The SRAM RED® Exogram Crankset is completely hollow all the way to the spider. Its hidden bolt pattern makes better use of carbon fiber to further improve stiffness and shed weight. The stunning X-GlideR™ chainrings are optimized for use with the Yaw™ Technology in the front derailleur, delivering seamless, flawless performance. Features: Exogram technology uses a large, hollow cross section all the way to the spider, minimizing weight while maximizing stiffness. Our stiffest crank ever Hidden bolt pattern leverages the characteristics of carbon fiber while presenting a sleek appearance Stiffer X-GlideR™ chainrings feature thicker construction, advanced shift timing pins and ramps, which are optimized for shifting with the Yaw™ front derailleur Stunning two-tone finish Exogram The new Hollow Carbon Construction starts in the crank arm and extends into the cranks’ spider. It maximizes the stiffness to weight ratio. X-GlideR Chainrings The chainrings are designed for an optimized shifting performance with the Yaw front derailleur. The stiffer rings (5mm 7075-T6 aluminum CNC-machined) feature upshift rivets with an advanced design adopted from SRAM XX. CNC machining allows for precision control of each tooth shape, ramp, and nearly every shifting feature of the chainring. Chainrings, chain, and front derailleur are designed as a single integrated system for optimized performance. Specifications:Arm Material: CarbonChainring Material: Machined alloy ringsWeight: 557g (BB30 172.5mm / BB not included), 609g (GXP 172.5mm / BB not included)Available Arm Lengths: 165mm, 167.5, 170mm, 172.5mm, 175mm, 177.5mmOther: Compatible only with SRAM Yaw™ front derailleur