I always use a small backpack or a" roll top" messenger bag... However I also have two bikes set up with a front wald basket and one bike with a front rack and small panniers. All of my personal belongings such as clothing , spare tubes ,tools, pump etc I carry on person in a backpack..When I go do my shopping or carry heavy bulky items I always put them in my baskets or front rack/panniers. I don't use rear racks panniers as I don't like lot's of weight on the rear, I prefer to have it on the front/