Matching Golf Clubs by Moment of Inertia –

Has MOI Matching ever been done previously in golf clubs?
Yes, there were two previous times with which we are familiar in golf equipment history in which companies engaged in the sales of assembled golf clubs attempted to offer MOI matched golf clubs for sale. First, in the 1970s, a company named Sounder Golf offered sets of woods and irons which were purported to be MOI matched by weighting the clubs at specific points within the shaft. The company promoted its clubs through the use of a device which would allow the shop to set two clubs in a pendulum swing motion to show how the Sounder clubs swung back and forth precisely the same in synchronous motion. When swingweight matched clubs were placed in the same device, two identical swingweighted clubs swung back and forth erratically. The clubs never caught on for two reasons: 1) Sounder was under-capitalized and unable to generate enough demand through their marketing programs. 2) Every set of Sounder clubs was built to only one specific MOI. Because golfers are different in strength, tempo and swing mechanics, one MOI measurement could never fit the MOI requirements of each golfer.

Much later, in the late 1990s, the Tommy Armour Golf Company introduced their EQL clubs to the market. By making all of the woods the same length and same total weight as the 5-wood, and all of the irons the same length/total weight as the 6-iron, the company did achieve an MOI match between the clubs. This concept failed again because the one MOI measurement to which all the EQL woods and irons were build did not fit all golfers, but also because the concept of all woods and all irons being the same length was much too radical for golfers to accept.

How is the right MOI determined for each golfer?
Virtually all golfers who play regularly have noticed they have a “favorite club” or clubs within their current or a previous set of clubs. A “favorite club” may be defined as a club with which the golfer is most consistent over all others in the set, and which the golfer has the utmost confidence in their ability to hit the ball solid and on-center more often than the other clubs in the set. After research and testing, TWGT believes that a very good reason for the fact that golfers do have “favorite clubs” is that the MOI of those clubs happens to match the strength, tempo and swing mechanics of the golfer noticeably better than the other clubs. Therefore, the concept of TWGT MOI Matching is based initially on asking the golfer to bring forth a “favorite club” from any set they may own or have used. The “favorite club” is measured for its MOI using the TWGT MOI Matching System, after which the other clubs are then built to match the MOI of that “favorite club(s)”. From testing with many golfers, and now from hearing from clubmakers who presently use the TWGT MOI Matching System in their work, we are very satisfied that the “favorite club” procedure is successful for identifying a suitable MOI for the golfer.

Does MOI Matching change the fitting process for the golfer?
No. MOI Matching is a replacement for swingweight matching in the fitting process. Clubmakers will fit golfers for the best clubhead, shaft, grip and length based on the same fitting procedures that they have developed and with which they are confident. Once the heads, shafts, grips and the lengths are determined by the clubmaker, and then MOI Matching is brought in to guide the clubmaker in how the clubs will be assembled with regard to final headweight, and in some cases, final length adjustments.

Is there any aspect of the fitting or performance of the shafts that is changed by MOI Matching?
Very Rarely, if ever. As we said, the selection of the shaft is made on the basis of the same fitting procedures the golfer is comfortable with using. However, it is very likely that because of the final head weighting requirements of the MOI Match, the frequency progression of the shafts will be different than it would be if the clubs were only swingweight matched. Normally, if the progression in butt frequency was 4cpm between clubs in a swingweight matched set, the progression will change in some cases, but only because of the headweight changes in the MOI set, and NOT because of any change in trimming of the shafts. In all of our testing, and in the reports of actual MOI fittings that clubmakers are performing, we have yet to hear of one case in which the golfer required an adjustment in the tip trimming to offset the progression of frequency from shaft to shaft within the set. In short, MOI matching will not affect the golfer’s perception of the shaft fitting.

What will a golfer notice when switching from swingweighted to MOI matched clubs?
No BS, we have yet to hear from a clubmaker using the MOI system who reported that a golfer for whom MOI matching was performed did not notice a difference in the swing feel of all of the clubs in the set, and an increase in the percentage of solid, on-center hits with the clubs. If the golfer “waggles” each MOI matched club, they may think that they detect a little different head feel. But as soon as the clubs are swung full, the golfers all report that they can close their eyes, switch clubs in the set, and not really detect any difference in the total swing feel of the clubs from each other.

If I take a set of MOI matched clubs and then measure each club on a swingweight scale, what will I see?
Depending on the MOI of the “favorite club”, the swingweight of the clubs in a set will normally increase from the longest club in the set to the shortest. However, what the longest club’s swingweight is compared to the shortest, and what the progression in between can be quite different, again, depending on the MOI to which the clubs in the set are built, the lengths each club is fit to the golfer, and the weight and balance point of the shafts in the set as well.

