Abstract: A golf club shaft includes an outer shaft and an inner shaft disposed in a hollow portion of the outer shaft. A void portion is formed between the outer shaft and the inner shaft. The golf club shaft has a double structure including the outer shaft and the inner shaft. This allows both of the shafts to integrally operate and also allows one of the shafts to primarily operate.

Abstract: A shaft selection assist apparatus according to this invention includes a storage means for storing recommended shaft information indicating a correspondence between measurement parameters obtained upon a test strike with a golf club to which a predetermined reference shaft is attached, and recommended shafts among shafts of a plurality of types, an acquisition means for acquiring the measurement results of the measurement parameters associated with a test strike actually made by a user with the golf club, a selection means for selecting a recommended shaft by referring to the recommended shaft information based on the measurement results acquired by the acquisition means, and an output means for outputting information indicating the recommended shaft selected by the selection means. The recommended shaft information stored in the storage means is information which specifies recommended shafts based on the relationship between the shaft rigidity distribution and the measurement parameters.

Abstract: A shaft selection assist apparatus according to this invention includes a storage means for storing recommended shaft information indicating a correspondence between measurement parameters obtained upon a test strike with a golf club to which a predetermined reference shaft is attached, and recommended shafts among shafts of a plurality of types, an acquisition means for acquiring the measurement results of the measurement parameters associated with a test strike actually made by a user with the golf club, a selection means for selecting a recommended shaft by referring to the recommended shaft information based on the measurement results acquired by the acquisition means, and an output means for outputting information indicating the recommended shaft selected by the selection means. The measurement parameters include the vertical launch angle of a struck ball and the back spin amount on the struck ball.

Abstract: It is to provide a putter adapted so that a head thereof can easily be drawn straightly backward at a back-swing. It is to locate a center G of gravity of the head more frontward (in a direction of a face side thereof than the center axis of a shaft.

Abstract: It is to provide a putter adapted so that a head thereof can easily be drawn straightly backward at a back-swing. It is to locate a center G of gravity of the head more frontward (in a direction of a face side thereof than the center axis of a shaft.

Abstract: In an iron club set, the lie angle of each iron club in an iron club set is selected to be 61 degrees or larger. The lie angles of the iron clubs are set at a fixed value for every type of the iron clubs including a short iron to a long iron or progressively increase in angle value from the short iron to the long iron. Further, a ratio (L/H) of the minimum height (L) of the face at the heel to the maximum height (H) of the face of the club head, progressively increase in value in going to the long irons.