Okay... I'm new to setting up disc brakes. I have a new SRAM 9.0 disck hub. I also have an Avid disc system. The hub has no 6-hole mount for the rotor - instead it has a sieries of 9 squat "splines" where the rotor should bolt on. IS THERE AN ADAPTER, or what??? I've searched the websites of both companies and have found nothing!