Shimano GRX 12 Speed Crankset - 48/31 FC-RX820 - 2The Shimano FC RX820 crank balances weight savings, optimized efficiency and an array of gearing options that cater to the segmented demands of mixed terrain riding. Gravel optimized 48 31t gear combination ratios preserve riding rhythm on rough surfaces The 17t range covers an array of riding conditions Smaller gear steps for cadence control on mixed terrain riding Hollowtech II crank arms provide strength and stiffness with the benefit of weight