Question: What is Center of Gravity, and How Does It Affect the Shot?

Answer: The center of gravity (CG) of any object is the one small point which represents the intersection of all the possible balance points of that object. In a golf clubhead, the CG can be determined by balancing the head on its face, sole, or any place on the head – the intersection inside of the head of all these different balance points is the center of gravity of the clubhead.

Because the center of gravity is a single point inside the clubhead, its location has to be defined in 3-dimensions. This means that a clubhead has a vertical CG location (how high up in the head the CG from the sole). It also has a horizontal CG location (how far over it is from the center of the shaft in the hosel of the head). Finally, the center of gravity is also defined by how far back from the face it is located.

The lower the center of gravity and the farther back the center of gravity is from the face of the club, the higher the trajectory of the shot will be for any given loft angle on the clubhead. Of the two CG locations that affect the height of the shot, the CG back from the face has a greater effect on the height of the shot than does the vertical CG (up from the sole).

The horizontal center of gravity location, or how far the CG is over from the center of the shaft, is a design factor that affects the accuracy of the shot. The closer the CG is to the shaft, the less tendency there will be for the golfer to push or fade the ball offline. And the farther the center of gravity is from the shaft, the more tendency there will be for the golfer to push or fade the ball offline.

The reason is that the closer the center of gravity is to the shaft, the lower the moment of inertia about the shaft axis will be, and the greater the tendency will be for the golfer to rotate the face of the club less open/more closed by the time the head gets to impact with the ball. The farther the CG from the shaft, the higher the MOI will be about the shaft axis, and the greater the tendency for the golfer to leave the face of the club open/less closed by the time the head gets to impact with the ball.

The center of gravity position in the clubhead is initially controlled by the height, width and breadth of the head. After that, it is influenced by how much of the head's weight is placed in different areas of the clubhead. The taller the clubhead and/or the more weight that is placed on the upper portions of the head, the higher the position of the CG will be in the head. The more shallow the clubhead and/or the more weight that is placed on the bottom or sole of the head, the lower the position of the center of gravity will be.

The deeper the head shape from face to back and the more weight is positioned in the very rear of the head, the farther back the position of the center of gravity will be (and vice-versa for narrow head shapes and/or weight placed more in the face area of the head).

Finally, the longer the head from heel to toe and/or the more weight that is placed out on the toe side of the head, the farther the center of gravity will be from the shaft (and conversely, the shorter the head from heel to toe and/or the more weight that is placed on the heel side of the head, the closer the CG will be to the shaft).