The SHIMANO FC-RX820-1 crank balances weight savings, optimized efficiency and an array of gearing options that cater to the segmented demands of mixed-terrain riding. By pairing a 10-45T or 10-51T cassette with 40T and 42T chainring, riders can choose closer gear steps or ultimate range. The FC-RX820-1 comes in 170, 172.5, and 175mm crank arm lengths, adding an additional level of customization.FEATURESOptimal gearing for mixed-terrain riding10-45T and 10-51T cassette options serve array of riding styles 42T and 40T chainrings available