i've had like 5-7 somewhere don't really remember, but i've already had 2 this season. one was very minor, and the otherone was really bad, doing a underflip on a 40ft jump, i remember coming around to land and it was fine, but then nothing just sliding down the landing. at first nothing seemed wrong until i starting riding down, didn't know where i was. ended up walking to the patrol hut, don't remember walking in just sitting down. turned out really bad, didn't remember who i was, where i was, or giving the patrol people anything. my friend also had 2 serious ones in under a month, he can't hit jumps at all this season. ALWAYS WEAR A HELMET! worth it even if you look "Stupid"