Aero Makeover: the Specialized Win Tunnel

Editor’s note: we’re revisiting this piece from 2015 as a result of some questions we’ve recently fielded regarding both aerodynamics and leg shaving, and the aerodynamics of leg shaving.

My life is full of competing desires. I want to be a good father. I want to drink wine (or beer) with dinner. I want to stay married. I need to write on a daily basis. And I love riding my bike fast. The number of hours I’d like to do each of those every week works out just fine until I factor in six hours of sleep per night. The plan actually goes to hell at four hours a night.

I’m simply not going to get as many hours to train each week as I’d like. The weeks where 18 hours on the bike and soft-pedaling a 53×19 uphill were routine are receding like a shoreline in a storm. If I get 18 hours on the bike now, it’s because I’ve taken a vacation from at least two major responsibilities, and I’m likely to pay once enough blood is flowing to my brain again for me to think straight.

With due regard for the pressures of fatherhood, marriage and career, I don’t want to stop riding my bike as fast as I’m able. I recognize that’s a bit like saying, I can get a great shot of that water buffalo once I move the lion off of it. Making a bike lighter, if you follow the math, won’t pay much in the way of dividends, and lifting weights at the gym only starts to pay off once I stop lifting, so neither of those will yield the benefits I’m looking for. However, my experience with aero equipment over the last few years has told me that I can reasonably expect to pick up at least one cog’s-worth of fitness by doubling down on aero.

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Normally, my story ideas don’t require much in the way of selling someone else on my escapades. I don’t have to write queries the way I did when I was freelance, or pitch my editor on what a terrific idea I have, what with me being the editor and all. But this occasion required some help.

I placed a call to one of my contacts at Specialized. The question was, would they be willing to allow me to visit their wind tunnel for some testing guided by questions I had? When I told them just what I had in mind, they gave a ready yes. Cool.

My idea was simple: I’d pretend I worked for the cycling equivalent of a women’s magazine and we’d do a makeover, just this one would be for aerodynamics. Kidding aside, when you encounter stories about pros going into the wind tunnel, the goal is to optimize equipment choices and position for the greatest possible gains. They change their position to achieve greater aerodynamic efficiency.

Um hello? I may not be old yet, but I’m getting old, so the last thing I want to do is mess with my fit. Any changes I make to my fit are meant to optimize comfort and efficiency. What if you used the wind tunnel to figure out what you can do to be faster without making yourself uncomfortable? I’d much rather give up some time and have a position that I can pedal in for a few hours than a position that renders me ninja to the wind but I can only maintain for 45 minutes.

That no one within Specialized had considered this and no one they worked with had mentioned it shocked me. It seems such a no-brainer, but maybe this is just another example of how I always end up at the shallow end of any given bell curve.

Specialized’s Cameron Piper walked me through how the testing would be done. I needed lots of instruction.

Slicing the pie
Because I wanted something that was direct in its analysis and appeal, and also because I knew I’d have a piece of one day to do all the testing, I suggested we analyze three different setups.

Test one was simple; it was as old school a setup as one might reasonably encounter today. I would don a traditional pair of bibs, a relatively loose-fitting jersey, an old helmet and ride my steel Bishop with a Dura-Ace group and box-ish rims. The cherry on top was that for five months I’d let the hair grow on my legs.

Test two would be the low-hanging fruit. I’d shave my legs and swap out my helmet for a Specialized Evade and trade my kit for a Specialized SL Pro jersey and bibs, a pro-fit kit. This was an upgrade any cyclist could make for less than $600.

Test three would be all-in. I’d keep the kit and add a Specialized Venge plus Roval CLX 60 wheels. We did our best to accurately replicate my position on the Bishop. According to the tape measure, we were off by less than a centimeter overall, but more importantly, in video analysis, my position on the two bikes looked identical. Test three was as aero a solution for someone riding on the road (short of going with a TT bike) as we could manage without going to other suppliers or geeking out over each and every detail. The point was to back up and look at the bigger picture.

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I can’t recall the last time I was so excited to shave my legs.

For each of the different configurations, we did five tests, or “blows.” We did two blows at 0 degrees, then the platform was turned left to 10 degrees and two more blows were performed. Finally, the platform was turned back to 0 degrees and a fifth blow was performed. Each blow lasted one minute. In between each blow Cameron Piper, the aerodynamicist I worked with, instructed me to sit up and spread my arms. This was mostly just to create a visual cue that would separate each test on the video analysis.

