to take one ruler, measure something with it, and you take your ruler, and measure something with that, and we will know which something is bigger or smaller, because those rulers are produced to a known standard. We can guess, if someone tests against a p5 and another tests against a p5, we can make some inferences on a gross scale, but not at a fine scale. So if I'm deciding between a crap bike and a good one, I can probably rile out the crap one. If I'm trying to decide between 2 pretty good bikes, most papers don't even present enough data within that one paper to really trust the conclusions. Like if you had a ruler, but the markings only went as fine as 1". If you tell me that my phone has a 4" screen with that ruler, I just know that it is somewhere between 3" and 5".

Then trying to compare different white papers is next to impossible.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Tom Demerly wrote:
So, we have a different story to tell. Dimond bikes are likely pretty aerodynamic. I don't know for sure. But they may also offer an additional sales feature entirely absent from the rest of the competitive set. They are a beam bike. They have different ride characteristics. Could it be that part of the reason they are faster is that they do have different ride characteristics? What if there is some measurable physiological benefit from having the rider sit at the end of a beam as opposed to on top of a nearly vertical seat tube? If every major and some minor brands can argue a case that their bike is the most aerodynamic, when all of them except one are wrong, then it isn't much of a task (relatively speaking) to construct an argument that beam bikes are measurably faster. And, since Dimond is really the only beam bike widely available (isn't there another that looks like the bat-bike?) then it becomes the "desired outlier". It becomes the De Soto two-piece wetsuit of the bike world.

Titanflex are still in business, they most probably have the greatest bounce, coupled with known durability, but don't have much market share or competitors which would validate that approach.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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JasoninHalifax wrote:
The part that you seem to be missing is that outdoor testing is actually less applicable to real world riding than the wind tunnel, because of the limitations of what can be tested outdoors.

The problem as it stands is that people can't compare 2 different tests in any meaningful manner.

Think of it this way. The wind tunnel is a fancy ruler. I should be able to take one ruler, measure something with it, and you take your ruler, and measure something with that, and we will know which something is bigger or smaller, because those rulers are produced to a known standard. We can guess, if someone tests against a p5 and another tests against a p5, we can make some inferences on a gross scale, but not at a fine scale. So if I'm deciding between a crap bike and a good one, I can probably rile out the crap one. If I'm trying to decide between 2 pretty good bikes, most papers don't even present enough data within that one paper to really trust the conclusions. Like if you had a ruler, but the markings only went as fine as 1". If you tell me that my phone has a 4" screen with that ruler, I just know that it is somewhere between 3" and 5".

Then trying to compare different white papers is next to impossible.

No, I understand fully well. I understand testing complex situations and both the limitations and ways to work around it. I'm not asking for perfection - I'm asking for ANY results.

And my point again is that I wouldn't be making such a big fuss over this if the magnitude was big enough to be readily measured outdoors, like with aerobars. I'm making a fuss precisely because here's a product that cannot be reliably measured by faster outdoors, yet its claimed through expensive and fancy testing that 'it is'.

If you tried to sell me a drug that lowered my blood pressure, but I was unable to measure that blood lowering effect without using some $10,000 blood pressure device instead of the regular BP cuff, I'd be skeptical. Similar with any product that seems to require some super high cost, exclusive controlled environment test to show a difference, yet claims to work in the 'real world', outside that environment. I'd definitely want validating proof it works in the real world in this case, which is why I'm demanding to see it in this case, ESPECIALLY if the wind tunnel is such a reliable, good model for outdoor testing. If it's that good, show us the data. Any data!
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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But it can be measured as faster outdoors, and is. It is just much more difficult to put solid numbers there, and the numbers are going to be less reliable than in the ones from the tunnel, which means they will then have to explain those differences.

A tunnel isn't magic. It's just a fancy ruler. Air inside the tunnel is the same as air outside the tunnel.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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JasoninHalifax wrote:
But it can be measured as faster outdoors, and is. It is just much more difficult to put solid numbers there, and the numbers are going to be less reliable than in the ones from the tunnel, which means they will then have to explain those differences.

A tunnel isn't magic. It's just a fancy ruler. Air inside the tunnel is the same as air outside the tunnel.

And again, I would LOVE for you to be right. But I want to see the numbers. Any numbers.

The lack of such data, when it really should be straightforward to measure (albeit not as precise - I'm ok with that), is a glaring omission. I unfortunately am a skeptic when companies make self-interested scientific claims, and I see all the wind tunnel and CFD gymnastics as attempts to obfuscate what should be a very straightforward measurement.

Anybody who knows statistics knows that with enough sample sizes, you can tease apart even the smallest differences (standard error, sample size is in the denominator) and something this straightforward lends itself extremely well to repeat outdoor testing.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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The other thing to remember is that outdoor testing is only good a zero yaw. IIRC, a lot of good aero frames are pretty similar at zero yaw, same with wheels. They diverge at non zero yaw, which can't be reliably measured outside without some seriously expensive testing equipment.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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With the number of variables to be controlled that can't be measured properly outdoors, the sample size would be ginormous.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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It's kinda like in swimming terms, who's faster, phelps or leclos. But you put each of them in pools in the ocean subject to currents and waves, you let the salinity and temperature vary considerably without measuring it, you change the height of the starting blocks, the pool is "roughly" 50m long, but you aren't quite sure because each wall is free floating.

How many trials do you need to run to get a meaningful number?

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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JasoninHalifax wrote:
With the number of variables to be controlled that can't be measured properly outdoors, the sample size would be ginormous.

No, it wouldn't.

Do you seriously think testing how fast a bike frame outdoors is more complex than testing medications across a range of human patients in the public? Yet that's what exactly medical drug and clinical trials do - across expansive populaces and across many different disease types. It doesn't always work, but it is effective enough that it is a critical point in medical testing to acknowledge that even if you can prove a 'statistically significant result p<.0005', the small magnitude of the finding is clinically irrelevant.

To someone like me, all these claims of 'wow, outdoor bike testing to tease out real world-outdoor frame differences' are just handwaving in the face of the very possible, if not likely reality, that there is essentially no measurable difference in speed between these frames once you're in an outdoor, noncontrolled racing environment.

