The XCX family of retention systems was designed with the XC racer and trail rider in mind. All XCX use our DH proven Lg1+ upper slider; the lower slider is nixed in exchange for simplicity, less drag and weight savings. As the original XCX, the BB mount is still a great option for riders with more traditional guide fitment needs and a threaded 68 or 73mm BB shell. A 6061-T6 aluminum back plate mounts under the BB with a pair of 0.5mm shims to allow for exact chain line adjustment and our precision upper slider keeps the chain secure while limiting drag and giving you the confidence to attack.