Did you know that STABILITY and MOI are directly related in your putting stroke? Let us explain.
MOI, moment of inertia, is resistance to twisting. It doesn’t matter if the the twisting (red arrows in the illustration below) is from an off-center hit, subtle unwanted face angle change from your hands and wrists, or even the yips.
How would a high MOI putter help? A high MOI putter resists and reduces ALL twisting. A high MOI putter is more STABLE than a low MOI putter; period.
STABILITY on an off-center hit is experienced as FORGIVENESS. A high MOI putter will twist less, and a low MOI putter will twist more due to an off center hit. Putter twist at impact will send the ball off line. The actual directional result is quite complicated, but twisting is not helpful. In addition to twisting off line, an off-center impact will result in a reduction of impact ratio. Less of the forward energy of the putter head is transferred to the ball; and the putt will not go as far as you intended.
So, a high MOI putter improves BOTH the DIRECTION and DISTANCE resulting from an off-center hit. Forgiveness on an off-center hit is important and beneficial.
But STABILITY in the stroke itself is even more important. MOI also resists the twisting (red arrows in the illustration above) from unwanted face angle change from your hands and wrists. A high MOI putter is more STABLE; and resists twisting away from square to the arc; it imposes STABILITY on the stroke itself. This is not just a theoretical improvement; it is real, and the improvement is substantial. Putter launch monitor testing of high MOI putters confirm that face angle variation can be reduced by more than 50% just by increasing the MOI of your putter. Read the last sentence again!
Every putter manufacturer is talking about stability. Everyone seems to know that STABILITY is a good thing in a putter. Obviously, no one wants an unstable putter. Manufacturers claim improved, increased, or enhanced STABILITY from combinations of materials as if it is magically produced. There is no STABILITY MAGIC. Putter stability can be measured and compared. Quite simply. The measure of STABILITY is MOI (moment of inertia), or resistance to twisting.
As explained, MOI and STABILITY are directly related. And if you don’t know the MOI of your putter, you should. A high MOI putter is more STABLE; period.