Gear that has a measurable difference, like aerobars, don't suffer from such problems, precisely because the magnitude is greater.

If the magnitude of the difference is so small that it's undetectable in race-like conditions, and requires a $100k wind tunnel to detect it, the most likely explanation is that the aero effect is so little that it is meaningless in the face of real world variables.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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clinical trials are controlled and randomized, and typically have very large sample sizes for phase 2 trials.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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JasoninHalifax wrote:
It's kinda like in swimming terms, who's faster, phelps or leclos. But you put each of them in pools in the ocean subject to currents and waves, you let the salinity and temperature vary considerably without measuring it, you change the height of the starting blocks, the pool is "roughly" 50m long, but you aren't quite sure because each wall is free floating.

How many trials do you need to run to get a meaningful number?


And I'd say to that - again, your best bet would be to use tests that mirror your racing conditions.

You want to find out who is the fastest at 100m free in a pool? Use a 50m POOL test.

You want to find out who is fastest in a 3-mile OWS? Test in OWS.

If the best swimmer has a much bigger gap than all the others, they'll likely win in all test trials, in all conditions, and in all races, which makes it easy to find the winner, no surprise.

But let's say you have 2 twin Michael Phelps's, both who train similar intensity, but one who does a lot of focused training as an open water 3 mile specialist, and the other specializes in pool racing from 100 to 1500m. THe difference will be a lot less, and your best bet in assessing their performance in a 3mile OWS vs 100m free in the pool - is to test it in that race condition. (Or in this case, just race them in that condition.)

In terms of the required sample size (n), that depends on the magnitude of the difference. It's the equation for standard error, you can wiki it.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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JasoninHalifax wrote:
clinical trials are controlled and randomized, and typically have very large sample sizes for phase 2 trials.

Yes, and we should do the same for bike trials. You will absolutely need far, far smaller sample sizes, as the testing is much more similar and fixed, and the samples aren't from as diverse a range as the general human population. You're dealing with one rider, one route, and similar weather conditions (wait for the days, do it it SoCal if you must.) MUCH easier to test than squaring off two bike frames against each other and asking whether there is a meaningful, measurable speed difference outdoors.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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Test in OW? How?

We are talking about 2 athletes who are pretty close. Give them a 3 mile OW course, and conditions can vary enough hour to hour that ou cannot actually tell who is faster by the time alone, unless you have them swim the same course at the same time.

Last I checked, it was impossible for one person to ride 2 different bikes at the same time.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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It's obvious that you don't know anything about clinical trials. The effect sizes that are detected in medical trials are typically large (50%+). Small effect sizes (2-5%) are basically undetectable in anything but the very largest trials, which involve tens thousands of people. Even these are very hard to separate from confounders. The gains between top bicycles are small, between 1-5%.

You're also saying that every major bike company in the world is wrong.

Think about that.

'It never gets easier, you just get crazier.'
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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For product development wind tunnels and CFD are very helpful. With rider interactions between different frames your best aero position on one frame will not be the same as another. Companies sometimes use stock mannequins and design frames around these which is one option, but does leave the possibility that a particular frame is designed for that mannequin and not a different shaped rider with a different aero position. It is still an excellent option though and not just frames but wheels/bars etc.

I'm not sure what data you want from "outdoor" testing based on your posts (we have reams of data from indoor velodromes, outdoor velodromes, test circuits and races) but there is a lot of it out there, you just have to hunt.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:
Anybody who knows statistics knows that with enough sample sizes, you can tease apart even the smallest differences (standard error, sample size is in the denominator) and something this straightforward lends itself extremely well to repeat outdoor testing.

In the hand's of an experienced individual and under ideal conditions (i.e., minimal wind), CdA can be measured in field tests with a relative precision of +/- ~2%. The same is true for wind tunnel tests of a pedaling human. Your homework assignment is to calculate the sample size required to detect a 2% difference in CdA with alpha = 0.05 and 1-beta = 0.80.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [georged] [ In reply to ]
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georged wrote:
It's obvious that you don't know anything about clinical trials. The effect sizes that are detected in medical trials are typically large (50%+). Small effect sizes (2-5%) are basically undetectable in anything but the very largest trials, which involve tens thousands of people. Even these are very hard to separate from confounders. The gains between top bicycles are small, between 1-5%.

You're also saying that every major bike company in the world is wrong.

Think about that.


The 50%+ required drug effect you throw out there is patently false, that's for sure. Not sure where you get that one.
Last edited by: lightheir: Oct 17, 15 5:22
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:
JasoninHalifax wrote:
clinical trials are controlled and randomized, and typically have very large sample sizes for phase 2 trials.


Yes, and we should do the same for bike trials. You will absolutely need far, far smaller sample sizes, as the testing is much more similar and fixed, and the samples aren't from as diverse a range as the general human population. You're dealing with one rider, one route, and similar weather conditions (wait for the days, do it it SoCal if you must.) MUCH easier to test than squaring off two bike frames against each other and asking whether there is a meaningful, measurable speed difference outdoors.

Congratulations. In just one thread you've shown you understand neither wind tunnel testing, nor clinical trials. Actually, your understanding of RCTs seems even much lower than your understanding of wind tunnel testing.

But of course you won't understand that as soon as you said "You're dealing with one rider, one route, and similar weather conditions" you've already introduced your own biases and fucked up the whole study. Anyway, please proceed with your conspiracy theory about wind tunnel, bike manufacturers and how they're out to get us. If anything, it's amusing.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:
georged wrote:
It's obvious that you don't know anything about clinical trials. The effect sizes that are detected in medical trials are typically large (50%+). Small effect sizes (2-5%) are basically undetectable in anything but the very largest trials, which involve tens thousands of people. Even these are very hard to separate from confounders. The gains between top bicycles are small, between 1-5%.

You're also saying that every major bike company in the world is wrong.

Think about that.


The 50%+ required drug effect you throw out there is patently false, that's for sure. Not sure where you get that one.

