I was bit taken back to hear that bike is one of the leading causes of accidents which leads to having a concussion. (sorry for the bad grammar. can't figure out to say it correctly) Anyway, it's up there with football players.

Another surprise is that helmet isn't designed to protect your brain but its meant to keep your skull from breaking. Keeping your skull intact is important in protecting the brain but it's not designed to protect the brain from the traumatic shock that propagates through your brain. Really worth watching.

Great video: https://www.youtube.com/watch?v=druJDI6hiiY

And yes I've seen the airbag helmet. Neato!!