Funny you should ask. I just bought a set of panniers. Most of the time I ride with a small trunk bag on my rear rack and wear a backpack during the winter when I need to carry extra ride clothing. The backpack was never really a problem because I rarely had anything heavy in there and it didn't make me sweat too much. However, I just started taking a night class and it was no fun carrying books in the backpack. After all these years of commuting I'm finally going to give panniers a try.