My only bike (well, besides the Trek) is a Raleigh 22 1/2" frame, which measures 56cm square. I'm 5'7" (seem to have lost an inch? ), and it fits me great. Stand over is grazing. Speaking of which, I disagree with the poster above who stated that you should have 1" to 2" standover. I've ridden this frame for nearly 40 years and it has never been an issue. I think that standover height is meaningless for the most part.

Also, I could be wrong, but modern shops seem to fit people to smaller frames than used to be typical?