Well it depens on your frame, although most road bikes have lower bb than mountin frames each is diffrent. I run 175's on everything, my Viscount frame clears the ground fine but my toe can hit the front wheel in a sharp turn. My Bianchi frame wont clear the ground but my toes dont get in the way of the front wheel. So it just depends, Perhpas you should shoot for the middle ground and find some 172.5's.