Abstract: A golf club includes a reinforcing member installed on an inner circumferential surface of a shaft near a tip-side end portion and extends in an axial direction of the shaft to straddle an upper end of a cylindrical portion. The reinforcing member has a cylindrical shape configured by laminating prepregs obtained by impregnating carbon fibers being reinforcing fibers with a matrix resin. The reinforcing member is provided with: a first bias layer located at the innermost side in a radial direction; a second bias layer laminated on an outer side of the first bias layer (16A) in the radial direction, an orientation direction of the reinforcing fibers having an opposite direction to the first bias layer; and a straight layer laminated on the outer side of the second bias layer in the radial direction, an orientation direction of the reinforcing fibers being parallel to the axial direction of the shaft.

Abstract: A golf club includes a reinforcing member installed on an inner circumferential surface of a shaft near a tip-side end portion and extends in an axial direction of the shaft to straddle an upper end of a cylindrical portion. The reinforcing member has a cylindrical shape configured by laminating prepregs obtained by impregnating carbon fibers being reinforcing fibers with a matrix resin. The reinforcing member is provided with: a first bias layer located at the innermost side in a radial direction; a second bias layer laminated on an outer side of the first bias layer (16A) in the radial direction, an orientation direction of the reinforcing fibers having an opposite direction to the first bias layer; and a straight layer laminated on the outer side of the second bias layer in the radial direction, an orientation direction of the reinforcing fibers being parallel to the axial direction of the shaft.

Abstract: The golf club head (14) of the present invention has a face portion (24) for striking a golf ball, a crown portion (18) connected to the face portion (24), and a sole portion (22) connected to the face portion (24). The ratio of either lower of a first equivalent rigidity of a crown member (18) and a second equivalent rigidity of a sole member (22) to the higher is equal to or less than 0.75. The present invention provides a golf club (10) provided with the hollow golf club head (14) capable of increasing the carry of a golf ball based on a technique for increasing the carry of a golf ball other than conventional ones such as adjustment of the loft angle and reduction in the thickness of the striking surface, and provides a method of designing such a hollow golf club head as well.

Abstract: A golf club head and a golf club provided with the golf club head. The head has outer shell structure portions including a hosel portion, a face portion, a sole portion, a crown portion, and a side portion and a joining portion where a crown member used in the crown portion is bonded to a member used in another outer shell structure portion. The member to be used as the crown member has an equivalent rigidity not more than 0.8 times as high as that of a sole member used in the sole portion where the equivalent rigidity of a member used in any one of the outer shell structure portions is defined as the product of the thickness of the relevant member and the elastic modulus of the member in a direction in which a golf ball-striking surface of the face portion is oriented.

Abstract: A hollow golf club head allowing to increase the repulsion and the degree of design freedom, while maintaining the durability. A hollow golf club head having a head body formed from a metal, wherein a hole is formed in the vicinity of the middle of a crown portion in the head body, the hole is closed with a cover member made of a material different from the head body, and the ratio (?m/?t) of the specific gravity ?m of the head body and the specific gravity ?f of the cover member is set equal or superior to 1.3.

Abstract: Disclosed is a golf club set having harmonized golf club performance among the club numbers. In the golf club set, for at least three golf clubs, a ratio or a sum of a frequency, the frequency being measured by vibrating a tip portion of a golf club shaft constituting each of the golf clubs, and a frequency, the frequency being measured by vibrating a rear end portion of the golf club shaft, is determined in relation with order of the club number.

Abstract: Disclosed is a golf club set having harmonized golf club performance among the club numbers. In the golf club set, for at least three golf clubs, a ratio or a sum of a frequency, the frequency being measured by vibrating a tip portion of a golf club shaft constituting each of the golf clubs, and a frequency, the frequency being measured by vibrating a rear end portion of the golf club shaft, is determined in relation with order of the club number.

Abstract: Disclosed is a golf club set having harmonized golf club performance among the club numbers. In the golf club set, for at least three golf clubs, a ratio or a sum of a frequency per unit time, the frequency being measured by vibrating a tip portion of a golf club shaft constituting each of the golf clubs, and a frequency per unit time, the frequency being measured by vibrating a rear end portion of the golf club shaft, is determined in relation with order of the club number.

Abstract: A hollow golf club head allowing to increase the repulsion and the degree of design freedom, while maintaining the durability. A hollow golf club head having a head body formed from a metal, wherein a hole is formed in the vicinity of the middle of a crown portion in the head body, the hole is closed with a cover member made of a material different from the head body, and the ratio (?m/?t) of the specific gravity ?m of the head body and the specific gravity ?f of the cover member is set equal or superior to 1.3.

Abstract: A hollow golf club head allowing to increase the repulsion and the degree of design freedom, while maintaining the durability. A hollow golf club head having a head body formed from a metal, wherein a hole is formed in the vicinity of the middle of a crown portion in the head body, the hole is closed with a cover member made of a material different from the head body, and the ratio (?m/?f) of the specific gravity ?m of the head body and the specific gravity ?f of the cover member is set equal or superior to 1.3.

