MOMENT OF INERTIA
Inertia describes the resistance of an object to being moved or accelerated; Moment of Inertia (MOI) is the resistance of an object to being rotated around an axis or fixed point. A clubhead with a high MOI is more 'forgiving' than one with a low MOI - the higher MOI clubhead resists twisting more when the ball is hit off-centre.
But there is another 'MOI' of a club that is important - its 'dynamic balance', which plays a crucial role in your ability to control, synchronise and repeat your swing.
In the simplified diagram a golf swing on the right, the arms rotate around the spine (solid circle). However, the golf club itself has a separate rotational axis, represented by the dotted circles, which are centred on the wrist joint of the upper hand (the left hand for a right-handed golfer).
At the top of the backswing, the golf shaft forms an angle of roughly 90º with the left forearm, but at impact, the shaft & arm will (or should) be pretty much in a straight line. The point at which that angle starts to straighten out is called the wristcock or club RELEASE, the timing of which is affected by the MOI of the golf club. The more closely the MOIs of the clubs in a set match each other, the easier it will be for a golfer to TIME the release consistently.
The swingweight scale was invented in the 1920s to provide a simple method of matching clubs for 'BALANCE'. Apart from the fact that swingweight is a STATIC measurement (and the golf swing is not), in any swingweight-matched set, different clubs will have DIFFERENT MOIs, for which golfers need to make compensatory swing timing adjustments.
Moment of Inertia (MOI) Matching is an emerging system that replaces swingweight in order to get around this problem. When the clubs in a set are matched to a golfer's optimum MOI setting, the swing tempo and the timing of the release become more consistent, which results in a higher percentage of shots hit on-centre and more consistent/efficient squaring of the clubface. When combined with heavier or lighter shafts that are a better match for individual golfer's needs, swingpath faults can also be reduced or even eliminated.
Unfortunately, because every golfer is different, a single MOI setting will not work equally well for all golfers (and nor does a single swingweight setting, incidentally), so using MOI to match the clubs in mass-produced sets is not feasible.
However, PROVIDED THAT TIME IS TAKEN TO IDENTIFY YOUR OPTIMUM SETTING, precise MOI-matching will offer you:
compared to swingweight matched clubs, regardless of your ability.
How do we know this? If you do not feel that MOI-matching is better than swingweight-matching, you can bring them back and we will re-match them to any swingweight setting you specify, free of charge; in over five years, only ONE golfer has taken up that offer.
In addition to MOI-optimising all the new clubs we make, we offer a retro-matching service for existing clubs.
This club was set-up too light for the player to swing with any consistency, as indicated by the erratic impact pattern ....
Same club, same golfer, but with the head weight adjusted to the optimum setting for this golfer's strength & swing ...