Bontrager's BackRack S Disc is made for disc-equipped mountain and hybrid bikes with frame sizes 18 inches and under, and road bike frames 54cm and under. This durable and light rack is perfect for turning your bike into a commuter and errand-runner. Tough and rustproof stainless-steel hardware is included and the single-bolt strut mounts allow for maximum adjustablility and ease of installation. Plus, the BackRack is compatible with standard trunk bags and panniers as well as Bontrager's Interchange models (sold separately). What's more, the BackRack includes a spacer to give you the necessary clearance for use with most disc brakes.