Originally Posted by alpha_bravo

I don't know if I agree with this. When I watch the pros, it looks to me like they've got extremely light grip pressure and a bare minimum of their weight on the bars when climbing. Standing while climbing is taxing enough aerobically. I wouldn't want to add a lot of grip pressure and pulling and pushing with the upper body to add to the aerobic costs. The videos of Armstrong and Carmichael are great examples.

Of course in a sprint or acceleration, push and pull on the bars all you want...