Wednesday, April 21, 2010

Old post from Andy Coggan on TT Position

Found a reference to this old post in the Wattage list today:

Tom Kunich wrote:

> It looked to me as if you really had to
>do a lot of trial and error research without a wind tunnel or SR power meter 

> to tell you what was going on in real time.

Not to be disagreeable, but I disagree. If my goal were to set myself up in an aero position with minimal drag and I didn't have access to a wind tunnel, I'd just drop the elbow pads far enough down below the saddle that my shoulders (acromion process) were within a couple of inches of being level with my hips (head of greater trochanter), move the elbow pads in to where my arms were as narrow or perhaps narrower than my thighs when viewed from the front, tilt the aero bars up ever-so-slightly, and keep my head down. I'd then go out and ride the bike - hard - in that position and see how far foward (and thus up) I needed to move the saddle to where my thigh-torso angle was similar to the "working position" on my road bike. I'd then ride the TT bike for at least one hour - hard! - each week for at least 6 weeks before any race. Sounds crude, I know, but for a flat TT this neandrathal approach will probably get you to within about 1 km/h of your maximal speed.

Now, the caveats:

1) achieving such a position will, as has been discussed, probably require special equipment, e.g., a frame with TT-specifc geometry, or at the very least a down-angled stem/forward seatpost. The latter approach is okay as long as you don't fall off your bike as a result of having too much weight on the front wheel.

2) the above isn't necessarily the fastest position for a rolling or hilly course, or at least may not be unless you devote more time learning how to go fast in such a position.

3) gaining that extra 1 km/h will probably require spending time in the wind tunnel further refining your position.

4) use of a power meter such as an SRM or Tune to try to refine your aero position can be entertaining, but unless you have access to an indoor velodrome probably won't help you go any faster than just following the advice of somebody with a well-trained eye (like John Cobb), or simply copying the positions of athletes known to have low drag. OTOH, having the power data can be very useful for training purposes, and for pacing during TTs.

To quote John: "The key to faster TTs is to step on the cranks harder ..."

Andrew Coggan