SPROCKET SUPPORT BODY

A sprocket support body comprises at least ten external spline teeth including a plurality of external-spline driving surfaces. The plurality of external-spline driving surfaces each includes a radially outermost edge, a radially innermost edge, and a radial length. A total of the radial lengths of the plurality of external-spline driving surfaces is equal to or larger than 7 mm. At least one external-spline driving surface has a first external-spline-surface angle. The first external-spline-surface angle ranges from 0 degree to 10 degrees. One tooth of the at least ten external spline teeth having a first circumferential spline size. The other teeth of the at least ten external spline teeth each have a second circumferential spline size that is smaller than the first circumferential spline size. A total number of the other teeth of the at least ten external spline teeth being equal to or larger than nine.