I guess I should have included the following too. Bike is a trek 7.3. Commute is short about 4 miles. Security not an issue. I would like to remove the bags if not in use for afternoon/evening rides. Backpack is 17 x 11 x approx. 5 inches. Not hardcore enough to ride in the rain (yet) but the backpack itself has been through some pretty big downpours so waterproof isn't a requirement. Prathman- I'm very intrigued by what you have done there. My backpack is similar to yours. Do you use anything as a bottom attachment on your bag or just the top hooks? My trip is over some pretty rough bikepaths and roads so there are quite a few big bumps along the way. Also sometime mine can get a little heavy, how about much weight do you carry in yours? Thanks for the feedback guys!