A splined drive body for supporting a plurality of sprockets is disclosed. The drive body is provided with at least one composite drive body spline which consists of a first portion made up of the drive body material and a second portion made up of a different, harder material. The second portion of the composite drive body spline is an insert which includes a force receiving surface and a force transmitting surface and is operable to transmit force transmitted to it into the drive body through a force receiving surface provided on the first portion of the composite drive body spline.