Fitting Month: Deciphering the language of shafts
Friday, April 26, 2013
Because it's hard to see the technology built into modern driver shafts, exotic terms and odd-sounding phrases often are used to describe what these magic wands do. Anytime "gearheads" start talking about shafts, words such as torque, tipping and kick point are tossed around. But do you really know what they mean?
To help better understand the finer points of these terms, I asked several experts from some of golf's major shaft manufacturers to decipher the mysterious language of shafts.
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1. What is kick point?
"A lot of people will say that a shaft has a low kick point or a high kick point, and then point at the shaft near the tip or up neat the butt section [the handle area]. But in most shafts it's really about a 3- to 4-inch section somewhere in the middle of the shaft where it's bending," says Pat McCoy, director of technical services for Fujikura. "Really it's the difference between a low bend and a high bend."
According to Don Brown, product development manager for True Temper who works on Project X and Grafalloy driver shafts, kick point is a somewhat-dated term that is used a lot more by consumers than tour pros and people within the industry.
"When we design a shaft, we don't actually measure where a kick point is," Brown says. "Consumers are used to it, but we really measure launch angles." However, Brown concedes that because the term is so common, a company may place a reference to kick point on a shaft so golfers can get an idea about how it performs.
In general, shafts with a lower kick point can help to create a higher launch angle; shafts with a higher kick point can help to create a lower launch.
John Oldenburg, vice president of engineering product and development for Aldila, says that instead of thinking in terms of kick point, golfers should think about stiffness near the bottom of the club.
"The stiffness in the lower-third of the shaft can affect the ball flight," he says. "A soft tip section corresponds to a lower kick point and higher launch. A stiffer tip section will produce a higher kick point and a lower launch."
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2. What is tipping?
Most driver shafts typically are 46-inches long and then are trimmed at the handle section to create the desired length. They taper from a wide diameter to a narrow diameter at the tip, but the last few inches of the tip section maintain a constant diameter. According to Danny Le, a marketing manager for UST Mamiya, a shaft's performance can be fine-tuned by trimming a length of the tip section.
"Tipping is a way to affect the flex of a shaft," he says. "For example, typically a golfer who swings at 100mph would fall into a stiff flex shaft, but depending on various factors, you might want something stiffer. To create something that plays between a stiff and an extra-stiff shaft, you could tip the shaft."
Brown says that by tipping a shaft, a fitter also can modify launch conditions.
"If you have a shaft that you like and it's launching your shots just a little too high or spinning the ball just a little too much, you can tip a shaft a half-inch or an inch and bring that launch angle and spin-rate down," he says. "It's not going to drastically alter the way a shaft plays. It's just for minor tweaks."
The more a shaft is tipped, generally speaking, the stiffer it will play.
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3. What is torque?
On the downswing, Oldenburg says that a shaft is not only bending, it's twisting. Torque is a measure of how much the shaft resists twisting – on the downswing and at impact, either on the heel or toe. However, because there is no industry-standard measurement for torque, it's difficult to directly compare the torque of one shaft with another.
"A lower torque shaft resists twisting more than a higher torque shaft," Oldenburg says.
But one's not necessarily better than the other.
"You hear a lot of people talk about torque and say things like, 'I need a shaft that has a lot of torque,'" Brown says. "But I think torque is one of the least understood things about shafts. I liken it to horsepower. People go out and pay a lot of money for a car like a Mustang that has a lot of horsepower, but then only drive it back and forth to the store, so they don't really need all that horsepower."
According to McCoy, the ideal torque for a golfer really comes down to preference. "A lower-torque shaft will feel stiffer," he says. McCoy adds that decreasing the torque of mid- and lightweight shafts can make them feel stiffer.
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4. What is the difference between a driver shaft and a fairway wood shaft or a hybrid shaft?
According to Phillip Foster, a tour marketing representative for Mitsubishi, companies today design shafts to be used in either woods or hybrids; there are almost no shafts designed strictly for fairway woods.
Hybrid shafts are shorter and have a wider tip diameter because the hosel openings of hybrids, like irons, are wider.
"They also need to be more stable that a driver shaft," Foster says, "because as you get shorter with your clubs, effectively you are hitting down on the ball. With a driver you are catching it on the upswing." He adds that hybrid shafts also need more durability on the tip section because golfers often take a divot and hit the ground when using a hybrid.
Another big difference is the weight. While most driver shafts weigh 73 grams or less, iron shafts commonly weigh between 110 and 130 grams. Hybrids, which are meant to bridge the gap between woods and irons, usually have a weight that falls between those two ranges – somewhere around 100 grams.
According to Brown, pros tend to prefer hybrid shafts that create a higher launch angle – and steeper decent angle – because unlike a driver or a 3-wood, which is typically hit to maximize distance, players usually want their hybrid to fly a specific distance and then stop.