Golf club shaft

Abstract

A shaft includes a tip end, a butt end, flexural rigidities E1 to E10 at respective points that are located 130 mm, 230 mm, 330 mm, 430 mm, 530 mm, 630 mm, 730 mm, 830 mm, 930 mm, and 1030 mm apart from the tip end. A ratio (E8/E1) is greater than or equal to 2 and less than or equal to 7. The flexural rigidity E1 is less than or equal to 2.5 (kgf·m2). The flexural rigidity E8 is greater than or equal to 5.0 (kgf·m2). When a formula of a straight line that passes through a point (230, E2) and a point (630, E6) is represented by y=ax+b, the shaft satisfies the following relationships R1 and R8:(130a+b)<E1≤(130a+b+0.5)  (R1), and(830a+b)<E8≤(830a+b+1.0)  (R8).

What is claimed is: 
     
         1 . A golf club shaft comprising:
 a tip end;   a butt end;   a flexural rigidity E1 at a point located 130 mm apart from the tip end;   a flexural rigidity E2 at a point located 230 mm apart from the tip end;   a flexural rigidity E3 at a point located 330 mm apart from the tip end;   a flexural rigidity E4 at a point located 430 mm apart from the tip end;   a flexural rigidity E5 at a point located 530 mm apart from the tip end;   a flexural rigidity E6 at a point located 630 mm apart from the tip end;   a flexural rigidity E7 at a point located 730 mm apart from the tip end;   a flexural rigidity E8 at a point located 830 mm apart from the tip end;   a flexural rigidity E9 at a point located 930 mm apart from the tip end; and   a flexural rigidity E10 at a point located 1030 mm apart from the tip end, wherein   a ratio (E8/E1) is greater than or equal to 2 and less than or equal to 7,   the flexural rigidity E1 is less than or equal to 2.5 (kgf·m 2 ),   the flexural rigidity E8 is greater than or equal to 5.0 (kgf·m 2 ),   when a formula of a straight line that passes through a point (230, E2) and a point (630, E6) plotted in a graph on an orthogonal coordinate system having an x-axis that represents a distance (mm) from the tip end and a y-axis that represents a flexural rigidity (kgf·m 2 ) is indicated by y=ax+b, the golf club shaft satisfies the following relationships R1 and R8:
   (130 a+b )< E 1≤(130 a+b+ 0.5)  (R1), and
 
   (830 a+b )< E 8≤(830 a+b+ 1.0)  (R8).
 
   
     
     
         2 . The golf club shaft according to  claim 1 , wherein the golf club shaft further satisfies the following relationship R81:
   (830 a+b+ 0.3)≤ E 8≤(830 a+b+ 1.0)  (R81).
   
     
     
         3 . The golf club shaft according to  claim 1 , wherein
 the flexural rigidity E9 is less than or equal to (930a+b−0.1).   
     
     
         4 . The golf club shaft according to  claim 1 , wherein
 the flexural rigidity E10 is less than or equal to (1030a+b−0.6).   
     
     
         5 . The golf club shaft according to  claim 1 , wherein
 the golf club shaft further satisfies the following relationships R3, R4 and R5:
   (330 a+b− 0.2)< E 3≤(330 a+b+ 0.2)  (R3),
 
   (430 a+b− 0.2)< E 4≤(430 a+b+ 0.2)  (R4), and
 
   (530 a+b− 0.2)< E 5≤(530 a+b+ 0.2)  (R5).
 
   
     
     
         6 . The golf club shaft according to  claim 1 , wherein
 the golf club shaft is formed by a plurality of carbon fiber reinforced resin layers,   the carbon fiber reinforced resin layers include an intermediate partial bias layer that is disposed apart from the tip end and apart from the butt end, and   an axial directional region in which the intermediate partial bias layer is disposed includes a point 830 mm apart from the tip end.   
     
     
         7 . The golf club shaft according to  claim 6 , wherein
 the intermediate partial bias layer has a length in an axial direction of greater than or equal to 250 mm and less than or equal to 550 mm.   
     
     
         8 . The golf club shaft according to  claim 1 , wherein
 the flexural rigidity E3 is less than (330a+b),   the flexural rigidity E4 is less than (430a+b), and   the flexural rigidity E5 is less than (530a+b).   
     
     
         9 . The golf club shaft according to  claim 1 , wherein
 the flexural rigidity E7 is greater than (730a+b).   
     
     
         10 . The golf club shaft according to  claim 1 , wherein
 the flexural rigidity E10 is less than (1030a+b).   
     
     
         11 . The golf club shaft according to  claim 1 , wherein
 the flexural rigidity E3 is less than (330a+b),   the flexural rigidity E4 is less than (430a+b),   the flexural rigidity E5 is less than (530a+b),   the flexural rigidity E7 is greater than (730a+b), and   the flexural rigidity E10 is less than (1030a+b).   
     
     
         12 . The golf club shaft according to  claim 1 , wherein
 the flexural rigidity E10 is less than the flexural rigidity E8.   
     
     
         13 . The golf club shaft according to  claim 1 , wherein
 the flexural rigidity E10 is less than the flexural rigidity E9.   
     
     
         14 . The golf club shaft according to  claim 9 , wherein
 an absolute value of [E7−(730a+b)] is greater than an absolute value of [E3−(330a+b)],   the absolute value of [E7−(730a+b)] is greater than an absolute value of [E4−(430a+b)], and   the absolute value of [E7−(730a+b)] is greater than an absolute value of [E5−(530a+b)].   
     
     
         15 . The golf club shaft according to  claim 8 , wherein
 an absolute value of [E8−(830a+b)] is greater than an absolute value of [E3−(330a+b)],   the absolute value of [E8−(830a+b)] is greater than an absolute value of [E4−(430a+b)], and   the absolute value of [E8−(830a+b)] is greater than an absolute value of [E5−(530a+b)].