this is interesting since I am considering going to 175 cranks and am currently riding on 170s. I'm 5'9 and ride a 54cm frame. I have been on 172.5s and 175s in years past, but went to 170s when I went to compact cranks. I love the compact cranks concept and lower gearing. I was thinking the lower gearing would work better with shorter cranks and I wanted to work on a faster spin. Well, my spin is faster, but I have always been a power stroker and I'm thinking longer cranks will help with power on climbs. I think I want to try 175s on my climbing bike which has a compact frame so I could lower the saddle without any problems.