Originally Posted by
cskena
To be frank, my situation was a bit easier. I just sat on the bike and rode. I have friends who are our height and ride 56cm frames, so its possible. The drop may be uncomfortable. I have a 31.5" inseam and could still adjust my seat upwards for more height if needed. Plus you can always get an adjustable stem just to be safe.
I just looked up the geo on your 58cm CAAD and it also shows a c-t seat tube of 56cm... I think it must just be something to do with the compact frame sizes and not an indication of the actual frame size which is 58... I think I've seen this called virtual size somewhere.