Patent ID: 7650818

Claim:
A bicycle crank shaft comprising: an outer tubular member including a center portion, a first end portion and a second end portion with an interior longitudinal passageway extending between the first and second end portions, the interior longitudinal passageway having a longitudinal center axis extending therethrough, the center portion extending between the first and second end portions and being configured to be rotatably mounted in a bottom bracket structure of a bicycle, the first end portion having a first externally splined surface, the second end portion having a second externally splined surface, the center portion having a thickness measured in a radial direction relative to the longitudinal center axis, the first and second end portion having respective thicknesses that are greater than the thickness of the center portion; and an inner member non-movably attached to the outer tubular member within the interior longitudinal passageway, the outer tubular member being constructed of a first material having a first specific gravity and the inner member being constructed of a second material having a second specific gravity that is lower than the first specific gravity of the first material and the first externally splined surface extending extends radially outwardly of the uniform external diameter and the second externally splined surface does not extend radially outwardly of the uniform external diameter.