The Deore M617 10 Speed 38/24 MTB Chainset from Shimano is a great value 2-piece chainset for 10-Speed Dyna-Sys MTB HG-X transmissions. The 2-piece design features an external bottom bracket system which is a lightweight rigid design that is incredibly strong and durable. The axle is made from a lightweight and rigid Steel and the chainrings are steel with a lightweight aluminium outer ring. The chainrings are SG-X Dyna-Sys plus chainrings with patented spike pins to give smooth and fast gear shifts, even under pressure. Available in Black with 170mm or 175mm crank arm lengths.