Tuesday, November 1, 2011

MOI Matching FAQ's

Recently, I’ve received a ton of questions from readers on MOI Matching. I’m at the ‘more knowledgeable than a novice, but far from an expert’ stage at the moment. But, I will try to answer the questions I’ve been getting here.


First, let’s understand some basic terms:

Static Weight– This is the weight of the club when it’s at rest. I could have a 5-iron weighing in at 15.6 ounces when I lay it down on a standard scale.

Swingweight – This is the effective weight of the club when I am swinging the club. There are many factors that affect the swingweight like the weight of the components (clubhead, shaft, grip, etc), balance point of the club, club length, etc.

MOI – For the purposes of MOI matching, we are measuring the MOI to be the amount of force required to swing the club.

Force – The scientific formula for force is Mass x Acceleration

The thing with swingweight is I can have 2 clubs with the same exact swingweight, but have very different characteristics. One can have a much heavier shaft, but I could backweight it (add weight to the butt end of the club) to keep it at the same swingweight as the other club with a lighter shaft. The balance point of the shaft could be different. In fact, back in 2009 I had some grips put on a set of old Hogan irons that weight 15 grams more than the old grips and that made the swingweight go down by 2 points.

With that, you can have 2 clubs with the same swingweight, but very different MOI (aka requiring very different amounts of force to swing the club).

Remember, Force = Mass x Acceleration. Thus, if the amount of Force required to swing a club is different from another club, that means the mass of the club and or the acceleration has changed.


First, the golfer needs to be fitted for MOI. We can do that one of two ways.

1. The ‘Best Club’ Method – Find the best club in your bag, measure the MOI

2. Add weight method – Get fitted for everything for a 6-iron *first*. Then the *last* thing you do is get fitted for MOI. Take a 6-iron with the shaft, grip, lie angle, loft, etc, all fitted for you. Then hit some shots. Add some weight (via lead tape or magnets), hit some more shots. Add more weight, hit some more shots. Experiment with the weight until you find what you hit the best and feels the best.

Method #2 has a lot of factors involved. Many believe that one can improve their sweetspot contact thru MOI Matching. Here’s a picture from UK MOI Fitter (www.theclubdoctors.co.uk) showing the before and after of a golfer they fitted for MOI

Again, being a little more advanced than a novice, I would think fitting somebody for MOI would be determined by things like ball flight, feel, and sweetspot contact. I would also think the process could be made a little easier with Trackman and looking at things like spin rate, smash factor, etc.

I think method #1 (best club) has some holes in it. For instance, your best club that you hit may not be the actual optimal MOI for your swing. And the shorter irons are generally easier to hit, so a golfer may favor the shorter irons even though they may not be the best MOI. Also, if you practice with one particular iron more than the others, you may start to favor that particular club over the others.

My feeling is that I would probably ask what the best club in your bag is and see if I can use that as a starting point, then use method #2.


This is done by adding weight. One can add weight either in the clubhead or in the shaft. I do NOT think lead tape is a favored method. I think MOI fitters prefer hosel weights, which go right into the tip end of the club shaft.

I’m still looking to see why lead tape is not liked other than cosmetics. My guess is that it doesn’t take much time for lead tape to wither away and that does affect the MOI. Believe me, the MOI machine is super-duper sensitive and the very slightest addition or subtraction of weight will cause the MOI to change quite a bit.


I believe so. Furthermore, I believe that a lot of golfers can already tell the difference in their own set.

Do you have a particular iron in your set, that has all of the uniform specs and the same shaft, but you don’t hit well? Chances are that the MOI is off.

For instance, the irons that I struggled a bit with are the 3-iron and the 9-iron. The 9-iron was a little less noticeable because it’s a higher lofted club. But, I did notice that I hit my 8-iron and my PW far better than my 9-iron. And the 3-iron I hit the worst. In fact, I hit my 4-iron great.

