What the heck is MOI? Is it just a new marketing ploy to sell clubs, or what?

[Director]

Who wants to answer this one?

[Colosse]

 ;)Here is a reply from another forum from a fellow named Richard Kempton:


Someone on another forum I correspond with suggested I look at this thread. Having done so, although reluctant to get too involved because of time constraints, I feel obliged to offer a few comments based on my own experience of MOI-matching clubs, but first I probably need to present my credentials, so to speak.

Briefly, I have been a professional clubmaker since the early 1990s. In 2001, I was named the GCA 'Clubmaker of the Year' for Europe. In early 2003, I acquired a prototype MOI 'Period Counter' system for evaluation. To cut a long story short, once I had learned how to work out a player's true optimum MOI setting - which in most cases will probably be different for the woods, the irons and the wedges - the advantages over swingweighting were so self-evident & overwhelming that every set of clubs I have built since about 2004 has been MOI-matched, rather than swingweight-matched.

How overwhelming? At the last count I had MOI-matched in excess of six hundred sets of woods and irons/wedges, a mix of 'new builds' and existing sets that I had 'retro matched'. From the outset I adopted a very simple policy with every customer whose clubs I MOI-matched: if he/she didn't think that the system offered any real tangible benefits, in terms of feel, improved consistency, ball striking or whatever, or they just didn't like it, for whatever reason, all they had to do was return them and I would re-make the clubs to whatever swingweight match they specified, free of charge.

I had expected to have some golfers take up the offer, but the percentage who actually did was astonishingly small:

ONE.

That's not one percent, by the way, that's ONE GOLFER - one data set out of the 600-plus sets I have on file. BTW, if I don't hear from a customer within a month of him or her collecting their clubs, I call them to enquire how they are getting on, so it's not a question of them just letting things slide because they can't be bothered to pick up the phone. I KNOW if they're happy or unhappy, because I ask them directly. I've never seen that level of acceptance of a new clubmaking 'technology' in all the time I've been in this business. Period.

But make no mistake - in order to get the full benefit of MOI-matching, you ABSOLUTELY have to spend time to identify the MOI-setting that works best for each and every golfer you fit (the 'favourite club' method does NOT work). Despite MonteD's experience, it can be done in about 15 minutes, provided that you adopt a structured approach. If anyone is interested, I'll be happy to post a description of the method I routinely use.

To take up some points made by other posters:

(1) In my experience, MOI-matching works for both hitters and swingers. In very general terms, 'hitters' will likely require higher MOI-settings than 'swingers' (for the same reason that they often require higher total weight clubs and higher swingweights).

(2) There are effectively three separate & distinct types of club 'weight' (or, if you prefer, 'heft') that I can feel - see below; in my experience, most golfers are able to re-educate their senses to home in on MOI, rather than total weight or swingweight.

- TOTAL WEIGHT is what I feel when I take a club out of my golf bag or hold it somewhere near its balance point;
- SWINGWEIGHT is what I feel when I hold the club out in front of me or address the ball;
- MOI is what I feel when I SWING the club.

If you think that the #9i of your swingweight-matched set of irons feels heavier than your #3i, the chances are that you are homing in on the TOTAL WEIGHT of the club rather than it's swingweight or MOI (because in TOTAL WEIGHT terms, assuming the same shaft & grip, your short irons will be heavier than your long irons, regardless of whether you use swingweight or MOI to match them).

With a MOI-matched set stepped in 0.5", 0.4" or 0.375" increments, because the headweights/club total weights increase at a faster rate than for a swingweight-matched set AND the swingweights of the shorter clubs also increase, the golfer - at least initially - will sense the combined effects of both changes.

The paradox is that although the shorter clubs of a MOI-matched set WILL be heavier, in both total weight AND swingweight terms, than for a conventionally swingweight-matched & stepped-length set, the resistance to the unwinding of the wristcock is BY DEFINITION more uniform, so the golfer generally receives two contradictory messages - the short irons feel heavier at address than before, but are more similar (by definition) in terms of how they feel during the release phase.

