I ride an XR650L and street bikes, and my 5 year old daughter has shown a ton of interest in riding with me, and more recently getting her own dirtbike. She's a little on the small side, but very strong and coordinated, and great on her two wheel bicycle / scooters, etc. After much deliberation, we finally pulled the trigger on her first dirtbike, a 2007 CRF50F. Though I don't know that it is the best in the long run, since she's a little small, I ordered a set of training wheels so she can get used to the throttle and braking systems without worrying about balancing the bike to start.. Her gear is on the way, though she was fired up to wear her new motocross pants ALL DAY LONG.