The GX crank is an integral part of SRAM's 1x drivetrain system and features the X-SYNC 32T chainring. Each tooth’s thickness is CNC machined to work seamlessly with the chain’s 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) and according to SRAM & Trek "this small increase in width results in significant gains to rear wheel stiffness — comparable to a 27.5in mountain bike wheel".