I would like to redefine “shaft loading” as stated by Jeff Jackson. Even though it can occur at the transition point between back swing and down swing, for most players the peak load occurs at some place during the downswing. The timing of this loading and most importantly the start of unloading is the key factor in club fitting. The key parameter that FitChip uses in selecting a shaft is the time between the start of unloading or shaft release and ball impact.
The golf shaft is a spring. Depending on the stiffness of that spring it takes a certain amount of time for the spring to recover from the deflected position to the neutral position (for the golf shaft, straight). It is at this neutral position that the golf shaft reaches its greatest effectiveness (maximum speed and club face square). As some may have suggested, if ball impact occurs at peak loading, the shaft will still be flexed and be much less than effective in aiding the golfer. Based on spring mechanics the stiffer the spring the shorter the time of recovery. The natural frequency of the golf club describes this recovery time and the mechanism that drives the shaft back to straight upon release. Therefore the earlier the release is in the swing the softer the shaft and the later the release the stiffer the shaft. You will quickly find out using this system that shaft selection has nothing to do with club head speed as the industry has used it in the past. In fact I can show you, that if two players have the same time between release and ball impact, the one with the higher speed needs a softer shaft. This occurs because there are two mechanisms acting on the shaft to return it to straight and square. The first one, which we all understand is the spring action of the shaft that is described by natural frequency. The second one is the centrifugal force pulling down on the weight of the head to straighten the shaft and is a direct function of club head speed. Since this Club head speed induced force is helping the spring action the spring action needs to be reduced to get the correct timing to be back to straight and square at the time of impact. Then since the high club head speed player gets more help from club head speed he would need the shaft with a lower frequency (softer shaft). Both of these timing mechanisms are accounted for in the FitChip Shaft Fitting System.
The FitChip analyzes this timing and club release problem and selects the clubs natural frequency that will return it to straight and square at ball impact. No other system available today for club fitting can identify the point of club release during the swing. This timing is what best creates the feel and timing between the player and his clubs. The data collected by the FitChip (up to 84 full swings) can be downloaded to any computer to view the pertinent individual swing data. You will find that many players have double loads and releases that make the process even more difficult.
Typical of FitChip Successes
Recently when working in Florida with one of the top 10 golf instructors that was interested in the FitChip as a fitting system for his school I had a chance to fit several of his students. The one student was a PGA professional and instructor from Canada taking lessons. He was hitting stiff shafted clubs but was not totally happy with them and was interested in trying the FitChip system. As a result of the testing I put him in a driver that was two flex ranges softer then a senior shaft. He just shook his head until he hit the test club against his, on the Launch Monitor and got more distance and less dispersion. I ended up building him a full set of new clubs. He called after he got home and played with the clubs saying “ My friends were laughing at me because the shafts were so soft, until we got on the course and I was out driving them by 50 yard and was always in the fairway”. He then proceeded to win the Canadian Club Professional Golf Tournament with his new clubs.