I'm more scared of mountain lions than bears. At least I'd know if a bear wanted to take me down. Mtn. lions stalk their prey, attack from behind, hold you down with their hind legs, and crush your neck.
Don't hike alone and be aware of your surroundings. That's the best piece of advice I can give you.
See the cougars power here:
http://tinyurl.com/qwekf
Reality:
http://tchester.org/sgm/lists/lion_attacks_ca.html
(See the death of a mtn. biker in 2004)