The XDR interface is 1.85mm longer than XD and is designed for road hub applications. This allows XDR compatible hubs to match the geometries of 11-speed road driver bodies. XDR driver bodies are compatible with all XD cassettes when the cassette is installed with a 1.85mm spacer. Any hubs equipped with XDR freehubs can be converted to an 11-speed road freehub body for use with a non-XD cassette.