By Coach Fred Matheny
John Cobb was Lance Armstrong’s aerodynamics consultant for his first five Tour de France victories. [Aerodynamics, of course, have nothing to do with PEDs, so Cobb’s advice holds true no matter what one’s opinion of Armstrong might be.] Cobb was known to draw artful pictures on an easel to illustrate his points. Here are nine you can use.
1. Wind tunnels aren’t necessary to achieve an optimum position for time trials and triathlons. Instead, get as low and narrow as possible for the distance you plan to race. For a 10-mile TT, throw comfort out. Lower your handlebar until your back is parallel to the ground. Position your aero bar armrests fairly narrow. For the bike leg of an Ironman-distance triathlon (around 110 miles), comfort becomes much more important.
2. Your hands must be close together but elbows can be wide enough for comfort and stability in bike handling. Looked at from the front, your elbows should mask your hips from the airflow.
3. Move your elbow pads forward so they support your forearms just behind the wrists. This gives you more leverage to pull up on the bar over short hills or into the wind.
4. Forearms should be horizontal, not angled slightly down like some pros have done in the past.
5. Skinsuits are crucial to aerodynamics and they must fit tight and smooth over the stomach and chest, where 45% of the airflow occurs.
6. Disk wheels are almost always faster than spoked wheels except for short and steep uphill time trials.
7. Backpack-style hydration systems (e.g., CamelBak) don’t hurt aerodynamics and may even help as long as the tube is tucked away. Tube shapes of any kind catch lots of air. A 6-inch section of round brake cable or drinking tube has the same drag as an 18-inch section of aero-shaped frame tubing.
8. Use spray glue to attach your number so it doesn’t flutter in the wind. Crumple the number first to help it mold to your body shape.
9. Tire width isn’t critical if rims are deep or you’re running disks or aero wheels. Tire width is less important on the rear wheel, so run a wider, more puncture-resistant tire back there to reduce the chance of a flat.
Read more about aerodynamics and cycling: Aero perfection: Finding Your Lowest Position
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Coach Fred Matheny is an RBR co-founder who has four decades of road cycling and coaching experience. He has written 14 eBooks and eArticles on cycling training, available in RBR’s eBookstore at Coach Fred Matheny, including the classic Complete Book of Road Bike Training, which includes 4 eBooks comprising 250 pages of timeless, detailed advice and training plans. The Complete Book is one of the many perks of an RBR Premium Membership. Click to read Fred's full bio.
Just be careful with that “get as low as you can for comfort” idea. Getting too low can cause a big drop in power output — even if you’re still fairly comfortable — resulting in a SLOWER ride, despite improved aerodynamics.
The tire width thing, with the widest being in the back was something we learned years ago because the frame of the bike protected the rear wheel from wind better than the front that had no protection, and a narrower tire in the front was more aero where it was needed due to it being right out in front hitting the wind first.
This tire thing had several people thinking back in the day, but I don’t see it today, is that the front wheel should have a more aero wheel vs the rear since again the rear wheel was protected somewhat by the frame, yet all we see today is the more aero wheel in the back. Much discussion has been said about this on various forums but to no conclusion except for the more aero wheel in the front would catch more side wind and cause handling issues. I still think if you’re using disk on a calm day that disk should be on the front? or at the very least the more aero wheel should be on the front? It kind of make sense due to this article with the narrower tire on the front being more aero vs the rear.