In order to commute to school, I need a way to carry my backpack on a rack. I found last year, the major source of sweat on my relatively short ride in was on my back and underarms, and when I didn't have to bring a backpack (last day of school, field day, nothing to bring in, whatever), I found I hardly sweat at all, maybe a bit on a particularly hot morning. So, to get to my point, and I do have one, is there something I could attach to a rack (specifically a basket) that isn't too bulky. I was thinking about a milk crate, but are there any other systems you've used to carry a backpack, briefcase, what have you, on your bike that is as non-obtrusive as possible? Thanks in advance...