I ride almost daily with a backpack. It's a Mountain Equipment Co-OP Velo 20(?) it's big enough for lunch and a change of clothes, has lots of mesh pockets and reflective tape on the outside, and the shoulder straps, waist belt and chest compressor are all long enough to adjust comfortably for a roadie riding position. Even a loop for a blinkie light aligned for maximum visibility. Never moves around in traffic - the only problem is it prevents effective ventilation.

Best of all, it takes a camelback bladder, but I don't use that for the daily grind. Cost? About CDN$40.

I love this pack, it's comfortable for biking, hiking, even XC/Downhill skiing.

Pick one up!

A.