I just finished listening to this great Podcast of an interview with some guys over at MIT regarding bikes and aerodynamics. What they had to say floored me. I knew that being aero mattered, but if you had asked me prior to listening to this I would have told you that power was more important if you wanted to be fast. Not so.
They said the typical triathlete creates about 6 lbs of drag on the bike. By using a wind tunnel they were able to look at different things that might help reduce this drag. High on my list would have been the ever coveted disk wheels. They are the sexiest item that you can add to your bike and you would probably be faster just for having them right? Well, they stated that having an aero helmet decreases drag 2 to 4 times as much as having disk wheels. What? So for a $200 investment I could be faster than using a $1800 wheel set? That's right mon frere. An aero helmet will reduce your drag coefficient by 1/2 a pound. That's nearly 10%. So over the course of a 40K (24.8 miles) the average triathlete will save 30 seconds to a full minute. I'm sold.
What about the aero drink? I think most people know this but the cylinder is the biggest enemy of aerodynamics. Having a bottle mounted on your down tube greatly increases the amount of drag you produce. Switching to a bottle mounted in your aero bars is not only an improvement, it's actually better than having nothing there at all. The bottle actually breaks up the wind and decreases the turbulence around the head stem thus reducing your drag. Who woulda thunk it?
They also discussed the straw coming out of the bottle. If you reduce the length of the straw by 10cm you can reduce the amount of drag on the straw by 1/10 of a pound.
How about the bent-o-box? It's been given the same kudos as the aero drink. It's actually a benefit to have a bent-o-box breaking up the wind coming off the stem of the bike as opposed to having nothing at all.
Lastly, body position. A lot of people try to improve their aerodynamics by buying a sleeker bike, but the bike only accounts for 15%-25% of wind drag. The rest is the triathlete's body. Spending a couple of hundred dollars on a bike fit will benefit you 3 times over what you could get out of spending a few thousand on the latest TT bike. You need a fit that is aero, but also comfortable so you are not having to get out of the aero position to stretch or relax your back. Staying in an aerodynamic position for the ride is key in reducing drag.
So stop eating beans and rice trying to save for the latest Zipp wheels. Go frugal and buy yourself a decent aero helmet and scorch the competition this season.
Tailwinds...
5 comments:
You're dead on my man. That's exactly why I bought the Giro Advantage II a several months ago. It's the cheapest way to reduce drag.
nobody's gonna believe you! ;)
Good post. We have a wind tunnel open to the public in Charlotte. It's a 2+ hour drive from here, but I'm thinking about going up for a 40K TT and see if I can get in!
Thanks for the update. I've seen that data on the aero helmet too...but I guess I'm not competitive enough to think that 1 minute difference in an Oly will do much for me. Did they mention how fast you had to go before the aero helmet made a difference? Great post!
I wish it weren't so. Cursed with a gigantic melon, my traditional helmet must be causing at least 20 lbs of drag; yet, I just can't bring myself to try on an aero helmet. Hopefully, they'll become so commonplace that people will look odd without them. I used to think I'd never wear bike shorts either.
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