While riding one of my touring bicycles, I feel that my feet are not really "biting" the pedals as much as I can on one of my other touring bikes. The sense is that the ball of my feet are not over the axle of the pedal; I want to move my body forward to get on top of the pedals. (This is after careful fittings from two different knowledgeable bike people.)
I lived with this sensation for a year, but found, a couple of days into arduous rides, that the muscles in my legs could no longer deliver power to the pedals. Basically, I ended up using my granny gears to pedal on flat ground, and walking up hills. And when it got that bad, the only solution was to rest for a few days.
In an effort to deal with this problem, I pushed the seat forward about 10 mm (between .25 - .5 inches). Almost immediately, I regained the sense of my leg muscles efficiently transfering power to the pedals. I thought I licked the problem.
Last week, I switched to a shorter stem (to reduce upper back pain from days in the saddle). I then returned to the fellow who designed the bike and did the original fitting, and asked his opinion about the new seat position. He was concerned because my knees were 10 or 20 mm further forward than optimal; he thinks that I may experience knee problems with the seat in its new position. Now I am concerned: I have had a lot of knee problems over the years, including those that resulted from inproper bicycle fit.
Is it possible that the cranks are too long, and that I can achieve a better fit by substituting slightly shorter cranks, raising the seat a little to compensate, and pushing the seat back 10 or 20 mm to restore the original knee-pedal relation? (The two people who originally fitted me arrived at the same seat position independently, so I was reluctant to mess with it. )
Do manufacturers offer the same cranks in different lengths? I have XT cranks now.