Clubhead Sole

Golf Club Components: Clubhead Sole

Golf Club Components: Clubhead Sole

The area at the bottom of the clubhead that interacts with the turf.

The sole of golf (clubs).

The sole of golf (clubs).

Clubhead Heel

Golf Club Components: Clubhead Heel

Golf Club Components: Clubhead Heel

The heel is the area of the face nearest to the shaft and hosel of the clubhead.

An excellent dead-on look at the heel of a driver.

An excellent dead-on look at the heel of a driver.

Clubhead Toe

Golf Club Components: Clubhead Toe

Golf Club Components: Clubhead Toe

A golf club’s toe is the area of the face farthest from the shaft and hosel of the clubhead. Or the toe is simply the front end of a clubhead. 

Follow the arrow to the clubhead toe. Right on the end.

Follow the arrow to the clubhead toe. Right on the end.

clubhead face

Golf Club Components: Clubhead Face

Golf Club Components: Face

The face, or clubface, is the area of the clubhead that is intended to strike the ball. For irons, the face includes grooves, or small channels within the face that impart spin on the ball. For irons, the face includes grooves, or small channels within the face that impart spin on the ball.

 

Any typical driver or other metalwood face (fairway woods, hybrids) appears like this Adams Speedline Driver.

Any typical driver or other metalwood face (fairway woods, hybrids) appears like this Adams Speedline Driver.

Tapered Shaft Tip

Golf Club Specs: Tapered Shaft Tip

Golf Club Specs: Tapered Shaft Tip

This is a configuration where the outside diameter of a shaft through the insertion area decreases. Unfortunately, tapered shafts cannot be shortened as easily as parallel shafts since they and require adjustable attachments to connect shaft, hosel and clubhead after a cut. Otherwise, the resulting bottom outside diameter would not fit all the way down into the hosel.

A graphic artist’s rendering of a tapered shaft end.

A graphic artist’s rendering of a tapered shaft end.

Parallel Shaft Tip

Golf Club Specs: Parallel Shaft Tip

Golf Club Specs: Parallel Shaft Tip

The configuration of the bottom-end of a shaft is where the outside diameter does not change throughout the insertion area. A benefit of parallel tip shafts in irons is that manufacturing can use blanks to both tip and butt cut to achieve the desired length and flex for each club in a set (This does not produce a set of constant weight shafts.).

Here's a clear-cut diagram example of a taper versus parallel golf club shaft tip.

Here’s a clear-cut diagram example of a taper versus parallel golf club shaft tip.

Shaft Tipping

Golf Club Specs: Shaft Tipping

Golf Club Specs: Shaft Tipping

This is the removal of any particular length from the tip-end of a shaft. Tipping has the effect of making the shaft play stiffer — generally a third to a half flex for every 1/2 inch removed. Tipping can only be accomplished with parallel or unitized or tapered shafts.

These are the shaft tips, near the hosel -- where the ferrule and shaft connect -- and clubhead, where sections of shafts are removed or greater stiffness.

These are the shaft tips, near the hosel — where the ferrule and shaft connect — and clubhead, where sections of shafts are removed or greater stiffness.

Modern materials (graphite, composites, metals)

Golf Club Specs: Modern materials (graphite, composites, metals)

Golf Club Specs: Modern materials (graphite, composites, metals)

Shafts, like clubheads, have increasingly benefited golfers with technological advances. Shafts, once made of wood, are now made primarily in graphite and steel. Stainless steel, in all its various gauges, ridges and ripples, remains the most common kind of shaft for irons and putters, although that’s starting to change.

Graphite-shafted clubs are generally lighter and have better vibration absorption characteristics than steel-shafted clubs. They are made up of layers upon thin layers of fiber material held together by various resins, all of which can be adjusted to conform to a certain degree of stiffness or flexibility for each player.

Steel-shafted clubs generally produce more consistent shot patterns and are generally heavier than graphite shafted clubs. Players desiring a softer feel than traditional steel shafted clubs will enjoy steel-shafted clubs equipped with vibration-filtering inserts.

Layered, fiber and resin composite graphite-shafted clubs are generally lighter and have better vibration absorption.