Many RCTs will start with the assumption of a medium Cohen's d of .5...that's where he got it...
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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lightheir wrote:
JasoninHalifax wrote:
With the number of variables to be controlled that can't be measured properly outdoors, the sample size would be ginormous.


No, it wouldn't.

Do you seriously think testing how fast a bike frame outdoors is more complex than testing medications across a range of human patients in the public? Yet that's what exactly medical drug and clinical trials do - across expansive populaces and across many different disease types. It doesn't always work, but it is effective enough that it is a critical point in medical testing to acknowledge that even if you can prove a 'statistically significant result p<.0005', the small magnitude of the finding is clinically irrelevant.

To someone like me, all these claims of 'wow, outdoor bike testing to tease out real world-outdoor frame differences' are just handwaving in the face of the very possible, if not likely reality, that there is essentially no measurable difference in speed between these frames once you're in an outdoor, noncontrolled racing environment.

Gear that has a measurable difference, like aerobars, don't suffer from such problems, precisely because the magnitude is greater.

If the magnitude of the difference is so small that it's undetectable in race-like conditions, and requires a $100k wind tunnel to detect it, the most likely explanation is that the aero effect is so little that it is meaningless in the face of real world variables.

A frame testing question was asked over on my forum not too long ago and this was my proposal:

Quote:
In the tunnel I've used historically, I'd suggest doing this set of 12 runs:
beta =[0 10];
drop = [0 -2 -4];
reach = [0 8];

...for each of the frames. this ought to give you the statistical power to detect a CxA difference of ~0.0025 with a p value of around 0.05 (about 80% of the time). more importantly, though, it has a false positive rate of 0%, and a reversal rate of about 0.1 %. This set of runs would take about 90-100 minutes in a tunnel and on top of that, you'll get real good heuristics for reach and drop (and insight into any interactions).

If you want to field test this in a velodrome, I'd suggest doing this matrix ~6 times depending on how good the repeats look (you can't do the beta runs in the velodrome, so you'll need to double up the runs to compensate) in order to give equivalent stat power. Oh dear, that sounds like a piece of work! Based on the field testing I've done, that test would take a whole heckuvalot longer than 2 hours.

=================
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=================
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Francois] [ In reply to ]
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Francois wrote:
lightheir wrote:
georged wrote:
It's obvious that you don't know anything about clinical trials. The effect sizes that are detected in medical trials are typically large (50%+). Small effect sizes (2-5%) are basically undetectable in anything but the very largest trials, which involve tens thousands of people. Even these are very hard to separate from confounders. The gains between top bicycles are small, between 1-5%.

You're also saying that every major bike company in the world is wrong.

Think about that.


The 50%+ required drug effect you throw out there is patently false, that's for sure. Not sure where you get that one.


Many RCTs will start with the assumption of a medium Cohen's d of .5...that's where he got it...


Ok, if you're talking effect size re: specifically, Cohen's d effect size, that's helps.

And what will be the putative effect size (Cohen's d effective size) of differences between top bicycles? Small or large?

And if it's a small Cohen's d, you realize that's exactly what I've been getting at all along? That the differences are small - so small that they are potentially negligible and nonmeasurable outside of highly controlled wind tunnel environments? (If the standard deviation of outdoor measurements is large, or at least a lot larger than the difference between the means, Cohen's d will be small, as per the Cohen's d equation.)
Last edited by: lightheir: Oct 17, 15 6:12
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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"If the magnitude of the difference is so small that it's undetectable in race-like conditions, and requires a $100k wind tunnel to detect it, the most likely explanation is that the aero effect is so little that it is meaningless in the face of real world variables."

You keep leaving out THE critical difference between bike performance and clinical trials. A tiny difference in blood pressure does not make a clinical difference, that is true. On the other hand, if a 1 mm Hg difference in pressure gave one patient a 1 million dollar "health" prize while the next got got nothing, all of a sudden it matters a great deal.

It is immaterial if the advantage of a big frame gives 3 minutes to a rider, but that difference is obscured by the time variations of more important variables on race day. He still got those 3 minutes.


If he wins by three minutes or less, that means everything.


Your analogy with clinical trials only holds water if your are talking about MOP racers who do not care about their time or placing. Then those few minutes do not really matter. But a lot of people are chasing podiums, or PRs and care a lot about small time differences.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [helo guy] [ In reply to ]
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helo guy wrote:
"If the magnitude of the difference is so small that it's undetectable in race-like conditions, and requires a $100k wind tunnel to detect it, the most likely explanation is that the aero effect is so little that it is meaningless in the face of real world variables."

You keep leaving out THE critical difference between bike performance and clinical trials. A tiny difference in blood pressure does not make a clinical difference, that is true. On the other hand, if a 1 mm Hg difference in pressure gave one patient a 1 million dollar "health" prize while the next got got nothing, all of a sudden it matters a great deal.

It is immaterial if the advantage of a big frame gives 3 minutes to a rider, but that difference is obscured by the time variations of more important variables on race day. He still got those 3 minutes.


If he wins by three minutes or less, that means everything.


Your analogy with clinical trials only holds water if your are talking about MOP racers who do not care about their time or placing. Then those few minutes do not really matter. But a lot of people are chasing podiums, or PRs and care a lot about small time differences.




But in racing, 3 minutes is a huge difference that exceeds even aerobars unless you're talking long course stuff. 3 mins in an hour is eminently measurable oudoors, even with the outdoor variables.

3 seconds is a whole different story. And in racing, even where people lose by 3 seconds in races, there is a lower threshold somewhere at which point it's just not worth it to worry about. To counterpoint your example, let's say there was a 0.3 sec time savings. Changes things a lot.

And again to counterpoint, let's say I say I'm selling you a new aerodynamic bike shirt that was designed in a wind tunnel with both human and dummy models, and per the independently validated wind tunnel testing, it will theoretically save 10sec/hr in a time trial. (I'm just making that number up of course, but sub in any other reasonable number.) You then ask me if I've tested this outdoors, and I say, 'well, I've have had some testers wear it outside, and there have been zero significant differences over our trials in outdoor measurements, but that's because the outdoor variables mask it. But you should still buy my shirt, because you're getting some aero benefits as per our wind tunnel tests.'

