Patent ID: 7137906

Claim:
A golf club head having a face portion, a crown portion forming a head upper surface, and a sole portion forming a head bottom surface, and wherein a thickness of the face portion is not more than 2.7 mm, a thickness of the crown portion is not more than 0.9 mm, a thickness of the sole portion is not more than 1.0 mm, and the head, when mounted on a horizontal surface to have a set lie angle and face angle, with a vertical cross section passing through a center of the face portion and being perpendicular to the face surface and said horizontal surface, has (1) a smallest radius of curvature of an outer surface in the crown portion of not less than 500 mm, measured at the vertical cross section, and (2) a smallest radius of curvature of an outer surface in the sole portion of not less than 1000 mm, measured at the vertical cross section, and wherein a frequency F (fix) indicating a primary minimum value of a frequency transfer function of a head obtained by firmly fixing the head to a vibrator and measured in accordance with a vibrator method is between 600 and 1200 Hz, a frequency F (free) indicating a primary minimum value of a frequency transfer function of the head obtained by placing the head in a free state and measured in accordance with an impact hammer method is between 2500 and 4000 Hz, and a ratio F (free)/F (fix) between said frequency F (fix) and said frequency F (free) is between 4.2 and 6.0.