I would love to get a road bike but can not afford new at all right now. I've been checking out craigslist but I have no idea what frame size to look for. I know it will vary by manufacturer but I would like to get a ballpark idea of what sizes would be worth the time to call on and possibly try.

I am 5'5 1/2 and have a 30" inseam. The bike I am riding now is a Giant FCR 3W and the frame size is small.