Important Terms

MOI – Moment of Inertia

Defines the relative difficulty of rotating an object based on its mass and pivot point. In golf, MOI come most into play on imperfect contact – when the clubface and ball come into contact outside of the sweet spot for the club. The higher the MOI, the greater the resistance to twisting when the club comes into contact with the ball. A high MOI supports improved performance on mishit shots.

CG – Center of Gravity

If you drew a line through all of the different vertical and horizontal balance points of a club, the intersection of all those lines is the center of gravity. CG location directly correlates to flight characteristics such as launch, spin and bias.

Bounce

The effective bounce of a club is determined mainly by the combination of the angle of the sole relative to the ground and the overall width of the sole. A larger bounce angle and/or wider sole, increases the effective bounce of the club. Bounce is necessary to prevent the club head from digging into the turf. Increasing the effective bounce protects players, especially with steeper attack angles, from the club digging too much and can help significantly improve the results of chunks or fat hits (shots where the club hits the ground prior to impacting the golf ball). Players of higher skill levels and shallower attack angles generally do not need as much bounce on their irons as players with less skill and/or steeper attack angles.