Golf club shaft condition judgment method, golf shaft characterized by characteristics expressed by the method, and golf club equipped with the shaft

摘要

PROBLEM TO BE SOLVED: To match measured characteristics of a golf club with a feeling in a swing by judging characteristics including bending point of the shaft by curvature distribution calculated from data of measurement of the distribution of bending moment loaded on a shaft in a swing and bending rigidity distribution. SOLUTION: The grip side of a shaft 2 is fixed by a fixing part 11. Bending moment is applied loaded on the tip end part of the shaft 2 by a torque sensor 12. A laser sizer 13 is moved from a measuring part 11 side to the tip end side. A flexure curve and an outer shape Dere measured and inputted into CPU. A load is inputted from the torque sensor 12. Then the flexure curve of the shaft center axis is calculated. CPU circular-approximates by the least square method to calcualte the curvature radius on which binding moment acts and the center to calculate the curvature distribution. CPU also calculates the bending moment from the load and the distance from the load to complete. The CPU calculates the bending rigidity distribution of the shaft 2.