I agree with Lambo about top tube length. The top tube length is everything. I used to own a Trek and that bike was a 60 cm frame. With a 34" inseam, most people will tell you that that is right. That's not always the case however. I now ride a Felt and my frame size is a 58 cm because Felt has a longer top tube than the Trek. It looks like my bike is slightly smaller than I should be riding until you see me on it. Also, if you fall between sizes, get the smaller size frame. It's easier to make adjustments to the smaller frame. One of my buddies rides a Lemond and his frame is actually a little too big for him. He's been fitted and has discovered that the bike is a little bigger than he should be riding. Seat position and shorter stem helped a little but he's still not fitted correctly on his bike.