The Schwinn site is so useless, they used to have the archive for the '10 Madison, now they don't even have an entry for a 2011. Wtf mate.

As I recall, a medium Madison was like a large...they are huge bikes. Scrod had a medium(53cm) I think and he's 5'11. It's best to contact Schwinn or dig through the internet for a geometry chart of a 2010 Madison and compare.