So if YOU sense the short irons of a MOI-matched set feel heavier than your long irons (or, if you prefer, your long irons feel lighter than your short irons), the chances are that you are picking up on total weight and/or swingweight rather than their MOI - although at the risk of stating the blindingly obvious, if the long irons of your MOI-matched set do feel lighter than your short irons - or vice-versa - it's always possible that they are, i.e. someone screwed up the MOI-match! If you think that golfers generally cannot discern MOI changes equivalent to less than a swingweight point (roughly 2g of headweight), you're in for a bit of a shock ...... because a surprising number are sensitive to half a swingweight point (about 1g of headweight change), or less.

(3) Almost all the golfers whose clubs I have MOI-matched end up with their woods set higher than their irons (as MonteD has also found) and their irons set higher than their wedges. However, you CANNOT assume that ALL golfers will conform to that general rule. Each golfer MUST be separately assessed for each group of clubs WITHOUT ANY PRECONCEPTIONS based on age, build, physical strength - OR even what MOI or swingweight setting you happen to think is 'normal'.

Dave Tutelman has suggested that one reason why it might make sense to set the wood MOIs higher than the irons may have something to do with ball position - the woods are generally played closer to the heel of the front foot (left foot for a right-hander) and the higher MOI takes care of the difference in ball position without the golfer having to try to 'control' the release. That does seems to have merit, because I generally find that the MOI-setting that I need to use for a golfer's 'Rescue' clubs is often affected by whether they position the ball more like an iron (i.e a bit back in the stance), or more like a fairway wood (i.e. closer to the heel of the front foot).

(4) If anyone has tried a MOI-matched set and found the results disappointing, then that is likely to be because they assumed that all they had to do was to pick a club - e.g. their longest iron - and match all the other clubs to the same setting, which is highly unlikely to work.

I doubt that MOI-matching will ever be adopted by the OEMs, because unless it is properly and carefully matched to each player - and the clubs are accurately matched to that player's optimum - it won't actually offer any significant benefits over swingweighting. Get it right, though and the results CAN be surprising, to say the least - and it further differentiates what I do from what the OEMs do.

If this sounds like a sales pitch for MOI-matching, it's not meant to be, because I do not make or sell MOI-matching equipment or systems and I have no financial interest in, or take sales commission or fees from, any other business making or selling MOI-matching systems or equipment.

If you don't think it makes any difference, or that swingweighting is better, I'm not going to try to persuade you to switch.

[Colosse]

And how he goes about finding out the right MOI for the golfer:

The reason that the 'favourite club approach does not yield good results is because a club may be a golfer's favourite for reasons other than its MOI - for example loft or length, or possibly because it has a different or mismatched shaft (in the sense that its flex does not match the other clubs).

I fit for MOI pretty much in the same way as I fit for swingweight, I just take more time fine tuning the final number I arrive at, because of what I've empirically observed about how sensitive SOME golfers can be to what I had previously thought were probably completely insignificant weight changes. Such golfers do exist - and you shouldn't assume that they only exist amongst the ranks of more skilled players.

You can get a few initial clues by asking questions & listening.

For example, does he (I'll assume that the golfer is male) play or has he played other sports that involve using an implement to hit a ball or other object, for example, tennis, squash, racquetball, ice or field hockey, baseball, or (in the UK), cricket. If so, does/did he develop a preference for a heavy or light racquet, stick, or bat.

If he's in a skilled manual job where he uses, for example, a hammer, does he wield a slightly lighter or a slightly heavier one than his workmates with a greater sense of control. If he's a dentist, for example, he'll generally have strong hands & wrists (or at least one strong hand & wrist). The same possibly applies to full-time clubmakers ...

Ask him about his playing problems. If he struggles a bit to maintain a good tempo or rhythm, if he has a noticeable tendency to hit balls fat or thin, he probably needs heavier clubs and/or a higher MOI/swingweight than currently.

If he is physically not very strong and finds that his fairway woods and mid/short irons are less easy to swing than his driver and/or longer (or if he tends to block his longer clubs and has a tendency to ‘heave’ at them a bit), that suggests that he needs lighter clubs and lower MOIs/swingweights.

