Abstract: In a head, a center vertical cross section passing through a face center satisfies the following (a) and (b): (a) when a boundary point between an inner surface of a crown portion and an inner surface of a face portion is defined as a CF inner surface boundary point, a curvature radius of a head inner surface at the CF inner surface boundary point is 6.0 mm or greater and 10.0 mm or less, and the head thickness at the CF inner surface boundary point is 2.0 mm or greater; and (b) when a spot located 10 mm apart from the CF inner surface boundary point toward the crown side is defined as a spot C10, the head thickness reduces gradually from the CF inner surface boundary point to the spot C10, and the head thickness at the spot C10 is 1.0 mm or less.

Abstract: A head includes a body member that has an opening, and a face member that includes a striking face and closes the opening. The face member includes a face portion that forms the striking face, and a peripheral portion that extends from a peripheral edge of the face portion toward a back side. The peripheral portion of the face member is welded to the body member. A weld bead that juts from the inner surface of the head is formed at a boundary position between the peripheral portion and the body member. A wall thickness at a face-side end point of the weld bead is greater than a wall thickness at a body-side end point of the weld bead. The peripheral portion has a length of less than or equal to 6 mm.

Abstract: In a head, a center vertical cross section passing through a face center satisfies the following (a) and (b): (a) when a boundary point between an inner surface of a crown portion and an inner surface of a face portion is defined as a CF inner surface boundary point, a curvature radius of a head inner surface at the CF inner surface boundary point is 6.0 mm or greater and 10.0 mm or less, and the head thickness at the CF inner surface boundary point is 2.0 mm or greater; and (b) when a spot located 10 mm apart from the CF inner surface boundary point toward the crown side is defined as a spot C10, the head thickness reduces gradually from the CF inner surface boundary point to the spot C10, and the head thickness at the spot C10 is 1.0 mm or less.

Abstract: A golf club 2 includes a head 4, a shaft 6, and a grip 8. A club inertia moment about a swing axis is defined as Isw. A club inertia moment about a grip end is defined as Ige. Ige is 2760 (kg·cm2) or greater and less than 2820 (kg·cm2). Isw/Ige is equal to or less than 2.42. A club weight is defined as Wc (kg), an axial direction distance from the grip end to a center of gravity of the club is defined as Lc (cm), and a club inertia moment about the center of gravity of the club is defined as Ic (kg·cm2). Isw is calculated by Equation (1) below. Ige is calculated by Equation (2) below.

Abstract: A golf club set includes a plurality of golf clubs 1 having different loft angles. The golf clubs 1 include at least one 1st golf club 1A having a loft angle of less than 34 degrees, and at least one 2nd golf club 1B having a loft angle of not less than 34 degrees. Each of the at least one 1st golf club 1A and the at least one 2nd golf club 1B comprises a clubface 3 provided with a plurality of face grooves 8 having a depth. The depth of the face grooves 8 of the at least one 2nd golf club 1B is larger than the depth of the face grooves 8 of the at least one 1st golf club 1A.

Abstract: A golf club set includes at least one first golf club whose loft angle is not less than 46 degrees and less than 56 degrees, and at least one second golf club whose loft angle is not less than 56 degrees and less than 60 degrees. The first and second golf clubs each comprise a face provided with score lines each formed by a groove having a groove bottom and a pair of opposite grooves walls which are inclined at an inclination angle with respect to a normal direction to the face so that the groove width between the opposite grooves walls is increased from the groove bottom toward the face. The inclination angle of the groove walls of the score lines of the first golf club is in the range from 28 to 42 degrees. The inclination angle of the groove walls of the score lines of the second golf club is in the range from 23 to 37 degrees and smaller than that of the first golf club.

Abstract: A golf club set includes a plurality of golf clubs 1 having different loft angles. The golf clubs 1 include at least one 1st golf club 1A having a loft angle of less than 34 degrees, and at least one 2nd golf club 1B having a loft angle of not less than 34 degrees. Each of the at least one 1st golf club 1A and the at least one 2nd golf club 1B comprises a clubface 3 provided with a plurality of face grooves 8 having a depth. The depth of the face grooves 8 of the at least one 2nd golf club 1B is larger than the depth of the face grooves 8 of the at least one 1st golf club 1A.

