110% anecdotal, but a friend of mine -- also, a woman -- sez the same thing, not specific to the frame on which the NuVinci hubs are installed, but all Citibikes. Also, she travels internationally, and this applies to e.g.: Paris's Vélib'. Her analysis: sure, the seat can be adjusted vertically, but the angle of the down-tube doesn't bring the seat sufficiently close to the handlebars for her comfort. Worth adding: she has engineering credentials. Considering the known shortfall of women amongst Citibike subscribers, perhaps this should be considered in frame design. I'm sure Motivate closely monitors these comments....