Spoked wheel disk manufacturing method and spoked wheel

A method of manufacturing a spoked wheel disk comprising:

• a step of preforming a plurality of bulging portions on a substantially circular plate blank, the bulging portions being located concentrically and circumferentially outward of a bolt hole, each of the bulging portions being a base of a reinforcing portion of a spoke;
• a step of forming a plurality of prototypical decorative holes on the respective bulging portions to form a prototypically-shaped spoke between the adjacent prototypical decorative holes;
• a step of forming a disk flange by bending an outer circumferential portion of the plate blank, on which the prototypical decorative holes are formed, at a right angle to be substantially parallel to a wheel axial direction, so that an outer periphery of a resultant decorative hole forms an upper end edge of the disk flange, wherein the step of forming the disk flange further includes substantially recessing a part of an outer circumferential edge of the plate blank, which faces the prototypical decorative hole, radially inward from a first reference circle that encircles a part of the outer circumferential edge of the plate blank which faces a distal end of the prototypically-shaped spoke;
• and
• a step of forming the spoke by providing the prototypically-shaped spoke with the reinforcing portion.