I would not trust a loaded weapon in my jersey pocket. Of course offroad my situation is much different than yours and I tend to wreck more often than I should.
Fanny pack would be the better choice. My weapon fits nicely in one or in a nice Cannon camera pouch on the belt.
The Camelbak I use is an older fanny pack design. The bladder goes in your lumbar area with side pockets for easy to reach stuff. I'm sure the HK would fit nicely but have never carried it biking.
With people now cooking meth in public parks/campgrounds perhaps maybe I need to start thinking about it more.
