July 29, 2019


Measuring Forgiveness; MOI Matters, a lot!

Independent testing at the Quintic Ball Lab USA in Massachusetts confirmed the importance of MOI, moment of inertia, resistance to twisting. STABILITY, forgiveness and MOI are clearly related.
The results shown below were obtained on a state-of-the-art robot. An traditional anser style putter was tested against a high MOI Cure RX Series putter: first, with a center hit; and then second, with a 1⁄2” off- center hit.

Measuring Forgiveness; MOI Matters, a lot!

Figure 1 (above) shows the comparison of the center hit and off-center lab test results. Both the traditional anser style putter (top) and the high MOI Cure RX Series putter (bottom) performed well on the center hit (left side), with 0.0o twist and a 1.70 impact ratio.

The off-center hit (right side of figure 1 above) exposed the weakness of the traditional blade putter and the strength of the high MOI putter. The anser style putter twisted 6 times as much as the high MOI putter at impact. SIX TIMES as much; 1.00o vs 0.15o of twist at impact. Putter twist at impact will send the ball off line. The actual directional result is quite complicated, but twisting is not helpful.

Impact Ratio is the ball speed divided by the putter speed at impact. The ball in this case was going 1.70 times as fast as the putter head. 1.70 is a relatively common impact ratio for putters. You may be more familiar with the concept of Smash Factor with your driver or irons. Smash Factor and Impact Ratio are EXACTLY the same number (ball speed divided by club speed). It is not helpful that the industry is using two terms for exactly the same thing. Both could be called Impact Ratio, but that is not going to happen. Smashing, think KABOOM!, works with drives; putting is more delicate and precise, so get used to impact ratio on the green.

The off-center impact resulted in a reduction of impact ratio. Less of the forward energy of the putter head is transferred to the ball. The anser style putter deteriorated from 1.70 to 1.52 on the off-center hit, enough to cause the putt to come up over 3 FEET short. The high MOI putter only deteriorated from 1.70 to 1.69, almost nothing at all, causing the putt to come up only about 2 INCHES shorter. So a high MOI putter improves BOTH the DIRECTION and DISTANCE resulting from an off-center hit.

Increased MOI, increased resistance to twisting, increased STABILITY, increased forgiveness, improve putting performance. This is physics. Higher MOI produces measurable improvement and forgiveness.