I have begun commuting to school this past month, and my back is already killing me. The problem is that I am using a backpack. Though the pack has waste and chest straps, the hilly commute with the pack is making it very difficult on my back.

In speaking with a fellow commuter at school, it was recommended that I get a back rack, and put a bag on there to hold my books, clothes, etc.

I have the problem of then needing a bag that I can remove from the pack, and easily convert to something with a strap to carry around while on campus (as I cannot leave the bag on the bike and risk it being stolen).

I have a Kona Dew, and wondering what would be a recommended rack and bag? I tend to carry a lot of books, so a larger bag would be good.

Thanks for your help.