I don't know if bike size changes with different brands, but I am 5'9 and ride a size 54 Cannondale. It has to do with your inseam, though, more than over all height. I believe my inseam is 32 in. You should have your bike professionally fitted for you to make sure you don't end up with unecessary back pain, etc.

Congrats on the new bike! Sounds sweet!