It's not all cookie-cutter formula for frame-size. Some folks have a "frog" torso - shorter legs and longer body & arms. They can ride well on a too-large frame than the usual formula of stand-over height would suggest. And the reverse is also true. Get a "real" measurement, then ride a few different sizes to find your personal comfort-zone machine. People who are good at customizing a bicycle to a customer should be able to help at this. A shoe-salesman masquerading as a bike-shop employee may well overlook this.