Category: Equipment Tips
Matching the Correct Shaft
from Jeff Jackson
Author, USGTF Member, and
Club Fitting Expert
Shaft Frequency: An Absolute Measurement for Shaft Matching
Jeff Jackson, for publication in Golf Tips Magazine
What is the flex of your shafts? A golfer used to be safe in saying that shafts were stiff, regular or ladies flex. That simply is not the case any longer. Most manufacturers have their own method of shaft measurement. What this means is that one company’s “S” flex shaft may actually be softer than another’s “A” or even “L” flex. How is a player to know how to choose shafts if there is no manufacturer standard? In a word: Frequency. The next time you choose a set of clubs – or even a single club – have a frequency check done to make certain the shafts match not only your swing, but each other as well.
Frequency is an absolute measure of the flex of a shaft. It is measured in a specialized machine and is defined as how many times per minute a shaft oscillates either vertically or horizontally. The units of frequency measurement are known as cycles per minute, or cpm’s. A shaft with a higher frequency is stiffer than one with a lower frequency. By using frequency as a method of comparing two different shafts, it is obvious which shaft is stiffer and by how much. Typically there will be 10 cycles between shaft flexes. Thus if one shaft registers 250 on a frequency machine and another is 270, there is a 2-flex difference between the shafts – regardless of what flex the manufacturer claims them to be.
By assigning a specific frequency number to a shaft, the shaft can be closely matched to a player. For example, a player finds a driver that he hits very well, but wants the latest in club head technology. The current driver shaft’s frequency can be determined and when a new club is purchased, the frequency of that shaft can be made to match the shaft the player hits best. Correspondingly, if the player wants fairway woods to match the flex feel of the driver, frequency can be used to determine what shafts to use and how to trim them to match.
The rules of golf state that a shaft is be manufactured with the same bending and twisting properties along its entire longitudinal axis.
In other words, golf shafts are supposed to be symmetrical. However, due to manufacturing tolerances, it is not always possible to make symmetrical shafts. By testing the cpm’s of a shaft in various planes, the club repair specialist will be able to identify the cpm that matches the desired flex for a particular player. That desired cpm reading should be positioned in the clubhead parallel to the target line to best match the shaft to the player.
When it comes to irons, a similar scenario applies. In a typical set of irons, shafts become stiffer as the clubs become shorter. That is, the shaft in your wedge is actually stiffer than the shaft in your #3 iron. The wedge won’t feel stiffer since the #3 iron is longer and the head is lighter, but the shorter shaft may measure 25 cycles or more stiffer than the longer one. Since the shaft length varies through a set of irons, each shaft will have a different stiffness, creating a sloped gradient of frequency through the set. In this way frequency plays a key role in matching the feel and playability in a set of irons.
A matched set of irons will have a similar number of cpm’s between each club in the set. The exact number will depend upon the shaft type, but there will be uniform increments between each club. This ensures that each club will feel and perform like all others in a set. Frequency can be used to duplicate a favorite iron set in the same manner as when choosing a driver. The cpm reading of a favorite club can be taken and a set made with that frequency reading as the target. This process is known as frequency matching.
It is important to realize that there is no flex standard in the golf industry today. Frequency provides an absolute way to measure the stiffness of a shaft. Shafts can then be matched to a player’s swing to improve performance. Frequency offers the ability to duplicate a favorite club, a demo club or a friends’ club that the player hits well. By duplicating this feel and playability and matching it through the set, frequency provides a concise measure of shaft performance. If you are still buying shafts based on them being “R” or “S”, think again. Have your clubs frequency checked and matched. The resulting feel and performance improvements will put you well on the way to lower scores.
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