They're not heavy, but it just puts a lot of stress on 1 shoulder. So the weight of the bag isn't spread across both shoulders, which can be a pain wearing and walking around in one all day. I used one for a few years though, it was the only bag I had so I kind of used it for everything vacations, biking, walking and whatever. But having a 2 strap bag now also, I usually do bring that one if it's not going to rain.