When I measured my clubs, the 3-iron and the 9-iron has the lowest MOI of all of my clubs and the 4-iron (and 7-iron) had the highest MOI of all of my irons. In fact, my 3-iron measured in at 2625 MOI while my 4-iron measured in at 2702 MOI. We want to get the MOI within +/- 5 and these clubs with the same swingweight had a difference of 77 MOI.


Not anymore. Tommy Armour had a model of irons called EQL. What they did was they made each iron the same length shaft, about the length of a 6-iron. Thus, the 3-iron would measure in at about 37.5 inches and so would the 4-iron, 5-iron, PW, etc. This created the same MOI. The problem is that the MOI may not be the optimal MOI for every golfer. And the single length iron concept is pretty radical.

The problem with MOI matching clubs is that:

A) That particular MOI may not fit golfers.

B) It’s too costly for OEM’s to do so.

That being said, I still think that MOI Matched clubs, even if you were not fitted for them, is probably better than clubs that are not MOI Matched because the consistency between the set for MOI Matched is there. You don’t have to worry about being able to adjust to one club that requires much more force than another club. Still, it’s not *optimal*, but I think it’s better than nothing.


No. What will happen is that if you MOI Match the set, the lower lofted irons will have a lighter swingweight and the higher lofted irons will have a heavier swingweight. Let’s say you find a 6-iron perfect for you and the MOI is at 2,750. You measure the swingweight and that 6-iron has a swingweight of D-4. If you match up the MOI of the rest of the set to 2,750, the swingweight with the 3-iron will be about D-2 and the 9-iron will be about D-6.

But, they will actually feel the same when you swing the club because of the difference in club length.


If this happens, you will need a lighter shaft and/or a lighter clubhead. For the most part, if you fit yourself for everything (club, shaft, grip, lie, loft, etc) and then fit yourself for MOI *last*, you shouldn’t have to worry about needing to take off weight to find the right MOI.


Absolutely. But the fairway woods, hybrids and driver will have a different MOI. Let’s say you have a 3-wood, 5-wood, 3-hybrid and 4-hybrid…then 5-PW. Let’s say the irons are matched to 2,700. Then the rest of the set would look something like this:

Irons: 2,700
4-hybrid: 2,775
3-hybrid: 2,775
5-wood: 2,800
3-wood: 2,800
Driver: 2,850

So you still match the MOI, you just have different MOI from the irons and from each other.


There’s no real reason to since you are not taking a full swing with a putter.


From what I’ve been told, there are no real drawbacks unless the person was not fitted properly or they made drastic swing changes. I have read some stuff, particularly from the Tutelman Web site (www.tutelman.com) about how it works best with having the same ball position. I don’t think I even change my ball position in the swing or at least I don’t change it very much with my irons. I think I just widen or narrow my stance depending on the club and that makes it look like my ball position has changed.

I have been told that it is *recommended* to use 3/8” clublength increments instead of ½” increments to make it easier to MOI match (for irons). You start at fitting yourself for a 6-iron length, then go in 3/8” increments from there.

It’s not all THAT radical. I use a 38 inch 6-iron. Under the 3/8” increments, I would still use a 38 inch 6-iron. But, I would have a 39-1/8” long 3-iron instead of my current 39-1/2” long 3-iron. And my 9-iron would be 36-7/8” long instead of my current 9-iron which is 36-1/2” long.

Now, it is NOT mandatory to use 3/8” increments. But, some MOI certified fitters may actually do that so I would question them about that.


Yes, but I’m going to hold off on that now until I actually MOI my own set and see what I think of it. If I don’t think it’s good, then I won’t bother. I also need some practice to get good at it.

I’m currently awaiting a KBS C-Taper shaft and I will install it in a Wishon 555M 6-iron head. I will then fit myself for MOI using lead tape, impact tape and Trackman to measure results. From there, I will experiment to see what the 3/8” increments feel like in my Wishon 555C 3-iron and my Wishon 555M 9-iron. If I like them, I will get the rest of the set done. If not, I’ll stick with the ½ increments.

From there, I will look at MOI matching the hybrid, 3-wood and driver.


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