Are you still going to buy my shirt?
Last edited by: lightheir: Oct 17, 15 6:37
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
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Check mate! hahaha


Tom A. wrote:
lightheir wrote:


I would absolutely love to see Bikeradar do the exact experiment you suggest, outdoors, with P3C vs P2k with same rider and equipment.

If I had to place a bet on the outcome, I'd bet that there would be no measurable advantage, meaning you're just as well off riding the P2k compared to the p3c. But I'd love to see this done.


I would love to see the bike companies stop all the wind-tunnel marketing BS, and just do this much more straightforward experiment, and show us the data, even if it's negative (shows no measurable effect), or not.


Bike radar doesn't need to...I already did it :-)

http://bikeblather.blogspot.com/...00&max-results=5

I don't think I would call ~2.5s/km of difference "potentially insignificant". You just lost that virtual bet you made ;-)



Heath Dotson
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Tom Demerly wrote:
  • Construction technique.

That is all I would love to know before buying a bike again. But i'm sure the company wouldn't give away the details of the cf layup of their frames or what equipment they used to put it all together. IF they let me know this though, I can easily justify certain aspects of the claims they are making about the quality/integrity/performance of their product. Everything else in that post I quoted is a factor but not as much as this one in my opinion.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
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Great link

Dan Kennison

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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"Are you still going to buy my shirt? "

For 10 seconds? If I am in the market for a new shirt anyway, and the price and fit are comparable, I would choose your shirt. This is of course assuming I find your wind tunnel numbers credible.

Just as with bikes, wheels, and other gear I need to occasionally buy new stuff. Why would I spend my money on lesser performing gear?

That is not to say I always buy the most expensive gear, just that I want to know the cost benefit ratio of where I put my money. The wind tunnel data is not perfect, but it is still the best data we have in most cases. Using it allows me to optimize the gains I get for what I spend.
Last edited by: helo guy: Oct 17, 15 7:40
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [dkennison] [ In reply to ]
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [helo guy] [ In reply to ]
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helo guy wrote:
It is immaterial if the advantage of a big frame gives 3 minutes to a rider, but that difference is obscured by the time variations of more important variables on race day. He still got those 3 minutes.

This is the point that lightheir keeps missing.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [helo guy] [ In reply to ]
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If you were in the market for a new aero bike (your budget was $7,500) and Wind Tunnel testing was done in a "side by side test" at A2 by an independent entity and the difference was 100 grams of drag: 2 watts.

Is that a difference that you think you could translate to the real world (absent of any additional data)?

Would you purchase the faster bike (according to the Wind Tunnel testing) if it cost $7,500 vs the other at $4,500?

or

Would that 2 watts be to close to the margin of error to justify the additional cost?

Dan Kennison

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [dkennison] [ In reply to ]
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dkennison wrote:
If you were in the market for a new aero bike (your budget was $7,500) and Wind Tunnel testing was done in a "side by side test" at A2 by an independent entity and the difference was 100 grams of drag: 2 watts.

Is that a difference that you think you could translate to the real world (absent of any additional data)?

Would you purchase the faster bike (according to the Wind Tunnel testing) if it cost $7,500 vs the other at $4,500?

or

Would that 2 watts be to close to the margin of error to justify the additional cost?

100 grams of drag is roughly .01 CdA or 10 watts. Which is roughly 40 sec/k. It would depend on how much those 40 secs were worth. How much would someone chasing KQ pay for 22 seconds if they missed it by one place? .01 CdA would work out to ~180 seconds over 112 miles.



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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [lightheir] [ In reply to ]
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Don't turn things around mate. You're the one saying we can easily do a cheap RCT for cyclists to test aerodynamics.
The typical RCT starts with an R01 for about 1.25M (I'm nice I'm not asking indirect costs from you). So please share your experimental design. I'm listening carefully.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Francois] [ In reply to ]
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lightheir also thinks that because he had some success by training on a VASA a lot, that technique doesn't matter much in swimming.

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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
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Well, he is correct. Technique doesn't matter much in swimming on a VASA. ;-)
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Francois] [ In reply to ]
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This thread is sapping my will to live.
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [RChung] [ In reply to ]
Quote | Reply
Be positive! It looks like we're going to get an R01 on ST test aerodynamics! How awesome is that?
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [dkennison] [ In reply to ]
Quote | Reply
100 grams of drag at 30mph is more than 2 watts.
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [RChung] [ In reply to ]
Quote | Reply
RChung wrote:
This thread is sapping my will to live.

This is exactly why I'm glad you are for stricter gun control. Who knows what you'd do if you had a handgun sitting on your desk right now!



Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Runless] [ In reply to ]
Quote | Reply
I was corrected by Ex-cyclist. Thank you as well.

Dan Kennison

facebook: @triPremierBike
http://www.PremierBike.com
http://www.PositionOneSports.com
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Runless] [ In reply to ]
Quote | Reply
I was trying to make a bigger point with my original post. Most bike companies publish data that is very close. But..10 watts is a lot (in my example) so I need to correct that.

I had a misunderstanding of the formula with grams/watts though; so at least I learned something:-)

I guess when the difference gets down to 20-30 grams, the trade off between low and high price bikes begin to be suspect based on error rates.

Dan Kennison

facebook: @triPremierBike
http://www.PremierBike.com
http://www.PositionOneSports.com
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Ex-cyclist] [ In reply to ]
Quote | Reply
Ex-cyclist wrote:
RChung wrote:
This thread is sapping my will to live.


This is exactly why I'm glad you are for stricter gun control. Who knows what you'd do if you had a handgun sitting on your desk right now!

For the win! Beware of an angry and armed RChung!
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [dkennison] [ In reply to ]
Quote | Reply
Yeah, I agree. I bought a P5 right around when the new P3 came out. My cost through my shop was about the same, so I went with the P5. If I was buying a bike now, I'd probably buy the P2, strip and sell the components, put a fast bar on it and call it a day. I think the two bikes would be within the error bars of testing.


dkennison wrote:
I was trying to make a bigger point with my original post. Most bike companies publish data that is very close. But..10 watts is a lot (in my example) so I need to correct that.

