SwingSyncGolf.Ca calls your attention to Eric Cook who 35 years ago developed his own unique Single Frequency Matching System.
It was my good fortune to know and learn from Eric Cook for a number years. He taught me his method before he retired in 2008, not to mention many other things about clubmaking he had learned over the years. He only taught his Single Frequency Matching to a hand full of people throughout his career.
SINGLE FREQUENCY MATCHING  WHAT AND WHY
Eric H. Cook, P.Eng. PCS GSED
Master Clubmaker & Fitter
In recent years you have heard and probably read a great deal about frequency matching golf clubs. Unfortunately, you have not been given the whole story and certainly not the whole truth about the subject of frequency matching.
"The concept of frequency matching is not new, but until the introduction of the parallel tip golf shaft, single frequency matching was not a practical consideration."
What does "frequency matched" really mean? Simply stated, frequency is a very accurate measurement of the shaft flex or stiffness in terms of cycles per minute (cpm) of vibration. The higher the frequency, the stiffer the shaft. You might assume from the terms used that a frequency matched set of irons will have the same stiffness of shaft in each club, but is that really the case.
In general, the theory of frequency matching suggests that the proper frequency (stiffness) of the golf club shaft is essential to the proper functioning of the golf club as it relates to the golfers swing. It would, therefore; seem logical that the golfer should, at some point, be involved in the selection process if the correct shaft is to be found. Let's look, in more detail, at the three frequencies matching systems currently in use.
The FM Precision Shaft System
Introduced by Dr. Joe Braly in the midseventies, was the first frequency matching system recognized by the golf industry. In his patent application, Braly says that when he checked the frequency of most manufactured clubs, he found that the frequency varied from one club to another in no consistent way. He also reports that when he tested the clubs used by the masters of the game like Byron Nelson and Harry Vardon, he found that their clubs varied in frequency by a consistent increment. This consistent incremental difference in frequency produces a gradient match wherein each club in the set is made incrementally stiffer than the next longer club. This incremental difference appears to be a constant value of about 3 to 5 cpm.
In order to pick the FM Precision shaft that fits, you are given a group of number five irons from which you select the one club that you hit best. These test clubs are designated by a number which represents the stiffness gradient, i.e., 4.5, 5.0, 5.5, 6.0, etc. These numbers represent the parallel (gradient) sloping lines that characterize the FM Precision System. From your selection (say 5.5) a set of clubs is assembled which follow the 5.5 gradient lines. See Figure 1. Using this line, the One Iron would be 272 cpm and the Pitching Wedge would be 330 cpm, a difference of 58 cpm. Similarly, the Driver would be 240 cpm at 43 inches and the Five Wood at 41 inches would be 268 cpm, a difference of 28 cpm. Obviously, by definition, each club in the set has a different stiffness.
The True Temper Dynamic Gold System
Almost a direct copy of the FM Precision concept, except that True Temper developed their own identification codes, i.e., R200, S100, etc., and their own slopes for the gradient lines. The steeper gradient lines used here result in a greater difference in frequency between the One Iron and the Pitching Wedge than does the FM System. The True Temper booklet on Frequency Matching, which includes the gradient matching charts, defines frequency matching by saying " In a frequency matched set of clubs, the frequency or stiffness difference between successive clubs are equal. It does not mean that each club in the set is the same stiffness or frequency." It would seem that this definition is based solely on the fact that,” golf clubs traditionally get stiffer as they become shorter."
The fact is that while both FM Precision and Dynamic Gold shafts are frequency matched to something, they are not actually matched to the swing of any particular golfer. At the very least, if two clubs are to react the same, they should be the same stiffness, therefore; how can all the clubs in a set that are made precisely different in stiffness, all be the same.
Now consider:
Single Frequency Matching System.
In 1975, Bud Malloy, CPGA, then Head Professional at Hylands Golf Club in Ottawa, ON. Canada, noted that most of the golfers that he instructed had a favourite golf club in their set. He reasoned, quite logically, that for some reason this favourite club matched the golfers swing better than the rest of the clubs in the set. He then decided to find out if the other clubs in the set could be matched, by frequency of vibration, to this favourite club. The logical approach dictated that all clubs in the set should be the same frequency. The problems were threefold; how could this be done, would this approach really help the individual play better golf and how would you determine the correct frequency for the individual golfer?
Under the direction of Mechanical Engineer Eric H. Cook, the next three years were spent testing golfers of various skill levels with a set of preset test clubs. These test clubs, made up of 2,5,7, & 9 Irons, covered a range of 25 cpm from the softest to the stiffest and were number coded so that the golfer was always performing a blind test. These tests showed exactly what each golfer selected as a matched set of clubs, based on both feel and performance of the test clubs. On completion of the tests, analysis showed that 87 percent of the test group had selected 3 of the 4 test clubs within a range of 5 cpm of the same frequency. This is rather an astounding figure when you consider that industry golf clubs have, on average, a 26 cpm difference between the most flexible shaft and the stiffest shaft within a set. These test resulted in the present day test sets made up of 7 & 5 Irons and Drivers, from which the golfer selects the proper frequency to match their particular swing. Over the past 20 years thousands of happy golfers have proven beyond a doubt that Single Frequency Matching works.
With few exceptions, golf teachers help students develop a repeating swing to be used for full shots with all clubs. To really be of help all clubs in the set should feel the same and respond the same way to this one repeating swing. The golfer is, however, normally provided with a set of clubs, which will produce thirteen different results, if the same setup and swing is used with each club.
Articles on this subject have suggested that frequency matching would be of little or no value to the average golfer because most amateurs do not have a consistently repeating swing. To the contrary, as our tests have shown, frequency matching will be of more significance to the amateur than it will be to the professional. The professional golfer practices enough to know how to set up and swing by adjusting the ball position to make each club work, in spite of the frequency difference. The average amateur, on the other hand, is hard pressed to develop one, let alone 13 different setups and swings.
The SwingSync Single Frequency Matching System eliminates one more variable in a game that is already consistently inconsistent and will contribute significantly to the accuracy of the weekend golfer because all clubs can be hit with equal ease from the driver to the wedge.
The above comparison of the three systems currently claiming to frequency match golf clubs to the swing, size, shape, age sex and handicap of the individual golfer, should give you insight into the truly important point; the shaft is the single most important part of the golf club and to be effective it must match your swing.
All of this information is condensed into a simple test procedure that will allow golf professionals to accurately select the frequency and moment of inertia for their customers. Combining these test results with other appropriate measurements, SwingSync is able to build custom fitted golf clubs for the customer that all feel the same.
But alas! What excuse will you have?

