Great value deore 2 piece design chainset for 9 speed transmissionsthe 2 piece design chainset features an external bottom bracket system which is a lightweight rigid design that is incredibly strong and durablelightweight and rigid steel bottom bracket axlesg x chainring with patented spike pins give smooth and fast gear shifts under loadlightweight aluminium outer with steel middle and inner chainringswe recommend that the bottom bracket is initially installed by a bike shop to ensure perfect