I said to my wife ' hey hun, specialized have done a bit of wind tunnel testing, and whaddya know, shaving the legs saves over a minute in a 40km TT'.....i got the same response as you.. 'do that shit and we are getting divorced'.

Please do whatever you need to do in order to fix the data that shows arm hair does not impact drag.

Between the legs, face, head and a little manscaping, I ain't got much left.

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Chicago Cubs - 2016 WORLD SERIES Champions!!!!

"If ever the time should come, when vain and aspiring men shall possess the highest seats in government, our country will stand in need of its experienced patriots to prevent its ruin." - Samuel Adams

You and me both. My wookie arse ended up 2nd in my AG by 6 seconds a couple weeks ago...

Question for Mark Cote and Chris Yu:

Wind tunnels and razors have been available for a long time now. Why did it take so long for some one to do a controlled wind-tunnel test of this? What I'm saying is - I'm sure this has been tested before and (I'm assuming) the tests have shown that aero gains from shaving to be insignificant. Has everyone who has ever said, "shaved legs don't matter except for road rash" just been BS'ing all of these years?

Not trying to troll - I'm genuinely interested in your answer to this.

I do not think that assuming this testing has been performed before is a good assumption. Why would someone test this before? Why would a bike company test this, they would spend their expensive windtunnel time actually improving their product. Same with a wheel manufacturer, they would test wheels, not test shaved legs. Sure some people may have had a bit extra time and tried a one off, but then maybe would have looked at the results and assumed they messed up. It really takes someone to be able to this a bunch of times.

Now that specialized has a windtunnel, they can now do this sort of thing as advertising. They can show the consumer, "Hey, look at our capabilities! We are putting these same tools and knowledge into our bikes!".

For you full sasquatch wookiee types, can i take it this to mean that you're alright with the hairs poking out of your shorts all over your ass and around your junk?

I agree... Some pretty odd things have been tested in the tunnel... I just have a hard time thinking this never came up before as often as it's given as a reason to shave your legs.
Admittedly it could've been tested and the info just never got out, and repeatability is there (w/ multiple athletes) in what Spec has put out.

Glad I've always shaved nonetheless. (I always did it because of the cultural thing...)

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My Blog - http://leegoocrap.blogspot.com

> They can show the consumer, "Hey, look at our capabilities! We are putting these same tools and knowledge into our bikes!".

It also shows that:

a) there will never cease to be amazingly counter-intuitive results from the wind tunnel

b) not everything can be easily replaced by computer modelling. Try a modelling a variety of leg hair in STAR CC+, etc. I bet it's not fun.

Why would someone test this before? Well at the beginning of the video one of them said that the shaved legs thing is one of the most frequent questions asked about aero, that's why.

Specialized is a bike / components company, and they just tested shaved vs. unshaved legs. You just answered your question "why would a bike company test this?" in your last sentence.

Wind tunnels have been around for a long, long time so I'm just wondering if there are any other studies / tests and if not, then why did it take so long. In fact you don't really need a wind tunnel to test this - people have been measuring the real-world effects of aero for quite a while outside of a wind tunnel using controlled roll down tests or riding around a track with a power meter. I even remember reading an experiment that Mark Cote did at Specialized using some Australian ProTour cyclist, a closed velodrome / track, and a power meter (I think it was to test effects of tri bike vs. road bike with aero bars, TT helmet vs aero helmet, and other stuff).

In short - since everyone has been debating this ad nauseum since the beginning of time, is this really the first test of shaved legs in a wind tunnel? If not - then how do the other studies compare?

no?

Wait, you don't think that would be fun? Seems like a fun project to me.

What about going from very hairy and using an electric shaver to trim down but still having stubble and not doing the full shave. Thoughts.

Because people love to debate thing, but people are less likely to put the actual work to actually test it and also it is not like many people have the tools and knowledge to test it (powermeters for field testing have been less common until recently and using them for it takes some skill).

Just imagine you are a Cervelo engineer and you have a limited amount of windtunnel time, do you think your boss would rather have you spend that time testing changes to a new frame design or seeing if shaved legs saves any time? Let alone getting the multiple people to do that testing. Or if you are testing pro tour cyclists that already shave their legs and would not be racing with unshaved legs anyway, why spend time in the tunnel with the pros testing this, it makes more sense using that time to test positions and equipment.

I think the biggest reason it has not been tested is that nobody thought it would be this big of a result.

These are good points. Also, your the last point could easily have the words "computer modeling" replaced by "wind tunnel". The goal of all of this is to find free real-world speed, and the computer and wind tunnel are just simplistic models of the real world.

In Michael Hutchinson's book Faster, Chris Boardman talks about how computer modeling enabled British Cycling to calculate esoteric stuff and just let the computer sit there and crunch for hours overnight to find marginal gains in areas that no one would ever think of looking (shape of the front fork, for instance). Then they would actually test what the computer suggested with a real rider on a real bike. More often than not, the computer's suggestions did not ending up making any significant difference in the real world. But sometimes it did. And it was a lot easier to have a computer point them in the right direction than just randomly guess and try changing everything one piece at a time.

