Crank length advice
May I ask for advice regarding crank length?
My current crank is 172.5 mm. According to the crank length formula on PeterWhiteCycles, my crank length should be about 168mm.
I'm experiencing a little knee pain when I pedal very hard that has been made much better by keeping my cadence above 75 rpm and raising my seat a little too high. It seems to me that I would feel better with a shorter crank. My LBS is very friendly and will happily install anything I want but think that I'm going to waste my money. They think that I will not notice the difference between 172.5mm and 170 mm and that 165mm would be too short.
BTW I'm 55yrs old back into riding for a little less than a year. I typically ride 50-80 fairly level miles at a time. Just finished my second orgainized century ride and hope to do a doulble this May.
Thanks.