My frames are all over the place-- it's all about geometry for me (I'm 5'5", inseam 31"). My Kona DD is a whopping 56 cm and fits me wonderfully. I love that bike. My Contessa CR1 (WSD) is a 52 cm and also fits like a glove. My Lemond Etape is a 53 cm and has never fit me properly. The 51 cm model was no better. I need a bike with a longer head tube or my short little arms just can't cope.