Ehhhh... I think I just came across your craigslist post looking to trade this for a smaller bike.

Your post says you're 5'7" and are looking for a 50 cm. It almost sounds to me like you'd be going one size too small there. But I have no real way of guessing. You can't just base it on your height. Have you taken any other measurements? At the very least, have you checked your inseam?

Protip: go to the competitive cyclist website and check out their fit calculator. You can take most measurements yourself (or get someone to help out - roommate, girlfriend, whatever) and the results will give you a BASIC IDEA of what size range you can try. Note the emphasis on BASIC IDEA. Always take results based on your own non-professional measurements with a grain of salt. Just use it for reference.

Anyways this whole thing was to make the following point: Maybe you should hold off on making any further "upgrades" until you sort out your sizing woes.