| 摘要 |
<p>PROBLEM TO BE SOLVED: To minimize vibrating ratio after hitting by improving shape of mid- shaft thereby preventing occurrence of injuries, to change deforming position of the shaft and to make gravity center of the shaft adjustable so as to fit the head, and together to make the largest bending point of the club adjustable by changing material of the shaft at upper and lower part of deformation, and to achieve better hitting depending on circumstances. SOLUTION: An expanded portion is formed at a mid-portion of the shaft, and if rigidity of the part (connecting part) in contact with the lower part (with a smaller diameter) of the expanded portion becomes higher, the largest bending point on the shaft can also be changed, while if rigidities of upper end (with a smaller diameter) of the expanded portion and the head portion become higher, the largest bending point on the shaft can also be changed and concurrently, the centroid of the shaft can be placed at the ideal point and further, the expanded portion can suppress vibration occurring at the impact to the lowest limit as well.</p> |
