Will was 10 when we started riding and he's as big as me (taller now). You're right about your daughter's weight/bike ratio! I know there are plenty of kid-size road bikes around, if you don't mind spending a little more than the regular kids bikes. I've got about $1200 in both of Will's bikes (road and mountain).

What I've noticed when I see kids on event rides is that their gearing is so low that they pedal way way more than most people have to, so they're going to get worn out.

Karen