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The Wedge Guy: Understanding CG

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One of the most misunderstood concepts involved in golf club design is that of “CG,” or “center of gravity,” also “center of mass.” While this particular measurement of any golf club head can certainly offer insight into its probable performance, it is not the “be all, end all” with regard to any club’s specific launch or forgiveness attributes.

What “CG” specifically refers to is the exact center location of a club’s distribution of mass, which will generally coincide with that club’s “sweet spot”—but that’s not always true. There are lots of ways to manipulate or manage any club’s exact CG location, and therein lies a “Pandora’s Box” of misunderstanding.

Let’s start back in the very old days, when irons were single pieces of forged steel and woods were made of persimmon. Since there was no science inside the club, CG was essentially a result of how the clubhead is formed—its essential shape.

A typical persimmon driver head, for example, was sized to deliver its ideal weight without any additional weights added. The solid block of persimmon, with some kind of face insert and an aluminum soleplate was all you had to work with. So, the CG was located pretty close to the center of the clubhead from all three axes – vertical, front-go-back and heel-to-toe. If you remember, persimmon fairway woods were smaller and had a brass sole plate to add mass lower in the head and often a lead weight under the sole plate to move the CG even lower to help produce higher ball flights on shots hit from the turf, rather than off a tee.

Traditional forged irons up to the 1960s-70s typically had a CG very close to the hosel, a result of the mass of the hosel itself and the typical design that put “muscle” behind the impact area, and very little mass out toward the toe. An examination of worn faces on those old irons would reveal the wear very much toward the heel. I distinctly remember fighting the shanks back in those days, and that ugly shot usually felt very close to a perfectly struck one, rather than feeling as awful as it looked.

As metal woods and cavity-back irons became the norm, designers were able to move the CG ever lower in order to produce higher ball flight, and more toward the center of the face to put the CG further from the hosel. As technology has continued to be refined, the use of tungsten inserts has further allowed designers to position the CG exactly where they want it – typically lower in the club and more toward the center or even the toe of the golf club.

And therein lies a problem with pushing this insert technology too far.

There is no question that in addition to making contact somewhere close to the CG of the clubhead, ball performance is also a product of how much mass is directly behind the impact point. Let me offer this example of how important that can be.

Let’s assume two identically shaped cavity-back 7-irons – same size, face thickness, overall weight and a design that places the CG in the exact same spot in the scoring pattern. The only difference between the two is that one is a single piece forged or cast steel head, with the other being cast of aluminum, with heavy tungsten inserts in the hosel and toe areas to achieve the same overall weight and CG location.
Which do you think would deliver the more solid feel of impact and better transfer of energy to the ball?

Now, we could take that even further by cutting out the entire center of both clubheads and increase the mass or the weight of tungsten in the hosel and toe to bring each back up to weight. The CG location would not change, but there would be absolutely no mass at all where the ball impact location would be. That would not work at all, would it?

I’ve learned long ago that it’s not just about the location of the CG that makes a golf club perform, but also the amount of mass that is placed directly behind the spot on the face where impact with the ball is made.

Here’s a fun, “non-golf” way to embrace this concept.

Suppose we had a two-pound sledgehammer and another 2 lb piece of steel hammered into a large circular sheet 1/16” thick. And then suppose someone hit you on the head with the exact CG of each one – which do you think would hurt the most?

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Terry Koehler is a fourth generation Texan, a native of a small South Texas town and a graduate of Texas A&M University. He has had a most interesting 40-year career in the golf industry. He has created five start-up companies, ranging from advertising agencies to golf equipment companies. You might remember Reid Lockhart, EIDOLON, SCOR, or his leadership of the reintroduction of Ben Hogan to the golf equipment industry in 2014. For almost 25 years, his wedge designs have stimulated other companies to slightly raise the CG and improve wedge performance. He has just announced the formation of Edison Golf Company and the new Edison Forged wedges, which have been robotically proven to significantly raise the bar for wedge performance. Terry serves as Chairman and Director of Innovation for Edison Golf, which can be seen at www.EdisonWedges.com. Terry has been a prolific equipment designer of over 100 putters and several irons, but many know Koehler as simply “The Wedge Guy”, as he authored over 700 articles on his blog by that name from 2003-2010.

