Oh, it's more a - ride defensively & wear your helmet, helmets don't make you bulletproof comment. (which is probably something that doesn't need to be stated)

For all I know, he had a congenitally weak blood vessel in the back of his brain, and it didn't take much force to tear that.

I just checked the book out from the library, it is a fairly easy read. I'd just been curious because I had heard of Dr. Epstein on and off over the years from friends or doctors and about the bike accident... So I finally googled him and found the book.