I had a misunderstanding of the formula with grams/watts though; so at least I learned something:-)

I guess when the difference gets down to 20-30 grams, the trade off between low and high price bikes begin to be suspect based on error rates.



Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Runless] [ In reply to ]
Quote | Reply
Runless wrote:
100 grams of drag at 30mph is more than 2 watts.


I was wondering if someone else would notice that...yeah, like ~5X more ;-)

Edit: Oops, I see Heath was on it first...

http://bikeblather.blogspot.com/
Last edited by: Tom A.: Oct 17, 15 11:56
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Ex-cyclist] [ In reply to ]
Quote | Reply
Ex-cyclist wrote:
Yeah, I agree. I bought a P5 right around when the new P3 came out. My cost through my shop was about the same, so I went with the P5. If I was buying a bike now, I'd probably buy the P2, strip and sell the components, put a fast bar on it and call it a day. I think the two bikes would be within the error bars.

Exactly what I did this last spring...which reminds me, I've got a bar, a crankset, and some brakes to sell ;-)

http://bikeblather.blogspot.com/
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom A.] [ In reply to ]
Quote | Reply


RChung summarized my thesis in eight words.

The aerodynamic argument is dead. It's over. It's trended. It's no longer relevant. It isn't a key part of how the majority of customers make a buying decision.

There are some people who still feel it is relevant. You see them in this thread, locked in the desperate death-spiral circular spread-sheet debate about aero-bestness that seldom progresses beyond a kind of weird discussion about how to determine if something is best, but really missing the main answer of which thing actually is best. Because that is impossible to determine since there is so much smoke obscuring the battlefield.

And so, the circular debate continues. And continues. And continues.

But somewhere out there, some sales, marketing or product manager will find fresh approach that speaks to consumers. They will be rewarded.

Tom Demerly
The Tri Shop.com
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
Quote | Reply
Tom Demerly wrote:


RChung summarized my thesis in eight words.

The aerodynamic argument is dead. It's over. It's trended. It's no longer relevant. It isn't a key part of how the majority of customers make a buying decision.

There are some people who still feel it is relevant. You see them in this thread, locked in the desperate death-spiral circular spread-sheet debate about aero-bestness that seldom progresses beyond a kind of weird discussion about how to determine if something is best, but really missing the main answer of which thing actually is best. Because that is impossible to determine since there is so much smoke obscuring the battlefield.

And so, the circular debate continues. And continues. And continues.

But somewhere out there, some sales, marketing or product manager will find fresh approach that speaks to consumers. They will be rewarded.


You're right...the aerodynamic argument IS dead, but not how you think. It's settled for those with the ability to use science and logic. Aerodynamics MATTER to anyone who wishes to go faster for a given effort. Period. (You may not have noticed, but on one side of the argument above is only ONE vocal outlier...which happens to be the side you think is the majority...Ummm...ok...)

The customers understand this and demand to see the data to ensure they aren't making themselves slower than they would be otherwise by focusing on other, much less relevant features (in regards to bike speed)...all those other things you wish to be able to tout for some reason. Probably because you aren't selling a bike that's as aero as other options :-/

Being good aerodynamically is the MINIMUM needed for a good TT/Tri bike. Everything else is "icing". THAT is why aero data is "King".

http://bikeblather.blogspot.com/
Last edited by: Tom A.: Oct 17, 15 13:10
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [dkennison] [ In reply to ]
Quote | Reply
dkennison wrote:
Great link

was the null hypothesis rejected?

=================
Kraig Willett
http://www.biketechreview.com - check out our reduced report pricing
=================
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [BikeTechReview] [ In reply to ]
Quote | Reply
BikeTechReview wrote:
dkennison wrote:
Great link

was the null hypothesis rejected?

At what alpha? P=0.05 might be traditional, but there seems little reason to adhere to it in this context.
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [RChung] [ In reply to ]
Quote | Reply
RChung wrote:
This thread is sapping my will to live.

Keep the faith! May the aero be with you! Personally I always keep my fingers crossed with threads like this that most of my competitors will deduce "it's all engine anyways, just buy a bike in a color I like, get comfortable, wear a helmet that keeps me cool, and use flat-proof tires."
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
Quote | Reply
Tom Demerly wrote:
somewhere out there, some sales, marketing or product manager will find fresh approach that speaks to consumers.

I've heard that "sex sells". Think there's anything to it?
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [GreenPlease] [ In reply to ]
Quote | Reply
Good luck with that.....but I don't read what others are saying that way...Tom A said it best..."Being good aerodynamically is the MINIMUM needed for a good TT/Tri bike. Everything else is "icing". THAT is why aero data is "King".

The pointy end of the scale for aero bikes is no longer pointy. Even the pioneers are finding it hard to beat themselves "numbers wise".

A few companies forged new ground with respect to aero frames. Now 7-12 years later (depending on who you like best), just about any competent manufacturer/designer should be able to produce and aero bike based off many examples, comparative modeling, CFD, and wind tunnel testing. If they can't; of course they are SOL.


So....What else you can offer the customer is becoming more and more important. And thats gonna be different strokes for different folks.





Dan Kennison

facebook: @triPremierBike
http://www.PremierBike.com
http://www.PositionOneSports.com
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
Quote | Reply
Tom Demerly wrote:

But somewhere out there, some sales, marketing or product manager will find fresh approach that speaks to consumers. They will be rewarded.

It's called price.

I've been in enough transition areas by now where I can say, with great confidence, that if someone made a bike within 50grams of drag of a Speed Concept but the frameset sold for $650 they would own the market.

That wasn't realistic ten years ago... maybe not even five years ago... but I think it's realistic to do that now with aluminum.

The aero argument isn't dead... it's certainly not dead. Cannondale's new Slice is a perfect example: aero dud so you're not likely to see any FOP pros on one... maybe not even FOP age groupers.
Last edited by: GreenPlease: Oct 17, 15 14:32
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [dkennison] [ In reply to ]
Quote | Reply
I don't think companies who don't understand automatically are SOL. You pay a marketing department to avoid such things.

