Flex, torque, kick-point, shaft length, and weight play important roles in affecting the balance and feel of golf clubs as well as ball trajectory.
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.
