I'm 5' 5" and normally ride bikes in that size range. In some product lines, I can ride up to a 52 cm. In others, down to a 46. Obviously that doesn't mean everyone my height has the same needs, but I don't think I've met a single person that short who would be comfortable on a 50 cm bike, and even a 48 would be questionable. Not sure where you pulled those numbers from tbh.