Do you have a polar bear suit? :-)
I have a birthday suit. Will that help?
No bear suit...the only effective defense against bears that I know of is a gun. When you hike outside of the city in Alaska, it's best to carry a gun in your backpack (or two guns if you prefer, in case the first one jams.) If you encounter a bear, stay quiet then back slowly away from the bear and hope he doesn't notice you and he's not hungry. Use the gun as a last resort and aim right between his beady eyes.