The Wind Tunnel

Monday, April 11, 2016 - 12:30

What an experience! A few weeks ago, I packed up my newly-built and aerodynamically improved 2016 CEEPO Viper and made a visit to the A2 Wind Tunnel in the middle of nowhere in Mooresville, NC, accompanied by my coach (Earl Walton) and a few training partners from Tailwind Endurance who were also there to test. The A2 Wind Tunnel is a top-notch facility frequented by professional triathletes, NASCAR drivers and even garbage can manufacturers (don't you hate it when your garbage can blows off down the street?!). Last year was the first time that I really began to tinker with my aerodynamics because in the first few years of doing the sport, there was plenty of lower hanging fruit than trying to squeeze a few extra watts out of my position or gear. At this point though, there isn't as much low-hanging fruit and making the trip sounded like a worthwhile venture. A huge thank you to Joe LoPorto from FitWerx for sending me to the tunnel and having the bike built and ready for action! Going in, we had put together a wishlist of things to test, including these:

1.) Bring my front end down by 1cm, then 2cm

2.) Bring the aerobars from a 0 degree position up to 10 degrees

3.) Test out various tri suits to find which is fastest on me, and purchase my custom tri suit for the year based on that knowledge

4.) Test out hydration setups to find what is fastest for my body, position and bike

5.) Test different aerohelmets to potentially replace the Lazer Tardis helmet I've raced in since I began the sport, which is typically slow in the tunnel

6.) See the impact of arm coolers vs no arm coolers, and wrinkly arm coolers (like I wore in Kona) vs smooth arm coolers

There are tons of claims out there by equipment manufacturers (bike companies, tri suits, aerohelmets, hydration setups, etc) that they are the fastest out there, sometimes quoting numbers that make it sound like you'll drop 20 minutes off your Ironman time just by using their sunglasses. There is also a wealth of information from people who have done aerodynamic testing before, whether it be in the velodrome or a wind tunnel, about what was faster for them. While there are certain things that tend to test faster for most people (ie sleeved tri suits vs sleeveless), the only way to really test the impact of your position and gear selections on your aerodynamics is to test it yourself. Some things are quite counter-intuitive: having a bottle or two in a rear hydration setup tends to be faster than no bottle for most people (though whether one or two is faster varies person to person), and having a well-fitting BTA (between-the-arms) hydration setup can actually be faster than no bottle at all!

After arriving at the wind tunnel and hearing Brian Stover and Heath Dotson talk about the testing, I decided to follow their lead. They're the experts and have spent countless hours in the tunnel, so I thought it best to let them guide me through what they think is most worthwhile to test, rather than pretend like I know best.

My first run in the tunnel was without me on the bike. For all the runs, we used the industry-standard wind speed of 30mph. It's faster than I'll ever ride a long course bike leg in, but necessary to help amplify the effects of the changes we are testing. For each run, we tested at 0 and 10 degrees yaw. We tested my oval-shaped Zipp Vuka base bar and ended up switching quickly from that to the flat tear-shaped Profile Design Prosvet which saved about 1.5w right off the bat. Then I hopped on the bike, got a tutorial from the wind tunnel crew, and did two baseline runs so that we would have an accurate starting point to compare the final runs off of. They wanted me to pedal at a pace I could pedal all day and to keep nice and steady from run to run and within each run. One of the tough parts of wind tunnel testing is keeping human error out of the statistics, even though there's a human in the tunnel. I thought I was pedaling steady, but after the first few runs, they asked me to ride steadier because the numbers were varying somewhat wildly, to the point where the variance was greater than the potential time savings.

After baseline, where we found my CdA to be 0.260, we moved my back up (0.6cm) and front down (2cm) which helped me get my back more parallel to the ground and resulted in 3.3w of savings. Bringing the pads in on my aerobars by 1.5cm each brought in another 3.6w. Then we moved the bars up from 0 degrees to 10 degrees and though the result was actually worse at 10 degrees, they took me up to a "praying mantis" style 30 degrees, contrary to intuition and something I wouldn't have thought to do on my own. It worked! My numbers got worse and then got better with the "praying mantis" actually being my fastest run yet by about 2.6w. After a number of aerohelmet tests where we found several helmets better than my Lazer Tardis, I was told that it was my last run. HUH!? That two hours went by REALLY fast. We didn't even get to test different tri kits, hydration setups or my arm coolers. I had even waited to order my custom tri kit because I wanted to test different brands and buy the fastest. Bummer. If I am able to make a trip to the wind tunnel again, near the top of my list will be hydration and tri kits. I did get to try on a couple of kits, and for this year, I'll have to choose which fit the best without the benefit of real data.

In the end, I moved my CdA from 0.260 down to 0.247 and saved 10.8w at 0 degrees yaw assuming a speed of 24.0mph, Ironman goal pace. I went in expecting to find 10-20w and for my final CdA to be in the realm of the professional triathletes who are about the same shape and size as me. I wasn't able to get down quite that far as the most "slippery" time trialists and pro triathletes have CdAs in the ballpark of 0.21-0.22. If I had a CdA that low to begin with, and only found 10w, I would have been thrilled as I could conclude that I am already very aerodynamic, but having gotten only down to 0.247 and finding only 10w, I feel like there must be more there. Don't get me wrong, I'm pretty aerodynamic in the grand scheme of things, but if I want to get to the top, every watt counts! After talking with the Heath about why I might not be as aerodynamic, he suggested that it might be because I'm "built like a swimmer." HUH?!?! That's the first time I've heard that one! I've always had a pretty scrawny and undersized upper body from all the years of running, so it was the last thing I thought I'd hear. It turns out he didn't think I had a big upper body like a swimmer, but that I have broader shoulders than most of the top time trialists. If I am able to scrunch my shoulders underneath me and round my back, I'll have a smaller front for the wind. That would require me to improve the flexibility in my shoulders and get to used to generating power in that position. That, or break my collar bone. I think I'll pass on the collar bone breakage.

Another thing to note is that many of these changes come with a cost. Some require an additional monetary outlay (i.e. buying a new aerohelmet or base bar) while others require a compromise to your comfort on the bike (i.e. butt up, front end down or the new praying mantis position). If I can't hold the more aerodynamic position comfortably for 112 miles during an Ironman, and I run terribly, then the 5 minutes I saved on the bike won't be worth much. I'll need to practice in the new position for a while and see if I can get used to it before I race Raleigh 70.3 and Eagleman 70.3 in June.

While I was at the tunnel, Melissa Alfano from TRS Triathlon happened to be there collecting material for an article on the wind tunnel, and she asked me to answer some interview questions. Check out the article!

http://trstriathlon.com/day-a2-wind-tunnel/

All in all, it was an extraordinary experience that I never thought I'd have the chance to do. We found over 10w, which for anyone who's done FTP testing knows, is not easy to achieve by increasing fitness. Theoretically, this will save me around 2.5 minutes in a Half Ironman and 5 minutes in an Ironman. Isn't "free" time awesome!?

CdA
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