Originally Posted by
shawn_f
I'm looking for a frame for a road bike so I can customize it with decent parts, and have been doing online research about sizing. I've come up with a broad range of numbers that seem to fall into two groups: a smaller size and a larger size.
My height is 5-9 and my inseam is 31 in.
Here's what I've found (from center of crank to top of seat tube):
About.com -- 56cm
Evanscycles -- 56cm
Bikesizing.org -- 53cm
eBicycles -- 54cm
Sierra Trading -- 53cm
Kleinbikes.com -- 57cm
So is that a 21in bike?
Since you are unsure about bike fit, why not have a pro look you over and get you into the right size, i.e. check things out at a local bike shop. And then buy a bike there. Don't go, have them do a quick sizing, and leave to buy online.
In Trek terms, you'd be on a 54 or 56cm road bike, probably a 20" hybrid, but without being able to evaluate reach to the bars (tt measurement), these are only best guesses.