I am about the same size as you are and just got the 21" Trek 520 last fall. The dealer I went to had a very fancy computerized measuring system that decided I needed a 22" frame. Since 22" is not an option, the dealer said I would be better off with the smaller frame rather than the larger. They worked with me a lot to make the bike fit, and we've gotten it pretty close. The biggest problem I've had is getting the handlebars high enough without being too far forward. We finally settled on a Dimension adjustable stem to give the right fit. I'm close, but still want to tweak it a little bit.

My old bike was a 24" Trek 520 (1983 model) and I will say it was too big for me. I made it work, but the top tube was really too high for safety and it required a special, really short, stem (the old quill type).

Overall, I sometimes wonder if the 23 would be better, but I really like the 21 and look forward to putting lots of miles on it. The old bike was good, but the new one is sooooo much better.

Just be sure you buy from a dealer that will work with you a LOT to make it fit right. The guys I bought from have really gone the extra distance to make me happy. They even promised (in writing btw) that if I didn't like the 21" they would get a 23" at no extra charge.

Bike America, 9514 Nall Ave, Overland Park, KS