My 7 year old daughter has a crappy "mountain bike" my dad came home with from a yard sale I think he got for $20. It really is a piece of junk but its BB is high enough for her to roll off of sidewalks. Just yesterday she showed me that instead of rolling off of the sidewalk she can lift her front wheel and can drop it. I was so proud. I may have to get her a proper mountain bike in the not too distant future.