Originally Posted by glassman
I bought a new bike and it came with 172.5 crank, my old bike has a 170 crank. After a 15 mile ride, I noticed my calves and knees were a little sore. Is the 172.5 crank more work on my legs or is it just something I need to get used to or change out the crank to a 170? I ride the 15 mile ride every day and have never experienced soreness with the 170 crank on my old bike. Any ideas?
Pay attention to your knees - something isn't right. Just a thought - were you fitted to the new bike, so that your saddle and knee/foot position were set up right? I just bought a new bike, and went from 170 crank arms to 175's. I was fitted to the bike after the purchase, and it has been a positive difference. Instead of pushing and grinding up hills on the old "not fitted to me" bike, I'm spinning and (relatively) flying up hills like the Wicked Witch of the West on the new "fitted to me" bike.
I'd say either you're not fitted right to the bike, or the cranks are too long for you.