oh that sauce is weak!

interesting that both cervelo and specialized did it.

something about the protocol that wouldn't favor either of them?

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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

1st post, a plug for a magazine review.

question: do you work for scott, or tour magazine?

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Where would you want to swim ?

What is the difference between wind speed and speed of bike/rider? What I mean is when they say they were tested with a wind speed of 45/h, does that mean that is like the bike going 45/h on the road? Or is this wind speed just used to test the drag of the frames. Do some frames do better when the wind speed is lower or higher?
M~

since I can't read the original german, was the test down over various yaw angles? or only at yaw angle 0?

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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

Neither of both. Until now I just read the articles here. But after that test in the magazine I was just wondering why they withdrawed. Since this is the most famous forum and even some bosses of bike companies read here I signed up and hope to get some answers.

Let's see...

0 and 10 degrees. With and without rider. For the comparison they used the results without rider since the error was too imense with rider.

well, if they were truly 'independent', they'd have procured the bikes on their own and tested them. I'm fully aware of the economic constraints faced by a magazine in the bike industry, but that's the reality. If they're accepting product from manufacturers to test, that calls into question their objectivity right there.

It shouldn't have been that hard to get these bikes from a shop, either on loan or purchased at a price that would have allowed them to test the bike and re-sell it at little/no cost.

Well then I think we can see why some bike makers would have pulled out. If one design has great 0 numbers but stalls at 11 degrees it will look really good in this test.

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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

Sounds like they need to work on their test protocol ;-)

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http://bikeblather.blogspot.com/

you took the words right out of my keyboard...

Good post! Sounds logical. But as far as I know all those magazines get the bikes from the manufacturer itself, but you're right anyway!

In my research methods class (a requirement for my M.S. degree), we have learned a thing or 2 about bias. It seems as if that could be applicable in several situations in this "research". I'd rather have NO data rather than BAD data.

I'm not claiming to know a lot about fluid dynamics, other than what has been taught in the biomech and physics classes I've taken. Also, the last time I checked, the bike doesn't ride itself. What have 'we' deduced from the bike+rider interaction?...how does it affect the air+bike?

We have deduced there usually isn't much.

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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

Tour may be "the best" of the "poor'.
Not meaning that they are good in what they do (mechanically), but who will be able to differentiate between bottom bracket stiffness measured in a few measly Newtons...I also only see one value for aerodynamics, that probably means 0 degrees of yaw.

Politically correct one could say that they probably not rip apart the bike from a manufacturer that has a whole page ad in the mag.
And as a normally pretty well informed "guesser" told me:

Neither Specialized nor Cervelo got a discount on advertisement space, so they withdrew.

Oh, B.T.W.:

To my knowledge the CANYON bike won.

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___________________________________________
Ego numquam pronuncio mendacium,
sed sum homo salvaticus

I saw take this studies and try not to worry about them that much, find the bike that fits and fits what you want it to do and it will be just as fast/aero as the next! To many people have got caught up in this aero thing from all of these companies, let it go, all the bikes on the market are good bikes!

well since you said so it must be true?

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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

Goes back to this idea of a unified standard for aero testing:

http://www.bikesportmichigan.com/...orials/0000133.shtml

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Tom Demerly
The Tri Shop.com

So, the magazine determined the most aerodynamic tri bike without testing, arguably, the most aerodynamic tri bikes...P2, P3, P4, Trek TTX, Felt, Ridley, and Specialized?

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Shawn
TORRE Consulting Services, LLC
http://www.TORREcs.com

Actually that's the conclusion of the tour test! They state that the differences between those aero frames are marginal whereas the gap between standard road frame and aero frame is recognizable! The outcome was: No need to spend thousands of dollars for a high end triathlon bike. Get a cheap tri bike and work on your position!

Hoorah for Scott Plasma!
The value of my used bike just increased (if/when I prepare to sell).

There's no such thing as bad data...it always tells you something ;-)

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http://bikeblather.blogspot.com/

Well...DUH! But, what happens when you've got that position all "worked out"? Now what do you focus on (assuming triaining is maximized, of course)?

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http://bikeblather.blogspot.com/

I guess I'll buy the Scott instead of the Cervelo this year.

...And therein lies the pitfalls of incomplete, yet commonly regarded as "definitive", data. Some people actually do what you're suggesting jyeager....

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Tom Demerly
The Tri Shop.com

that is, of course, if you can actually see said data...

I'm having a de ja vu all over again...kinda like the Tour data Zipp poorly photocopied then used as marketing material on it's website. Let's see: I can't really read German,but even if I could, I really can see anything...

I think it's great that they're taking some bikes into the wind tunnel and all, but I almost feel that there should be a 'for entertainment purposes only' warning on the data.

With that said, I think that devising a testing protocol that would be realistic and 'fair' to all of the various bikes/companies would end up being a bit more tricky than it would initially appear.

If it comes from Cervelo, its treated like gospel around these parts.

Please tell me again where Cervelo finished at Paris-Nice in stage one, Oh, that is right 16th place, 30 secoinds behind over a 9.3Km distance, what happened there?

Not by me...as I've said before, I'm an "equal opportunity skeptic" :-)

I also think you might be overgeneralizing a tad bit...

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http://bikeblather.blogspot.com/

Doubt fear had anything to do with it.


100% speculation on my part, but I can see it going down like this: any bike company with a reputation for aero prowess and a history of megabucks spent on tunnel time might ask for details on exactly how a magazine intends to conduct a test like this...and if a "wrong" answer (or no answer) can't be resolved, they elect not to participate.


