Hi Mimi: I learned that assumptions were made based upon my height as to what size frame I needed by many bike shops. I am 5'6" with longish legs and I am most comfortable and fit best on many brand's 51cm. frame. I kept getting steered towards 53cm and 54 cm. Once I actually sat on the bikes and they could see the complete fit, then the sizing changed. I also like having the option of not riding as if I am stretched to the point of no return. I agree, get yourself professionally fitted, riding is supposed to be fun, not painful.