I'm about 177cm - just short of 5 foot 10, and I ride a girl's bike. Or, as the serious bikey people encourage me to call it, a "stepthrough" frame. My height is exactly average for the population, androgyne, so why do i like this frame?
Turns out, the big difference in a "female-specific" frame (another carefully-worded phrase) is geometry. They're made for "relatively longer legs and shorter torsos". Which describes me!
Hooray for queer bicycling.
And before it's mentioned - no, i don't like it for the wide, squishy "female-specific" saddle. I swapped that for a narrow firm one almost at once. This seems to be a "male-specific" preference, but like many people I can't understand why.
(source - http://lifeandhealth.guardian.co.uk/experts/mattseaton/story/0,,2167976,00.html)