Selecting the Right Loft

Selecting the right loft for your swing may be one of the most critical decision in driver selection. The common misconception is that lower loft equals more distance. The truth is actually the opposite for most golfers.

Driver Swing Speed	Suggested Loft
50 mph	15-20
60 mph	14-18
70 mph	12-15
80 mph	11-14
90 mph	10-13
100 mph	9-12
110 mph	8-11
120 mph	7-10

Today’s larger drivers have deeper face heights than drivers from just a few years ago, allowing more impact area above the center of gravity (CG) of the head. When the ball is contacted above the CG, there is gear effect that reduces backspin.

For tour players that are swinging over 100 mph, that’s a good thing. They’re getting the magic formula of high launch and high ball velocity with low backspin. What the average 80-90 mph male golfer needs to keep in mind is that reduced backspin off the larger driver may lead to shorter drives if the launch angle is not high enough to keep the ball in the air.

In general, keeping the ball in the air longer pays off more than a lower ball that depends on roll. You may benefit from one or two degrees higher loft on your driver.

Selecting the Right Design

The first thing you need to know when selecting a driver design is what you want to improve.

The two most important performance factors that help most golfers are trajectory and forgiveness. If you natural ball flight is low, look for a driver with a high trajectory rating. If you tend to hit the ball off-center more often than not, look for a driver head that has a maximum forgiveness rating as well.

Next, find a model that fits your directional needs. Don’t forget about offset as an option in your driver. If you tend to slice or fade the ball, you may benefit from driver heads that feature an offset hosel design and a closed face. Offset is a bigger influencer of ball flight on a wood that it is on an iron.

Size
Grip sizes can have a significant impact on your golf swing. In general, larger grips inhibit free release of the club-head through the hitting zone, and smaller grips do the opposite.  The popular sizes of the grip range from 0.58 inches to 0.6 inches – 0.58 is considered as standard.  Grips can be built up by adding wraps of tape to the shaft – on wrap would increase the size by 1/64 inches.  Depending on your preference, grip sizes of a certain section can be built up by partially adding wraps of tape.

Materials and Designs
The majority of the grips are slip-on today. Natural rubber, synthetic rubber and compound materials in conjunction with a number of code and surface configurations offer different gripping characteristics.  Grip can be either round or a reminder – which is a line or rib on the underside of the grip that reminds the golfer where the hand should be placed.

Basically there are two types of grips – soft type and hard type. Hard type grips are often built with cord made of cotton. A variety of types of cords (classic, GX, tour wrap) are available, and grips could be half or full corded. As a result, a wide range of selection in grips are available today. The cord provides not only harder surface textures but also other functions such as additional frictions and moisture absorption. Corded grips tend to be heavier. On the other hand, soft grips are made of compound materials.

It is also notedworthy that hardness (or softness) of a grip seems to cause a similar effect on club-head release as in grip sizes. In general, a harder grip inhibits free release of the club-head through the hitting zone, and a softer grip does the opposite.

Putter Grips
There are two primary putter grip styles – puddle style, and pistol style. The puddle grip features a wide flat part for the placement of thumbs, which is conducive to a one-piece stroke. The pistol grip is characterized by the protruding section of the grip which is to provide more control.

It is impossible for the collision of the golf club and golf ball to produce a perfectly elastic collision (COR of 1.000) in which all energy is transferred for two reasons:
The clubface and the ball are made from completely different materials;
The clubhead and the ball are of two totally different weights, or masses.
The current USGA rule limiting the coefficient of restitution of a clubhead states that the COR cannot be higher than a measurement of 0.830. This means that when the clubhead impacts the ball, there cannot be more than an 83 percent transfer of energy to the ball.

To give a frame of reference for performance, with a driver, the difference in carry distance between a head with a COR of 0.820 and another with a COR of 0.830 would be 4.2 yards for a swing speed of 100 mph. It is true that as swing speed increases, the distance difference increases.  This is one of the reasons why the USGA rule which limits the COR of a clubhead has the effect of penalizing the slower swing speed golfer much more than the higher swing speed player.

