i am now a backpack person. i use to use messenger bags, but the one strap on the shoulder with ~15pounds in it or more became to much of a hassle. moreso for quick stops the bag would swing around and would almost throw me off my bike. just the stuff inside moving around was anoying. so i switched back to backpacks, and then a rear rack with a basket and now i keep my bag in that. best soultion so far, back is free of sweat, less aches and pains(btw i'm 23) and really just makes sense. the rear rack has more uses. for rain i just put bag into a garbage bag. i havn't tried painners yet.