Abstract: The golf club head (14) of the present invention has a face portion (24) for striking a golf ball, a crown portion (18) connected to the face portion (24), and a sole portion (22) connected to the face portion (24). The ratio of either lower of a first equivalent rigidity of a crown member (18) and a second equivalent rigidity of a sole member (22) to the higher is equal to or less than 0.75. The present invention provides a golf club (10) provided with the hollow golf club head (14) capable of increasing the carry of a golf ball based on a technique for increasing the carry of a golf ball other than conventional ones such as adjustment of the loft angle and reduction in the thickness of the striking surface, and provides a method of designing such a hollow golf club head as well.

Abstract: The inner surface of the hollow portion of the golf club head according to the present invention includes either or both of a concave surface and a flat surface. On the other hand, the projecting portion provided on the inner surface of the hollow portion, if any, is so formed that it has a convex surface with a radius of curvature equal to or greater than 3 mm, or chamfered at a level of C3 or more (JIS B0701-1987 standard). Owing to such structure, the golf club head can be manufactured with good efficiency even if the molding is performed using a bladder because the rate of molding failure upon such molding is reduced while the characteristics of the golf club head are ensured. The golf club of the present invention has such a golf club head as above.

Abstract: The golf club head of the present invention comprises outer shell structure portions including a hosel portion, a face portion, a sole portion, a crown portion, and a side portion; and a joining portion where a crown member used in the crown portion is bonded to a member used in another outer shell structure portion. The member to be used as the crown member has an equivalent rigidity not more than 0.8 times as high as that of a sole member used in the sole portion where the equivalent rigidity of a member used in any one of the outer shell structure portions is defined as the product of the thickness of the relevant member and the elastic modulus of the member in a direction in which a golf ball-striking surface of the face portion is oriented.

Abstract: Provided is a hollow golf club head capable of improving repulsion and degree of design freedom compared to the case where a golf club head is formed using only a single metallic material, by combining different kinds of materials as component materials of a face section. The face section of the hollow golf club head is made of a composite material in which metal and fiber-reinforced plastic are combined. For example, in the hollow golf club head comprising a plate member disposed on the face section, the plate member is partially made of fiber-reinforced plastic in a plane direction and the remainder of said plate member is made of metal.

Abstract: Disclosed is a golf club set having harmonized golf club performance among the club numbers. In the golf club set, for at least three golf clubs, a ratio or a sum of a frequency per unit time, the frequency being measured by vibrating a tip portion of a golf club shaft constituting each of the golf clubs, and a frequency per unit time, the frequency being measured by vibrating a rear end portion of the golf club shaft, is determined in relation with order of the club number.

Abstract: Disclosed is a golf club set having harmonized golf club performance among the club numbers. In the golf club set, for at least three golf clubs, a ratio or a sum of a frequency per unit time, the frequency being measured by vibrating a tip portion of a golf club shaft constituting each of the golf clubs, and a frequency per unit time, the frequency being measured by vibrating a rear end portion of the golf club shaft, is determined in relation with order of the club number.

Abstract: Disclosed is a golf club set having harmonized golf club performance among the club numbers. In the golf club set, for at least three golf clubs, a ratio or a sum of a frequency per unit time, the frequency being measured by vibrating a tip portion of a golf club shaft constituting each of the golf clubs, and a frequency per unit time, the frequency being measured by vibrating a rear end portion of the golf club shaft, is determined in relation with order of the club number.

Abstract: A golf club head capable of obtaining both vibration damping performance and pleasant hitting sound by combining materials different in kind. This golf club head has a hollow structure, and a constitution where fiber reinforced plastic having a mass ratio of 4% or more in the entire head is used for at least one of neck, face, sole, crown and side portions, and the rest is made of metal. An outer shell of the hollow structure includes both of a part made of only metal and a part made of only fiber reinforced plastic.

Abstract: Disclosed is a golf club set having harmonized golf club performance among the club numbers. In the golf club set, for at least three golf clubs, a ratio or a sum of a frequency per unit time, the frequency being measured by vibrating a tip portion of a golf club shaft constituting each of the golf clubs, and a frequency per unit time, the frequency being measured by vibrating a rear end portion of the golf club shaft, is determined in relation with order of the club number.

Abstract: A hollow golf club head allowing to increase the repulsion and the degree of design freedom, while maintaining the durability. A hollow golf club head having a head body formed from a metal, wherein a hole is formed in the vicinity of the middle of a crown portion in the head body, the hole is closed with a cover member made of a material different from the head body, and the ratio (&rgr;m/&rgr;f) of the specific gravity &rgr;m of the head body and the specific gravity &rgr;f of the cover member is set equal or superior to 1.3.