Originally Posted by RobbieTunes

I may well be wrong but in climbing, wouldn't it be as a fraction of the total weight, bike + rider?
(Given equal wheelsets, rotational weight, etc.)

For example: A 135 lb rider (Quintana) with a 15 lb bike = 150 lbs vs. a 135 lb rider (Quintana) with a 20 lb bike = 155 lbs, and the additional load is 5 lbs, or 3.2%

But, in acceleration, the additional weight has more of an effect because you are trying to increase velocity instead of maintaining it, so the weight "penalty" increases with velocity? (I never got past a D in physics, but A's in calculus, go figure).

Again, I look at things in a simple light, being a simple person, because it seems like my quads don't quit 3.2% earlier or later, they just quit, and it doesn't really matter what I'm riding. On my workout rides, on heavier bikes, I tend to use 4-5 cogs, and on lighter bikes, I use 2-3 cogs, and I'm absolutely no faster.

These and other deep issues, like why do clowns scare people, keep me up at night.