Gates Carbon Drive Carbon Drive CDX belt 111t - 1221mm Patented carbon cords offer the tensile strength necessary to provide the smooth, greaseless, long lasting ride advantage of a belt driven system (up to double the life of chains) Belt is only compatible with Gates CDX CenterTrack cogs and sprockets For belt sizing chart and other info (can use the same belt for gearing changes up to a max of 4 teeth) visit http://www.gatescarbondrive.com/ or download the Gates Carbon Drive iPhone app for drivetrain calculations and tension analysis Important: Frames must have a split or opening to allow the belt to loop through the rear drive-side triangle design varies by frame builder