Abstract: A golf club set includes at least one first golf club whose loft angle is not less than 46 degrees and less than 56 degrees, and at least one second golf club whose loft angle is not less than 56 degrees and less than 60 degrees. The first and second golf clubs each comprise a face provided with score lines each formed by a groove having a groove bottom and a pair of opposite grooves walls which are inclined at an inclination angle with respect to a normal direction to the face so that the groove width between the opposite grooves walls is increased from the groove bottom toward the face. The inclination angle of the groove walls of the score lines of the first golf club is in the range from 28 to 42 degrees. The inclination angle of the groove walls of the score lines of the second golf club is in the range from 23 to 37 degrees and smaller than that of the first golf club.

Abstract: Provided is a fitting apparatus that accurately and objectively determines an optimal swingability index, which is a swingability index of a golf club suited to a golfer. The fitting apparatus is provided with an acquisition unit, a calculation unit, and a determination unit. The acquisition unit acquires a measurement value obtained by measuring a swing action of a test club by the golfer with a measurement device. The calculation unit calculates a swing index indicating a feature amount of the swing action, based on the measurement value. The determination unit determines the optimal swingability index, according to a magnitude of the swing index.

Abstract: A golf club 2 includes a head 4, a shaft 6, and a grip 8. A club inertia moment about a swing axis is defined as Isw. A club inertia moment about a grip end is defined as Ige. Ige is 2920 (kg·cm2) or greater and less than 2970 (kg·cm2). Isw/Ige is equal to or less than 2.48. A club weight is defined as Wc (kg), an axial direction distance from the grip end to a center of gravity of the club is defined as Lc (cm), and a club inertia moment about the center of gravity of the club is defined as Ic (kg·cm2). Isw is calculated by Equation (1) below. Ige is calculated by Equation (2) below.

Abstract: A golf club 2 includes a head 4, a shaft 6, and a grip 8. A club inertia moment about a swing axis is defined as Isw. A club inertia moment about a grip end is defined as Ige. Ige is 2870 (kg·cm2) or greater and less than 2920 (kg·cm2). Isw/Ige is equal to or less than 2.46. A club weight is defined as Wc (kg), an axial direction distance from the grip end to a center of gravity of the club is defined as Lc (cm), and a club inertia moment about the center of gravity of the club is defined as Ic (kg·cm2). Isw is calculated by Equation (1) below. Ige is calculated by Equation (2) below.

Abstract: A head 2 includes a face surface 4, a back surface 6, and a sole surface 8. The back surface 6 includes a top side region Rt and a sole side region Rs. The sole side region Rs includes a sole side inclination surface Sb1 inclined to increase a face thickness toward a sole side, a plurality of back recessed parts Rb1 formed on the sole side inclination surface Sb1, and a wall WL1 formed between the back recessed parts Rb1 adjacent to each other. A low specific gravity member X1 having a specific gravity lower than the specific gravity of the face material is disposed on at least one of the back recessed parts Rb1. The head 2 has a loft angle of equal to or greater than 42°. The head 2 has a sweet spot height of equal to or greater than 19 mm.

Abstract: A golf club 2 includes a head 4, a shaft 6, and a grip 8. A club inertia moment about a swing axis is defined as Isw. A club inertia moment about a grip end is defined as Ige. Ige is 2820 (kg·cm2) or greater and less than 2870 (kg·cm2). Isw/Ige is equal to or less than 2.42. A club weight is defined as Wc (kg), an axial direction distance from the grip end to a center of gravity of the club is defined as Lc (cm), and a club inertia moment about the center of gravity of the club is defined as Ic (kg·cm2). Isw is calculated by Equation (1) below. Ige is calculated by Equation (2) below.

