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Feb7-13, 09:43 AM
P: 4
In the bicycle industry, there is a lot of marketing saying that rotational weight is more important than static weight when it comes to accelerations and competition. I understand I=mr^2 but how do you compare differences.

Keeping the the hub/spokes constant, how much advantage would you get from removing 150 grams from each rim over a 2hr race. For this problem, r=31.1cm

Here is what I "think" I know. It only counts for acceleration and has little to no affect on keeping a steady speed, so lets assume the race is constantly accelerating and decelerating like a criterium or mountain bike race.

Am I wrong saying that watts = I/s^3 ?
If that is the case, then the following problem would break down as follows

I = 150g x 31.1^2 = 145,081.5g/cm^2

to convert to kg/m^2 you multiply by 10 = 1,450,815 kg/m^2

now over a 2hr race divide by 7200^3

Would that mean the savings would only be .00000388 Watts!

And if so, is that per second savings or total savings over the entire race? Either way, it seems basically negligible.

Or am I way off and did this wrong?
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