In my youth I was 5' 10 1/2" with a 32.5" inseam. Down to 5' 9" but same inseam. I find a 54-55 is perfect. If my inseam was like yours I'd go no larger than a 54 and probably a 53. Be careful when buying a bike with a sloping TT. My CAAD 12 is a 53 but using virtual TT measurement it is actually a 55.