Golf shaft system and golf shaft

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 each point along the shaft length has (i) a shaft flexural rigidity including a maximum shaft flexural rigidity, and (ii) a shaft torsional rigidity including a maximum shaft torsional rigidity;
• the shaft having a butt portion joined by a coupler to a tip portion;
• 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;
• the tip portion having a tip portion distal end, a tip portion proximal end, a tip portion length that is (a) 8-26″, (b) 25-75% 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 elastic modulus, a butt portion shear modulus, 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 including an average butt portion flexural rigidity, a maximum butt portion flexural rigidity, and a minimum butt portion flexural rigidity, and (iv) a butt portion torsional rigidity including an average butt portion torsional rigidity, a maximum butt portion torsional rigidity, and a minimum butt portion torsional rigidity;
• the tip portion formed of a tip portion material having a tip material density, a tip portion elastic modulus, and a tip portion shear modulus, 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 including an average tip portion flexural rigidity, a maximum tip portion flexural rigidity, and a minimum tip portion flexural rigidity, and (iv) a tip portion torsional rigidity including an average tip portion torsional rigidity, a maximum tip portion torsional rigidity, and a minimum tip portion torsional rigidity;
• wherein:
• the average butt portion flexural rigidity is 50-110 N*m2 and the average butt portion torsional rigidity is 20-70 N*m2;
• the flexural rigidity of a portion of the shaft located 5-36″ from the shaft proximal end is at least 125 N*m2 and at least 50% greater than the minimum butt portion flexural rigidity, the flexural rigidity of the shaft exceeds 125 N*m2 for no more than 15% of the shaft length, the torsional rigidity of a portion of the shaft located 5-36″ from the shaft proximal end is at least 100 N*m2, and the torsional rigidity of a portion of the shaft exceeds 100 N*m2 for no more than 15% of the shaft length;
• the maximum shaft flexural rigidity is no more than 600 N*m2 and the maximum shaft torsional rigidity is no more than 450 N*m2;
• and
• the shaft CG distance is no more than 65% of the shaft length, and the shaft CG distance is greater than a distance of any portion of the coupler from the shaft proximal end.