I have several sizes of the topeak bags and the f25 fixer on a few bikes. It's not a bad system. Pretty easy to remove/attach the fixer if you need to for some reason. I also have a Rixen & Kaul KLICKfix Berthoud saddle bag that I move between two bikes. I like the topeak system a little better for small bags and the KLICKfix system better for larger bags.