Because we wanted as consistent a data set as possible, Cameron asked me to find a position in the drops that I could maintain for long periods, a position I would be able to ride in reasonably efficiently. I adopted a position with a slight bend at my elbow, just the sort of position I’d take if I was at the front of a group and planning to stay there for 10 minutes. Cameron also asked me to find a point on the wall ahead of me and fix on that during the blows so my head wouldn’t move around.

When I shaved my legs and changed my kit and helmet, I could feel a difference in the tug of the wind.

Finally, to produce realistic results, I needed to pedal at 100 rpm, and a heads-up display projected a graphic representation of my cadence on the floor ahead of me. I’d be able to maintain head position and look down at it periodically to make sure I was as near to 100 rpm as possible.

We followed this procedure for each of the three setups. At the end of this series of testing we then did a final series of blows that differentiated between riding on the hoods, riding in the drops and then assuming an aggressive position in the drops. That final set of tests will be covered in a separate post.

I’m going to stop here and address the readers out there who are going to ask why we didn’t do blows at 5, 15, or any other yaw angles, or why we didn’t swap out just the kit or make other incremental changes. The answer is simple. Specialized gave me the time in their wind tunnel, gratis and they devoted a half a day to me. Had I rented that much time at the San Diego Low-Speed Wind Tunnel, I’d have needed to sell my car to pay for it. We needed to be efficient.

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That I was faster with an aero kit, an aero helmet, shaved legs while aboard an aero bike with deep-section wheels was unsurprising, a foregone conclusion. The point behind the testing was to get a sense of just how great the gain would be.

After doing our first round of tests, I whipped out the clipper and razor to take the hair off my legs. The process of growing the hair out on my legs had been follicular equivalent of nails on chalkboard. After the first month, the feel of the wind through the hair on my legs had been torture. I hadn’t had hair on my legs since the winter of 1995-1996 and the sensation of having the follicles teased by the wend was intense and distracting, like trying to have sex on a bed of nails. Interestingly, the intervening years had seen some follicles cease growth. Chris Yu, another of Specialized’s aerodynamicists, gave me a Wookie Factor of just 5, so shaving my legs wasn’t going to make as much difference as it would for someone who had never or only rarely shaved their legs.

At 0 degrees, my coefficient of drag (CdA M²) on the Bishop with the old-school kit was .345; with the aero kit and helmet it dropped to .326, while swapping the Bishop for the Venge and CLX 60s saw it drop to .308. At 10 degrees the effect was more dramatic. Rolling old-school, my drag was .368. Swapping kit saw it drop to .346 and with the Venge it dropped to .307, even lower than at 0 degrees; this lower number was as a result of negative drag, also known as sail effect.

Figure 5

But let’s be real. CdA M² is just a fancy number, one that’s as difficult for most of us to digest as it would be to eat sand. Let’s talk time, instead. With the Bishop, hairy legs and old-school kit as the baseline, swapping to aero kit, smooth gams and the Evade helmet would result in between 73 seconds (0 degrees) and 126 seconds (10 degrees) saved over a 40km effort. That 73 to 126 second savings is consistent regardless of output, which is to say that if you rode 40km at a consistent 150-watt effort, the aero setup would save you 73 to 126 seconds over the distance. That 73 to 126 second savings would also be true if you killed it at a consistent 300-watt output. This is because as you go faster, the aero savings is greater.

When we substituted the Venge with the Roval CLX 60 wheels for the Bishop, the savings went up to between 143 seconds (0 degrees) and 244 seconds (10 degrees) saved over a 40km effort. It roughly doubled the aero benefit.

If we rephrase this in terms of what I like to call the Right Now Effect. Just changing your kit and helmet and shaving your legs is good for about .5 mph. Adding the bike and the wheels is good for more than 1 mph. My personal experience is that the psychological benefit you get from experiencing the higher speed results in a boost that can double that effect. That why when I talk about aero equipment, I don’t talk about energy saved, I talk about faster rides. Give me an aero bike with aero wheels and I won’t arrive home fresher, I’ll arrive home wrecked.

Chris Yu (left) and Cameron (center) didn’t sleep through math the way I did. They spoke slowly for me.

Here’s the part that shocked me: I thought the Venge with aero wheels would result in a greater aero benefit than swapping the kit and helmet and shaving my legs. That’s the big lesson of the testing. You needn’t spend thousands to see a big gain. There is lots of low-hanging fruit.

No matter where you are in the life cycle of being a cyclist—getting faster, holding fitness, or aging with as much grace as possible—you can be faster. That can mean better placings at races, faster fondos or more time at the front of the group ride. Faster is almost always more fun.

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