Will the woods and irons all be built to have the same single MOI?
No. TWGT testing along those lines showed that because woods and irons are so different in their length ranges, better results were obtained by matching all the woods to a “favorite wood” MOI, and then matching all of the irons to a “favorite iron” MOI.

What about the wedges – should they be built to have the same MOI as all of the rest of the irons?
Again, this was another aspect of MOI fitting and matching that TWGT spent time investigating. What we found was that any of the wedges that are used by the golfer for less than a full swing most of the time the wedge is used, it should not be matched to the same MOI as the rest of the irons which are almost always used for a full swing. In general, because many golfers do use the PW and AW (gap wedge) more for full swings than they do the SW and LW, it is ok to make the MOI of the PW and AW the same as the rest of the numbered irons. But for the SW and LW, they are better off being built to a lower MOI than the rest of the irons.

How about the putter – should it be MOI matched?
Most definitely finding the right MOI of the putter for each golfer would improve performance on the greens. However, that is far easier said that done at this point in our MOI research. In the woods and irons, because there are multiples of each type of club, it is not difficult to ask a golfer to provide a present or past wood and iron that has been a “favorite club”, to which all of the other woods, and then all of the other irons would be MOI matched. But with the putter, it is not that practical to ask a golfer who is not putting all that well to bring in a “favorite putter” to act as the MOI guide – logic says if the golfer had/has a favorite putter, he would be using it at present and thus not need to change the MOI. However, if the golfer DOES presently like the feel of their putter but was interested in trying a different head model in a new putter, then the favorite putter should be MOI tested to provide the MOI benchmark for building or altering the new putter so that it had the same stroke feel the golfer likes.

How does the TWGT MOI Matching System work?
The TWGT MOI Matching System consists of a piece of hardware called a Period Counter, with the MOI software. These two elements of the MOI system, along with your ruler and gram weight scale, are used to perform all of the measurements and calculations required to determine the MOI and make the assembly adjustments for ensuring the MOI match for all clubs.

Remember, MOI matching of clubs is a replacement for swingweight matching. Therefore, the clubheads, shafts, grips, and length of the clubs are to be fit in exactly the same way each clubmaker has learned to make these decisions. Then the MOI Matching System is used to guide the final assembly of the clubs to make the clubs all have the same final MOI. The TWGT MOI system allows you to MOI match clubs in three different ways –

1. MOI matching of already assembled clubs
   o This part of the system allows you to measure the MOI of any “favorite club(s)” or any existing set, identify the MOI to which the assembled clubs are to be matched, and tells you how much weight to add/remove from the head to achieve the MOI match through the set.
   
   
2. 2. MOI matching using all TWGT components
   o We measured all of the individual MOI aspects of all of our heads, shafts and grips and put all that information into a data base that lives within the software. Thus you can select any heads, shafts and grips to “virtual build” the set to a specific MOI. In this module, he adjustments for matching the MOI can be done either by head weight addition/removal, or by slight length increase/decrease to achieve the MOI match
   
   
3. 3. MOI matching from components NOT within the data base
   o Yes, aren’t we a nice company for allowing MOI matching with heads, shafts and grips that are not of our design!! Using module in the software for MOI matching from already assembled clubs, you can “dummy assemble” the clubs using any heads, shafts and grips and the software can tell you the weight addition/removal to the heads to achieve the MOI match

MOI Software Screeshot Descriptions (click on screen image for a larger version)

MOI – 1 In the MOI Analyzer module of the software, the length, total weight, balance point and period measurement for all clubs are inputted into the box in the left center of the screen. If the "favorite club" is a different club from those clubs in the set, it will be entered just as another club in the MOI Analysis data. By clicking on <calculate> the MOI and the swingweight of each club is displayed on the right side of the screen.
MOI – 2 The club number and the MOI measurement for the "favorite club" is entered into the box indicated by the arrow. Click <calculate> again, and in the middle column on the right, the gram weight adjustment to each clubhead in the set is shown. By adding or removing this weight for each clubhead, the clubs will be MOI matched to the MOI of the "favorite club."
MOI – 3 To "virtual build" a set completely from TWGT clubheads, shafts, and grips, the Component Matching module is opened in the software. Clicking on <unlock> and then on each <list> button, the model of clubhead, then shaft, and then grip can be selected from the component database files in the software.
MOI – 4 The club number and MOI measurement for the favorite club are entered in its box on the left side of the screen. By clicking on <fmoi> the software makes all calculations in the boxes near the bottom of the screen to show the MOI matching adjustments of headweight change, or length change, which will ensure that each of the clubs will have the "favorite club" MOI when they are assembled.

And that’s it. If you were a little intimidated by the MOI Matching System at first glance, we hope this overview of how MOI matching is actually done will show you that stepping into this very exciting and new method of club matching is not difficult, and will put your clubmaking services on the “cutting edge”.