Tech Talk
by Rene Cleaver, Professional Clubmakers' Society European Clubmaker of the Year

New Drivers - The Square Facts

It’s January. New Year’s resolution time. What’s your New Year’s resolution?
Many golfers I see this time of year tell me their resolution is to get their golf clubs custom fitted to help them improve their golf. They’re the savvy golfers, doing what all golfers should do, and doing it at the perfect time to be ready for the start of the new golf season. The majority of golfers and the mass market wake up too late… when serious golf has already begun for the season.
What’s my New Year’s resolution? To get the message out to golfers wanting the best in custom fitted equipment and to fulfil this intention during the off season. I started working on my resolution in October. So thank you to all who took my advice and came for your fittings with me in November and December, and to those booked in for January and February. Club Masters is cranking, while others hibernate. From this year onwards, I will be reducing my summer schedule. During the summer months I will certainly be less available – you have been warned! Meanwhile, as predictable as ever this time of year, it’s happening again in this crazy industry – marketing hoopla.
This time the hype is spearheading the introduction of square drivers to the mass market. Huge numbers of golfers, who have just bought last year’s all singing, all dancing hot driver will be made to feel they have been left behind in the technology stakes yet again. Is this fact? Or is this yet another example of the ever turning product cycle?
As always, I offer you the facts. Firstly, you have to understand what MOI means. MOI stands for Moment of Inertia. Replace these mysterious words with ‘Resistance to twisting’ and you’ve got it. The higher MOI – resistance to twisting – a club head has, the less it will twist when a ball is struck off centre. The result: less distance lost on off centre hits.
In 2006, the USGA and R&A placed a limit for the MOI of clubheads – 6000g/cm2. No drivers have reached this level. Thus, the stage was set for golf companies, helplessly hobbled by all of the other technology limits now in place, to design driver heads with a higher MOI than before.
The marketing claims for square drivers will be that their head shape provides a higher MOI and be more forgiving when hit off centre. Technically, a square head could allow some weight to be positioned in the back corners, further from the head’s centre of gravity than in a conventionally shaped head. However, pushing weight out to the corners of a square head will not ensure that its MOI is any higher than a well designed high MOI driver of conventional shape.
FACT: Just because a driver head is square does not mean its MOI is higher than the MOI of a conventionally shaped driver head.
Just like every major marketing campaign, there will be plenty of square driver “wannabees” offered by companies who have no design and engineering skills. How much of the head’s total mass is able to be placed around the perimeter and in the “back corners” is what will determine if the square driver has a higher MOI than a conventional head or not.
Current reports say that the MOI of well-designed square drivers will be in the region of 5200g/cm2. Current well-designed driver heads generally have an MOI of 4000g/cm2 and some in play are as high as 4500 – 5000g/cm2.
I can assure the large majority of golfers that ensuring that a driver fits for the major specifications – club length, shaft flex, loft and face angle will improve accuracy and distance off the tee to a far greater extent than worrying about these numbers.
FACT: For the MOI of a driver head to deliver more forgiveness equivalent to 5 yards or more, the MOI has to be increased by at least 1000g/cm2, while all other fitting specs such as loft, face angle, shaft, length, swing weight, have to be matched to the golfer’s size, strength and swing.
Therein lies the rub – you are not going to know the comparative measurements. In the mass market, you are back to the trial and error testing out of the ‘cocktail cabinet’ that I discussed in a previous article (By the way, if you ever want copies of any of my previous articles, feel free to contact me).
For any golfer who can hit their 3-wood as far or almost as far as their driver, MOI will not be their saviour off the tee. Why? Because the MOI of any 3-wood head will be way lower than the MOI of any driver head. It is, therefore, the major specifications that are allowing the golfer to hit the 3-wood well and denying success with the driver.
FACT: Square is not the only unconventional shape that can allow a skilled clubhead designer to increase the MOI.
Stop for a moment to think about the change in putter head shape over the past few years. Putter heads have grown larger in the dimension back from the face to increase the MOI and make the putter more stable. Very common in putters is what can best be described as triangular shape. Increasing the MOI of any head is all about moving more weight away from its centre of gravity than before. Shape means nothing unless the designer knows how to create discretionary mass than can then be moved further away from the centre of gravity.
FACT: Off-centre hit distance is not strictly a product of the MOI of the head. The design of the clubface is a hugely important factor for generating good distance from an off-centre hit.
If one driver face is designed to flex more in off-centre areas than the face of another driver, it will produce greater distance when impact is off-centre. What’s more, a driver with a superb face design will hit the ball further (off-centre and on-centre) than another driver with an average face design with an MOI that is 1000g/cm2 higher. Interesting industry, isn’t it?
The Rules of Golf governing equipment have closed almost all possible areas for designers to use physics to design clubheads and shafts that offer visible improvements in shot distance and accuracy. What’s left is professional custom fitting, which for many golfers is an untapped area of equipment technology that can make a real difference in shot making and lower scores.
Back at Club Masters I look at the superbly designed club heads I use to custom build drivers. While I have their MOI measurements, other factors and specifications will take priority in discussing my head design recommendation with each client – and this is just a small part of professional custom fitting done properly.
For custom fitting services of the highest level, visit a certified member of the Professional Clubmakers’ Society. We are a world apart from the mass market. And after all, when it comes to your game, you deserve the best.

Rene Cleaver is a Professional Clubmakers Society Class A Clubmaker, Class A Clubfitter and Golf Clubmakers Association Advanced Clubmaker. PCS European Clubmaker of the Year, Rene is owner of Club Masters, at Dundry Nurseries, Bamfurlong Lane, Cheltenham. If you have any questions about golf equipment contact Rene directly at: rene@clubmasters.co.uk or tel. 01452-715007.