I converted a backpack into a pannier by adding the pannier hooks made by Lone Peak. These have a little lever that locks the hook to the rack so it won't pop off over bumps. When used as a pannier I just loop the backpack straps over the outside of the pack to keep them out of the way (I put a clip on them so they stay put). The pannier hooks are out on the corners of the pack so they don't touch me when used as a backpack.