8 Comments

8 Comments

  1. Reid Thompson

    Mar 4, 2021 at 12:51 pm

    I was kind of looking for if low CG creates low spin or the opposite.

    • Terry Koehler

      Mar 7, 2021 at 2:50 pm

      A low CG will tend to reduce spin and elevate ball flight.

  2. Jon

    Mar 4, 2021 at 7:19 am

    You’re correct… I believe they’ve gone from extreme perimeter weighting , thinking forgiveness to understanding that if you create more back spin with a lower center of gravity, you create less side spin. .. Therefore, more forgiveness than perimeter weighting.

  3. Martien Schwencke

    Mar 4, 2021 at 6:45 am

    The point of percusion is not always where the centre of grafety is.
    A good desined club the point of percusion is locaed in the middel of the face.

  4. T Carter

    Mar 3, 2021 at 1:12 pm

    Not saying any of these comparisons are wrong, they are just not porportional to the game of golf. Another comparison you could make is pounding fence posts. You could use a sledge hammer to hit the top of a post or you could use a post pounder which provides consistent results due to innovative shaping of metal. A sledge hammer could be more effective in the use of very skilled hands, but the pounder is much much much more user friendly and even professionals use them too for consistency.

    Also keep in mind that we are swinging golf clubs at a very high speed and everyone could use some forgiveness even though a perfect shot may not perform like a perfect shot with blades.

  5. Joe

    Mar 3, 2021 at 11:00 am

    The last comment in this article proves this guy has no understanding of engineering. This literally just reads like a marketing piece to explain why his wedges are better.

    • Raj lp

      Mar 3, 2021 at 11:12 am

      Care to explain?

    • Engineer

      Mar 3, 2021 at 5:39 pm

      Agree. This makes no sense. If that 1/16″ thick metal hit you in the back of the head it would feel the same, except that the metal flexes and the load is distributed. Look at track man if you think there’s some kind of difference. Track man doesn’t ask you if you’re playing a cavity back iron or a muscle back blade. It simply says, path + face angle = ball flight.

      Very little of this article is about cg.

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Golf's Perfect Imperfections

Golf’s Perfect Imperfections: Responsible speed training for sustainable personal bests

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It is truly awesome what is happening with Bryson DeChambeau and Kyle Berkshire and more of their young friends who are in shape are joining the bandwagon. But at an all-out slash fest trying to get 160mph ball speed with a 7-iron for a two-hour session would send 90% of us to the hospital. It’s safe to say it is not for everyone. To increase your clubhead speed responsibly long term really starts with us.

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Opinion & Analysis

The 23 players who can win the Masters

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Each year for the Masters, I create a filtering process to help determine the players who are most likely to win the green jacket based on criteria that have strongly predicted outcomes at Augusta. I usually get the list down to roughly 20-25 players.

Last year, Dustin Johnson was one of my 21 players who could win the Masters. Dustin was at 9/1 odds. The other top finishers, like Cameron Smith and Sung Jae Im, were filtered out unlike previous years where players that were in contention were typically shortlisted. My theory on that is that due to the tournament being played in November, the course was not playing as firm and as fast as it normally does, and that allowed players who typically do not get through my filter to get into contention.

Before I discuss my picks for this year’s Masters, I want to go over what I call the “critical holes” for Augusta National. The critical holes in any tournament are the ones where the top finishers typically gain the most strokes on the field, as well as where the greatest deviation in scores exist. One of the interesting aspects about critical holes is that they often change over time due to changes in the course conditions, course design or a change in player strategy, which can create a smaller deviation in scores.

