I'm 5'10" and my current bike is a 56 cm, so I'll be OK with just about anything (my current bike is actually a guy's model -- when we looked at the WSD model geometry with my shop it was exactly the same and the only differences between the women's model and men's model was the saddle and color which I new I'd be replacing anyway). My work colleagues are all tall too :-) I hadn't even thought about the flat kit -- I've never rented so I didn't know what they'd send you out with. Thanks!