Deore m617 double chainset 10 speed great value deore 2 piece design chainset for 10 speed dyna sys mtb hg x transmissions the 2 piece design chainset features an external bottom bracket system which is a lightweight rigid design that is incredibly strong and durable lightweight and rigid steel bottom bracket axle sg x dyna sys plus chainrings with patented spike pin give smooth and fast gear shifts under load lightweight aluminium outer with steel inner chainrings we recommend that the bottom