I'm 5' 11" with a 34" inseam, and I ride between a 54cm to 56.5cm, depending on make and model. Not all bikes of the same size fit the same. For example, not all 56.5cm bikes fit the same, not even if they all are theoretically "road bikes". Each manufacturer build their frames with some criteria in mind. Highly recommend that you take your time making sure the bike not only fits, but fits comfortably to you. Remember you will very likely need to consider different stem, handlebar positioning, and saddle. The key is comfort. If you don't look forward to getting on your saddle and riding your bike... then you most likely will not. Ask yourself... would you look forward to being on the bike you are considering purchasing for two hours at a time?