Well, I originally bought the 16" Trek WSD for my gf but after bringing it home as a surprise I quickly realized she needed a larger bike. We went back and Atlanta Cycling put her on the 18" WSD 4300 and it fit great. I knew for a new mtn biking female to feel comfortable riding off-road she would appreciate the smaller controls and different geometry and she definately does. My gf is actually closer to 5'8" and needed the larger frame although she rides a mens size small Giant ORC2 road bike. Thanks for the input and I'll report again after a long trail ride tomorrow. Thanks again.