Actually, AFAIK most confirmed reports of predatory bears have been blacks, not grizzlies (plus polar bears, but who worries about polar bears while riding motorbikes?). Predation--stalking and killing in order to eat--of humans is quite rare, but it does happen.

I've run into both kinds on my bike: it's a privilege, and depending where you are might not be uncommon. If you're camping in bear country, use bearproof containers and don't bring smelly stuff into your tent (duh). That includes actual food, toiletries, cooking gear, trash, stuff which has recently held food, chewing gum, and whatever else you can think of. If camping in true wilderness, where troublesome bears are not routinely transported elsewhere or killed, you'll want to think carefully about cooking odors or spills which get into your clothes: I often wear goretex while cooking and leave it away from the tent at night. And unless you're willing to practice up and have nerves of steel, don't bother with the bear spray.

I've had a bear pawing through my pack a couple of feet from my head at night--it was the sound of ripping Kelty packcloth which woke me up. I've met bears on trails and had them wander through my camps at night. It's ok: they're not really interested in messing with you unless you happen to smell like salami, peanut butter or cooking lard, or you appear to take an unseemly interest in their cubs. Mostly. You'd be better off worrying about distracted drivers and slow-witted moose blocking narrow roadways.

Hope that's helpful.

Mark