Ok, from what i've experienced and heard from others, that fanny pack is useless. When I got my new backpack, i was wondering about it as well. so i asked around at a couple different outdoor places. the experienced workers actually laughed at me. seriously. apparently, they aren't that great. mine has one, but it's so freaking annoying to attach and detach that i've never even used it. So then i bought a little cheap biker backpack from REI. i guess it't better for biking because i didn't use it, instead just used an old messenger bag i had. that way, i was always aware of my belongings.
i do know people that used the camel backs, but it just felt safer to me to have my stuff in front of me.
We are not here for ourselves alone