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How the idea of shaft frequency began



Forty years ago, Kim Braly and his father Dr. Braly went down to West Palm Beach to visit Wilson Golf, and that trip forever changed the way the golf industry thinks about the shafts in golf clubs.

“My father and I invented frequency matching,” Kim told me.

“And what’s that?” I asked.

“It’s the process of matching the stiffness of the shafts in your clubs to the heads so you can hit a golf ball rather than snap the shaft or hit the ball all over the place,” Kim said.

OK, that got my attention. So I ask how he stumbled upon the idea.

“My dad was an engineer and got into golf,” Kim said. “Eventually, I got interested in golf as well. In the early 1980s, we went to see the original ‘Iron Byron.’”


A modern-day golf robot at Titleist’s Manchester Lane Test Facility.

Iron Byron was the first club-testing machine, and it was modeled after smooth-swinging legend Byron Nelson. It’s basically an early robot — a motor in a box with an arm — built to use a regular golf club to hit a golf ball.

Kim and Dr. Braly watched the engineer operating Iron Byron put a club into the mechanical arm, place a ball in front of the club face and then press a button to swing the club. The result: perfection. It produced a high, piercing ball flight that was hit on a rope, not far removed from the storied ball flight of Nelson himself. This was followed by another and another. Kim and his father were ecstatic.

With great anticipation, they watched the engineer load the next club. The results were much different. Balls flew all over the place. The dispersion was awful. The Wilson engineer operating Iron Byron slowed down the machine. Balls flew shorter distances, but they landed closer together. The dispersion had been reduced. This was the inception of their game-changing idea; dispersion was a result of certain shaft characteristics matched with a club head and swing speeds. This “AH HA” moment changed how we fit and purchase golf clubs today.

Based on this observation, Kim and Dr. Braly designed a method to measure the performance of a golf shaft. Later, this led to the concept of frequency: very simply, stiffness is not the letter on the shaft, but a measurement based on characteristics like weight of shaft, weight of the head, length of the shaft and several other characteristics. The year was 1977 and they submitted a patent on this idea called “Frequency Matching.”

Armed with the power of measurement, Kim was ready to change golf shafts forever. He and his father started traveling the PGA Tour, and in doing so became the first “PGA Tour Van.” Over the last 40 years, Kim has worked as a researcher and designer, mastering the golf shaft. He’s worked at True Temper, Royal Precision and is currently as the head designer of research and development at KBS Golf Shafts.

Kim, working with a player

Kim working with a player on his golf equipment.

In 2008, Kim launched a shaft company called KBS, which became the fastest growing shaft company in golf. Since that time, the company has gotten some of the best golfers in the world to use its shafts products, including Rickie Fowler, Justin Rose and Phil Mickelson.

The next time you’re struggling with shots that fly sideways, think about Kim and Dr. Braly. You might want to try try being fit for shafts if you haven’t already, because they may just be the most important part of your golf club.

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Brendan is the owner of Golf Placement Services, a boutique business which aims to apply his background in golf and higher education to help educate players, their families and coaches about the process! Website - Insta - golf.placement.sevices Twitter @BMRGolf



  1. TeeBone

    Jun 7, 2017 at 5:34 pm

    Further, frequency matching a set doesn’t mean that the clubs all have the SAME shaft flexibility, only that the DIFFERENCE in flexibility is uniform from club to club. As the clubs get shorter, frequency and stiffness increase. Add to this the fact that as the clubs get shorter and heavier, they are swung at a slower speed. In the end, each shaft in a set flexes more and more overall as the clubs get longer. This silly “dispersion” theory suggests that a shaft must flex a specific amount to behave consistently.

  2. TeeBone

    Jun 7, 2017 at 2:39 pm

    Tour players, unless they have a specific shaft manufacturer deal, are free to play whatever shaft they want. Their decision to play graphite over steel has to do with performance, not money.

  3. TeeBone

    Jun 7, 2017 at 2:27 pm

    So Iron Byron, set at any particular swing speed, only reproduces the same ball flight with one specific shaft flex? This “dispersion” theory would mean that the same shaft can behave quite differently, from swing to swing, for an otherwise same swing input. Nonsense. There is no mention of this in any of the best-regarded scientific studies of shaft flexibility. This is a made-up marketing story designed to sell equipment.

  4. Ned

    Jun 6, 2017 at 8:06 am

    Brunswick Golf developed the Frequency Matching System in 1981!

    • Rico

      Jun 6, 2017 at 4:04 pm

      The article states that the Braly’s submitted a patent for “Frequency Matching” in 1977.

  5. J.

    Jun 5, 2017 at 7:15 pm

    And stiffness of an EI profile may be invisible to CPM matching? Does SST PURE shaft alignment work better?

