Differences Between Swingweight and MOI Matching
Swingweight Matching: Swingweight is obtained by placing a golf club on a specialized balance scale with a fulcrum positioned exactly 14 inches from the butt end of the grip. A sliding weight on the scale is adjusted until the club balances around the 14" fulcrum, which is expressed using an alphanumeric code. This alphanumeric code ranges from A0 to G10, with A0 being the "lightest" and G10 the "heaviest" swingweight value". Swingweight
is not a weight, but a measurement of the balance point of the club on a 14" fulcrum.
The club will "feel" lighter or heavier to a player depending upon it's swingweight value. Most players have experimented with the swingweight scale and have determined which value on the scale suits them. Most players are comfortable with swingweight between "C6" to "D5". The idea is to make each club with the same swing weight value.
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Swingweight is controlled entirely by the following relationship factors:
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Clubhead Weight: Heavier clubheads increase and lighter clubheads decease swingweight. Adding 2 grams of weight to the clubhead with out changing the other factors will increase swingweight by approximately 1 point.
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Shaft Weight: The weight and balance point of the shaft significantly impact the final swingweight. In general, a 9 gram change in shaft weight will change the swingweight by about 1 point. Different shaft balance points can change the outcome slightly.
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Grip Weight: A heavier grip will lower swingweight, while a lighter grip increase swingweight. A 5 gram change in grip weight will change swingweight by approximately 1 point.
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Length of the Club: A longer club increases the swingweight, while a shorter one decreases it. A 1/2" change in length will change swingweight by approximately 3 points.​​​​​​
Golf Mechanix Auditor MOI Speed Match Machine
MOI Matching: MOI is the measurement of the effort required to put "an object" in motion around a "fixed axis". For matching golf clubs "the object" would be the "golf club" and the "fixed axis" would be "the player".
Most of us have that "favorite club" we always seem to be able to hit, it just seems effortless to swing it The idea behind MOI matching is to identify that "favorite club", measure the MOI value of that club and then build an entire set of clubs as closely as possible to that MOI value.
MOI Matching vs. Swingweighting: A Practical Perspective
It’s a sound theory, based on science, so it should clearly be the right way to match clubs, but in most cases, it isn’t. Let’s say a player’s favorite club is a 9-iron. How many golfers swing their 9-iron the same way they swing a 4- or 5-iron? I’ll answer that for you....not very many!
If the goal is to determine the MOI of our favorite club, match that MOI value to all the other clubs in the set, and then turn around and swing some of those clubs with a different level of effort, haven’t we essentially defeated the purpose of MOI matching?
This same inconsistency exists with swingweighting. Up until some clubmakers began promoting MOI matching in the early 2000s, swingweighting was the only method used to match clubs for nearly 80 years. While swingweighting isn’t grounded in pure science, it remains an effective way to balance clubs of varying lengths and total weights.
Bryson DeChambeau is a unique case. He plays single-length irons, all the same length, lie angle, shaft weight and profile, clubhead weight, and grip weight. This customized set up makes his irons the most perfectly MOI-matched set possible. The uniformity of his clubs inherently produces identical moments of inertia, with loft being the only variable. As far as I can tell, DeChambeau is the only professional currently playing with truly MOI-matched irons.
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I used to believe MOI matching was the superior method because it’s rooted in physics. But over time, I’ve come to realize that the key to consistent performance lies not just in the matching system used, but also in the player as well. A consistent swing, with steady tempo, downswing, and release, will yield consistent results, regardless of whether the clubs are matched by MOI or swingweight.