Carl


(disclaimer: I don't know if we were even contacted...might start developing a SuperDave complex ;-) )

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Carl Matson

Tom, it seems to me that the whole idea of aero testing, and differentiating between frames is anti-thetical to what you preach.

you have always been on the 'fit-first' message (which i agree with), so based on that, aerodynamics shouldn't be much of a concern (especially if aerodynamic differences are small, which they may be for aero frames). unless aero frames have the exact same dimensions, one must be a better fit for a person.


so, can you support aero testing? is it against your own principles?

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mckenzie

There is quite a bit of difference between wind speed and when the bike is moving to cause the "wind". Wind is laminar and the speed increases as the distance above the ground increases. Riding into the wind the speed of the wind is the same 1 inch above the ground and 10 feet above the ground. It could change the outcome of the test if this is not accounted for.

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Frank,
An original Ironman and the Inventor of PowerCranks

Well, my guess is that the TOUR testers still could buy the Cervelos and then test them anyway, right?

Doubt that a bike manufacturer has any recourse against that practice. Unless the mag does never ever want to sell ad space to Cervelo again.

So maybe TOUR has the data, but they don't publish them in the mag.

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___________________________________________
Ego numquam pronuncio mendacium,
sed sum homo salvaticus

100% speculation on my part, but I can see it going down like this: any bike company with a reputation for aero prowess and a history of megabucks spent on tunnel time might ask for details on exactly how a magazine intends to conduct a test like this...and if a "wrong" answer (or no answer) can't be resolved, they elect not to participate.

I think the fear answer makes more sense. If your bike is a bad ass as you say it is, then send it to be tested. Anything short of being included will bring up many questions. here is my 100% speculation: the P4 wasn't sent because it hasn't passed UCI requirements and is being re-designed so the cervelo team can race it.

 

Where did they finish in stage 2 and what does that mean?

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"the trick is to keep losing weight until your friends and family ask you if you've been sick. then you know you're within 10 pounds. if they start whispering to each other, wondering if you've got cancer or aids, you're within 5. when they actually do an intervention, you're at race weight." - Slowman

I'm looking forward to the day when we finally have a tri or TT where the course is actually in a wind tunnel so all of this data that we talk about can finally be relevant. Unfortunately in reality (where we happen to race) wind doesn't happen at a steady yaw and we do not pedal in a completely stable position at an even cadence. Every time our body moves slightly or we turn the wheel just so or we take a drink or eat some food or lift our asses to fart changes things just enough so that all the data we get from a wind tunnel is pretty much useless.

And the thing that almost never gets mentioned in all of the debates on this subject is that certain bikes will be more or less aero in a wind tunnel for certain riders since we all come in different shapes and sizes. Just because one bike might test better than another in a wind tunnel under one rider or even the DZ dummy doesn't mean that it would test as the most aero bike with you on it. And that says nothing about what your specific best position is on that bike or which bike would be most aero for your position. Since none of us will ever have the opportunity to test every bike out there with our specific position over every possible yaw angle all of this debate is meaningless. We talk about it because it is fun but it is no different than trying to argue whether Joe Montana, John Elway or Peyton Manning is the best quarterback ever. Fun but useless in any meaningful way. What I think is more telling is how sold some people are on the whole importance of bike aerodynamics despite the overwhelming evidence that it doesn't mean squat proven very and over by the fact that just about every bike out there wins in proportion to their ability to sponsor good athletes. And yet it is those people who preach the aero gospel who will dismiss those who do not buy into it as ignorant while never realizing that it is them that has been duped by marketing.

Find a bike that appeals to you AND allows you to get into your best possible position. Refine that position over time as you see fit and you'll likely get faster. Your position has WAY more effect on your speed than the relatively small bike you are riding ever will.

You know...you're right. It's all complete hooey and has zero utility whatsoever.

What was I thinking?? Carry on...

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http://bikeblather.blogspot.com/

Funny thing is I read somewhere recently where Steve Hed basically said the same thing and he makes his living off aero stuff. He said that aero testing of a rider in a wind tunnel makes a much, much bigger difference than the aeroness (is that even a word) of a bike, whells or other goodies. I'm sure someone can link to the quote. I think most of your aero testing is done in the real world with you on your bike. I'm not poo pooing that. Just the whole notion that one aero fram has any significant real world difference over another aero frame.

That sounds like a stunning result for a team with no time trialist on the 2nd best bike!

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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

fatbastard

as has been mentioned 1000 times here

wind tunnel tests are done at a variety of yaw angles, they move the bike this way and that in realtime and get data to replicate real world conditions.

I KNOW that you KNOW this, so why do you act like you don't?

It is also talked about here endlessly, that people HAVE experimented with how different riders interact with the frames to change the results, and it has been found that they rarely do, with weird bikes like the Trimble being exceptions. I'm pretty sure you have been around here long enough to know this as well. Do you just not BELIEVE it?


Furthermore guys like TomA/Andrew Coggan/Chung have done convincing REAL WORLD tests with power meters to show that frames do make meaningful differences

how can you go on believing otherwise?

I really don't get it. Give me insight into your mind here.

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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

Ummm...I don't think anyone denies that your position on your bike is the largest determiner of your total drag. But, what do you do when your done tweaking THAT lever?



Well...then how do you explain this?

http://forum.slowtwitch.com/...%20borrowed;#1802183

...of course, I guess it all depends on your definition of "significant", huh?

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http://bikeblather.blogspot.com/

Well said....

Find a bike that appeals to you AND allows you to get into your best possible position. Refine that position over time as you see fit and you'll likely get faster. Your position has WAY more effect on your speed than the relatively small bike you are riding ever will.

