A 0.22 will be like a mosquito bite.

There are a number of 0.44, 0.45, and 0.50 caliber handguns that would cause some significant injury to a bear. Most, however, don't have a 17 shot magazine.

It sounds like that death was a mountain biker. Road bikers are probably less susceptible to the risk, as long as they exercise some caution and common sense.

Also, know where one is riding. There are only a few places in the USA with Grizzlys.