Shimano GRX FC-RX610 1x Crankset Optimized Efficiency The crank is what allows riders to send pedaling power to the rear wheel. With an upgraded crank, you'll have more of your power transferred to the rear wheel. The Shimano GRX FC-RX610 1x Crankset balances weight savings, optimized efficiency, and an array of gearing options that cater to the segmented demands of mixed-terrain riding. With a 10-45T or 10-51T cassette on the rear with a 38T or 40T chainring upfront, you'll have all the gearing you need to ride any trail. Features Balances weight savings and has optimized efficiency Pairs well with a 10-45T or 10-51T cassette Comes in 165, 170, 172. 5, and 175mm SPECIFICATIONSSpeeds1x12BB Compatibility68mm, 24mm Spindle Chain Ring38T, 40TCrank Arm Length165, 170, 172. 5, 175mm BB Spindle Interface24mm Chainring Material Aluminum Bolt Center Diameter (BCD)110mm Crank Arm Material Aluminum Chainline49. 7mm Bottom Bracket Included No, BB-RS501/BB-RS500-PB Recommended Intended Use Gravel Weight791g (38T), 812g (40T) | Shimano | Grx Fc-Rx610 1X Crankset 170Mm, 40T | Aluminum