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?