Thursday, June 27, 2013

The Road to Golf Club Fitting Nirvana - Part XI

Part I:
Part II:
Part III:
Part IV:
Part V:
Part VI:
Part VII:
Part VIII:
Part IX:
Part X:

This will be the final part of this series. I still have to do my 3-wood, switch out the KBS C-Taper shafts in my wedges with the KBS C-Taper R+ shafts and I will also be getting my YAR Putter tomorrow. I will save those for regular blog posts. First, here are my final specs:


Here are some of my final thoughts on the MOI and MBI matching process:


With my irons that were only MOI matched, I noticed that the long irons flew lower and the short irons flew higher. With MBI, I was able to hit the ball higher and produce more spin with the long irons while getting a more penetrating ball flight with the short irons. While I cannot reconcile with Monte Doherty's claims that his path changed when his Balance Index got closer to his target, I do believe him when he states that he gained distance.

From a simple perspective, if we have a greater percentage of the weight towards the head, that would logically produce a higher launch with more spin. Thus, if you have a greater percentage of weight in the shaft+grip, that will produce a lower launch and less spin.

The problem we have with long irons is that they tend to fly low and not get much spin. Thus with MBI, we are getting a higher percentage of weight in the head and thus producing a higher launch and more spin. Conversely, with the short irons we are getting a smaller percentage of the weight in the head and thus the ball will penetrate more in flight. These changes in launch and spin have allowed me to gain a little more distance (about a 1/2 club). I think it allows for better yardage gapping as well. And that's why I believe Doherty was hitting his clubs further; the distribution of weight fit his swing better.

With the feel, I think it is advantageous to get the feel of the heft of the clubs the same. Imagine your brain trying to adapt to the feel of a 3-iron which normally has a low MBI on one shot and then switch to a 9-iron with a high MBI on the next shot. The distribution of weight is very different and I think it throws a lot of golfers off.


The typical irons fitting, even with MOI matching, consists of hitting a 6-iron until the clubfitter can find specs and components that produces the optimal results for the golfer. Then the rest of the set is built according to the baseline, the 6-iron.

I believe the flaw here is that the golfer ends up being optimally fitted for the 6-iron.

If you ask golfers 'what is your favorite club in your bag?'

I would say that almost all of them will say the 6-iron. If not, they will say the next closest club, either the 5-iron or the 7-iron. Again, they were fitted for a 6-iron.

I believe that if we were to use a 3-iron as a baseline, we would find golfers being fitted for lighter shafts. Conversely, if the Pitching Wedge was the baseline I believe that most golfers would be fitted for heavier shafts.


Iron shafts are designed the same in the sense that the longer the club, the more the shaft weighs. Looking at how shafts are designed in woods and then in irons, I start to see some failed logic in the design.

Typically we use the lightest shaft in our driver. We then have heavier shaft weights in our 3-wood and then a heavier shaft weight in the 5-wood or the hybrid.

Yet, with irons we go the other way around. With the heaviest being the 2-iron and then they will typically get incrementally lighter. So with woods we have them getting incrementally heavier and then with the irons they get incrementally lighter.

And with my findings that the distribution of weight influences the ball flight and spin, we can see why the iron shaft design is flawed. It's likely to produce trajectory that is too low with the long irons and too high with the short irons.


While we cannot match the Balance Index just by using MOI matching, I found that it helps narrow the gap in the Balance Index between clubs. I disassembled my Wishon 555 irons which are stand-alone MOI matched clubs and found that Balance Index ranged from 35-45.

When I did the same with my swingweight matched Titleist 690 MB irons, the Balance Index ranged from 32-56.

I have also seen time and time again where MOI matching by itself greatly improves a golfer's impact dispersion.


Like anything you put together, it's a lot easier when you have the right tools. I would recommend the GolfMechanix MOI Auditor Machine, the Balance Point measuring setup as described in Doherty's spreadsheet, a good digital scale (measuring to the nearest tenth), Wishon's Shaft Bend Profile software and plenty of lead tape.


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