I know... science is the new religion. I'm generally a believer myself. Only the facts are constantly changing which suggests to me that they were never facts to begin with. I think we have all seen TomA/Andrew/Chung question the testing methodologies when they are published by the bike companies and rightly so since they tend to only release the data that shows them in the best light (also rightly so). Those guy should also know that in the real world it is virtually impossible to eliminate all possible variables which makes the margin of error potentially significant. And when you throw in the variables associated with trying to prove that the aero benefits of one aero frame over another aero frame with a rider in the exact same position over the course of an Ironman distance event it becomes next to impossible.

I want to believe but I'd rather just ride. Either way I still enjoy TomA and those guys trying to keep the bike guys honest with the geek stuff.

So basically they are saying that the Scott just might be the third or fourth most aerodynamic bike on the market. I suspect its actuall the fifth given the Felt's testing numbers and the P3s numbers.

Don't try to confuse this discussion with "data" and "facts". That is a really low blow. ;-)

I would argue that the data set is too small to extrapolate that time savings. It is a theoretical time savings. I'm guessing that you tried to really hold your position as steady as possible to eliminate variables. Your theoretical time savings assumes that you can hold that stable position over the distance we race in which we don't. Once we start popping up to grab bottles blow snot out of our nose or stretch our necks the theoretical time savings you got over your 10 minute test start decreasing. I would argue that on a 100 mile race there are enough of these little adjustments that equalize and ultimately marginalize the theoretical savings you achieve. Not to mention that with slightly different wind conditions the results you got on your test could have been even less significant.

Of course you are a much smarter guy than me (not meant sarcastically at all) so you would undoubtedly have great counter arguments to this. And I would ultimately have to retread my original argument which is that every bike out there wins a lot of races. The engine makes a huge difference. Positioning that engine correctly makes a huge difference. The bike under that engine makes a very, very small difference in the real world as race results prove over and over and over again.

Dude
if a frame is faster over an entire reasonable yaw sweep

it is going to be faster

its going to be faster if you sit up like a grandma

it is going to be faster if you are as aero as zabrisky

it is going to be faster if you use a sub9 disc

it is going to be faster if you use a box rim

it is going to be faster if you fart often, or rarely on the bike

theres simply less drag!

but i am glad people are skeptical, I for one can use the few extra minutes I get from being an aero weenie. Hell I see the direct effects of my efforts when I go to the local outdoor velodrome. On my commuter bike I get my ass handed to me. On my aero weenie bike I am unstoppable. it is like cheating!

;)

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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

So what? If you don't take racing seriously and can't hold a good position for most of the race you only get half the free speed of a guy who does it right?

What is the problem?

Not to mention, if you are blowing your nose on a P4 or Specialized transition, you are losing less speed than a guy blowing his nose on kuota

because it is more aero

if you blow your nose, you DEFINITELY want an aero frame, because no power is being applied, aero is all you have!

=)

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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

If you what you wrote above were true, then it would not be possible to use wind tunnel measurements to predict the power requiremet of cycling outdoors in very windy conditions to within 1-2%. As we demonstrated about a decade ago, however, it is; ergo, what you wrote above is not true.

No, science is science, and always has been.


Like so many, you are confusing absence of evidence with evidence of absence. Or, to put it "science-y" terms: there is a difference between making a type I error and a type II error.

That is almost certainly true if the individual in question hasn't already taken to heart all the advice that is out there re. aero positioning. If they have, however, then optimizing equipment choice can make just as big of a difference.

What would it cost to develop a test protocol, reserve wind tunnel time and conduct our own slowtwitch wind tunnel test? What if enough of us kicked in money, donated bikes and time, and paid for the testing? Is this feasible?

Cervelo has often talked about their wins in the prestigious German Tour magazine tests in their ads, so why wouldn't Scott be allowed to do the same?

Why are you asking me??

So Cervélo and Specialized pulled out...OK, but why didn't they test the Dean, this is one of the more popular euro offerings to date. Also, I wish they tested the Canyon TT bike.

I was a bit surprised that the Focus TT bike didn't test better since Andy Walser was supposedly involved in the project. Also, once you remove the Plasma 2, the bikes that placed 2-6 seemed to close to really matter.

If the Plasma 2 is so good then is the Giant TT superbike of Team Highroad/Rabobank that much better??

Dave in Va

The Walser TT bike bases its aerodynamics on the narrow BB standard. Once you default to the regular BSA BB then much of the aerodynamic advantages are lost.

Regarding the Plasma2, from what i understand the pros prefer to use the Giant TT bike because they found the headtube of the plasma2 too tall to achieve optimal position. Scott are apparently redesigning the headtube lengths for these pro cyclists to help them get lower.

I’m sure - think that they are afraid of not being as good as they proclaim (especially Cervélo with their P4).

Are you sure?

Did you contact people at those companies to know that this is the case?

Did you contact the magazine to verify their "testing" protocol?

Do you know that magazines have paying customers - in this case bike companies - who pay for the magazine to be published. Are you aware of the influence that these companies and advertisers may have on editorial?

With due respect, you need to be very careful of what you say in matters like this, because all is not what it seems on the surface.

