The principal contributors to this problem are shaft flex and head weight. Head weight distribution also contributes to this situation. To maintain the performance sequence near the green line requires that shaft stiffness increases as the club length increases, or a significantly greater head weight reduction, than the current standard, as the shafts become longer. There is a very specific zone where shaft stiffness and current standard head weight allows the fine tuning of directional control and consistency. The zones are generated where the torque and flex come into alignment.
Torque frequency is three to four times higher than flex frequency, dependent on the flex frequency.
At certain flex frequencies the torque frequency becomes harmonic. At these points the club can be tuned from draw to nonfunctional to fade by slight changes in flex frequency. The tuning zone is defined by frequency using an eight inch grip clamp which supports the club in the address position. The exact frequency is dependent on the actual head weight, and to a lesser degree the head weight distribution. Add weight at the red arrow to shift the club from hook to draw or nonfunctional to fade.