Originally Posted by
smontanaro
No, however... If I'm going from a common 170mm crank length to 175, leaving the distance from the saddle to the pedal the same means that my foot will be 1cm higher at the top of the pedal circle. I will probably compromise a bit to start, raising my saddle a tad, then listening to see if my knees tell me I've got it wrong.
I can't really help with that. I've relied on the saddle to pedal at the bottom and never considered where it ends up at the top. I've also never changed crank length and I'm almost 69.
I do move around on the saddle when riding which changes the relative position a bit, I'm sure. Like when on a flat section, I will slide back and try to get aero (which isn't very aero). Or I move around when climbing.
Good luck with the knee issue! I've been very fortunate with my knees and I attribute at least part of that to spinning instead of mashing years ago.