And aeroness isn't what most people think it might be. Beautifully-painted aero shaped carbon on a tall frame with integrated aero bars that can't be adjusted ... still sell well.

I won't make any friends with this, but a customer recently bought the brand-new Pinarello Bolide right after Wiggins' Hour Record. That was a very bad experience in trying to position him into something that was aero. And it involved scrapping the integrated bars that he paid so much money for. But Pinarello will continue to sell lots of bikes because they're viewed as being so aero.

Aero marketing works, I guess.

AndyF
bike geek
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
Quote | Reply
Andrew Coggan wrote:
BikeTechReview wrote:
dkennison wrote:
Great link

was the null hypothesis rejected?

At what alpha? P=0.05 might be traditional, but there seems little reason to adhere to it in this context.

P=0.01

=================
Kraig Willett
http://www.biketechreview.com - check out our reduced report pricing
=================
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
Quote | Reply
Tom Demerly wrote:
The thing that boggles me about always trying to sell bikes in the same way is the "blank space".

The blank space is everything left over to sell a bike. Everything left besides bicycle aerodynamics.

Things like:

  • Appearance (more important than most of us are willing to admit).
  • Weight.
  • Warranty.
  • Frame stiffness (Note here: one highly credible brand has a unique feature that makes their bikes stiffer, but none of their P.O.P. displays mention it.)
  • Component specification. (I dare someone to run an ad that says, "Best value in a Dura-Ace equipped triathlon bike).
  • Fit. (Everyone acknowledges the importance of bike fit. No manufacturer actively uses it as a selling tool in their marketing.)
  • History.
  • Construction technique.
  • Durability.
  • Ride quality.
  • Comfort.
  • Ease of maintenance (honorable mention to Quintana Roo for their "Ease of Packing" campaign for their very good PR bikes).
  • Mise en scene (the cache' of the brand, an analogue that is more important than most consumers are willing to admit since some of it is subconscious.)
.

Details?

Doesn't Cervelo, on their website?

Who cares, isn't it all made in the same 5 factories anyway? Does this make a difference in other industries(that aren't handicraft)? Nobody I know goes, 'no, I want the truck with the hyrdoformed chassis'-they look at the towing&bed capacity.
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [JasoninHalifax] [ In reply to ]
Quote | Reply
JasoninHalifax wrote:
lightheir also thinks that because he had some success by training on a VASA a lot, that technique doesn't matter much in swimming.

Honestly wish he'd take up decathlon...think of all the sports disciplines he could be wrong about!
Quote Reply
Post deleted by Administrator [ In reply to ]
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
Quote | Reply
I'm late to the party, that's what driving across country does to you. Since everyone, or at least many tried to poit out is aero matters. What I'm going to do is point out why your list is a bunch of bullshit, maybe more bullshit then you thinking aero doesn't matter.

Sure appearance matters but aerodynamics will beat aesthetics. Orbea is a good brand to point this out. Their bikes were shit slow but they looked good. They tried to make something look fast and here they are 5+ years late to the aero game and they lost a lot of market share, enough they won't get it back.

Weight - who gives a shit, aero trumps weight every time. There is so much written on this, it's a tragedy you even brought it up.

Frame stiffness - Someone made a contraption so they couldn't see which bike they were riding, compared a stiff bike to a non stiff bike, couldn't tell the difference. It may have been Jonnyo. If you're selling a bike based on this it's malpractice

Components - matters some especially if comparing tiarga to ultegra

FIT - I can't tell you how many piss poor fits I've redone or tweaked when doing aero testing from some famous fitters and not so famous fitters. I've also seen many of your fits through the years. You fit more for comfort, more upright. Basically you're negating a lot of the benefits of an aero frame. If someone can touch their toes they can ride more along the lines of an aero pro. If you can't get them into an aero position that's comfy have you thought about a different saddle?

History - Orbea anyone?

Ride quality and comfort are more the same then different. Most test rides are too short to determine this for the long haul.

I think you get the point, or I hope so. A lot of what you say will sell a bike will sell it. But why sell a piece of slow shit when you can sell a fast bike and not further hinder your customer. Do no harm. Which means don't sell slow shit.

It took 4 minutes to type why those companies aren't having those conversations.

Brian Stover USAT LII
Accelerate3 Coaching
Insta

Last edited by: desert dude: Oct 17, 15 16:01
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [gabbiev] [ In reply to ]
Quote | Reply
Yup, we agree.

Even here on Slowtwitch, how many intelligent, avid readers will go out and get an expert bike fit FIRST, and THEN go and find a frame, crank, and aerobars that work?

Why? Because carbon and colourful epoxy paint sells better than fit.

AndyF
bike geek
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [RChung] [ In reply to ]
Quote | Reply
RChung wrote:
This thread is sapping my will to live.

This question probably won't help.

What's the p-value for these post-hoc pairwise comparisons:





=================
Kraig Willett
http://www.biketechreview.com - check out our reduced report pricing
=================
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [BikeTechReview] [ In reply to ]
Quote | Reply
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
dkennison wrote:
Great link

was the null hypothesis rejected?

At what alpha? P=0.05 might be traditional, but there seems little reason to adhere to it in this context.

P=0.01

You don't have much of a grasp of statistics, do you?
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
Quote | Reply
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
dkennison wrote:
Great link

was the null hypothesis rejected?

At what alpha? P=0.05 might be traditional, but there seems little reason to adhere to it in this context.

P=0.01

You don't have much of a grasp of statistics, do you?

Ad hominem.

=================
Kraig Willett
http://www.biketechreview.com - check out our reduced report pricing
=================
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [GreenPlease] [ In reply to ]
Quote | Reply
GreenPlease wrote:
Cannondale's new Slice is a perfect example: aero dud so you're not likely to see any FOP pros on one... maybe not even FOP age groupers.

5th place in Hawaii isn't FOP?

Swimming Workout of the Day:

Favourite Swim Sets:

2020 National Masters Champion - M50-54 - 50m Butterfly
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [BikeTechReview] [ In reply to ]
Quote | Reply
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
dkennison wrote:
Great link

was the null hypothesis rejected?

