I saw a speedway bike slide backwards for about 10' before the rider hit the dirt 
a guy i went to grade school with and raced bmx against used to race the speedway at the fairgrounds in victorville.....one day he just didnt come back to class....bike caught in the middle of his drift around the turn and shot straight into the wall....broke his back in several places.
enough about speedway......back to the minibikes....
i ordered a new seat for mine this morning. i busted it climbin the hill in parker on the north side of the pits thanksgiving weekend.....bike made the hill climb fine, but my ass bouncing on the seat busted the thin ass plywood under it. i think im gunna make some seat rails for this next one.