I need a new backpack and was considering a messenger bag style, as they look like they'd be pretty convenient, but I wondered if anyone here used them while cycling. I wondered how well they stay put, and how comfortably they actually do balance out the load. Would I be better off sticking with a conventional backpack? I need to be able to carry up to 6 library books, a couple of pieces of fruit, a cup of yogurt, a small makeup bag, a notebook, and miscellaneous paperwork (bills, notes, ect) my wallet and checkbook. The bag needs to be a very bright color for visibility. Yellow, orange, or lime green for choice. Also, a reasonable price is of the essence. Under $50, if possible. It does not need to be beautiful; just bright, durable, and capacious. Any suggestions?