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Steve Fleck @stevefleck | Blog

Demerly has floated that idea A LOT over the last 6 months and even wrote an article about it. He wanted to do a Slowtwith aero test. Everytime the question has been posed Slowman is noticeably absent in the response (to my recollection but feel free to correct me if that is not true). My guess is that it would hurt ST's ability to sell ads to bike companies who didn't perform well who would ultimately never agree to whatever protocol is agreed upon. To develop the protocol would be fairly cheap as TomA and those guys have probably devised one in their heads already BUT the professional engineers and wind tunnel engineers would undoubtedly say that the protocol was incomplete. Let's say you wanted to test 10 bikes. I think a2 charges $450 per hour plus an additional cost if you use their people for set up. So you are at $4500 for just 1 hour with each bike which would never be enough time to make an adequete determination. The test could easily be 10 times that cost once a protocol is developed plus travel expenses for those involved. The only way to make that happen is corporate sponsorship which will almost always mean giving up something (likely control over the protocol if the sponsors are the bike companies) for the money.

What we should do is set up a donation drive and see how much money we can raise over the next year. If we don't hit the goal then everyone gets their money back. Slowtwitch probably has the most credibility to do something like that but I doubt we could raise that much money with only the hard core people really giving a hoot about the data. Most people on ST are lurkers who are ammused by these discussions but are unlikely to pony up. We should try and see though. We might be surprised at the results.

Well one reason must be that the German distributor of Cervelo (and Zipp for that matter) just su'$s!

It is indeed true that I (1) wondered why Specialized & Cervelo would withdraw the frames but even more why (2) Tour didn't just go to a local bike shop an got two frames. Even it were only a P3C it would have helped. Then again they might argue: Why give then (possibly positive) exposure if they don't cooperate.

A real neutral tester would have bought/borrowed the frames in order to minimize the possibility to accused of manipulating the results. In a world driven by money however...

If you have to ask, you can't afford it? ;-)

Seriously, most wind tunnels seem to charge $750-1000/h for bicycle testing, and at least at TAMU you could easily test two bikes per hour at multiple yaw angles if the bikes were all configured ahead of time. So, figure at least $5k for 10 bikes for wind tunnel time - however, first you need to have the bikes, then you have to get them and the testers to the wind tunnel. That means you now need to budget for shipping costs, airfare, rental vehicle(s), food, and lodging for a couple of nights as well. In addition, if you were interested in measuring small differences, and/or if you felt it necessary to test with a pedaling rider aboard (which could readily obscure any small differences, due to their inability to precisely recreate their position each and every time), you would need to test each bike multiple times, ideally after removing it from the wind tunnel mount and then replacing it so as to account for all sources of variability. That $5k therefore could quickly become $20k or more...not a huge sum, by any means, but more than most individuals or entities would be willing to throw at the problem.

As for a protocol, I would suggest yawing the bike from 0 deg out to 20 deg or so (i.e., beyond the highest yaw angle you think the average consumer might typically experience), then back to 0 deg, then out to 20 or whatever deg in the opposite direction, then finally back to 0 deg. This would allow to not only check for hysteresis in the drag-yaw angle relationship, but also allow to test for asymmetries due to, e.g., an offset down tube as on the new Quintana Roo.

I am asking you nothing. This was a general question and you happened to be the last person in the thread.


sy

I’m not discounting your test but is it possible that you’re influenced by the placebo effect? I realize that a blind test is not possible.

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Duke

Then why not edit the subject line so as to avoid such confusion? (Also, please stop top posting).

It wasn't a life and death situation. Relax.

Could you describe the mechanism by which this placebo effect would work?

It wasn't a life and death situation.

Herbert,

For some this is life and death! :)

Here's the thing - and this is from my non-technical view. The testing and the numbers are great, but from what I can tell the differences between many of the top bikes, with the rider aboard are so small that my guess in a real world situation on the road, they would not matter that much. That the type of differences we are talking about here can easily be over-come in other areas and with better training.

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Steve Fleck @stevefleck | Blog

Cervelo probably spends more on advertising than most of those companies combined. Does that mean that we should be even more skeptical of the editorial claims made in their favor of which there are many? By your logic it would seem so and I don't disagree. Frankly, I'm with TomA as an equal opportunity skeptic. Only TomA is convinced that the differences are significant while I think they are marginal in the real world. The search, while fun, is a bit futile given the variables.

Would you say the same thing about wetsuits? ;-)

Cervelo probably spends more on advertising than most of those companies combined

Maybe. The funny thing is that Cervelo got to 2/3's of the way to where it is now by not advertising.

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Steve Fleck @stevefleck | Blog

I don't see how for a couple of reasons:

1. I can't WILL the power meter to read higher or lower while I'm pedaling and doing the test. In fact, the way the test is run, I have absolutely NO idea what the results are until I download and process the data.

2. In 2 actual TTs I did while borrowing the P3C, the magnitude of improvement in my times matched what was expected from the testing results. For equal power, I actually went faster...go figure ;-) In fact, every time I raced that P3C in the ~1 month I was able to borrow it, I set a PR on each course...now, in at least one case I had done it on more power than the year before, but even correcting for that, I was faster for a given power...and by the same magnitude as in the testing.

3. Being the "CheapAssEngineer^TM"...do you think I REALLY wanted to know that a much more expensive frame was significantly faster than my P2K? :-)

It's funny...if I had to pick a "seat of the pants winner" after doing the test runs and before looking at the data, I would've said that the P2K "felt" faster...but, the power meter doesn't lie...and that further emphasized to me the fallibility of human perception, or "feel", in making these sorts of determinations.

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http://bikeblather.blogspot.com/

Would you say the same thing about wetsuits?