The wind tunnel is the same thing - results in the wind tunnel often do not match up with what you get in the real world. Boardman talked about how surrounding trees / foliage and buildings would often complicate things, especially when you're talking about things like dirty air caused by rotating wheels and churning legs.

A lot of wheel companies, I suspect, test their wheels in the wind tunnel by themselves (not on a real bike with a real rider pedaling). Which doesn't really have any applicability to how they will be used in real life. Same way a lot of tire companies test their tires on a steel drum (not on a real bike with a real rider pedaling).

Anyways I'm not trying to argumentative or simply trying to be a contrarian here. I'm by no means a professional aerodynamicist, I'm just interested in this topic and try to read as much as I can about it. That's why I'd like to hear what Mark and Chris have to say about this.

Huge thanks to Specialized for doing this and letting us all know. My next bike will be a Specialized, such a great idea publishing these short videos.

I wouldn't entirely agree with this. Yes trees/foliage will change the wind speed you might have expected at ground level if you were modeling things, but generally if you take a rider with a wind tunnel measured CdA, have them do a time trial, run the power meter data through the equations of motion of cycling, you get results accurate within a few seconds.

Or, you can look at the TT results and compute the power the cyclist must have done and compare that to the measured power, and that is also very close, see: http://www.recumbents.com/...20road%20cycling.pdf

Given the numerous confounding factors, such as not having perfect data about ambient wind, power meters not being perfectly accurate, riders not holding their wind tunnel positions perfectly all the time, that modeled vs measured data is so close suggests a wind tunnel represents the real world very, very well.

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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

Thanks for the response - that's what I was looking for. A quick Google search does turn up lots of references to the Chester Kyle report (0.6% saved when shaving legs), but unfortunately I can't find any links to the study itself. So we can't really compare it with yours and discover why there was such a big discrepancy between the two studies.

I agree that wind tunnel testing is prohibitively expensive. A few years ago Bicycle Quarterly did a very comprehensive wind tunnel test, which they were able to rent out either for free or at heavily discounted rate (it was at a local university and one of their testers either worked there or had connections there, please don't quote me on that). They tested the effects of baggy clothing, loose cycling jersey, skintight jerseys, handlebar height, front vs rear panniers, front vs. rear fenders, pretty much anything you can think of. Except for shaved legs, since they assume that they were so insignificant as to not even merit testing.

So I guess the answer is - no one has tested this before because no one has thought it was worth testing.

did you look at just leaving a strip on the backside of the legs :) kinda like what some folks say to do to the trailing edge of forks

Wind tunnel testing is very expensive. Who is going to pay for 2-4 hours of tunnel time just to test shaved legs? For just one person. To do a real study with a bunch of riders like Specialized did would probably take several days of tunnel time. I believe commercial tunnels cost in the vicinity of $10k a day. Who's going to pay for that? As somebody else mentioned before the manufacturers aren't going to do it. They don't care. Any individual who is paying for their own tunnel time is already shaving their legs and if they are wondering, they aren't going to spend the close to $1,000 for the tunnel time it would take to test this.

I believe that the Specialized tunnel is completely unique in that they have the leeway to do this kind of thing. Other tunnels need to make money to stay open. I would imagine that the Specialized tunnel falls into a mixture of R&D and Marketing overhead costs for Specialized.

Basically, it's a whole lot cheaper to play better safe than sorry and shave your legs than it was to spend money on tunnel time to find out for sure.

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Kevin

http://kevinmetcalfe.dreamhosters.com
My Strava

+1 jackmott's comments. We use three "tools/methods" for aero research - on road/track, win(d) tunnel, and CFD. Each has its strengths and weaknesses but each is setup to represent real world conditions. We do a ton of correlation work to make sure that what we measure in one tool is calibrated to the experience on the road.

Mark

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Mark Cote
MITAerobike
Specialized Bicycle Components

Well your last point also applies to just about anything that people buy to gain free speed - wheel sets, helmets, skin suits, shoe covers. All of these cost less than a day in the wind tunnel so should we just be safe and buy them all?

I agree that no one would spend thousands of dollars to just to test shaved legs, since they're probably doing it anyways if they're at that level. But lots of people rent out wind tunnels for days at a time to test dozens of variables, and I just found it curious that no one else thought to just test shaved legs for the heck of it (until Specialized just did).

Some people assuredly have tested it, and not told anybody.

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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

This really makes me like Specialized.
You will have my heart next bike I buy.
Thanks for the info

Well here's another question I have - if this is true, then either they found the same thing Specialized did and kept it to themselves (unlikely). Or what they found mirrored what everyone previous figured (shaved legs don't make a significant difference). If it's the former, you can bet I'd let other people know about it. Because an 8% drag reduction is very significant. If it's the latter, then that's valuable to know as well.

It's great that Specialized has done this study, and I hope there will be future studies to compare it with. Because ultimately that's how everyone comes to a consensus on something - peer-reviewed studies and tests either put forth or confirm hypotheses, and eventually they become accepted as fact. It's a shame that we can't take a closer look at the previous study done by Chester Kyle. If we could, then it would possibly even further strengthen the case for shaving your legs, if it can be proven that Kyle's study was flawed in some way or was less rigorous than Specialized's. The converse could also be true.