Never Off-the-Shelf!

I don’t think there’s a clubmaker out there who will tell you that Frequency Matching isn’t necessary, well...maybe one will. It once had a legitimate purpose, but that time has long since passed.  In my opinion, Frequency Matching no longer serves any useful function and has instead become little more than a marketing tool within much of the custom club fitting industry.  I won’t leave you hanging, I’ll explain exactly why I believe Frequency Matching has become obsolete.

Some background on the subject follows:

 

•  Steel Shafts:  Steel shafts were a major improvement over hickory when the USGA legalized their use in 1924, but early manufacturing processes were far from perfect.  Even as production methods evolved, steel shafts remained inconsistent in both weight and stiffness from one to the next, a problem that persisted well into the 1970s.

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In the 1960s, a device now commonly referred to as a “Frequency Analyzer” was introduced to measure the general flex characteristics of a golf shaft by recording its oscillation rate in cycles per minute (CPM). In this test, the shaft was clamped at the butt end, a weight was attached to the tip to simulate the mass of a clubhead, and the shaft was set in motion to record its CPM value. The resulting reading indicated the relative stiffness of the shaft — but only in the butt section.

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This limitation wasn’t seen as critical at the time, since it was widely assumed that shaft wall thickness remained uniform from butt to tip. Even so, the introduction of the Frequency Analyzer represented a major advancement over earlier, less precise methods of evaluating shaft flex.

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Before the introduction of the frequency machine, clubmakers relied on weight sorting, grouping shafts of similar total weight to achieve greater consistency within a set.  The arrival of the frequency analyzer added another layer of precision, allowing shafts to be frequency sorted within specific tolerance ranges.  In essence, Frequency Matching refers to the process of assembling a set of clubs whose shafts have been matched for both weight and frequency, producing what was once considered a more uniform and consistent feel throughout the set.

 

As frequency machines became more widely available, several manufacturers began producing their own versions, each with different operating procedures.  One model might clamp the shaft 7 inches down from the butt end, another 9 inches, and yet another 5 inches.  These variations in clamping position produced different frequency readings, meaning that measurements taken on one machine could not be directly compared with those from another.  This lack of standardization made it difficult to establish any universal frequency benchmarks across the industry.

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Fast forward to the early 2000s.  By this time the manufacturing process for steel shafts, and the devices used to measure their frequencies, had been refined to near perfection.  Raw shaft weights were typically consistent within 1 to 3 grams, and frequency variations were often limited to just 1 to 2 CPMs.  This level of precision virtually eliminated the inconsistencies that frequency matching had once been designed to correct.

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Frequency matching steel shafts works in conjunction with head weight, shaft weight, and club length to produce a desired 4-CPM ascending slope from the longest club to the shortest.  This progression was intended to create a consistent feel from club to club throughout the set.  However, with modern manufacturing processes producing steel shafts of exceptional consistency, there was no longer a practical need to frequency sort individual shafts.  By simply increasing head weight by approximately 7 grams and shortening each club by ½ inch from longest to shortest, clubmakers could achieve both consistent swing weights and the desired frequency slope, without ever having to frequency sort the shafts first.

 

• The Graphite Shaft:  Graphite shafts didn’t even exist when the industry first began measuring shaft frequencies in the 1960s.  It’s fair to say that frequency matching was never developed with any material other than steel in mind, and that statement would be entirely accurate.  Early graphite shafts, particularly the sheet-wrapped versions, were notoriously inconsistent.  Variations in wall thickness, fiber alignment, and resin distribution created irregularities throughout the shaft, resulting in significant inconsistencies in flex and performance from one club to the next.

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• EI Shaft Profiles:  Improvement in graphite shaft manufacturing has led to greater consistency.  Modern, high-performance graphite shafts have been engineered to complex stiffness profiles along the entire length of the shaft. These shaft profiles are referred to as "EI Profiles".

 

The letter “E” represents the Modulus of Elasticity, a fundamental engineering property that measures a material’s stiffness—its ability to resist deformation under stress. In golf shaft design, the Modulus of Elasticity is determined by the chemical composition and structure of the shaft material itself.

 

The letter “I” represents the Area Moment of Inertia, which quantifies a shaft’s resistance to bending at various points along its length.  The Area Moment of Inertia is influenced by key engineering design factors such as the shaft’s diameter and wall thickness at different locations along its length.

 

With a basic understanding of a modern graphite shaft’s EI profile, it becomes clear why a single CPM (Cycles Per Minute) measurement taken at the butt end of the shaft cannot accurately represent its true flex characteristics along the entire length.

 

​I believe there are two fundamental methods for matching a set of golf clubs; and neither involves frequency matching. It’s important not to confuse frequency matching with true set matching.  Frequency matching merely sorts shafts by frequency, rather than ensuring the clubs perform consistently as a cohesive set.

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Most custom golf club shops still use frequency matching as a marketing tool. It certainly served a purpose decades ago, but those days are long past. Greg Bayley of Sydney Golf Tech recently posted an excellent YouTube video explaining why frequency matching modern golf shafts is essentially a waste of time. The video runs just over 12 minutes, and it’s packed with valuable insight into why this old methodology no longer aligns with today’s shaft designs or manufacturing realities.   Here's a Link to Greg's video.   

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So, if you’re looking for frequency matching, I’m not your guy, I sold my frequency machine almost 15 years ago!

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The two primary methods I use for matching sets of golf clubs are Moment of Inertia (MOI) Matching and Swingweight Matching.  Both techniques are designed to ensure that every club in the set delivers a consistent feel throughout the swing, and neither requires the shafts to be frequency matched.

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I go into more detail about these techniques in the “Swingweight vs. MOI Matching” section of this tab.