Possibly. With wetsuits it's even more complicated. With a bike, you can put it in a wind tunnel on it's own and get some numbers. You can't do that with a wetsuit. You have to put someone in the suit and then they have to swim. That's why it's very hard to really rank wetsuits. One person could do some timed tests. You could do it enough times to get some consistent data. You would then get a ranking on those suits. Then someone else could do the same test and there is a good chance that, that ranking would be different - possibly very different. That's why with wetsuits, it's all about fit, because generally speaking the wetsuit that fits the swimmer the best, is the one that will test the best and thus be the best performing(faster) suit. In a way it's similar to bikes in that when you put the rider on the bike, those test numbers from the rider-less bike go right out the window!!

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Steve Fleck @stevefleck | Blog

Man can land on the moon and you think man can't figure out that a bike frame is faster?

Holy shit there is someone even more cynical than me

=)

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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

Now what if you took care of those other areas AND did better training AND had the best frame. This argument comes up all the time. It's not an either or. It's not like if you ride a Cervelo, Felt, Ridley, Trek (that's alphabetically ordered) that you somehow can't also train appropriately and also worry about the other details.

The *ONLY* time this isn't true is in cases of financial limitations - i.e., a p1 & the extra cash pumped into coaching/training camp/etc. is probably a better overall investment than just spending the same total dollars on a p4 if you can only spend the sum total cost of the p4.

But if that's not the limiter, then it becomes a moot point. Or, if time, and not money, is your limiter, then you can't necessarily train more/better/etc.

So there's a balance to all of this. But, for many people, this is never an either/or question. Especially if we are talking about the difference between equivalently priced frames.

There is one other example that I can think of, and that's pro athletes being paid. For example, if bike company X will pay you $X but makes aerodynamically inferior bikes to company Y that won't pay you, then you need to do the math on how much of an advantage in races the Y bike is vs. the X bike, and how much of an advantage in races is everything that you were able to do with the $X you got to ride bike X. It's not good math to ride a Cervelo in races if you have to work a job to pay for it instead of spending that time training/recovering properly.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp

Slowtwitch blasphemy! You mean you can't just buy speed?

I am willing to put money on the fact that you can take 2 athletes who are reasonably similar in morphology, experience, and ability, and put them head-to-head in an Olympic distance tri - one on a P4 and one on any 'decent' < $2k tri bike... any difference in finishing times will primarily come down to quality of training, transition times, how they feel on the day, pure HTFU, and any number of other factors - before the difference between the two bikes becomes a factor.

As has been said before, there's absolutely nothing wrong with buying nice things because you like having nice things. But all this endless back-and-forth over identifying what bike is truly 'the fastest' puts the lie to the idea that the guy who just dropped $5k or more on the new hot tri bike 'just likes having nice things'. At least on Slowtwitch, it certainly seems that people are buying P4's and the like because they actually want to be faster. A ridiculous idea in my opinion. That extra cash would better be spent on plane tickets to a training camp, or more frequent massage, or even a nicer road bike that gets you out riding more. All those things would likely have more effect on your finishing times in a tri than a marginally more aero frame would.

It's not good math to ride a Cervelo in races if you have to work a job to pay for it instead of spending that time training/recovering properly.

Jordan,

But that's what more than a few Pro triathletes do anyways!!

. . my wonderful wife being one of them! :)

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Steve Fleck @stevefleck | Blog

No, it would be possible because most of the resistance is well above the BB, where the speed of the airflow is more constant. So, in most instances this problem results in only a small error and it would be pretty much the same for all bikes. Besides, the wheel is turning so the spokes at the bottom are moving at zero speed in relation to the ground and twice the bike speed at the top, where the wind is the greatest, which minimizes the problem even more. However, I could see a bike manufacturers concern, if a lot of their improvements were near the ground (the P4 around the BB?) that a wind tunnel test, done by someone else who didn't understand this issue, would not reflect the full benefit of their design on the road.

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Frank,
An original Ironman and the Inventor of PowerCranks

the mechanism would be as follows:
the though of riding a faster sexier bike caused the air molecules to part like the red sea and created a vacuum into which his bike was sucked forward . This obviously could not be measured by his PT. Had he used an iAero at the same time he would have noticed that his iAero suddenly underestimated his bike speed because of less pressure on the iAero sensor.

Sigh...yet another person who apparently doesn't know the difference between a type I and a type II error.

Frank, Frank, Frank...just how thick do you think the boundary layer along the wind tunnel floor really is??

ok and what about once you have done the training?

Whats illogical about buying another 30 seconds?

*especially* when you can often buy those 30 seconds at the same price that you could buy 0 seconds with a less clever frame?

I mean seriously, what is wrong with using your head to chose a good bike that gives you free speed?

explain yourselves you luddites!

;)

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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

[/reply] If all bikes in your equation are priced the same then it obviously makes sense to buy the best performing frame out there - given other factors like fit and overall quality.

But if we're talking about a $2000 bike vs. a $5000 bike then it comes down to ROI... and the number of hours you have to work to pay for that $3k difference.

ok and what about once you have done the training?

Whats illogical about buying another 30 seconds?

*especially* when you can often buy those 30 seconds at the same price that you could buy 0 seconds with a less clever frame?

I mean seriously, what is wrong with using your head to chose a good bike that gives you free speed?

explain yourselves you luddites!

Jack,

If we were talking about a pure bike ITT here, then it would make sense. However, this is triathlon and their are so many other variables that go into a race as to make the real differences that are really at play here seem insignificant.

There is nothing illogical about what you propose - it makes perfect sense. However:

- Most triathletes do not train anywhere near to their best capacity

- Most triathletes waste tremendous amounts of time with other race day variables as noted above

- There are clearly other and better ways to improve triathlon performance

- Most triathletes load down their bikes with so much crap, that I am positive that it voids any gains some super aero frame/bike produces

Of course people are free to do what they want!

