I need an inexpensive, used, women specific bike.

Anyone have one? I don't mind if it is several years old. I just need a bike that has more than five gears and doesn't have the shifters on the down tube. I'm 5'7", but I would need help knowing what size to buy. I'll be doing my first tri in a few weeks on a 15+- year old Cannondale 10 speed with the shifters on the down tube, but I can never get it up on the largest sprocket in front, so I'm stuck with 5 gears! :-( I've had it adjusted twice in the last couple months and it never works for more than a few minutes. So, I'm slow up hills and I'm slow down hills! LOL.