"High-siding" a motorcycle All, I hope this is the appropriate place for this post (it is a physics problem). I am a motorcycle enthusiast and have recently noticed more and more novice users buying motorcycles, due to the high price of gas. Just about the worst wreck you can have on a motorcycle is "high-siding." This happens when the rear brake locks up and the back of the bike starts to skid out from under the rider. The rider then panics and releases the rear brake. When the rear brake is released, the tire bites and the bike flips over in the direction that it was skidding. There is a reasonably clear diagram of the sequence of events here: http://www.msgroup.org/tip.aspx?num=001 Or, to use more simplistic illustration, the bike starts to slide out to the right, like this: \ \ \ \ but when the brake is released, the bike stops sliding sideways and immediately becomes upright and goes over on the other side, like this: \ | / _ My question is, what is the impact speed of the driver (let's say his head), when he flips over the bike and onto the ground. Let's say that the rear of the bike is sliding out at 30 mph and is leaning over at 70 degrees. The rider releases the brake and the bike goes upright to 90 degrees and then over in the other direction to 0 degrees. The top of the rider's head is 48" off the ground. Can anyone give me an idea of the speed his head will hit the ground? I know it is kind of a morbid question, but I am trying to get people to take safety courses and wear helmets. Thanks in advance.