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Steve Fleck @stevefleck | Blog

Huh? Boundary layer? This principle of fluid dynamics holds everywhere. It is why it is better to put windmills high in the air than close to the ground. 100 feet up has stronger winds than 50 feet up and this difference follows a mathematical relationship. The difference, of course, is the wind tunnel also has a ceiling. The speed is only what one thinks it is in the center of the wind tunnel, which is why the model (or the major part of interest - the rider perhaps) is generally placed in the center of the tunnel, not on the floor.

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Frank,
An original Ironman and the Inventor of PowerCranks

Just to pick a nit and maybe make things more clear (or muddy ) I think this should be slightly rephrased:

There is always a substantial bike/rider interaction effect. However, there is little or no evidence that (with the exception of the Trimble) the bike/rider interaction is substantially different from bike frame to bike frame. Therefore if bike frame 1 tests faster without a rider than bike frame 2, when you test *with* a rider bike 1 will still be faster than bike frame 2.

I'd suggest with only pure eyeball speculation that maybe some other "odd" frames could have different rider/bike interaction effects, like the BP Stealth and possibly Zipp, Titanflex or Softride too. But with no tunnel data to back it up that's pure SWAG speculation.

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30 seconds saved on the bike per 40k is 30 seconds, no matter what happens to your run or swim.

though I do agree about loading bikes up with too much stuff!

which is why the P4 is so critical, you can finally put that crap in the aero frame holder =)

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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

The boundary layer is a reflection of the phenomenon of which you speak. My point is simply that, contrary to your initial claim, the effect is entirely insignificant, at least in this context.

I am not aware of any evidence to support that claim. (Indeed, since it is hard to assume a cyclist's posture without actually sitting on a bike, I'm not sure exactly how you would go about testing that hypothesis...although the fact that the drag of downhill skiers in a crouched racing position is comparable to that of a cyclist certainly implies that it isn't true.)


Older designs such as the Lotus, Zipp, Softride, etc., were often included in wind tunnel tests, but again, only the Trimble showed clear-cut evidence of an interaction effect.

30 seconds saved on the bike per 40k is 30 seconds, no matter what happens to your run or swim.

Jack,

I don't deny that. But at some point it becomes strategic in the context of the triathlon race as a whole. That's great that you saved 30 seconds on the bike. You get off the bike exactly with your key competition - can you now out run him/her? Suddenly, that amazing 30sec you saved on the bike becomes rather insignificant - you need to beat that guy to the finish line on the run!!

Or you could look at it in another way - maybe, it's not a 30 second time saving but a watts saving and that watts and energy saving will allow me to run that much faster then the other guy.

Or say I just transition faster - maybe 30 seconds faster bike and that gain is gone in a flash!!

I have won/lost races by 10 seconds or less over the years and not once did I ever feel the need to blame, second guess or think about, how aero my bike frame was.

This is what I meant about all the variables at play in a triathlon race - it's not just a straight up ITT. If it is, then you ALWAYS would want the bike that you would be faster on. Here, that is important, but not critical.

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Steve Fleck @stevefleck | Blog

It may or may not be insignificant. We are talking about pretty small differences between these bikes. My point is I could see why a bike manufacturer who has substantial improvements near the ground might be concerned about wind tunnel tests. When riding a bike in still air the speed of the wind at the BB is exactly the same as it is at the riders shoulders. These wind speeds are not the same in the wind tunnel which could affect the reliability of the results.

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Frank,
An original Ironman and the Inventor of PowerCranks

All you need to do is look at some smoke trail photos to see that the rider has a significant effect on the air movement around the bike tubes. When your calf is rotating around and knees 1/4" from the top tube there is indisputably an interaction. I don't think this point is in dispute, just that it isn't substantially different from frame to frame. Thanks for the info about the other odd frames, I wasn't aware that they were included in the same sort of testing as the Trimble.

Edit: Actually I think you probably could attempt a test like that, but it would require a pretty big investment in welding and machining. Simply set up the three points (seat, cranks and armrests) with a space frame that is very far from the rider. Then test the same rider in the same position on the actual bike...and the bike solo. As long as you keep the support structure for the "fake" bike frame far from the rider it would be functionally similar and might be a "good enough" approximation to see if there were significant differences.

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Just because you didn't feel the need to blame the bike doesn't mean you wouldn't have won that 10 second race on a better frame. I understand that perhaps your competition would have still outrun you once you pulled along side him. But maybe he wouldn't!

Of course it isn't critical

But if I need a tri bike, and have say, $X to spend.

There are bikes that are a a lot slower than others in every price category.

Taking some time to find the faster ones is perfectly reasonable to do

and for those of us that just enjoy being aero weenies, we would LOVE to have rational discussions without people constantly pointing out shit that is either not true, or obvious stuff we all knew anyway.

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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

To reiterate: about a decade ago we published data demonstrating (if you think about it, anyway) that the effect is insignificant. Or to put it another way:

"The great tragedy of science - the slaying of a beautiful hypothesis by an ugly fact." - Thomas Henry Huxley.

Just because you didn't feel the need to blame the bike doesn't mean you wouldn't have won that 10 second race on a better frame. I understand that perhaps your competition would have still outrun you once you pulled along side him. But maybe he wouldn't!

Jack,

That may be true.

As I said their are way too many variables that go into a tri race that loosing sleep over small gains/losses from bike frames is not worth the time.