MOI

Moment of inertial, or MOI, is a property of physics that indicates the relative difference in how easy or difficult it will be to set any object in motion about a defined axis of rotation.  The higher the MOI of an object, the more force will have to be applied to set that object in a rotational motion.

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 MOI for the whole golf club which, when swung, is “rotated” around the golfer during the swing.

There are also three different MOIs which can be measured for the clubhead itself.  Two of these MOIs are important in the design of any clubhead.

First, when you hit a shot off the center of the face, even though the head is secured to a shaft, the head will try to rotate around the vertical axis going through the clubhead’s center of gravity.  Second, and at the same time, when the golfer swings the club on the downswing, the clubhead is rotating around the axis through the center of the shaft.

The first example refers to the MOI of the clubhead about its center of gravity. In marketing terms, this is the head design property that has a bearing on the amount of “forgiveness” a clubhead offers for off-center strikes.  The larger the clubhead, and/or the more the designer incorporates perimeter weighting, the higher the MOI of the clubhead about its center of gravityvertical axis will be.  The higher the MOI of the head about its vertical CG axis, the less the head will twist in response to an off-center hit, and the less distance will be lost from that off-center hit.

The second example refers to the MOI of the clubhead about the shaft axis. Little is spoken about this MOI in equipment marketing, but it is an important head design factor that can affect the accuracy of the shot, not the distance. The bigger the head or the more weight that is placed far out on the toe of the clubhead, the higher the MOI of the head will be about the shaft’s axis.  The higher the clubhead MOI around the shaft, the more tendency there is for a golfer to leave the face open at impact. The lower the clubhead MOI around the shaft, the more tendency there is for a golfer to rotate the face more closely at impact.

The whole golf club also has an MOI. The longer the club, the heavier the head, the heavier the total weight of the head, shaft, and grip added together, the higher the MOI will be for the whole club. The MOI of the club is important to matching the swing feel of all the clubs in the bag.

CG
The center of gravity (CG) of any object is the one small point which represents the intersection of all the possible balance points of that object. In a golf clubhead, the CG can be determined by balance the headof its face, sole, or any place on the head – the intersection inside the head of all these different balance points is the center of gravity of the clubhead.

Because the center of gravity is a single point inside the clubhead, its location has to be defined in 3-dimensions.  This means a clubhead has a vertical CG location (how high up in the head the CG from the sole). It also has a horizontal CG location (how far over it is from the center of the shaft in the hosel of the head). Finally, the center of gravity is also defined by how far back from the face it is located.

The lower the center of gravity and the farther back the center of gravity is from the face of the club, the higher the trajectory of the shot will be for any give loft angle on the clubhead.  Of the two CG locations that affect the height of the shot, the CG back from the face has greater effect on the height of the shot than does the vertical CG.

Graphite shafts in particular come with a wide range of specs.  While steel shafts in general weigh roughly 90 to 120 grams, graphite shafts usually weigh in the range of 50 to 90 grams. The most popular graphite shaft weight for drivers seems to be 65 grams. The torque of steel shafts is usually around 3.0, while that of graphite shafts could be as low as 2.0 or as high as 12.0.  As to the kick-point, graphite shafts are more versatile, too.

Advance shaft technology is a result of the advance in new material development and its applications.

It appears that the recent trend in the market is not lighter shafts with consistent properties in torque or strength, but rather more performance oriented considerations such as lower torque, damping effect, or application of flow design.  These changes are seen in both steel shaft and graphite shaft markets.

Balance and Feel

When we access the performance of a shaft, it is important to understand that a combination of flex, torque, kick-point, club weight, and swing weight determines the balance and fee, and consequently the performance of a club.