Particularly if he is a decent player and the impact wear on the faces of his short irons & wedges show that he generally hits them no more centrally than his long irons, in my experience that's highly likely to be because the MOI of the shorter clubs has dropped well below the optimum level for that golfer (because shorter clubs should be easier to hit on-centre, but in any swingweight-matched set, the club MOIs will generally decrease with clublength).

In a lot of sets, the #9i is likely to have the lowest MOI - it won't always be the case, so I always check before I do the next step; if it's not the #9i, it will probably be the #8i or the PW.

In order to check if he can consciously discern MOI differences, I ask him to make some smooth three-quarter swings with whatever is the longest iron he generally carries, concentrating on how the club feels as the wristcock unwinds (when the hands get to a point just above waist level for most players, at or below waist level for better swingers). I also ask if he is aware of the club and/or clubhead at the top of the backswing.

I get him to repeat that with the #9i (assuming that to be the lowest-MOI club in the set) and ask him to tell me what, if any, difference he notices in the 'swinging balance' of the two clubs. The #9i should feel lighter, so if he says the #9i (or whatever) is heavier, then he's likely homing in on the total weight of the club and if he says they feel the same, then he's likely homing in primarily on the swingweight.

If he can't pick up on the MOI difference, switching back & forth between the two clubs a few times usually results in a 'eureka' moment, but if he tends to cast the club, it sometimes helps to get him to concentrate on how the two clubs feel at or just after transition, or possibly as he starts to **** the wrists during the backswing .

I then ask him to hit some balls into my net with his own #5i and measure his clubhead speed, but I also apply some impact spray to check for consistency of strike (or lack of it). I then repeat the exercise with the #9i and look for any discernible change in the tempo or transition (for example a tendency to get quicker with the #9i or 'heave' at the #5i) and check the impact pattern he gets with that, compared to the #5i. I also look to see if the clubhead speed is more consistent with one club vs. the other.

Once I've determined what shaft & head specs the customer needs, I have him hit a test #5i that I initially set to whatever MOI I feel is appropriate, based on what I noted about his swing & impact patterns with his own #5i & #9i. For example, if he swung his #5i OK, but tended to quicken up or was more erratic with the #9i, I'll initially set the MOI close to his own #5i. If he looked more comfortable or was more consistent with the #9i, I'll set the initial MOI of the test #5i closer to that of his own #9i.

The final stage is to have him hit 5 balls with the club and check the impact pattern, swingspeed and tempo, then add 2g of lead tape to the head and hit another 4-5 balls. If the results with that extra 2g strip of tape are better in terms of impact pattern, and/or tempo and/or clubhead speed), add another 2g and re-test. Repeat this until the customer starts to sense that:

? the club is feeling slightly too heavy;
? you notice any tendency for the swing to look a bit laboured;
? the impact pattern starts to deteriorate; and/or
? the clubhead speed starts to drop off.

Once you get to that point, take off the last 2g strip (or the last two 2g strips, if you've added more than 3-4 strips), have the customer hit 5 more balls and re-assess impact pattern, tempo and clubhead speed (and also ask him how the club feels).

If he says it’s a bit light (if you’re used to working with swingweight, you’ll probably be surprised at how many golfers are sensitive enough to notice a MOI change equivalent to one swingweight point), apply one 1g (I repeat: 1g, NOT 2g) strip of tape and re-test.

If you removed two 2g strips, apply 1, or 2 or possibly 3 1g strips in turn and watch for the ‘tipping point’ in terms of what you can see happening to the swing, or what the customer says as you add each 1g strip.

If necessary remove & replace the last 1g strip several times and re-test to see if it makes any discernible difference to impact pattern etc., or whether the customer has a preference for the club with or without the last 1g strip. Often, when you reach the ‘tipping point’, the customer will tell you it’s too heavy before he’s even hit it (in which case remove the last strip). The object is to hit the optimum MOI to +/- 1g of headweight). Once you and he are happy, measure the MOI of the club and assemble/match the other clubs to that, preferably to a tolerance of +/- 5 kgcm².

