Do you really need a square driver to increase MOI? read the following first
article
New Revelations on Driver Head MOI

In case you haven’t heard, the whole reason you’re about to see the new “square shape" drivers hit the market in 2007 is the big companies’ effort to offer standard drivers which have a higher Moment of Inertia, specifically the MOI that dictates how much resistance the head will have when impact occurs anywhere on the toe or heel side of the face. But in this case, even by using conventional shaped drivers with slightly lower MOI measurements than the new OEM models, Clubmakers will be able to offer their golfers a much higher MOI on the drivers they custom fit.
Whaat? You mean TWGT is coming out with a super high new MOI driver this year? No, that’s not what we mean. We mean you have had the ability to custom build drivers in which the head has a higher MOI than any of the new OEM square drivers for years – you just didn’t know it. Well, for that matter, neither did we until we got a little deeper into an R&D project we have been working on this winter. And man, is this not only cool, but it puts the big companies who only offer standard made clubs off the rack in a real second place position to you when it comes to really offering golfers a driver head with a higher MOI!
You’re well aware by now that the stock drivers all of the major brand name companies make and ship to their retailers are between 45" and 46" in length. We can’t tell you who makes what lengths in between, but this is the standard length range for all the big brand name companies’ men’s drivers which are sold off the rack to millions of golfers every year. As a clubmaker who works in the world of swingweight and/or MOI of the assembled club, you should be aware of how much the OEMs driver heads have to weigh to be able to end up with a D0-D2 swingweight with their 65-75 gram graphite shafts. That’s right, somewhere between 188 and 198 grams is what the headweight has to be for today’s OEM brand name driver heads.
The MOI of a clubhead as measured about the vertical axis through the center of gravity is now limited under the rules of golf to a maximum of 5,900 g-cm2 with an additional tolerance of 100 g-cm2. This means any driver with an MOI of 6,000 g-cm2 or lower is OK with the USGA
First a word on g-cm2, the USGA ordained form of measurement of the MOI. In simple terms, two things cause the MOI to increase or decrease. First one’s easy. The heavier the clubhead, the higher the MOI. For proof, look at the array of high MOI “branding iron style" putter heads that have come on the market in the past 3-4 years, all trying to achieve a higher MOI than the one before. There are putter heads in the industry today which have an MOI in excess of 10,000 g-cm2! Why are the big companies only able to achieve an MOI in a driver head of 5,000 to 5,250 g-cm2? Headweight, that’s the main reason.
Putter heads with an MOI over 10,000 g-cm2 weigh well over 400 grams. Driver heads, as we just mentioned, weigh between 188 and 198g. At least the heads on the OEM standard made drivers do. If you are a really smart and good clubmaker, most of the driver heads on the custom fit drivers you build weigh more than that.
Why? Because smart Clubmakers fit and build far, far more drivers at lengths shorter than the OEMs’ standard range of 45-46" than they do at those OEM standard lengths. TWGT is firmly convinced that perhaps 80% of all male golfers currently using a 45-46" driver would hit the ball farther, straighter and more consistently on center if they were properly custom fit into a driver that is at least an inch or more shorter than the OEMs standard driver lengths. Thousands of Clubmakers have tens of thousands of golfers who enjoy the game more now because of just that – a shorter driver that is properly swingweighted or MOI’d for that golfer’s ability.
Here’s how you will continue to build drivers with a higher head MOI than any of the big companies will offer this year. The headweight of a driver built in a range from 43.5 to 44" with the same 65-76g graphite shaft, and 50 gram grip to a swingweight of D1 will be 205 to 212 grams.
From TWGT’s recent studies, the average increase of the MOI for the average 460cc driver today when ONE GRAM is added to the headweight is 35 g-cm2. That means if you fit a golfer into a driver that is 44" in length with a driver head that has a starting MOI of 4800 g-cm2, that same head will have an MOI of 5,220 g-cm2 when you finish building it to a D1 swingweight. If you built it 43.5" in length, which many, many golfers need to really improve their driving consistency, the driver head’s MOI would be 5,430 g-cm2.
Next time some golfer waves his new square driver in front of you bragging about his 5,000+ MOI, just smile at him and tell him that you can beat that by several hundred or more! (And by making th driver a little shorter, you’ll do the things on the driver the golfer needs to hit the ball farther, straighter, and more on center than he does now!)
Clubmakers, you have always had an advantage over the competition from the get-go because you have the ability to custom fit golfers with the best specifications that will allow each different golfer to get the most from their size, strength, athletic ability and swing characteristics. The only difference with this little revelation about driver head MOI is that you now have a NUMBER to put in front of your golfers to PROVE that you can make a better golf club than they can buy off the rack. In a world that is all too often fraught with marketing hype, you now have something of scientific fact that might make a little sense to golfers who are more difficult to convince of your skills.