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.

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!"

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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/

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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Swimming Workout of the Day:

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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.

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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Swimming Workout of the Day:

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2020 National Masters Champion - M50-54 - 50m Butterfly

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.

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.

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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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.

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.

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?

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Dan Kennison

facebook: @triPremierBike
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zero

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.

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Tom Demerly
The Tri Shop.com

Thank you for your thoughts. I think you have some very interesting ideas.

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Dan Kennison

facebook: @triPremierBike
http://www.PremierBike.com
http://www.PositionOneSports.com

"Obsessive-compulsive behavior: it's not a character flaw, it's a way of life." - Dr. Jim Martin

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.

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.

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.

"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.

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...

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'.

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.

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/

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http://bikeblather.blogspot.com/

They ain't even second :)

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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/