This silo-ization of the bike in a triathlon and everything to do with the bike be it, equipment or training etc . . I have always found odd and it reaches it's zenith here on Slowtwitch. Triathlon is made up of three sports. People who are serious about improving their triathlon performance would be wise to expand their view beyond just what happens and goes on with the bike.


and for those of us that just enjoy being aero weenies, we would LOVE to have rational discussions without people constantly pointing out shit that is either not true, or obvious stuff we all knew anyway.

Go nuts! :)

Saw an interesting video clip at TriFest during Dave Scott's Keynote address at the big dinner. Everyone goes on and on about 1989 and the great Iron-War bewtween Mark Allen and Dave. Dave showed a few video clips from 1986 - that to me is the real shocker - Dave went 8:20 something on that day on a steel road bike, with box rims, road handle bars, a Bell helmet that looked like a giant mushroom on his head, toe-clips and straps, a loose fitting singlet flapping in the wind and baggy tri shorts!

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Steve Fleck @stevefleck | Blog

Well … I know I’ll be more determined and motivated riding on a new fast and slick bike versus on an older and slower one.

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Duke

And what do you think the power meter will say when you are more determined and start pedaling harder?

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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

I spent the last year basically not riding a bike at all, just running running running, and doing my first marathon

as it was a weak point

during that time I gave some thought to aero weenie concerns.

I then hopped on my aero weenie bike and was FAST (relative to local sprint tris) well beyond my actual talent level should probably indicate.

time well spent, I think =)

and I didn't spend a lot of money either, mine is an old 'n busted model =)

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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

Very cool. Just out of curiosity could you give a link to that study or tell us how you did that. It seems to me that is is impossible to look at this data on the road without a rider on the bike. Is it possible this effect is being lost by the resistance of the rider, which is mostly much higher off the ground than much of the bike, which dwarfs the resistance of the bike. Seems to me all you could say from such an analysis is the effects of the bike are small compared to the whole and not that wind tunnel tests of a bike alone are reliably reflect drag resistance on the road. But, you may be right but I would like to see how you did it.

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Frank,
An original Ironman and the Inventor of PowerCranks

WHERE IS THIS MYTHICAL PLACE OF WHICH YOU SPEAK?

My favorite are the people that don't understand what it is to harvest meaningful, repeatable data in a lab setting. Like one just puts up the DUT and the computer machine says 'drag' or not. Most likely what occurred, as already described, is the two companies that withheld their product from the test didn't feel that the testing protocol was reliable. I wouldn't have my well-designed product lend credence to a study that was all over the map either.

http://www.humankinetics.com/...N6NX6jJ2fszN8Ttsite=

www.wattagetraining.com/forum

I don't just pedal harder. I may also focus on staying in the aero position longer and make myself more slippery.

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Duke

Thanks. But, that paper didn't address the question at hand. It simply said that cycling power (total power that included the rider) can be modeled with about a 3 % error. No attempt was made to look at the bike frame component at all, which is what is being discussed here, as I understand it. That paper simply does not address the issue I brought up.

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Frank,
An original Ironman and the Inventor of PowerCranks

It figures that you would attempt to obfuscate things so as to cover up the fact that you were wrong.

Here is what M~ originally asked (emphasis added):

"What is the difference between wind speed and speed of bike/rider? What I mean is when they say they were tested with a wind speed of 45/h, does that mean that is like the bike going 45/h on the road?"

Here is what you said in reply (again, emphasis added):

" There is quite a bit of difference between wind speed and when the bike is moving to cause the "wind". Wind is laminar and the speed increases as the distance above the ground increases. Riding into the wind the speed of the wind is the same 1 inch above the ground and 10 feet above the ground."

So, don't go trying to claim that the question pertains to bike-only tests...

(BTW, the S.E.E. was 2.7 W, which was only 1-2% of the mean...this is not "about a 3% error" as you erroneously stated.)

speaking of obfuscation, the OP then wrote, which you conveniently left out: "Or is this wind speed just used to test the drag of the frames. Do some frames do better when the wind speed is lower or higher?" That part of the OP's post went to the frame alone. The question also came up in this thread as to why certain bike manufacturers would not want to participate in a wind tunnel challenge to determine frame aerodynamics. Reading my answer that you copied does deserve a little clarification however. What i should have said is: Riding into still air, the speed of the perceived "wind" is the same 1 inch above the ground and 10 feet above the ground. My comments regarding the usefulness of the paper you referenced to address this question stands.

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Frank,
An original Ironman and the Inventor of PowerCranks

On the contrary: since there is a boundary layer during wind tunnel tests, the fact that you can use wind tunnel data to predict the power requirements of cycling outdoors with such precision demonstrates that the impact of such a boundary layer is - as I have said all along - inconsequential.*

*As can also be demonstrated by simply reading the wind tunnel specifications found here:

http://lswt.tamu.edu/...ance_Characteristics

which report that the boundary layer is only 1.5" thick, i.e., way below any frame member on a bicycle.

What are these changes in position and, at the moment that you're on the bike collecting the data, how do you know that they lower rather than raise CdA?

Oh, phooey. That might be true if one were looking at the bike frame alone on the road and in the tunnel. But, when there is a rider on the bike these changes from the bike frame, especially those that are only close to the ground where these differences are more pronounced, are going to be so small that it is unreasonable to conclude that data that looks at the rider and frame together (where the vast majority of the drag is coming from the top tube of the bike up) is so sensitive to pick up this small effect. Perhaps your 2% error is due entirely to this effect. That would suggest that if one were to look at the frame alone the error would be much greater.

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Frank,
An original Ironman and the Inventor of PowerCranks

Man can land on the moon and you think man can't figure out that a bike frame is faster?

