I have a sling backpack bag that I love. I bought it about 10 years ago, I think it's Eagle Creek brand. It's not full backpack sized, it's sort of triangular shaped and low profile if that makes sense, but it holds everything we need if we are not packing in water bottles. I like that my shoulders are free and my back doesn't get hot. It's small enough to slide around to my side or front and hold when I get on most rides (like I would a cross body handbag, instead of having a backpack that I have to store at my feet).