I dunno... not an expert but I'm only 5'8" and both my bikes are 17... just seems so small for someone 6' or more. Regardless if you have incredibly short legs, your torso then would be much too long for a 17. You'll would to put a mundo stem on there, something huge!!!

Best thing to do is have fitting and allow the fitter to recommend bike size. No matter how great a deal the bike if it don't fit you won't be happy!