    • Skip

      Jun 7, 2017 at 1:18 pm

      SST pure is pure Kool-Aid. Drink it if you so choose.

  6. tim crider

    Jun 5, 2017 at 4:05 pm

    There is no doubt that shots can be saved every round by every player with changes from the shaft to the swing weight to the compression of your golf ball,,, hell practicing on the driving range could improve your game. There is a lot to know about this game and if you have the money and the time you may be able to cash in on these findings. Think how much better play got when shafts changed to steel from hickory. A lot to know and even more to learn. How much more can be found and improved, it was a very good article.

  7. Charles Bartholomew

    Jun 5, 2017 at 3:38 pm

    Interesting article. A little history lesson now and then is a good thing.

  8. cgasucks

    Jun 5, 2017 at 8:20 am

    If the Iron Byron can make crappy shots with a shaft that isn’t compatible with its swing speed, imagine it with a human being.

    • talljohn777

      Jun 5, 2017 at 12:14 pm

      Yes, if you have a club shaft that is too soft you can slow your swing down to allow the clubhead time to catch up and square, but why would you want to do that? The preference would be to hit a club that matches your top swing speed allowing you to get the most out of your swing.

  9. artie j

    Jun 5, 2017 at 6:59 am

    I didn’t know the backstory. Very cool article Ryan

  10. SH

    Jun 4, 2017 at 10:25 am

    Yup, awesome

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pga tour

Marc Leishman WITB 2018



Equipment is accurate as of the 2018 Arnold Palmer Invitational (3/13/2018).

Driver: Callaway Rogue (9 degrees)
Shaft: Fujikura Speeder 757 Evolution IV X-Flex

Fairway Woods: Callaway Rogue (15, 21 degrees)
Shaft: Fujikura Motore Speeder VC Tour Spec 9.2X

Driving Iron: Callaway X Forged UT (18, 21 degrees)
Shafts: Nippon N.S. Pro Modus3 Tour 130X

Irons: Callaway X Forged (4-PW)
Shafts: Nippon N.S. Pro Modus3 Tour 130X

Wedges: Callaway Mack Daddy Forged (54-10S), Titleist Vokey SM7 (58-04L)
Shafts: Nippon N.S. Pro Modus3 Tour 130X

Putter: Odyssey Versa 1W (BWB)
Grip: Odyssey Pistol

Golf Ball: Callaway Chrome Soft X


Discussion: See what GolfWRX members are saying about Leishman’s clubs.

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pga tour

Kiradech Aphibarnrat WITB 2018



Equipment is accurate as of the 2018 Arnold Palmer Invitational (3/13/2018).

Driver: Callaway GBB Epic Sub Zero (9 degrees)
Shaft: Mitsubishi Kuro Kage XD 60TX

Driver: Callaway Rogue Sub Zero (10.5 degrees)
Shaft: Mitsubishi Kuro Kage XD 60TX

3 Wood: Callaway Rogue (15 degrees)
Shaft: Mitsubishi Kuro Kage 70TX

Driving Iron: Callaway Epic Pro (3)
Shaft: UST Mamiya Elements Fire 100X

Irons: Callaway X Forged (3-5), Callaway Apex MB (6-PW)
Shaft: Project X Rifle 6.0

Wedges: Callaway Mack Daddy Forged (52-10R) Callaway Mack Daddy 4 (58-08C)
Shaft: True Temper Project X 6.0

Putter: Odyssey Versa #7 CS
Grip: Iomic Pistol

Putter: Odyssey EXO Seven
Grip: Odyssey Pistol

WITB Notes: Aphibarnrat was spotted testing drivers ahead of the Arnold Palmer Invitational. We’ll update this post when we confirm his decision.


Discussion: See what GolfWRX members are saying about Aphibarnrat’s clubs. 

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pga tour

Ernie Els WITB 2018



Equipment is accurate as of the 2018 Arnold Palmer Invitational (3/13/2018).

Driver: XXIO X (9.5 degrees)
Shaft: Project X Even Flow 6.5X 65

3 Wood: XXIO X Fairway (15 degrees)
Shaft: Project X Even Flow 6.5

Irons: Srixon Z U65 (18, 20, 23 degrees)
Shaft: Nippon N.S. Pro Modus3

Irons: Srixon Z745 (3-PW)
Shaft: Nippon N.S. Pro Modus3 Tour 125X

Wedges: Cleveland RTX-3 V-MG (52-10, 56-11, 60-06LG)
Shaft: Nippon N.S. Pro Modus3 WV125S Tour Only

Putter: Bloodline R1-J Els Gen 1
Grip: Bloodline

Golf Ball: Srixon Z-Star XV


Discussion: See what GolfWRX members are saying about Els’ clubs. 

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19th Hole