The Spin On Center of Gravity
Author: Jack Moorehouse

If you've been reading my golf tips newsletter, scanning
golf Web sites, or perusing golf magazines, you've probably
come across the term center of gravity (COG). More than
likely, you've seen the term in conjunction with ads for or
an article about golf clubs. That's because it's one of the
hottest concepts in golf club manufacturing technology,
along with moment of inertia (MOI). And like many
recreational golfers, you probably wondering what COG is
and how it affects your game.

Actually, the concept isn't new. It's been around for
years. What's new is its execution. Thanks to advances in
golf club manufacturing technology and golf club research
and design, center of gravity is a concept whose time has
come. And while it's not a term you'll hear a lot about
during a golf lesson, it's a term you should know because
it can have a decided impact on your golf handicap.

COG Defined
One golf Web site defined center of gravity as "the point
within the head of a golf club at which it would be
perfectly balanced." That's as good a definition of COG as
any I've read. Technically, COG is determined by balancing
the clubhead 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.

Since the center of gravity is a single point inside the
clubhead, its location has to be defined in 3-dimensions.
There's a vertical COG location (how high up in the head
the COG is from the sole), a horizontal COG location (how
far over it is from the center of the shaft in the hosel of
the head), and a depth COG location (how far back from the
face it is located). If you alter the position of any of
these points, you alter both the COG and the club's
performance.

Position of COG
The position of the center of gravity within a clubhead
alters both the trajectory and the accuracy of shots. A COG
position that's low and toward the back of a clubhead
encourages a higher trajectory for any given loft angel on
the club. On the other hand, the closer the COG is to the
shaft, the less a golfer tends to hit a ball offline. The
farther the center of gravity is from the shaft, the more a
golfer tends to hit the ball offline.

In theory you would always want the COG in line with the
center of the clubhead's face. But moving the COG helps
"mitigate" some swing flaws. That's great for those of us
who don't hit the ball in the face's center, which judging
from my golf lessons and my experience in general, is the
category where most recreational golfers fall. The more the
designer incorporates perimeter weighting in the clubhead's
design, then, the better off a recreational golfer is with
the club.

COG also alters ball flight, which is good for players with
some ability. Moving the COG toward the heel helps you hit
a hook. When contact occurs away from the center of
gravity, the ball's axis of rotation tilts toward the heel.
That imparts sidespin, causing the ball to move. However,
as moment of inertia (MOI)—the relative stability of
off-center hits—increases, the more you have to move the
COG to produce the sidespin you need to hook the shot.

Impact of COG
What does all this mean for a golfer and his/her golf
handicap? When you're buying golf clubs, research the COG
of the clubs your considering. Since you're not a
professional, look for a club offering the best center of
gravity for your caliber of play. Cavity-back irons, for
example, where the COG has been moved more toward the
club's outer edges are great for beginners because they're
more forgiving of off-center hits, which means the new
golfer find the fairway a lot more than with clubs lacking
perimeter weight design.

However, be careful when considering clubhead design.
Manufacturers often add or subtract design features in an
attempt to make their clubs perform better and
differentiate them from other clubs. Some "improvements"
impact COG, which means they will affect the clubs
performance, too. What you need to do is find the clubhead
that works for you, test the club if you can. Testing is
the best way of determining if a club is right for you.

Now that you know what center of gravity is, take advantage
of it the next time you're in the market for new clubs. COG
will impact a club's performance, including trajectory and
accuracy. That in turn impacts your golf handicap. For best
results, look for a club with a center of gravity that fits
your game.


About the Author:

Jack Moorehouse is the author of the best-selling book "How
To Break 80 And Shoot Like The Pros." He is NOT a golf pro,
rather a working man that has helped thousands of golfers
from all seven continents lower their handicap immediately.
He has a free weekly newsletter with the latest golf tips,
golf lessons and golf instruction.
http://www.howtobreak80.com .