If the horse is dead, who cares? A few year's ago (1998-1999) I was enjoying a nice steep downhill in town when my ride partner failed to point out a large rock in the roadway. I have no idea how fast I was going when I hit the pavement, but I actually blacked out for 3-5 minutes. My left hip, knee, elbow, etc were all pretty much useless for days, but my head was fine very shortly after I came to. I haven't had a crash since then, and often consider tossing my helmet, but then I think about that 3 minute black out and wear it anyway.