I am building a bike for my daughter based on 20" wheels, with a steeper seat tube (74) and slacker head tube (70 or 71). Is there a trail (or a head tube angle and fork rack combo) that works well for new riders? Also, been trying to figure out why all the production kids bikes I've seen (and that we own) have such high bottom brackets (i.e. little drop)... am I missing something? Just watching my daughter ride her bike makes me think a frame with more drop would be appropriate and helpful. And thoughts/suggestions on some general design parameters would be appreciated. Thanks.