Nice grind. I've seen some videos of people grinding their quads before but it's only for a brief touch and usually against a smooth metal or glass surface.
A guy named Charpu did it 3 years ago by putting cut in half ping pong balls on his quad. He has the only video i can find like it. found it watching a top 5 tricks video
I did a 360 spin under my truck yesterday. got it from two view points. ill edit that up soon and put it up.
Le drib, b4 he got with rotor riot bought chunks of flint for the bottom,& was grinding all day. Not for me though I like to keep my bolts sweet along with the bottom plate. Them vibrations not doing the gyro on good.