I have always run 172.5 cranks on road bike. New bike came with 175s as a surprise to me. I have been riding them and MAY have some knee pain (but how many causes of that are there?) Does it make sense to go back to 172.5 and see if this changes things? Has anyone been able to fine tune and/or feel the difference? Related question: should I run same crank length on mtb and road? (Sheldon Brown says no). Does anyone use same crank length, seat height, and seat model on road and mountain? All responses welcome.