At what alpha? P=0.05 might be traditional, but there seems little reason to adhere to it in this context.

P=0.01

You don't have much of a grasp of statistics, do you?

Ad hominem.

Constitutio fact.
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
Quote | Reply
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
dkennison wrote:
Great link

was the null hypothesis rejected?

At what alpha? P=0.05 might be traditional, but there seems little reason to adhere to it in this context.

P=0.01

You don't have much of a grasp of statistics, do you?

Ad hominem.

Constitutio fact.

Was the null hypothesis rejected at a p-value of 0.01?

=================
Kraig Willett
http://www.biketechreview.com - check out our reduced report pricing
=================
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [BikeTechReview] [ In reply to ]
Quote | Reply
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
dkennison wrote:
Great link

was the null hypothesis rejected?

At what alpha? P=0.05 might be traditional, but there seems little reason to adhere to it in this context.

P=0.01

You don't have much of a grasp of statistics, do you?

Ad hominem.

Constitutio fact.

Was the null hypothesis rejected at a p-value of 0.01?

As I said, your grasp of statistics seems to be lacking. Here is a link that might help you understand why the alpha level you've chosen is ridiculously low - scenario D in particular is highly relevant:

http://www.graphpad.com/...r_which_values_o.htm
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
Quote | Reply
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
dkennison wrote:
Great link


was the null hypothesis rejected?


At what alpha? P=0.05 might be traditional, but there seems little reason to adhere to it in this context.


P=0.01


You don't have much of a grasp of statistics, do you?


Ad hominem.


Constitutio fact.


Was the null hypothesis rejected at a p-value of 0.01?


As I said, your grasp of statistics seems to be lacking. Here is a link that might help you understand why the alpha level you've chosen is ridiculously low - scenario D in particular is highly relevant:

http://www.graphpad.com/...r_which_values_o.htm

ad hominen, again. dkennison commented about a great link...so i read it and posed a question. if you can't answer my question to him, oh well. <shrug>

=================
Kraig Willett
http://www.biketechreview.com - check out our reduced report pricing
=================
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [BikeTechReview] [ In reply to ]
Quote | Reply
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
dkennison wrote:
Great link


was the null hypothesis rejected?


At what alpha? P=0.05 might be traditional, but there seems little reason to adhere to it in this context.


P=0.01


You don't have much of a grasp of statistics, do you?


Ad hominem.


Constitutio fact.


Was the null hypothesis rejected at a p-value of 0.01?


As I said, your grasp of statistics seems to be lacking. Here is a link that might help you understand why the alpha level you've chosen is ridiculously low - scenario D in particular is highly relevant:

http://www.graphpad.com/...r_which_values_o.htm

ad hominen, again. dkennison commented about a great link...so i read it and posed a question. if you can't answer my question to him, oh well. <shrug>

Constitutio fact, again...as the link I provided so clearly demonstrates.
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [desert dude] [ In reply to ]
Quote | Reply
haha! Still waking up on East Coast time I see!



Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
Quote | Reply
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
dkennison wrote:
Great link


was the null hypothesis rejected?


At what alpha? P=0.05 might be traditional, but there seems little reason to adhere to it in this context.


P=0.01


You don't have much of a grasp of statistics, do you?


Ad hominem.


Constitutio fact.


Was the null hypothesis rejected at a p-value of 0.01?


As I said, your grasp of statistics seems to be lacking. Here is a link that might help you understand why the alpha level you've chosen is ridiculously low - scenario D in particular is highly relevant:

http://www.graphpad.com/...r_which_values_o.htm


ad hominen, again. dkennison commented about a great link...so i read it and posed a question. if you can't answer my question to him, oh well. <shrug>


Constitutio fact, again...as the link I provided so clearly demonstrates.

Since you don't seem to want to answer that question, how about this one (I'd ask rchung, but he's looking into p-values for other comparisons):

In the link dkennison mentions, what is the p-value for the best to worst comparison (bicyle+equipment) outdoors?

=================
Kraig Willett
http://www.biketechreview.com - check out our reduced report pricing
=================
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [BikeTechReview] [ In reply to ]
Quote | Reply
BikeTechReview wrote:
Since you don't seem to want to answer that question

It's a naive question.

Paraphrasing Dr. Motulsky:

"The sample size required to show statistically-significant differences using conventional values for alpha and 1-beta are too high to be feasible. You simply can't run that many replicates. After thinking about it, you realize that the consequences of making a Type II error (falsely concluding that one frame is faster than another) are much less than making a Type I error (falsely concluding that two frames are equal). A false hit will have little impact on your performance. On the other hand, falsely calling two bikes to be equal means that you'll miss out on a real competitive advantage. Therefore you choose a low value of alpha and also a low power."
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
Quote | Reply
Andrew Coggan wrote:
BikeTechReview wrote:
Since you don't seem to want to answer that question

It's a naive question.

Paraphrasing Dr. Motulsky:

"The sample size required to show statistically-significant differences using conventional values for alpha and 1-beta are too high to be feasible."

Seems like you didn't actually read the article dkennison gave kudos to if you ask me. A simple p-value calc by you, as requested, could end this.

=================
Kraig Willett
http://www.biketechreview.com - check out our reduced report pricing
=================
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [BikeTechReview] [ In reply to ]
Quote | Reply
BikeTechReview wrote:
A simple p-value calc by you, as requested, could end this.

The difference I found between my wife's P2T and P3C track bikes is significant at alpha = 0.01 with 1-beta = 0.27.

Conversely, if in this context* you foolishly insist on 1-beta = 0.80, then alpha = 0.16.

(*Personally, the statistic I've always relied upon is $ per second per km saved, with something around $500/(s/km) being my cut-off.)
Last edited by: Andrew Coggan: Oct 18, 15 15:50
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
Quote | Reply
Andrew Coggan wrote:

(*Personally, the statistic I've always relied upon is $ per second per km saved, with something around $500/(s/km) being my cut-off.)

Sorry, screwed up my math - standard has been ~$1500/(s/km).
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
Quote | Reply
This has been an interesting thread.

