I got rear ended by a drunk driver going at 50+ mph on a quiet Sunday morning. I flew over and above a city bus and landed left shoulder first with my head whip-lashing onto the tarmac. Helmet (a cheap B'twin one) cracked right through the middle. No head injuries, and no scratches on the covered area. I looked like Harvey Dent for a while, couldn't walk for long, couldn't ride for longer. But that made me a believer.

EDIT: Technically not on a trail, on the way to one.