Originally Posted by
NormanF
I'm 5'7" and I ride a 55 cm road bike. But I go down one size smaller in a cyclocross frame due to the higher bottom bracket. My 52 cm Bianchi San Jose is sized accordingly. Hope this helps.
The last 2 comments are the most useful, I think.
I will just add to them by saying that I ride 55cm road frames and 53cm touring/cross frames.
The discrepancy in sizes is due to the cross frame being slightly more elevated from the ground by the positioning of the wheels (allowing for wider tire clearance vs a road bike).