The spin on center of gravity

By Bomb (aka E. Michael Johnson) & Gouge (aka Mike Stachura)
Illustration By +ISM October 2007

Q. Why would I want the center of gravity on my driver somewhere other than in line with the center of the face?

BOMB: Like a snow-covered mountain slope in the Rockies, this question seems serenely simple and peaceful—right until the avalanche. Here it comes ...

GOUGE: In theory, you would always want the CG in line with the center of the face. But moving the CG can help mitigate—that's mitigate, not eliminate—some flaws, especially for those of us who don't hit it in the center of the face all the time.

BOMB: Not only can having the CG somewhere other than the center mitigate a chopper's flaws, it can enhance the ball flight of players with skills. According to Brad Schweigert, one of Ping's smart guys, the most efficient energy transfer occurs when the force vector axis intersects the CG of the head. (Your head hurts? Mine, too.) Translation: Because of loft and the rearward position of the CG on most drivers, maximum energy transfer lies slightly above a straight line parallel to the ground drawn from the CG to the center of the face.

GOUGE: Great news—if you're on tour. Moving the CG toward the heel helps you hook it. When contact occurs away from the CG, as shown above, the ball's axis of rotation tilts (toward the toe when the CG is toward the heel, for example). That degree of tilt causes sidespin. Again, this has to do with force vectors, but I don't want to give you another headache. Of course, as moment of inertia increases (remember that MOI is the relative stability on off-center hits), you have to move the CG more to produce the same amount of sidespin. It's also worth noting that there is some research that suggests that as more weight is stored in the heel, the clubhead will tend to close as it comes into the ball, a good thing if you have trouble squaring the face. The challenge, of course, is finding ways to move the CG. But theory is one thing, titanium is another.