One of the terms we use often in the club design world is “gear effect”. This is certainly not a term that pops up often in regular conversation, but when it comes to creating golf clubs, you simply have to consider this very influential aspect of any clubhead design.

Please understand that I am a club designer, though not an engineer. I learned about gear effect very early in my golf industry career, when I had the amazing privilege of spending lots of time with the late Joe Powell, who was simply a master craftsman of the finest persimmon woods, and I still have several of his drivers in my collection.

Those of you who had the privilege of learning to play golf with persimmon drivers should distinctly remember that a shot hit low in the heel would tend to start left then curve back to the right, towards the centerline. Conversely, a shot hit toward the toe would take on a draw curve to get back to the centerline. The reason for this is called “gear effect”. At a very basic level as it applies to a golf club, if the mass of the clubhead is to either side of the impact point, the ball will take on a spin in the direction of the mass. So, the heel miss has most of the mass right of the impact, so the ball takes on a right-hand spin. Conversely, the toe impact has most of the clubhead mass to the left of the ball, so the ball takes on left-hand spin, bringing it back toward the centerline.

Even modern drivers have this same tendency, of course, because they cannot avoid this law of physics. But in my observation of 60+ years of playing this game, we do not seem to see it to the same degree, because of perimeter weighting and the other pixie dust in modern drivers.

It is important to realize that gear effect also works from the top to the bottom of the clubhead. Generally speaking, regardless of the club, a shot hit high on the club launch higher with less spin that one hit low on the clubhead. That’s because a shot hit high has much more of the mass below the impact point, which minimizes the spin imparted by the loft, clubhead speed and swing path.

Likewise, we all know the old adage, “thin to win” – a shot hit very low in the clubhead flies lower and has lots of spin, especially with those short iron and wedge shots that are almost bladed. That’s because when the ball is hit that low, much more of the mass is above the impact point. Tour professionals are masters at repeating their short iron and wedge impact lower on the clubface than most recreational golfers, so that helps them optimize spin from any distance. Of course, when you add their clubhead speed, they get crazy amounts of spin.

Over the past decade or so, we have seen the driver guys harnessing gear effect for maximum efficiency in launching the ball ever higher with less and less spin. They have been able to achieve this driver performance by continually lowering the CG of the clubhead by devising ever thinner crown pieces of the driver, even going to composite crowns.

As these design concepts have migrated into irons with the concepts of thin faces and tungsten weighting in the sole of the club, designers are able to deliver much higher ball flights in the lower lofted clubs, but that does come with a reduction of spin. For the most part, you have to choose between the two to some degree.

Because I have focused almost all my time on the design and function of wedges for the past 30 years, I’ve always been puzzled why wedges have not applied the power of gear effect to deliver more penetrating trajectories and increased spin for the millions of recreational golfers who are seeking those two performance attributes. The only explanation I can come up with is that most manufacturers feel the need to “prove” their products with their staff tour players, who are just not seeking those two performance criteria – they have learned to hit wedges lower and with tremendous spin through thousands of hours of practice.

Golf club design is a wonderful blend of art and physics, technology and aesthetics. We all have clubs we like the looks of, and others we just don’t. But no golf club can function outside the laws of physics, and gear effect simply has to be acknowledged for its effect on performance.