position-power/aero tradeoffs

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Is the 25mph with the new position?

If so, a 2mph difference under near identical conditions with only 10 watts seems a little off to me- but regardless, one test doesn't mean better always.  4-6 TT's under indentical conditions would be better for predicting.

If the slower speed was a result of the new position, I'd say you might be able to improve some with adaptation, but not enough to rival some of your original position.  Sacrifing watts for aero has rapid diminished returns.  My experience is it's always better to maximize the watts, then make small improvements with the least expensive changes (clothing, cables, knee position, helmet- but that's debateable b/c a aero helmet doesn't mean free speed for some-, h2o bottles, etc), and then train with high motivation and with a solid plan.

Just like more isn't more (training volume), lower and narrow isn't faster.  Intuitively we think it is, and logically it makes sense, but with alot of this there is a "sweet spot" that optimizes it.

Without a wind tunnel and power meter it is very hard to gage where the optimum aero vs. power point is for each individual.  Having a lower CR gives someone the opportunity to put out less power to attain similar speeds to others with a worse position and big power numbers.

The thought is that you want to use the least amount of power to go as fast as possible while being efficient and comfortable.  If your position is set up correctly then you should not have to worry about the "comfort" part of the equation no matter how much your drop is.  There are simply some people though that cannot make that aggressive of a drop.

The only real issue with pulling in the arms is that there will be some compression in the chest which may restrict your breathing some if it is too aggressive.  I recently made some tweaks by taking out the last available spacer and moving my pads in, but after even 10 minutes on the trainer it did not feel right at all and I moved the pads back out a notch.  I had really felt a lot pinching in my shoulders and chest.  I think this is often the case with triathletes because of the more developed upper body from swimming.

My recommendation would be to use the same course in the same day and go at a prescribed speed that is easy to hold (some measurable value like 22 or something) using the different positions.  Then get your average power for each of those.  Make it a flat out and back, no turns and no hills if possible.  And make sure you hold your position the entire time.  This will give you a sense of whether or not the position reduces your power needs at the same speed and you can extrapolate from there.

Just my suggestions.

thanks guys.

reathcon, i am not looking for an easy fix here, i am training and have the other small things i can do, wheels, helmet, cables, clothing etc. the position is one of the last things i can tweak right now.


rick,

breathing wise i had no issues at all. will get out today and play around again, see how things go and report back.

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Sorry, didn't mean to imply you weren't doing those things.  But as was already stated, you're probably looking at outdoor Crr (ref: Chung methodology) and windtunnel work if you're really serious about it.

Personnally, I'd say go with the Crr, simply because you can evaluate more on a practical application, and not feel like you're under the gun for adjustments and such.  I've know some to have a couple hours in the windtunnel, and half of that time be for aerobar/stem changes alone (not a good use of money).

Here's a good place to start if you haven't looked at anything-

http://sportsci.org/2006/jcm.htm

Good luck- please post back with what you find- I'm sure it will benefit alot of us.

thanks for the info, will start trying to digest as soon as brain starts functioning properly (too little sleep)