Alpha Golf

Moment of Inertia (MOI) has been a popular buzzword in golf recently. I’ll spare you the boring formulas and theories that I learned from my studies in physics. And instead apply MOI to golf driver design, and explain its important.

MOI is the inertia or resistance of a rigid rotating body with respect to its rotation. In other words, it’s the measure of difficulty in changing the angular motion about the axis of rotation. High MOI means more resistance to club twisting, so we want to maximize this resistance as much as possible.

During a driver swing, the clubhead will twist if it doesn’t hit the ball on the axis of the center of gravity. The less a club twists before impact, the more stable it is. And, therefore, the straighter and farther the ball goes. So a high MOI promotes forgiveness in off-center strikes.

The USGA imposes a limit in MOI in drivers of 5900 (g*cm^2). In a letter to manufacturers last year, the USGA said “further increases in MOI could reduce the challenge of the game by reducing the skill required to hit the ball straight. In addition, that could also result in an increase in average driving distance by reducing the likelihood that swinging faster will produce a poor result.”

So there you have it - MOI is so important that making it too high will give some golfers an unfair competitive advantage in distance and accuracy. But that doesn’t stop golf club designers like Alpha from getting as close to the USGA MOI limit as possible (without exceeding 5900).

So how do we maximize MOI? Without giving too many design secrets away, clubheads with maximum MOI have the following characteristics:

1) 460CC - the larger clubhead naturally puts the center of gravity deep inside the head, away from the face. The separation of mass and COG raises the MOI metric

2) Perimeter weighting - More weight can be pushed out farther from the center of gravity of the clubhead and towards the outer shell. Square drivers are an example of this. But drivers with traditional geometries can also push weight out.

3) Large club face with variable weighting - more distance and weighting on the heel and toe again separates mass from the COG axis of rotation, reducing torque and twisting.