The gx crank is an integral part of sram39s 1x drivetrain system and features the x sync 32t chainring each tooths thickness is cnc machined to work seamlessly with the chains inner and outer links and with five available chainrings you can personalise your gear range to match the way you ride boost148 boost148 hub width 148mm x 12mm is targeted at 29ers and is designed to increase wheel stiffness via the hub the hub flanges are slightly wider apart from standard hubs 142mm x 12mm