By Zak Kozuchowski

GolfWRX Managing Editor

There’s a simple rule most golfers follow when making equipment changes – don’t mess with success.

And golfers certainly shouldn’t switch from a set of clubs that helped them win the biggest tournament of their lives – at least not for a while. But that’s exactly what K.J. Choi, winner of The Players Championship last year, has done in 2012.

In early March, Choi put away the set of Miura CB-501 irons that he used in his victory at the TPC Sawgrass Stadium Course for a set of Cleveland 588 CB Forged irons. Just a few weeks later he sampled another manufacturer’s clubs, Ping i20 irons. But as the one-year anniversary of Choi’s win approaches, he again finds himself using the same set of irons that he used last year at The Players.

Many people will jump to point out that Choi’s tinkering was unnecessary – he should have been working on his game instead of trying to catch lightning in a bottle with an equipment change, they might say. But there’s another way of thinking about equipment changes. Bill Choung of CompuGolf Center in Dallas has been working with Choi on his equipment since March 2010. Since Choung opened CompuGolf nine years ago, he has been seeking to answer a simple question,

“How does an equipment change impact the golf swing?”

He’s found that changing equipment has a very real impact on a player’s swing, especially with tempo and rhythm.

The goal of Choung’s work with Choi has been to give Choi a higher trajectory and more spin on his iron shots. Choi felt that he wasn’t hitting the ball high enough or with enough spin to control his distances at major championships – setups that generally have firm greens and tight pin positions.

There are several different ways of achieving that goal, and Choi and Choung have tried just about all of them. Choi played the 2011 Masters with a 6-iron hybrid, which gave him a higher trajectory, more forgiveness and more spin. But Choi felt that he was sacrificing workability and feel, which led to more experimenting.

Choung hit paydirt when he built Choi a set of Miura CB-501 irons just days before the 2011 Zurich Classic. To create Choi’s desired ball flight, Choung used KBS Tour parallel tip shafts, which are different than the taper tip shafts used by nearly every other PGA Tour player. Whereas taper tip shafts are precut to a specific length for a certain club (6 iron shafts are generally used in 6 iron heads), parallel tip shafts are uncut, which means that they can be trimmed to fit any iron head. This allows the club builder to trim the shafts to the exact stiffness that a player desires.

Shaft stiffness, which is measured by the frequency of a shaft, is important because according to Choung it changes the way a player loads and unloads the club during the swing. When trimming Choi’s parallel tip shafts, Choung cut more off the butt end of the shaft and less off the tip, creating a “softer” tip that allowed for a higher trajectory and more spin. Choi liked the combination of the parallel tip shafts and the Miura CB-501 head, and the results proved it. That week he put the clubs in play to finish in the top 5 at the 2011 Zurich Classic, and of course, to win The Players two weeks later.

There are at least two reasons why Choi decided to change from the iron set that brought him a $1.7 million payday and a new level of fame in the golf world. First, he received information that parallel tip shafts were not generally played on the PGA Tour, which made him interested in trying taper tip shafts. Second, he changed because he was in the process of trying out different iron heads and shaft combinations that he thought might improve on the results of the Miura set he used to win The Players.

When Choi changed to a taper tip shaft, he was forced to use a softer flex to give him the trajectory he wanted. While this resulted in the desired higher flight, he lost consistency and control.

Science or art?

Talking about Choi’s golf clubs in terms of shaft frequency, spin rate and launch angle creates the assumption that his swing is always the same. While Choi does have one of the most consistent golf swings on Tour, even he falls in and out of bad habits. That’s why it’s Choung’s belief that no matter how technically sound a golfer’s fundamentals are, the golf swing is still an organic movement.

“When [golfers] change clubs, what they are really doing is changing their swing,” Choung said. “More than anything, they are inducing a change in tempo and rhythm.”

So it’s no surprise to Choung that Choi has returned to his Miura CB-501 irons with parallel tip shafts. He was struggling during the time he was playing Cleveland and Ping irons, shooting only two rounds in the 60s during that period. Last week, when he returned to the Miuras, he shot two rounds in the 60s and finished tied for 39th. It wasn’t a huge improvement, but it was his best finish in relation to par since the Hyundai Tournament of Champions in January.

Choung said that Choi’s performance since switching back to parallel tip shafts might have improved because of the increased tip diameter of parallel tip shafts — .370 inches instead of the .355 inch tip that taper tip shafts offer. So why don’t more Tour pros opt for parallel tip shafts if they offer more stability? According to Choung, it’s because parallel tip shafts are much more labor intensive to build. Choung and his staff at CompuGolf can build a set of taper tip shafts in about 30 minutes, while it takes them about three hours to build a set of parallel tip shafts.

A lot of independent club builders and even Tour vans can’t justify spending extra time to create frequency-matched sets either, but Choung’s research has shown the value in it. Because of the chaotic nature of the shaft industry, where one industry’s stiff flex is another’s x-flex, Choung places huge value in frequency matching, which streamlines the frequency throughout the set. For example, Choi’s driver shaft frequency, the base measurement Choung uses to find the frequencies for the rest of his clubs, is 271. As shaft length decrease, however, frequency must increase to match. Choung and his team did testing of exactly how many cycles frequency should increase as the shaft shortens .5 inches, and their researched concluded that four cycles is best. That’s why Choi’s 4 iron, which measures 38.5 inches, has a frequency of 314, while his 60 degree wedge, which measures 34.5 inches, has a frequency of 334.

So what does all this mean for the average golfer? Even if you don’t swing like Choi, Choung said that there is still good reason to go through a verifiable fitting process, especially processes like his that have an improvement guarantee.

“A lot of golfers come to me and they say I’m hitting my driver well, but can’t hit my irons,” Choung said. “Or they say that they’re hitting their irons well and can’t hit their driver. Often there’s a total mismatch between the driver and the irons. They’ve adapted their swings to either the driver or the irons.”

If you still can’t be swayed to go through a custom-fitting process, Choung has this advice for you. The club that you liked demoing so much – buy it. But don’t order it. Buy that exact club. Because chances are, the one you order will be slightly different.

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