Golf club shaft
A shaft 6 includes a first butt partial sheet s 4 and a second butt partial sheet s 5. The first butt partial sheet s 4 includes a first tapered part TP 1. The second butt partial sheet includes a second tapered part TP 2. The first butt partial sheet s 4 and the second butt partial sheet s 5 satisfy the following (1) to (4). L 11, L 12, L 21, Lt 1 and Lt 2 are shown in FIG. 3. L11>L21 (1) Lt 1≧ CF 1× Te1/20 (2) Lt 2≧ CF 2× Te2/20 (3) L 21− L 12<50 (4)
1. A golf club shaft comprising a plurality of fiber reinforced layers, wherein:
the fiber reinforced layers are formed by a plurality of wound prepreg sheets;
the sheets include:
a full length sheet disposed wholly in an axial direction;
a tip partial sheet disposed to include a position separated by 20 mm from a tip end of the shaft;
a first butt partial sheet disposed to include a position separated by 100 mm from a butt end of the shaft; and
a second butt partial sheet disposed to include a position separated by 100 mm from the butt end of the shaft,
the first butt partial sheet includes a first tapered part;
the second butt partial sheet includes a second tapered part;
a fiber weight per unit area of the first butt partial sheet is defined as CF 1 (g/m 2 ), and a fiber elastic modulus of the first butt partial sheet is defined as Te 1 (tf/mm 2 ),
a fiber weight per unit area of the second butt partial sheet is defined as CF 2 (g/m 2 ), and a fiber elastic modulus of the second butt partial sheet is defined as Te 2 (tf/mm 2 );
an axial-directional length of a long side of the first butt partial sheet is defined as L 11 (mm), and an axial-directional length of a short side of the first butt partial sheet is defined as L 12 (mm);
an axial-directional length of a long side of the second butt partial sheet is defined as L 21 (mm), and an axial-directional length of a short side of the second butt partial sheet is defined as L 22 (mm);
an axial-directional length of the first tapered part is defined as Lt 1 (mm);
an axial-directional length of the second tapered part is defined as Lt 2 (mm);
the golf club shaft satisfies the following formulas (1), (2), (3) and (4):
L11>L21 (1);
Lt 1≧ CF 1× Te 1/20 (2);
Lt 2≧ CF 2× Te 2/20 (3); and
L 21− L 12<50 (4).
2. The golf club shaft according to claim 1 , wherein an EI change rate is equal to or less than 13 kgf·m 2 /m over the whole shaft.
3. The golf club shaft according to claim 1 , wherein
when a distance between the tip end and a center of gravity of the shaft is defined as Lg, and a full length of the shaft is defined as Ls,
Lg/Ls is equal to or greater than 0.555.
4. The golf club shaft according to claim 1 , wherein
the full length sheet includes a full length bias sheet,
in the full length bias sheet, a total width at the tip end is defined as Wt, and a total width at the butt end is defined as Wb,
Wb/Wt is equal to or greater than 2.
5. The golf club shaft according to claim 1 , wherein the tip partial sheet includes a glass fiber reinforced sheet.