GOLF CLUB SHAFT AND GOLF CLUB
Its objectives are to provide a golf club shaft that is capable of responding to a wide range of characteristics of a head to be mounted, levels and preferences of golfers, and the like; maintaining the ease of swing even when a heavier head is mounted; providing a preferred feel for a golfer, even when the subject is a professional or low handicap golfer; and increasing the carry of a ball. A golf club shaft made of multiple fiber-reinforced resin layers, containing a heavy substance with a specific gravity of 7 or greater positioned between 0 and 400 mm from the grip end of the golf club shaft; in such a golf club shaft, when the entire length of the golf club shaft is set as Ls and the distance from the head end to the gravity center of the golf club shaft is set as Lg, the ratio Lg/Ls is 0.54˜0.65.
1 . A golf club shaft made of a plurality of fiber-reinforced resin layers, comprising:
a heavy substance with a specific gravity of 7 or greater positioned between 0 and 400 mm from the grip end of the golf club shaft,
wherein when the entire length of the golf club shaft is set as (Ls) and the distance from the head end to the gravity center of the golf club shaft is set as (Lg), the ratio (Lg/Ls) is 0.54˜0.65.
2 . The golf club shaft according to claim 1 , the golf club shaft being made of a plurality of fiber-reinforced resin layers, further comprising a 20˜400 mm-long filler-containing resin layer (W) which contains the above heavy substance as a filler.
3 . The golf club shaft according to claim 2 , the golf club shaft being made of a plurality of fiber-reinforced resin layers, wherein the weight per unit area of the filler-containing resin layer (W) is 500 g/m 2 or greater.
4 . The golf club shaft according to claim 1 , the golf club shaft being made of a plurality of fiber-reinforced resin layers, wherein the outer diameter of the grip-end portion is set at 14.5 mm˜15.7 mm.
5 . The golf club shaft according to claim 2 , wherein the filler-containing resin layer (W) is set at less than 10 mass % of the entire mass of the golf club shaft.
6 . The golf club shaft according to claim 2 , wherein the filler-containing resin layer (W) is set at 4 mass % or greater of the entire mass of the golf club shaft.
7 . The golf club shaft according to claim 2 , further comprising a fiber-reinforced resin layer (X) which is positioned on the grip-end side to be adjacent to the filler-containing resin layer (W) and set to have a thickness difference of −70 μm˜+110 μm with the filler-containing resin layer (W).
8 . The golf club shaft according to claim 1 , wherein the heavy substance is tungsten.
9 . The golf club shaft according to claim 1 , wherein the kickpoint obtained by the formula below is less than 45.0%.
kickpoint (%)=( LK/LB )×100
LK: when a shaft is curved by a compression load applied on both ends of the shaft so that the straight-line distance between both ends is 98.5˜99.5% of the entire shaft length, the distance from the tip end of the shaft to the intersection of the straight line connecting both ends and a vertical line drawn from the apex of the curve.
LB: when a shaft is curved by a compression load applied on both ends of the shaft so that the straight-line distance between both ends is 98.5˜99.5% of the entire shaft length, the straight-line distance between both ends of the shaft.
10 . The golf club shaft according to claim 9 , wherein the kickpoint is less than 44.0%.
11 . A golf club, comprising:
a golf club shaft made of a plurality of fiber-reinforced resin layers,
wherein the golf club shaft comprises a heavy substance with a specific gravity of 7 or greater positioned between 0 and 400 mm from the grip end, and when the entire length of the golf club shaft is set as (Ls) and the distance from the head end to the gravity center of the golf club shaft is set as (Lg), the ratio (Lg/Ls) is 0.54˜0.65.
12 . The golf club according to claim 11 , wherein the filler-containing resin layer (W) is set to have a length of 20˜355 mm and to be present between 0 and 355 mm from the grip end of the golf club shaft.