You can fit a range of frame sizes. In my case, with a 32 1/2 " inseam it's about 54-56, although I can make up to a 58 work but it's not optimal. And, don't trust manufacturer's stated frame sizes. My CAAD 12 is 52 w/sloping TT. But, when actually measured with a virtual TT it's actually a 54. I'd start with inseam and go from there.