Layered, fiber and resin composite graphite-shafted clubs are generally lighter and have better vibration absorption.

Moment of Inertia (MOI)

Golf Terminology: Moment of Inertia (MOI)

Moment of Inertia (MOI)

A ball curves due to a tilt in its axis of rotation. And the axis of rotation is the absolute center point that a ball is spinning around.

Golf Terminology: Golf Club Moment of Inertia (MOI)

The “Moment of Inertia” or MOI is a term thrown around very loosely in the golf industry. But when it comes down to it, MOI basically is how well-balanced a clubface. It can get a bit more complicated when you factor in how a golf ball reacts itself — and the clubface MOI (or twisting of the face at impact) then what will occur on an off-center hit as a result of the manufacturer’s engineering and your personal adjustments to the club, such as loft or swingweight.

The idea behind applying MOI to golf at its heart is just making sure that the face strikes the ball cleanly without without twisting too much, throwing off the ball’s motion so it doesn’t move efficiently — like straight and far. But throw in a round ball and it gets more complicated, yet the physics behind MOI essentially are the same.

Generally speaking, MOI is used in golf by distributing the weight of clubheads and balls outward to lessen twisting and other golf equipment and human variables (Hopefully, you’ll understand why as you read on and watch the video below.).

In physics, strictly speaking, MOI is a property that indicates the relative difference it takes to put an object in motion from a defined axis of rotation (Keeping up? See diagram below.). The higher the MOI of an object, the more force will have to be applied to set that object in a rotational motion. On the other hand, the lower the MOI, the less force is needed to make the object rotate about an axis. So let’s explain the whole axis and rotational stuff first.

(This is where golf club engineers get creative. But more on that at another time.)

Here’s a common example of MOI: The ice skater. When the skater starts a spin, she reaches out her arms and the speed of the spin is intentionally slow as it builds and she begins to pull her arms closer to her body. She is no longer resisting the speed of rotation, so her MOI is falls to a low point. It’s an inverse kind of formula since when she puts her arms out again, she slows and her MOI goes up higher as her resistance to the speed of rotation increases. 

Now here is the official physics definition of MOI in golf:

“Moment of inertia is the name given to rotational inertia, the rotational analog of mass for linear motion. It appears in the relationships for the dynamics of rotational motion,” according to the Georgia State University Physics Department“The moment of inertia must be specified with respect to a chosen axis of rotation. For a point massthe moment of inertia is just the mass times the square of perpendicular distance to the rotation axis, I = mr2.

“That point mass relationship becomes the basis for all other moments of inertia, since any object can be built up from a collection of point masses.” 

“There are several different moments of inertia that are factors in the performance of a golf club. Remember, MOI has to first be defined by identifying what axis the object is rotating around. There is an MOI for the whole golf club, which, when swung, is “rotated” around the golfer during the swing.”

These are the two examples of MOI in a golf club. But let’s not get too far ahead of ourselves for right now.

These are the two examples of MOI in a golf club. But let’s not get too far ahead of ourselves for right now.

Not too bad to understand, right?

As far as golf goes, here’s a nice, down-to-earth explanation of MOI from Rotary Swing golf instructor Clay Ballard:

Kickpoint (a.k.a. bend point, flex point)

Golf Club Specs: Kickpoint (a.k.a. bend point, flex point)

Kickpoint (a.k.a. bend point, flex point)

In general, it is believed that the higher the kickpoint, the lower the ball flight and vice-versus. It’s where the shaft bends the most during impact with the ball.

Golf Club Specs: Kickpoint (a.k.a. bend point and flex point)

The point on the shaft where the greatest amount of bending occurs during a downswing right before impact the ball is called the kickpoint or bend point.

A shaft that bends near the head has a low kickpoint. A shaft that bends near the grip has a high kickpoint.

There is an inverse relationship between kickpoint and ball flight. A shaft with a high kickpoint will produce a low ball flight, and a shaft with a low kickpoint will produce a high ball flight.

However, today there is some debate about how significant kickpoint is in determining ball flight. As clubs and golf science become more and more advanced, other relatively new factors are being taken into consideration — such as droop and shaft differential.