Golf shaft system and golf shaft
A multi-component golf club shaft possessing unique characteristics including flexural and torsional rigidity profiles.
1. A golf club shaft, comprising:
a shaft having a shaft distal end, a shaft proximal end, a shaft outer diameter, a shaft length, a shaft mass, a shaft center of gravity located a shaft CG distance from the shaft proximal end, a kickpoint located a kickpoint distance from the shaft proximal end, wherein the shaft has a maximum shaft flexural rigidity and a maximum shaft torsional rigidity, and each point along the shaft length has (i) a shaft flexural rigidity, and (ii) a shaft torsional rigidity;
the shaft having a butt portion joined by a coupler to a tip portion, wherein the coupler has a coupler mass that is no more than 15% of the shaft mass;
the butt portion having a butt portion distal end, a butt portion proximal end, a butt portion length of 20-40″, and a butt portion mass of no more than 60 grams;
the tip portion having a tip portion distal end, a tip portion proximal end, a tip portion length that is (a) 8-26″, (b) at least 25% of the butt portion length, and (c) at least 20% of the shaft length, and a tip portion mass of no more than 35 grams and less than 75% of the butt portion mass;
the butt portion formed of a butt portion material having a butt material density, a butt portion mass, a butt portion clastic modulus, a butt portion shear modulus, an average butt portion flexural rigidity, a maximum butt portion flexural rigidity, a minimum butt portion flexural rigidity, an average butt portion torsional rigidity, a maximum butt portion torsional rigidity, a minimum butt portion torsional rigidity, and each point along the butt portion length having (i) a butt portion area moment of inertia, (ii) a butt portion polar moment of inertia, (iii) a butt portion flexural rigidity, and (iv) a butt portion torsional rigidity;
the tip portion formed of a tip portion material having a tip material density, a tip portion clastic modulus, a tip portion shear modulus, an average tip portion flexural rigidity, a maximum tip portion flexural rigidity, a minimum tip portion flexural rigidity, an average tip portion torsional rigidity, a maximum tip portion torsional rigidity, and a minimum tip portion torsional rigidity, and each point along the tip portion length having (i) a tip portion area moment of inertia, (ii) a tip portion polar moment of inertia, (iii) a tip portion flexural rigidity, and (iv) a tip portion torsional rigidity;
wherein:
the average tip portion flexural rigidity is 10-50 N*m 2 and the average tip portion torsional rigidity is 5-40 N*m 2 ; and
the flexural rigidity of a portion of the shaft located 5-36″ from the shaft proximal end is at least 100% greater than the minimum tip portion flexural rigidity.
2. The golf club shaft of claim 1 , wherein the tip portion mass is no more than 30 grams, the tip portion mass is less than 70% of the butt portion mass, and the coupler mass is no more than 60% of the tip portion mass.
3. The golf club shaft of claim 2 , wherein the tip portion mass is no more than 25 grams, and the tip portion mass is less than 60% of the butt portion mass.
4. The golf club shaft of claim 2 , wherein the maximum shaft flexural rigidity is no more than 300 N*m 2 and the maximum shaft torsional rigidity is no more than 250 N*m 2 .
5. The golf club shaft of claim 4 , wherein the maximum shaft flexural rigidity is no more than 250 N*m 2 and the maximum shaft torsional rigidity is no more than 200 N*m 2 .
6. The golf club shaft of claim 4 , wherein the tip portion mass is 20-30 grams, and the tip portion mass is no more than 70% of the butt portion mass.
7. The golf club shaft of claim 4 , wherein the tip portion mass is no more than 20 grams.
8. The golf club shaft of claim 4 , wherein the tip portion mass is no more than 60% of the butt portion mass.
9. The golf club shaft of claim 8 , wherein the tip portion mass is at least 35% of the butt portion mass.
10. The golf club shaft of claim 4 , wherein the shaft CG distance is no more than 65% of the shaft length.
11. The golf club shaft of claim 10 , wherein the shaft CG distance is no more than 55% of the shaft length.
12. The golf club shaft of claim 4 , wherein the flexural rigidity of a portion of the shaft located 5-36″ from the shaft proximal end is at least 200% greater than the minimum tip portion flexural rigidity.
13. The golf club shaft of claim 12 , wherein the flexural rigidity of a portion of the shaft located 5-36″ from the shaft proximal end is at least 50% greater than the minimum butt portion flexural rigidity.
14. The golf club shaft of claim 12 , wherein the flexural rigidity of a portion of the shaft located 5-36″ from the shaft proximal end is at least 125 N*m 2 .
15. The golf club shaft of claim 14 , wherein the flexural rigidity of the shaft exceeds 125 N*m 2 for no more than 15% of the shaft length.
16. The golf club shaft of claim 4 , wherein the kickpoint is within 6″ of a portion of the coupler.
17. The golf club shaft of claim 4 , wherein the average butt portion flexural rigidity is 50-110 N*m 2 and the average butt portion torsional rigidity is 20-70 N*m 2 , and the average tip portion flexural rigidity is no more than 40 N*m 2 .
18. The golf club shaft of claim 4 , wherein the tip portion length is no more than 75% of the butt portion length, the average tip portion flexural rigidity is no more than 35 N*m 2 , and the average butt portion flexural rigidity is 60-100 N*m 2 and the average butt portion torsional rigidity is 25-60 N*m 2 .
19. The golf club shaft of claim 4 , wherein the flexural rigidity of a portion of the shaft located 5-36″ from the shaft proximal end is at least 50% greater than the minimum butt portion flexural rigidity.
20. The golf club shaft of claim 4 , wherein the butt portion mass is at least 40 grams.
21. The golf club shaft of claim 20 , wherein the butt portion mass is no more than 50 grams.
22. The golf club shaft of claim 21 , wherein the butt portion length is 26-36″, and the tip portion length is 10-22″.
23. The golf club shaft of claim 4 , wherein the coupler comprises a thermoplastic material.
24. The golf club shaft of claim 4 , wherein the coupler comprises fiber-reinforced composite material.
25. The golf club shaft of claim 4 , wherein the shaft flexural rigidity is constant throughout at least 10% of the shaft length.
26. The golf club shaft of claim 4 , wherein the shaft tapers over at least 70% of the shaft length, and a portion of the coupler is tapered.