I favour different MOI settings for the woods, the irons and the wedges), because that's what seems to work best for most of the golfers I've fitted. Inevitably, there will be golfers who buck that tendency, so I always treat the woods, hybrids/irons and wedges as sets within a set.

As a rough rule of thumb, I find that the woods need to be set anything between 60-120 kgcm² higher than the irons and the wedges 20-40 kgcm² lower than the irons. Hybrid irons (Rescues) can be set to match either the woods or the irons, but I’ve found that that often depends on what ball position the golfer uses for the hybrids.


‘Rules of Thumb’ for MOI changes

? 1g = 10-11 kgcm² (equivalent to about half a swingweight point)

? 1/8 inch length change = approx 13-14 kgcm²

? ½ inch ferrule = approx 5-6 kgcm²

? 1 inch ferrule = approx 12 kgcm²

? 10g grip weight change = approx 3-4 kgcm²

? 30g counterbalance = approx 5-6 kgcm²

? 1/16" BP change = approx 10-12 kgcm²

? Swingweight cork = approx 1-2 kgcm²


To reduce a club’s MOI (e.g. if it is too heavy by 60 kgcm²):

Either reduce headweight by approx 6g (60 kgcm²/10 kgcm²), or shorten the club by 4.28 eighths of an inch (60 kgcm²/14 kgcm²), or a hair over 0.5".

[clubfxr]

I give the following information to customers who may be in question whether they want their clubs MOI matched or not.  This seems to be a thorough explanation and gives them knowledge what is going to happen when I produce this technique to match their clubs.

What IS MOI Matching?

·   MOI Matching is simply a replacement for Swingweight.  If the goal is to get the clubs to feel the same to the golfer from club to club, then MOI does this much better than Swingweight because it is a measurement of how much force it will take the body to rotate the golf club.

·   In a golf industry that is tossing around the term MOI in different ways, it can be confusing to know what MOI Matching of clubs really is.  The recent marketing of drivers with a high MOI refers only to the driver head.  By making new driver heads in which a farther from the head’ center of gravity, the high MOI drivers attempt to offer golfers more off center hit forgiveness.

·    Every object you can think of has an MOI.  However, only when that object is intended to be put into motion to rotate about some axis does its MOI mean anything.  MOI Matching of the clubs in a set is all about making the Moment of Inertia of each FULLY ASSEMBLED CLUB to be the same.  It is the release, otherwise known as the unhinging of the wrist-cock angle, which is the axis of rotation for each club.  When the MOI of each club is the same, the golfer will use the  same amount of swing force/effort  to release the club through impact.  Swingweight matched clubs don’t do this.  In a swingweight matched set, each club requires a little different swing force/effort to release the club through impact.

What will MOI Matching DO in Terms of Performance?

• Club matching, no matter what the method, is all about trying to offer the golfer more consistency with all the clubs in the set. Swingweight has attempted to do this through a method centered on the use of a swingweight scale that has been made with an arbitrarily chosen 14” fulcrum point built into the scale. MOI matching is based on pure physics. Scientists have known for decades that if the goal is to make the force required exactly the same to move an object around an axis of rotation, making those objects to have the same Moment of Inertia is the only way to achieve that goal.
• So far, using this technique in building clubs, the response has been phenomenal. Not once have we been asked by a golfer to have their clubs changed back to a swingweight matched set. In addition, the results are that golfers now enjoy a higher percentage of on center hits than before, when their clubs were swingweight matched.
• Recently a report came from Dennis Piant, of Performance Fit Golf, in the Chicago area who works with Senior Tour Pro, Chip Beck. Chip had his clubs stolen and had Mizuno send him out replacements which were then torn apart and rebuilt by Dennis. Chip took delivery of his new sticks and after a couple of days, reported to Dennis that his clubs “didn’t feel right”. So Dennis got the clubs back, asked Chip if there was one that he particularly liked (in this case it was the 7 iron) and rebuilt the entire set to match that 7 iron’s MOI. Chip got back the set and was amazed at how great they felt. Now, whenever he’s in Dennis’ shop he tells all the golfers “you’ve got to get your set MOI’d”.
• One of the significant benefits we’ve seen of MOI is better and faster skill acquisition for the golfer. This eliminates the need to “learn” each club and figure out how to properly square it.

