US Patent 8157672 Golf club head

A golf club head with an increased moment of inertia (MOI) about the X axis and the Z axis. Generally, the MOI about the Z axis is at least about 4400 g·cm2 and the MOI about the X axis is at least about 2500 g·cm2. The radius of the bulge of the club face is increased while the radius of the roll is reduced to compensate for the gear effect produced by the increased MOIs. The bulge curvature is generally between about 0.016 cm−1 and about 0.028 cm−1, and the roll curvature is between about 0.033 cm−1 and about 0.066 cm−1. The roll curvature is greater than the bulge curvature.