How many times have you heard the saying “The Golf Shaft is The Engine”? What is being said is that we depend on the Golf Shaft to provide our peak performance. In our automobiles we tune our engines for peak efficiency so why not with the engine of our golf club? So what are we looking for in a golf club to provide peak efficiency? First of all we are looking for distance and secondly for accuracy. Many club fitters will offer you these to attributes as separate objectives but an understanding of shaft mechanics will lead you to understand they do occur at the same time. That time is when the shaft is back to straight at ball impact. That is because peak club head speed will occur when the shaft is straight or at the equilibrium point on its natural frequency cycle. When the shaft is back to straight and the spine has been aligned the head will be square with your swing path/plain.
Now lets take a look at swing timing and the sequence of the golf swing. In figure 10 we have broken the swing down into four separate sections (not to any specific scale). The light blue area represents the start of the payers down swing during which the player puts or releases energy into accelerating the club head up to speed. This energy input can be accomplished in various ways. 1. pulling the club down with hip turn, shoulder rotation, arm movement and then wrist action by allowing them to freely hing or forcing/powering the release of the hands. Powering the release of the hands in many cases will cause the shaft to be double loaded. The red area of the diagram represent the area in which the shaft kick or release begins. The criteria for this shaft release is that the loading phase of the swing is completed and the load on the shaft has started to fall off faster than the natural frequency cycle of the shaft its self will release its load. The time in which this shaft release will occur is only .05 seconds in duration. In the case of a driver if it has occurred at the beginning of this .05 second period it would call for a 170 CPM shaft in the club to get back to straight at ball impact which occurs at the end of the light green area. If the it occurs at the end of the .05 second period it will require a 300 CPM frequency shaft to get back to straight at ball impact. If we look at the frequency range of the OEM shafts the red area becomes only .025 seconds wide. To select a shaft that best responds to a players swing timing (+ or – 4 CPM) our time for accurately selecting the proper release point is .003 seconds. The green area represents the time the shaft is returning to straight though its 1/4 cycle time of its natural frequency which is in the range of .1 to .045 seconds.