All of these "weight loss" calculations assume only losing blubber... and not losing muscle.

Those of us that carry a little "spare tire", can often stand to lose some weight, and still remain strong and healthy. But, it also depends on mixing dieting, exercise, and proper nutrition.

But, a 130 pound rider isn't necessarily stronger, faster, and a better climber than a 180 or 200 pound rider.

When I wrestled years ago, the 150 pound wrestlers could always just crush the 98 pounders, and the 200 - 250 pounders were just wicked. But the heavyweights also depended a bit on fat vs muscle, so the lighter wrestlers might have a chance against those heavy wrestlers that weren't strong.

I also thought that some of the wrestlers that were into extreme weight lifting and dieting became "muscle bound", and might have put them at greater risk for injury.

Cycling, of course, is a little different since it is all proportional. But, some things like the weight of one's bike, water, and gear is somewhat fixed independent of the person's weight. Certainly, as has been pointed out, losing body fat to a point is good, but beyond that, getting bony skinny is of no benefit to strength and speed.