How to optimize a golf clubhead design to maximize moment of inertia while staying within the USGA regulation

Since March 1, 2006, the United States Golf Association (USGA) imposes a limit on maximum moment of inertia (MOI) of golf clubheads. The limit is on moment of inertia around the vertical axis through the clubhead center of gravity (Izz). Since April 11^th, 2006 the maximum allowed MOI is 5,900 g-cm² with a tolerance of +/- 100 g-cm².

As discussed in our article "How to comply with the USGA ruling on Moment of Inertia", the actual MOI limit of a clubhead is 5,908 g-cm². But how can we make sure that a particular clubhead complies with this requirement? It needs to be measured. And here comes into play your own ability to measure moment of inertia. If you measure MOI with a 0.5% accuracy instrument, you have to leave the same margin for your own measurement. It means that you can only design clubheads with a moment of inertia of 5,908 - 92 = 5,816 g-cm².

Space Electronics can help you achieve better designs. Our different models of instruments can measure moment of inertia with an uncertainty of 0.01% to 0.25%. Here are the results achieved with these instruments.

MOI instrument model	MOI measurement accuracy	MOI through CG accuracy	Highest MOI achievable that will pass the USGA test
XKR5A	0.01%	2 g-cm²	5,906 g-cm²
XKR5B	0.1%	18 g-cm²	5,890 g-cm²
XR10	0.25%	46 g-cm²	5,862 g-cm²

At this point we believe that the moment of inertia of clubheads is far enough from the limitation imposed by the USGA that an XR10 gives results accurate enough. However getting closer to the limit will become a concern with the advances in technology.