How Does MOI Matching Differ from Swingweight Matching?

• In terms of fitting and building there isn’t a lot different between the two processes. The same key things that a fitter will do for determining the proper head, shaft, grip and playing length for the golfer still apply. When it comes time to do the build out instead of building all the clubs to a SW designation, the build out will be to a specific MOI number.
• The easiest way to explain this is to say what would happen if you had a set in which all clubs were built to the same MOI, and you put each club on a swingweight scale to measure its individual swingweight. As you know, when clubs are built to the same swingweight, each club records the same letter and number measurement on the swingweight scale. For example, if the golfer’s desired swingweight were D-1, all swingweight matched clubs would read D-1 on the swingweight scale.

• In an MOI matched set of clubs, the swingweight progressively increases from being lowest for the longest club in the set, to being highest for the shortest club in the set. In a set where each club is built to have the same MOI, this progressive increase in swingweight from longest to shortest length club is not exactly the same increment of swingweight increase because of slight variables in the shaft weight, shaft balance point, grip weight, and accuracy of the length change from club to club. But in general terms, it can be said in an MOI matched set of clubs, the swingweight progressively increases from being lowest for the longest club in the set, to being highest for the shortest club in the set.
• Another key difference between SW and MOI is that you can’t “trick” the MOI. We all know the old saying about being able to swingweight a telephone pole to D1 which is a great illustration of the deficiencies of SW. We know that any weight we put on the grip end of the fulcrum will lower the SW, but does this actually make the club lighter to the golfer? It doesn’t, and when we do the same thing the MOI number will slightly increase.

How Do You Know What MOI Measurement is the Right One for Each Golfer?

• Choosing the right MOI for any golfer is somewhat similar to choosing the right swingweight for the golfer. The stronger the golfer, the more forceful the golfer swings at the ball, the higher the swingweight and the higher the MOI would be to best match the golfer’s requirements. Likewise, the weaker the golfer and more smoothly they swing the club, the lower the swingweight and the lower the MOI would need to be to work best for the golfer.
• Again, it is important to remember that when you choose the proper head, shaft, grip and playing length for a particular golfer, you’ll be in an MOI “range”. Now it’s just a matter of fine tuning to find where the golfer likes the feel and shows good on center contact within that MOI range.
• Pinpointing the right MOI can be done in a number of ways. Using a test club and adding lead tape to the head while letting the golfer hit shots is the most effective and efficient method of finding the right MOI that each club will have when built.

If MOI Matching is so Great, How Come the big golf companies Don’t Do It?

• The OEM golf companies are all about making millions of standard made clubs. All of their production methods and head specifications have been set up for swingweight matching. All men’s clubs are built to one swingweight and ladies to one other swingweight that is primarily established by their clubs being an inch shorter in length than the men’s. For any of these companies to change to MOI matching would require them to spend a fortune to try to re-educate golfers about the change.
• Without naming any names, we know that a few of the OEM companies are aware of MOI Matching and are aware of its scientific justification for being better than swingweight matching to achieve the goal of making all clubs in a set swing with the same feel to the golfer. However, since all the OEM companies make their standard clubs to a single swingweight for each gender, were they to switch to MOI matching, they still would have to choose a single “standard” MOI to which all their clubs would be built. Since MOI Matching only works to full improvement benefits when customized to each golfer’s unique strength, athletic ability and swing characteristics, by making their clubs to one MOI, the OEM companies know that they would not be offering much of an improvement to the golfers over what they are doing now with a single standard swingweight for men and for women.
• Building the clubs to a matched MOI would cost the OEMs a little more than simply building to swingweight. Accurate MOI matching takes a little more time, and one thing the OEM companies do NOT like to do is increase the cost of the standard clubs they make.