The effect of extra weight is painfully obvious on a climb, but since there's more to push through the air, it actually hurts on the flat, too.
People have analyzed the relationship of body mass and frontal area. (Link to summary. download of the article requires payment--I'm too cheap). According to the author of that article, frontal body area scales by the power of 0.762 as a function of mass. The authors of that article found that the total frontal area of rider and bike only scales by a power of 0.594 since the frontal area of a bike is similar regardless of the size of the rider.
So I'll break that down for myself. My college riding weight was pretty close to my ideal body weight, and is 20% less (yikes!) than I am now. According to the paper, that would have been a 12% reduction in total frontal area, which should more or less translate to 4.3% increase in speed on the flat.
So, if college me rode the Leroy TT with my current legs, my season best riding my road bike would have ridden better than a 19:08, since there would also be an increase in speed up the hill.
I'm actually stunned by that. I've learned that there's not much I can do to increase my threshold power, so really, I should just go all Ghandi and drop the weight to get to the next level.
2 comments:
Interesting comparison. Since your power level is already pretty high, weight loss makes the most sense (but it is the least fun).
Yeah, the first couple of years I started racing again, I dropped 30 pounds without even thinking about it. The next 20 have been very stubborn. I'm basically in equilibrium, I guess.
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