I use a seat post rack and made 2 short bungee cords that attach to the 2 hooks on the panniers and onto my lower seat stay frame. I don't preload them very much but its just enough to hold the panniers in place. It works great. I made the bungee cords out of those color coordinated ones that would match my bike and just cut off all the extra after adjusting them to length. They ended up being quite short about 6in long ea.