  • It's posted on a forum contributed to by the top percentages of triathlon athletes and technology mavens. The "Alphas", the top 1%'ers.
  • Part of that is my error- part isn't.
  • I asked how much credibility you assign to Bike Brand wind tunnel testing. Some people answered that question. Most didn't.
  • The behavior of the thread then seemed to draw frequent and learned contributors out. They discussed topics only peripherally related to original inquiry.
  • I theorize, but cannot prove, that the bottom 80% or so of triathletes would respond differently to this inquiry.
  • Since the bottom 80% is the group that buys most of the full-price (key words: "full-price") triathlon equipment and bikes, that is the response group I'm most interested in. That's where the business is. The sport has filled from the bottom. Look at any big 70.3 or 140.6 race results page.
  • The "Alpha" contributors in this thread have been contributing here for years and likely have not paid full retail price for a triathlon or road bike in a long time.




Tom Demerly
The Tri Shop.com
Quote Reply
Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Andrew Coggan] [ In reply to ]
Quote | Reply
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview wrote:
Andrew Coggan wrote:
BikeTechReview[/font wrote:
]
Andrew Coggan wrote:
BikeTechReview wrote:
dkennison wrote:
Great link


was the null hypothesis rejected?


At what alpha? P=0.05 might be traditional, but there seems little reason to adhere to it in this context.


P=0.01


You don't have much of a grasp of statistics, do you?


Ad hominem.


Constitutio fact.


Was the null hypothesis rejected at a p-value of 0.01?


As I said, your grasp of statistics seems to be lacking. Here is a link that might help you understand why the alpha level you've chosen is ridiculously low - scenario D in particular is highly relevant:

http://www.graphpad.com/...r_which_values_o.htm


ad hominen, again. dkennison commented about a great link...so i read it and posed a question. if you can't answer my question to him, oh well. <shrug>


Constitutio fact, again...as the link I provided so clearly demonstrates.


Since you don't seem to want to answer that question, how about this one (I'd ask rchung, but he's looking into p-values for other comparisons):

In the link dkennison mentions, what is the p-value for the best to worst comparison (bicyle+equipment) outdoors?


It's a naive question.

Paraphrasing Dr. Motulsky:

"The sample size required to show statistically-significant differences using conventional values for alpha and 1-beta are too high to be feasible. You simply can't run that many replicates. After thinking about it, you realize that the consequences of making a Type II error (falsely concluding that one frame is faster than another) are much less than making a Type I error (falsely concluding that two frames are equal). A false hit will have little impact on your performance. On the other hand, falsely calling two bikes to be equal means that you'll miss out on a real competitive advantage. Therefore you choose a low value of alpha and also a low power."


Seems like you didn't actually read the article dkennison gave kudos to if you ask me. A simple p-value calc by you, as requested, could end this.


The difference I found between my wife's P2T and P3C track bikes...<snip>


shorter, less mathy, less University of Marylandy (circa 2001 - click the linky-link), more empathetic andy:


"I'm sorry, Kraig, for not actually reading dkennison's link and subsequently calling you names".

=================
Kraig Willett
http://www.biketechreview.com - check out our reduced report pricing
=================
Last edited by: BikeTechReview: Oct 18, 15 21:31
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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Perhaps you'd be better off posting elsewhere? Maybe like Beginner Triathlete. Everyone who has been on here for several years knows you have an axe to grind re: Aerodynamics, which what led to what you feel is a devolution of the OP.


Tom Demerly wrote:
This has been an interesting thread.

  • It's posted on a forum contributed to by the top percentages of triathlon athletes and technology mavens. The "Alphas", the top 1%'ers.
  • Part of that is my error- part isn't.
  • I asked how much credibility you assign to Bike Brand wind tunnel testing. Some people answered that question. Most didn't.
  • The behavior of the thread then seemed to draw frequent and learned contributors out. They discussed topics only peripherally related to original inquiry.
  • I theorize, but cannot prove, that the bottom 80% or so of triathletes would respond differently to this inquiry.
  • Since the bottom 80% is the group that buys most of the full-price (key words: "full-price") triathlon equipment and bikes, that is the response group I'm most interested in. That's where the business is. The sport has filled from the bottom. Look at any big 70.3 or 140.6 race results page.
  • The "Alpha" contributors in this thread have been contributing here for years and likely have not paid full retail price for a triathlon or road bike in a long time.





Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [Tom Demerly] [ In reply to ]
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I buy in the mid-price range, of just about everything in tri. (top of the line wetsuits excepted).

In the mid range (and probably higher than that) for frames and wheels, I think there is actually very little difference between brands and models. they all claim to be the best and if you dig into the data, it will be one data point they're talking about, and overall, 5/8 of sweet FA difference.

The only (aero) data I trust, even a little bit, is independent testing, and only when all brands are tested in the same tunnel at the same time etc etc.

At the end of the day, even when I trust independent aero data, it's only one factor I consider, when making a purchase. Many times, I will buy say a wheel, and aero is important but so are other factors weight,braking surface, bearings and their serviceability and then of course price.

If I was at the pointy end of the race, I'd probably be searching for greater gains from my equipment, with cost being less of a consideration, but as MOP living in a variation of the real world, lotsa things impact on my purchases and aero is just one of those factors.

TriDork

"Happiness is a myth. All you can hope for is to get laid once in a while, drunk once in a while and to eat chocolate every day"
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Re: How Much Credibility do you Assign to Bike Brand Wind Tunnel Claims? [BikeTechReview] [ In reply to ]
Quote | Reply
I'm not sure why people are so reluctant to provide p-values, it seems like a reasonable request to me, if someone is trying to convince people of the value of their testing.

For example, a paired t-test gives a p-value of 0.0004 for my CdA change from 2011 to 2012, and 0.0003 for my CdA change from 2012 to 2013, pairing the CdA values from the same course:



Of course, it's easier to get a low p-value if the change is larger, so the standard deviation and number of reps are arguably more informative. In my example above, the low p-value is mainly a result of the changes being large rather than the testing being high quality (however it did cost me nothing to collect the data, and very little time to analyse it).
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