likebike23

I am also 5'7" but with a 30" inseam. I like my frames a little larger, more like a 52-54cm. The larger frames allow me to get my bars higher without resorting to a super long quill stem/high stack of spacers. It all depends on what you are most comfortable with. If you want a large drop from your saddle to your bars for a more aero position, a smaller frame will allow that. If you want a more relaxed upright position where the bars are slightly below/level with your saddle, a larger frame is better. My experience is that it is harder to raise my bars on a small frame than to lower them on a larger frame. With my 52cm frame, if I slam the stem, I can still get about 4" of drop.

One thing to be aware of, is that there are a few schools of thought on fitting. The competitive, Eddy, and French fit philosophies are the 3 main ones. Bottom line, bike fitting philosophy is a very personal thing that evolves with experience. I think everybody has gotten the wrong bike at one point or another in their cycling life, it happens. Just make sure you get a good deal, you can sell it and hopefully not lose if it doesn't work out.