Golf club shaft fitting method

1. A fitting method of a shaft of a golf club for selecting a shaft matching a golfer based on a swing of the golfer, the method comprising the steps of:

obtaining measurement values from a sensor attached to a grip of a golf club and capable of measuring angular velocities about three axes when a golf ball is hit by the golf club;

determining address, top, and impact of a swing from the measurement values; and

selecting a shaft that matches a golfer through a usage of the following swing characteristic amounts of (a) to (d) obtained from the measurement values:

(a) amount of change of grip angular velocity in a direction of a wrist release around the top;

(b) an average value of grip angular velocity in the direction of a wrist release, from the top to a point during a downswing where a grip angular velocity in the direction of a wrist release becomes a maximum;

(c) an average value of grip angular velocity in the direction of a wrist release, from a point during a downswing where a grip angular velocity in the direction of a wrist release becomes a maximum to the impact;

(d) an average value of grip angular velocity in the direction of a wrist release, from the top to the impact,

wherein the above described (a) to (d) are respectively measured so as to correspond to bending stiffnesses of the shaft at plural positions including a position at a front end side of the shaft and a position of the shaft near hands of the golfer,

an approximate expression that is created in advance with test-hitting and that represents a relationship between bending stiffnesses of the shaft and each of the swing characteristic amounts of (a) to (d), and the swing characteristic amounts of (a) to (d) obtained from the measurement values, are used to acquire bending stiffnesses of the shaft plural positions including a position at a front end side of the shaft and a position of the shaft near hands of the golfer, and

from multiple shafts whose bending stiffnesses are measured in advance at the plural positions, a shaft matching a golfer is selected based on the acquired bending stiffnesses of the shaft at plural positions.

2. The fitting method of a shaft of a golf club according to claim 1 , wherein the plural positions including a position at a front end side of the shaft and a position of the shaft near hands of the golfer are four positions of 36 inches, 26 inches, 16 inches, and 6 inches each from a tip end of the shaft.

3. The fitting method of a shaft of a golf club according to claim 2 , wherein one rank value among multiple-scale rank values is given to each of the bending stiffnesses at the four positions in accordance with the acquired bending stiffness values; and

a shaft matching a golfer is selected based on the given rank values at the four positions, from multiple shafts whose bending stiffnesses have been measured in advance at the four positions and that are each given one rank value among multiple-scale rank values in accordance with measured bending stiffness values.

4. The fitting method of a shaft of a golf club according to claim 2 , wherein multiple approximate expressions are created in accordance with head speed.

5. The fitting method of a shaft of a golf club according to claim 2 , wherein when a length of the golf club of a user is different from a length of a golf club having the shaft selected from multiple shafts, a total weight of the golf club is changed based on the difference of the two lengths.

6. A fitting method of a shaft of a golf club for selecting a shaft matching a golfer based on a swing of the golfer, the method comprising the steps of:

obtaining measurement values from a sensor attached to a grip of a golf club and capable of measuring angular velocities about three axes when a golf ball is hit by the golf club;

determining address, top, and impact of a swing from the measurement values; and

selecting a shaft that matches a golfer through a usage of the following swing characteristic amounts of (a) to (a) obtained from the measurement values:

(a) amount of change of grip angular velocity in a direction of a wrist release around the top;

(b) an average value of grip angular velocity in the direction of a wrist release, from the top to a point during a downswing where a grip angular velocity in the direction of a wrist release becomes a maximum;

(c) an average value of grip angular velocity in the direction of a wrist release, from a point during a downswing where a grip angular velocity in the direction of a wrist release k becomes a maximum to the impact;

(d) An average value of grip angular velocity in the direction of a wrist release, from the top to the impact,

wherein the above described (a) to (d) are respectively measured so as to correspond to bending stiffnesses of the shaft at four positions of 36 inches, 26 inches, 16 inches, and 6 inches each from a tip end of the shaft;

an approximate expression that is created in advance with test-hitting and that represents a relationship between bending stiffnesses of the shaft and each of the swing characteristic amounts of (a) to (d), and the swing characteristic amounts of (a) to (d) obtained from the measurement values, are used to acquire bending stiffnesses of the shaft at our positions of 36 inches, 26 inches, 16 inches, and 6 inches from the tip end of the shaft; and

from multiple shafts whose bending stiffnesses are measured in advance at the four positions, a shaft matching a golfer is selected based on the acquired bending stiffnesses of the shaft at four positions.