Welcome to the EGT Club Geek page! Here you will find an in depth analysis of every factor pertaining to custom club building and custom club fitting and why they are vital to ensure truly custom fit clubs. After the main sections there is an index for some of the club fitting jargon. Happy reading you club geek, you!

Frequency & MOI matched Sets

It is imperative to have a matched set of clubs.

A Club Fitting is the first step in the process, followed by precision club building. 

Two of the key items to match are Frequency and MOI. 

Let’s start with Frequency:  what is it, and why is it important to match?  Frequency is a measurement of flex in the shaft. It is measured in Cycles Per Minute, (CPM). This is measured by putting a weight on the tip or club head end of the shaft, then clamping the butt or grip end of the shaft in a 5” clamp. The shaft is “twanged” and the number of up and down oscillations is counted.


Frequency Gauge Machine.

 Most clubs have a flex labeled somewhere on the shaft, (X, S, R, A, L). The problem with this label is there are no real standards for each of the flex designations. One manufacturer’s S Flex could be another’s R Flex or somewhere in between. In other words, an S Flex of a 6 iron of one manufacturer could be 315 CPM while another’s is 305 CPM. So, it is very important during the Club Fitting process that the frequency of the shaft is known. The club builder takes the frequency measurement and will trim the shafts to match.

Why is it important to match the Frequency of the shaft? The main reason is consistency. You want the distance gapping to be predictable. The other reasons are feel (clubs need to feel the same throughout the set) and accuracy. Slight differences in stiffness can cause miss hits left, right, short or long.

Frequency -Matching-Chart.png

Two compared charts. A poorly matched set on the left and a well matched set on the right.

Following frequency we have MOI or moment of inertia. First, it is important to understand that a correct club fitting is required to identify the correct MOI for a specific golfer. There are so many different strengths, tempos and swing mechanics that the club fitting is critical. The MOI of any object is a measurement of its resistance to being put in motion around a defined axis of rotation. As it relates to golf clubs, if each club in a set requires a different amount of effort to swing the club, it is almost impossible for the golfer to swing every club consistently. In the most simple form, MOI matching scientifically makes each club require the same amount of effort to swing.  MOI matched clubs offer better shot making consistency than swing weight matched clubs.


MOI Gauge Machine.

There are a couple of methods to determine the correct MOI. For new clubs a club fitting is the appropriate method. Different total head weights, distribution of weight in the club head, (Heal to toe, top to bottom, front to back) will impact the golfers swing motion. Once the right combination of shaft and club head is determined all clubs in the set will be built to match, MOI is one of these factors that is determined through the club fitting process. The other method is for existing club sets. Golfers who play quite often will be able to tell us what club in the bag is their favorite. The custom club builder will measure the MOI of the favorite and, via changing weight distribution of the other clubs, be able to match the MOI of the rest of the set to the favorite club.

FLO (Flat Line Oscillation)

What is it? 


Most shafts are not perfectly round or evenly weighted around the circumference or length of the shaft.  FLO is method to determine the most stable position a shaft should be installed into a head during the custom club building process. 

How important is this:

There is a lot of debate, (pros and cons) on the effectiveness of this on the impact to club performance. While there is no quantitative data to support a negative or positive performance impact, we believe there is a qualitative impact. Our belief is any thing we can do to potentially reduce variation in your equipment will increase your confidence in your equipment. Leaving you to focus on the variations in you swing.

How is it determined?

The process we use at EGT is a done first with the raw shaft, (uncut) then post tip and butt trimmed. For the sake of time we will discuss the steps of the post tip and butt trimmed shaft.

  1. Spine the shaft (see Spinning a shaft). 

  2. Dry fit the appropriate head, (head that is matched to that shaft) to the shaft with the spine mark to 90 degrees left of the toe.

  3. Clamp the shaft into a five inch clamp with the toe of the club pointing up, (we use our frequency measuring tool for this) add the special laser that as affixed to a clamp that can be clamped to the shaft just above the hosel of the head. 

  4. We use a target of white stiff plastic for our laser to shine on, (distance from the laser to the target is not critical). Start the shaft in motion by pulling the shaft so that is oscillates parallel to floor.  

  5. If there is any ovaling pattern, (see Figure 1) at the target rotate the shaft counter clockwise and 8th of a turn, re-adjust the head to the toe point up and the laser to parallel to the floor. Twang the shaft as before, continue doing this until you laser line is flat, (no ovaling)  See Figure 2.

  6. Mark the shaft at the 12:00 position, you will install this in this position during the final assembly of the shaft and head.


Figure 1


Figure 2



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