MOI. It’s been a buzzword in putters for years. MOI stands for Moment of Inertia. We won’t bore you with the details of how it’s calculated (there are plenty of places to find that on the net), but suffice it to say that MOI is a measure of how stable and forgiving a putter is. The higher the MOI of a putter head, the less it will twist on an off-center strike and the more energy it will transfer to the ball.
The animation below visually shows how a high MOI putter is more forgiving on a mis-hit than a low MOI putter. At impact, the low MOI putter twists. Some of the energy that should have been transferred to the ball to get it to the hole is instead converted to rotational energy of the putter head. As a result, the putt comes up short and offline. A high MOI putter twists less and transfers more of its kinetic energy to the ball, keeping it closer to its intended line and speed.
Importantly, MOI is essentially the only objective and quantifiable metric we have in the putter industry. There are tons of gimmicks and claims out there about various aspects of putter designs. “These (insert gimmick here — grooves / alignment lines / color scheme / whatever) — help you sink more putts!” But none of those claims can ever really be quantified, nor can one gimmick claim to be objectively better than another. But MOI can be measured and quantified and used as a point of comparison. Take two virtually identical putters with the same dimensions and weight, with the same general look and feel - if one of them has a substantially higher MOI, that putter is better, period. It will twist less on off-center strikes, transfer more of the energy of the stroke to a ball on a mis-hit, and be more “forgiving” in general.
How does Round 4 use 3D printing to make higher MOI designs? Click here to read more.
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