Dude, it is common knowledge that the moon landing was staged. You are so gullible. ;-)

Maybe it wasn't staged; maybe it was a placebo effect.

Maybe it wasn't staged; maybe it was a placebo effect.

Well since we really wanted to get to that sexy new moon you are probably right. I bet they were a lot slower coming back to this old boring planet.

You should use your connections and create a DVD on bike aerodynamics and the relationship to power production. I think the only way for people to appreciate this subject is to understand it visually. You could probably work with A2 (since they seem to be eager to get their name out there) or the one in Colorado. I'm quite sure you could sell that DVD. After all tons of people pay $20+ for a dvd just on transitions. Get to it, bro!!!! I'll take my 10% if you make any money. ;-)

If we act now, we can probably get stimulus funds for the aero testing. What is $30K for the government? Can we all stop arguing and write a proposal?

This is really silly.

It's not just silo-ization of the bike and it makes complete sense. Sure, there are a tons of variables that go into a race that can affect the overall time of the athlete. But by your reasoning, there's no reason to worry about which wetsuit fits me best and is therefore fastest. It's only going to make a difference of a few seconds and I could easily lose that because I stumble on the way out of the water. There's no reason to have my shoes clipped in to my bike since that's only going to save me a few seconds, and I might lose that because I didn't train enough on the bike. There's no reason to use the most aerodynamic frame I can afford, because that's only going to save me a few seconds and I might lose that because my position isn't optimal. There's no reason to use yankz or speed laces because those will only save me a few seconds and I might lose that because I didn't hydrate adequately. And on and on and on.

Everything from training to pacing to race day conditions will affect your time, but the equipment you select is completely independent of all of those factors and will save you time in every single case.

I'm pretty sure you missed the point by silo-izing your response!

Everything from training to pacing to race day conditions will affect your time, but the equipment you select is completely independent of all of those factors and will save you time in every single case.

That's right.

My point was that people seem to overly analyze everything related to the bike here almost the exclusion of everything else.

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Steve Fleck @stevefleck | Blog

Please see my edited comment. I'm thinking how a placebo effect may have on ME if I conduct a similar test. Not knowing any details of Tom A.'s testing, I asked him if he could be biased. It was a question and not an attack on his testing and note that I didn't argue with his reasons.

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Duke

I did not interpret your question as an attack, nor should you interpret mine as an attack. Since Tom has linked to a thread where many of the details of the test procedure have been discussed, I'm asking about the mechanism by which a placebo effect could both explain the size of the observed difference and be undetectable.

Really?

Do a search on "running" and "pose method" or "chi"...or on "high arm" and "swimming"...and tell me how many threads come up ;-)

Also, in a typical tri, isn't more time spend cycling than either swimming or running?

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http://bikeblather.blogspot.com/

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I think first of all bikes are built to be ridden by an athlete. With a test without rider we know now a Scott alone in the Windtunnel is the best choice. If you have alot of races like this on your schedule, the buy it. If not, then you have to wait for a serious test with a pedaling rider on the bike. But:

Fuer die abschliessende Bewertung der aerodynamischen Qualitaet haben wir daher nur die reproduzierbaren Messungen der nackten Raeder ohne Fahrer verwendet.

makes not so much sense.

Did you read the whole test? Then you would've realized that the bias was just to high with rider. The only rational hing to do is to put a kind of plastic dummy on the bike. But obviously there's no bike/rider interaction aerodynamic wise, so you just can test the bike alone.

Btw: I don't wanna offend you and many others but this kind of post of know-it-alls, who try to sell their half knowledge makes 80-90% of all those posts here rather useless. I rather trust a renowned bike magazine than anonymous slowtwitch posters :-)

Yes, for sure if the differences between each frame with rider have been too small to come out of measuring tolerance, there is no interaction from the rider to the frame aerodynamic wise and we can measure the bike alone. And the difference between riding against wind or standing air we can forget completely.

But weak people still better wait for a test with real experts, who do not sit on the bike with the most wrinkled winter suit I ever have seen, fleece gloves and neoprene ear warmers under the helmet. And if they think they have to do a test in a tunnel, maybe they find one next time with adjustment of the temperature to bring the character of the air flow to a normal race level.
But til then we know that in winter air a Scott without rider is the best choice. No more.

I think you need to read the paper that Andy Coggan links to SO often (such as previously in this thread itself) describing the correlation between tunnel data and actual field measurements.



It makes perfect sense if you have read and understood the Kyle data that Doc C also refers to often showing the correlation of bike alone vs. bike with rider drag (with the rare exception of bikes like the Trimble, which is VERY different than the bikes being discussed).

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http://bikeblather.blogspot.com/

The bias?, or the "noise"?



Or...refine the test protocol ;-)




Are you talking 'bout me? :-)

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http://bikeblather.blogspot.com/

Test is flawed, Euros have such a fetish for everything Scott- it's outrageous. Ski, bike, they just dig it. Conflict of interest makes this test non-legit.

Depends on what the source of the error is (mechanical, positional, architectural), but in some wind tunnels the precision of estimated CdA of a bike with rider is around .001 - .002 m^2.

I thought the problem of the rider is that he will always sit a little bit different or move and falsify the result because of that...

The imprecision that Robert mentions (i.e., CdA being reproducible to 0.001-0.002 m^2) includes - and indeed, mostly reflects - the source of variation that you describe.

The cheapo magazine should have just purchased the spec and cervelo frames. They don't need permission to test them.

I'd hardly call it a complex. It's my job.
-SD

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https://www.kickstarter.com/...bike-for-the-new-era