http://janheine.wordpress.com/2013/0...ws-of-physics/

In the last issue of Bicycle Quarterly, we compared the performance of a 17-pound titanium racing bike and of a 26-pound steel randonneur bike. We were surprised when both bikes climbed at the same speed in a set of controlled experiments. Others shared our surprise, but added: “That cannot be true. Physics require that the heavier bike climbs slower.”
Having ridden the bikes myself, I know that their performance was evenly matched. And as a scientist, I also know that this result does not contradict the laws of physics.

Our critics assume a constant power output. If we always put out 600 Watts during these climbs, then any added weight will slow us down, all other things being equal. And an extra 9 pounds is significant enough that it should be measurable. There is little disagreement on this.

And yet the two bikes did climb at the same speed, despite their different weights. It’s clear then that our power output was not constant. On one bike, we were able to put out slightly more power than on the other – just enough extra power to equalize the weight handicap.