Flex and Frequency Matching

A general guide line for shaft flex selection is:

Driver Head Speed (mph)  -> Shaft Flex

70 – 90   ->  R

90 – 100   ->  S

100+   ->  X

Shaft flex can be determined by the vibration frequency, which is measured by fixing the butt of the shaft and attaching a 10-ounce weight on the tip of the shaft and then vibrating it to the vertical direction.  If the number of vibration or frequency is 280, the flex is defined as 8.0; likewise, the frequency of 260 is 6.0.

Torque

Torque of a shaft describes how much a shaft would twist given a certain twisting force (1 oz weight is used for the measurement) during downswing. The torque value is expressed in degrees, so the lower the degrees of torque, the more resistance the shaft will have to being twisted from the force of the downswing on the clubhead attached to that shaft.

We use the simple formula for calculating the torque of the shaft: T = FL (Torque = Force x Length). By substituting Newton’s equation on Force (F=ma) to the Torque equation, and we get T=maL (Torque = mass x acceleration x Length).

*(Please be noted that we are talking about the Torque of the shaft – and not the torque of the golf swing. In a golf swing we refer to the rotary force a golfer generate on a downswing as the torque.)

In steel shaft, because the type of steel material is the same throughout the entire shaft, the torque exists in a very narrow range of degrees, one that is much more narrow than in graphite shafts.

Graphite shafts can be and often are made with a variety of different graphite fiber strength, stiffness an dposition on the shaft.  This allows the torque in graphite shafts to range from as high as 7 or 8 degrees to as low as 1 degree, white in steel this range is only from a little more than 2 degrees to a little under 4 degrees.  The, torque is not a factor to worry about in the selection of a steel shaft, but it is a point to keep in mind for some golfers when selecting a graphite shaft.

The shaft guru Tom Wishon states: the fitting ramifications of torque even in graphite shafts is not that severe.  Simply stated, it means that if you are a big strong, powerful person with an aggressive swing tempo and a late release, you never want the torque in a graphite shaft to be any higher than 4 to 4.5 degrees. Otherwise, your strength and downswing force may cause the clubhead to twist the shaft, causing the clubface to be more open at impact, and resulting in a shot that hangs or fades to the right of your target.

For most golfers, as long as the torque of a graphite shaft is between 3.5 and 5.5 degrees – which is the case of the vast majority of graphite shafts today – the golfer will be OK and torque will never be a factor to worry about in the shaft fitting.

Kick-point

It refers to a maximum bending point of the shaft.  The lower the kick-point, more tip-flex the shaft, which in turn makes you feel that the club-head moves more through impact, while a high kick-point shaft tends to make you feel the opposite. However, a high kick-point shaft is much easier to control the direction.  Since more golf clubs are made with low CG clubheads, low kick-point seem to have lost its role to play to some extent.

Shaft Length and Weight

Today, the standard length of drivers seem to be 45″. Standard shaft length for a 9 iron is 35.5″. To determine the length of your club, stand at attention and ahve someone measure from the creasewhere your wrist and hand meet to the floor. Do this with both hands and take an average. If you measure:

29 to 32 inches, your irons should be based on a 5-iron of 37 inches.

33 – 34 inches – 27 1/2 inches

35 – 36 inches -> 38 inches

37 – 38 inches -> 38 1/2 inches

39 – 40 inches -> 39 inches

40+ inches -> 39 1/2 inches

The weight of the shaft is a major factor in determining the total weight of all golf clubs. While clubhead weight and grip weight can and do vary depending on the golfer’s need for a higher swingweight or larger grip size, neither the head nor the grip exist in nearly as wide a range of weight as does the shaft.

Shafts can be bought that weigh as much as 130 grams or as light as 40 grams. Thus, when a golfer switches from an average steel shaft to an average graphite shaft today, the drop in total weight will be in the area of 50 grams or more.

Swing speed is the most direct factor affecting shot distance. The lighter the total weight of the golf club, the higher the swing speed the golfer should be able to generate with the club.  However, the swingweight of the club must be fit properly to the strength and tempo of the golfer or else any significant decrease in the total weight of the clubs will simply result in a higher percentage of off-center hits, which in turn will reduce distance.