57 at your height is a mistake. I'm the same height and a 52/53 would be about right. Also note that virtual top tube is more important than seat tube, which unfortunately is what most people are still primiarly concerend about.

At any rate, you should be looking for bikes in around 52-54cm range. Top tube length should be your primary concern when purchasing a new bike. Don't buy a bike from anyone who doesn't understand that.