Originally Posted by
79pmooney
My knees do not like crank length change at all (chondromalacia patellae) and I have 6 bikes, all riders, so changing crank length is a big deal.
Not as big a deal as knee surgery, if it were to come to that.
After a year or so of increasingly worrisome discomfort in my left knee, I just last week replaced the 172.5-mm cranks on the bike I use on my smart trainer with 165-mm Sora cranks. So far so good. Maybe a bit of an improvement. I rode 165-mm cracks on various of my track bikes for decades, so at least they don't feel weird to me.
MIght be worth your considering buying a cheap knockoff Hollowtech II crank set in 165 or even 160 to experiment with. I bought a set of cranks, plus a set of chainrings and a Hollowtech II bottom bracket bearing set, for around $60 or so.
Might end up buying Hollowtech II cranks for all my bikes, since I love how absurdly easy they are to work on.