Oh but I didn't answer the how/where question.... For most of my bikes it's in a bag under the seat. I like Jandd's mini mountain wedge. Despite the name, it's got more capacity than a lot of seat bags, which seem to be designed for 700x19 tubes. Even with the Jandd the pump needs to go in a jersey pocket (I don't use any frame mounting systems). A couple of my bikes have either trunk bags or handlebar bags, which tend to result in a lot of extra cargo coming along for the ride, including a bigger pump.