Abstract: An iron-type golf club head comprises a head main body and a face plate attached thereto. The face plate has an annular outer edge portion fixed to the head main body, and a noncontact portion not contacting with the head main body. The noncontact portion includes a first thin part and a second thin part having a thickness less than that of the outer edge portion. The first thin part extends in a peripheral side along the upper edge, the toe-side edge and the lower edge of the face plate. The second thin part is formed to have a thickness less than that of the first thin part. The area of the first thin part is 10% to 35% of the area of the noncontact portion. The area of the second thin part is 65% to 90% of the area of the noncontact portion.

Abstract: An iron-type golf club head has a face for hitting a ball, a sole extending backward from the lower edge of the face and extending in the toe-heel direction of the head so as to define the bottom surface of the club head, and a hosel extending upward in a heel-side of the face and provided with a shaft inserting hole. The club head is composed of a head main body including the face, and a weight member having a specific gravity larger than that of the head main body and fixed to the head main body. The weight member integrally includes a first part extending in the toe-heel direction in the sole, and a second part constituting at least substantial portion of the hosel.

Abstract: An evaluation method for hit feeling of a sport implement according to the present invention includes an acceleration measurement step for measuring acceleration of a sport hitting tool 4 and a data analysis step for analyzing data obtained in the measurement. In the data analysis step, an amount of change in acceleration in a first cycle of vibration after hitting is calculated. The evaluation method evaluates hit feeling to be felt by a person, using the amount of change in the acceleration. Preferably, in the data analysis step, an amount of change in acceleration in the first cycle of predetermined time is calculated. The predetermined time is within 1.5 msec from the time of hitting. Preferably, the sport hitting tool 4 has the hitting section detachably attached to a shaft section.

Abstract: A golf club 2 includes a head 4, a shaft 6, and a grip 8. A club inertia moment about a swing axis is defined as Isw. A club inertia moment about a grip end is defined as Ige. Ige is 2870 (kg·cm2) or greater and less than 2920 (kg·cm2). Isw/Ige is equal to or less than 2.46. A club weight is defined as Wc (kg), an axial direction distance from the grip end to a center of gravity of the club is defined as Lc (cm), and a club inertia moment about the center of gravity of the club is defined as Ic (kg·cm2). Isw is calculated by Equation (1) below. Ige is calculated by Equation (2) below.

Abstract: A golf club 2 includes a head 4, a shaft 6, and a grip 8. A club inertia moment about a swing axis is defined as Isw. A club inertia moment about a grip end is defined as Ige. Ige is 2760(kg·cm2) or greater and less than 2820(kg·cm2). Isw/Ige is equal to or less than 2.42. A club weight is defined as Wc (kg), an axial direction distance from the grip end to a center of gravity of the club is defined as Lc (cm), and a club inertia moment about the center of gravity of the club is defined as Ic(kg·cm2). Isw is calculated by Equation (1) below. Ige is calculated by Equation (2) below.

Abstract: A golf club 2 includes a head 4, a shaft 6, and a grip 8. A club inertia moment about a swing axis is defined as Isw. A club inertia moment about a grip end is defined as Ige. Ige is 2820 (kg·cm2) or greater and less than 2870 (kg·cm2). Isw/Ige is equal to or less than 2.42. A club weight is defined as Wc (kg), an axial direction distance from the grip end to a center of gravity of the club is defined as Lc (cm), and a club inertia moment about the center of gravity of the club is defined as Ic (kg·cm2). Isw is calculated by Equation (1) below. Ige is calculated by Equation (2) below.

Abstract: A golf club 2 includes a head 4, a shaft 6, and a grip 8. A club inertia moment about a swing axis is defined as Isw. A club inertia moment about a grip end is defined as Ige. Ige is 2920 (kg·cm2) or greater and less than 2970 (kg·cm2). Isw/Ige is equal to or less than 2.48. A club weight is defined as Wc (kg), an axial direction distance from the grip end to a center of gravity of the club is defined as Lc (cm), and a club inertia moment about the center of gravity of the club is defined as Ic (kg·cm2). Isw is calculated by Equation (1) below. Ige is calculated by Equation (2) below.