A pal attempted to use this exact unit on a BattleBot. It wouldn't take pavement at all. It barfed its bearings and then the ball vanished.

        A replaceable fiberglass skid would be a better solution.

        If you are set on something that rolls, perhaps you could use one of the wheels we use for wheelie bars on our drag vehciles. Better yet, the folks that drag race snowmobiles have special wheels they put on the skis.