Originally Posted by
PeteHski
Of course decreasing cadence will decrease power in the same gear if the slope is a constant. But if you are maintaining power as the slope increases then pedal force will increase at a constant cadence or often increase even with a falling cadence. The whole point of gearing is to balance cadence against pedal force for a given power output. Running out of gears means you lose that flexibility and pedal force inevitably ends up higher than you would prefer when you have no more lower gears. Slowing down is often a limited option by that point.
Whether or not a high pedal force and low cadence actually hurts your knees is really a different argument. It certainly hurts my leg muscles and increases joint loading.
This is the reason I have really low gears. It's a PITA that it's so far between them, but better that than the alternative if you're over, say 50.
OTOH, I do low cadence intervals, but that's not the same as a pass climb. Seems to me they build up rather than tear down, more like a gym workout. rchung is of course correct.
Responding to the OP, my best climbing cadence is 80-83, my best flats cadence is 88. If I'm riding competitively or just having fun, coming into a hill, I like to downshift early, to ~100 cadence and then shift again at ~90 until I get low on gears, then I just drop down to steady state and suffer. I have my best luck at going over the top of short steep hills doing that and not suffering, just blowing my HR up for a little bit.