Welcome, this is the first article in our Influencer Series where we break down the 10 most important club specifications and how we use them to influence shot performance. First up, Club Head Weight.

Head Weight is one of the specifications which can affect almost every launch condition we measure when fitting. Because of this, it is extremely important. Exploring all the effects of head weight can get overwhelming so for now let’s focus on five of the most critical launch conditions.

1) Club Head Speed
It stands to reason that most golfers swing faster with a lighter head and slower with a heavier head. While this is most often true, there are many players who swing faster with a heavier head weight. Strange right? Well, the golf swing is not a linear event. It’s dominated by centripetal and centrifugal forces as the clubhead is simultaneously thrown with velocity and restricted on an arc.
As head weight changes, the angles of the hands, wrists, shoulders, and shaft may be affected. This can change the amount of acceleration and, in some cases, change the point of maximum acceleration to a more desirable location, closer to impact. Other players react to heavier head weights in a more direct way by swinging harder. This can of course increase head speed. It’s important to test every player to find the sweet spot. We’re all different

2) Ball Speed
Although lighter head weight can increase club head speed, the lower mass also results in less energy transfer at impact. This resulting loss in strike efficiency can limit the benefits swing speed increases as Sasho J. MacKenzie proves in The influence of clubhead mass on clubhead and golf ball kinematics.  In fact, we rarely see meaningful changes in ball speed across a reasonable range of head weights for the average weekend warrior.
If a player’s increase in club head speed is not accompanied by an increase in ball speed, it will never net a distance increase. This is why club fitters obsess about ball speed and not club speed. In your next session stop looking at the swing speed numbers and start looking at ball speed.

3) Launch Angle
The biggest influencer for the Launch angle of any golf shot is dynamic loft. Dynamic loft is the loft of the head at impact, and it differs from the measured loft of the golf club at rest. Although static loft is a component of dynamic loft, a player’s shaft lean as well as the deflection of the golf shaft at impact also factor in to dynamic loft.

Many players are under the misconception that the club head lags behind the shaft at impact. While this is true at the start of the downswing, by the time a player reaches impact, the shaft has unloaded and is bent towards the target. In club fitting we call the bending forward lead deflection and the bending backward lag deflection.

As the club bends towards the target at impact it adds more loft to the equation There are a bunch of other influencers of dynamic loft as well but those are for another time. For now, more bending equals more loft at impact if all things are equal. Since a heavier club head will increase the amount the shaft bends, we can expect an increase in dynamic loft and launch angle as we increase head weight.

Now, I said if all things are equal because many golfers tested negate increases in shaft deflection by increasing forward shaft lean and or angle of attack during their swing. Although we still measure an increase in the lead deflection of the shaft for these players, the change in hand angle negates any increase in dynamic loft at impact.

4) Back Spin
Depending on where it is placed, Head weight also affects the back spin rate. It does this in two ways. The first one we just discussed, dynamic loft. More loft at impact always increases spin and less loft always decreases spin so our changes in shaft deflection can also result in back spin rate changes.

The second way head weight changes spin is through a phenomenon known as vertical gear effect as explained here by Dave Tutleman. Weight changes can increase or decrease this amount of phenomenon resulting in changes in the spin rate.

5) Dispersion from Center
As the club head weight changes, we can not only see changes in swing speed but also changes in the speed of the face rotation. We refer to this as closure rate or rate of closure and it is directly affected by head weight. Since timing the face is a crucial component of accuracy, changes in closure rate can have big positive or negative effects on the accuracy of any player.

As most of the club head rotation happens late in the downswing, even small changes here can produce different results. It’s important to test each player to find their most consistent set up.

I’m guessing by now you can see how important it is to consider your ideal head weight when optimizing the performance of your golf clubs. Because head weight affects so many launch conditions, even slight variances can have a big impact on performance.

We hope you learned a bit about the dynamics of club fitting and can use this information to get more out of your next session. If you’re interested in learning more watch out for the next installment of the Influencer series.