To manufacture a hub from a single part of structural fibers like a carbon fiber material.

Since radiant pressure is applied to a tubular main body comprising a layer having a structure based on structural fibers, the wheel hub of a bicycle is formed from the single part of a material based on the structural fibers by the expansion in a mold utilizing the expansion action of a core. A plurality of layers comprising a fiber structure mixed with a plastic material substrate are applied to the periphery of the expansible core 1 to form the tubular main body 9 of layered constitution having a given shape and thickness to the periphery of the core 1 and the whole is arranged in the cavity 13 of the mold 14 and, after internal pressure is applied to the tubular main body 9 to expand the core 1, the tubular main body 9 is detached from the mold 14 and the core 1.