If a bear wants to get into your chicken coop, it is getting in. Hell, they can break into houses if they are so inclined.
I keep mine (10 Hens, 1 Rooster) in a fenced in area - I repurposed an old 30 x 30 dog kennel/run, then did two different sizes of chicken wire - one inside, one outside. I also excavated four inches down and buried wire mesh before covering it with soil again - to keep out mice/fishers.
The coop itself is raised on eight inches legs and is enclosed inside of the fenced area itself.
During the warmer months, I have a portable run that is wire-mesh roofed, 12 feet long (2 feet of it has a solid roof to provide shade) and 10 feet wide. Every week or so, I move it to another spot in one of the fields. The chickens are pretty good about following me to it, as it is where I feed them and they return to the coop of their own accord without much prodding at the end of the afternoon.