On many fork mounted bike racks, the disc caliper (the pod bolted to the fork leg) can hit the tray and not allow the fork to engage the quick release. To solve this problem, Rocky Mounts made the Disc Brake Adapter. The Lariat and Noose work with a few bikes with disc brakes. If your caliper does contact the tray, the Disc Brake Adapter can be bolted in between the head and the tray, and allow additional clearance for your disc brake. Good news--Adding the Disc Brake Adapter will not prevent regular, non-disc brake bikes from working on your RockyMounts.
Compatibility note: only works with the Lariat and Noose, will not work with older RockyMounts or any other manufacturers bike racks