I have yet to have a black bear do anything other than haul a** directly away from me (knock on wood). I am more nervous about mountain lions anymore. I know three guys that have been stalked by them while they were bowhunting. 2 of the guys killed them with thier bows. The other guy "got big" and walked toward it yelling. It ran off, and the guy headed back for camp - watching his 6 the whole way.
Nothing like being down in a canyon, covered in elk blood, in the dark, to make you start feeling like cougar chum