I have a history of knee problems and I read that to save my knees I should be cycling at 90-100 RPM. Well I installed my spiffy new cyclocomputer yesterday with cadence and wow, 90 rpm is a lot faster than I realized. When I try to keep up 90 I am definitely faster with less effort on the flats but climbing just feels awkward. I have to shift into a couple of gears lower than I'm used to and then I'm spinning so fast with so little resistance that I'm bouncing around in the saddle.
Am I missing something? Does the 90 rpm recommendation not apply to climbing?