Originally Posted by
GlassWolf
TL;DR entire thread.
If you can't be personally fitted for a frame/bike at your LBS, here are two things to use as a guide for a road bike frame:
stand-over height. should have a minimum of 1" between groin and top tube. Preferred is 2-4"
Top-tube length, should be: (your inseam x 0.67)
that's a good starting point.
Using that, I take a 48-50cm frame on most road bikes, or a "Small"
I'm 5'7" with 30" inseam.
That sounds huge to me for level top tube frames. I'm 5'10" 32.5 cycling inseam, and the last frames that gave me that much room was both a 53 IRO and a 50 Fondriest. Both were horribly small. I'm now on a 57 Look with a very slightly sloping top tube that is just touching my bits. And an IRO mark V size 59 with a touch higher (level) top tube. Both bikes feel great and handle beautifully when ridden.