Mizuno Corporation

Hiroki Ashida

Takeshi Saito

Takashi Ishii

Goro Hisamatsu

Yasushi Matsui

Toshimitu Shimizu

Susumu Hironaka

A golf club shaft selecting system includes a head speed detecting unit detecting a head speed at impact in a swing of a golfer, a swing tempo detecting unit detecting a swing tempo of the golfer, a chart indicative of a shaft mass and a shaft flex point corresponding to the swing characteristics of each golfer, a selecting unit selecting a golf club shaft suitable for the golfer referring to the chart and based on the head speed and the swing tempo detected by the head speed detecting unit and the swing tempo detecting unit, and a displaying apparatus displaying the golf club shaft selected by the selecting unit.

Golf club shaft selecting system and golf club shaft selecting method

A golf shaft made of fiber reinforced plastic and including a tip portion attached to a head, a butt portion attached to a grip, and a middle portion located between the tip portion and the butt portion. The golf shaft has a generally tapered shape in which the outer diameter generally increases gradually from the tip portion to the butt portion. The golf shaft includes a first portion in which linear density is generally uniform. A second portion is defined by the part of the shaft excluding the first portion. The first portion occupies 30% or more of the entire shaft length, and the linear density of the first portion is greater than that of the linear density.

Fiber reinforced plastic golf shaft

A golf club shaft has a braid layer including first and second diagonal yarns. The diagonal yarns are positioned at the degrees of orientation (&plus;&thgr;, &minus;&thgr;) of &plus;30&deg; to &plus;60&deg; and &minus;30&deg; to &minus;60&deg; against the longitudinal axis of the shaft, respectively. The braid layer has a portion that satisfies an inequality, n&middot;&lcub;(t&minus;&sgr;t)/cos &thgr;&rcub;&lE;&pgr;&middot;D&lE;n&middot;&lcub;(t&plus;&sgr;t)/cos&thgr;&rcub;, wherein t is the average width of the diagonal yarns, &sgr;t is the standard deviation of the width of the diagonal yarns, D is the shaft diameter, and n is the number of diagonal yarns. The braid layer satisfying the inequality minimizes spaces S between the diagonal yarns. With the shaft of the present invention, the ratio of the longitudinal modulus of the shaft during a swing to the longitudinal modulus of the shaft when the head speed is zero gradually increases along with the increase in the head speed, thus suppressing shaft's deformation caused by centrifugal force during a swing and facilitating swings of the club.

FRP golf club shaft

The golf club shaft comprises a reinforced tip portion from the tip end to the position 300 mm toward the grip end, gripping butt portion from the grip end to the position 100 mm toward the tip end, and an intermediate portion between the reinforced tip portion and the gripping butt portion. The shaft satisfies an equation EI&equals;&agr;&middot;X at its intermediate portion, where EI (Nm ) is the flexural rigidity, X (mm) is the distance from the tip end of the shaft, and &agr; is a given constant. The &agr; values of the shafts in accordance with the embodiments 1 through 3 are 0.12, 0.09, and 0.06, respectively. Thus, the present invention has an improved deflection during downswing and is liked by a majority of players.

Golf club shaft

A golf club has a shaft made of fiber reinforced plastics. The shaft has braided layers with substantially symmetrical diagonal yarns which are positioned at orientation angles &plus;&thgr;, &minus;&thgr; from more than 0&deg; to &plus;10&deg; and from less than &minus;0&deg; to &minus;10&deg; respectively, and/or from 45&deg; to less than &plus;90&deg; and from &minus;45&deg; to more than &minus;90&deg; respectively, against the longitudinal axis of the shaft at at least a portion along the longitudinal direction of the shaft. The Poisson's ratio &ngr; expressed by the ratio of lateral strain to longitudinal strain is 0.5 or less at least at the portion when load is applied to the shaft. The portion with the Poisson's ratio of 0.5 or less is preferably on the grip side, thus facilitating a swing of the club.

Growing community of inventors

Gifu, Japan

Hiroki Ashida