As others have pointed out, it all depends on your body measurements. I'm 5'8" and have been considering their 47 or 49. The measurement that is most important for me is the top tube length. My current bike, a 48 cm Redline, has a 52.1 cm top tube. A 54cm Kona has a top tube of 55.2cm which would be way too big for me. The best thing to do would be to test ride it to see if it would really work for you. I would be hesitant if buying from ebay or somewhere similar.