Like Eric I only seem to get cramps on really long and hot rides. I don't think I've ever gotten one less than 6 hours in. The times I was able to scrounge up some endurolytes they have helped stave off the cramping. By cramping I mean total leg lock. It's only happened a few times but it's hell when it does. I've always been covered in a crust of salt on my face and clothes when it's happened.