A sprocket support body is rotatably mounted on a hub axle of a bicycle rear hub assembly. The sprocket support body comprises at least ten external spline teeth configured to engage with a bicycle rear sprocket assembly. Each of the at least ten external spline teeth has an external-spline driving surface and an external-spline non-driving surface. The at least ten external spline teeth has an external-spline major diameter equal to or smaller than 34 mm. The sprocket support body is free of external spline teeth having another external-spline major diameter that is different from the external-spline major diameter.