This year, the projected critical holes are No. 8, 13, 14, and 15.

The 15th hole, Firethorn, should be considered the most pivotal hole on the course as over the last five Masters the top finishers in the event have gained 0.391 strokes per round on the hole.

Moving on to the tournament, I filtered out the amateurs and all first-time professional attendees. The Masters has only been won once by a first-time attendee: Fuzzy Zoeller in 1979 and Gene Sarazen in the inaugural event

  • Joe Long (a)
  • Robert MacIntyre
  • Carlos Ortiz
  • Charles Osborne (a)
  • Tyler Strafaci (a)
  • Will Zalatoris

Despite being first-time invitees, the data likes both Ortiz and Zalatoris as they would have gotten through all of the other filters to be selected as players that could win the Masters.

I also filtered out eight past champions I do not believe can contend at Augusta National anymore

  • Fred Couples
  • Bernhard Langer
  • Sandy Lyle
  • Larry Mize
  • Jose Maria Olazabal
  • Vijay Singh
  • Mike Weir
  • Ian Woosnam

The Zach Johnson debate

Every year I do my Masters picks, it’s always pointed out that I do not pick former Masters Champion Zach Johnson due to his lack of length off the tee. Augusta National greatly favors long-ball hitters. They can play the par 5s more like par 4s, and typically the longer hitters can also hit the ball higher so they can get their long approach shots to hold the green more easily.

When Johnson won the Masters in 2007, the event featured record-low temperatures in the mid-40s and wind gusts of 33 mph. This made it very hard for any player to reach the par 5s in two shots and allowed Johnson to get into a wedge contest on the par 5s, his strength.

This week the forecast is calling for high 70’s to low 80’s with winds topping out at only 10 mph. There are some scattered showers in the forecast that may soften up the greens and give shorter hitters more of a chance to win.

But I believe that it will not be enough to take the advantage away from the longer hitters.

Therefore I filtered out the following players.

  • Abraham Ancer
  • Brian Gay
  • Brian Harman
  • Mackenzie Hughes
  • Zach Johnson
  • Kevin Kisner
  • Matt Kuchar
  • Francesco Molinari
  • Kevin Na
  • C.T. Pan
  • Ian Poulter
  • Patrick Reed
  • Webb Simpson
  • Henrik Stenson
  • Robert Streb
  • Michael Thompson
  • Brendon Todd

A part of the game that is just as critical as distance is the trajectory height a player can create. Last year, I filtered out four players for hitting the ball too low. Out of those four players, the best finish was Patrick Reed at T10. I use a combination of max height, carry distance, and launch angle to determine if the following players hit the ball too low to win at Augusta.

  • Daniel Berger
  • Christian Bezuidenhout
  • Patrick Cantlay
  • Cameron Champ
  • Harris English
  • Matthew Fitzpatrick
  • Lanto Griffin
  • Jim Herman
  • Matt Jones
  • Sebastian Munoz
  • Victor Perez
  • Xander Schauffele
  • Bernd Wiesberger
  • Lee Westwood

Since the inauguration of the event, there have only been two winners of the Masters that have previously never made the cut: Fuzzy Zoeller in 1979 and Gene Sarazen in 1936. Let’s filter them out as well.

  • Max Homa
  • Jason Kokrak
  • Joaquin Niemann
  • Hudson Swafford
  • Matthew Wolff

I will also filter out the players who missed the cut at San Antonio. Historically, players that miss the cut the week prior have a substantially lower likelihood of winning the following week compared to the players that made the cut in the previous week or did not play at all.

  • Tony Finau
  • Phil Mickelson
  • Danny Willett

Lastly, I have filtered out the weak performers from the “Red Zone,” approach shots from 175-225 yards. While Augusta is known for its greens, the winners are determined mostly by the quality of their approach shots throughout the event. In fact, 11 of the last 12 champions have hit at least 49 greens in regulation during the week.

  • Jason Day
  • Tommy Fleetwood
  • Dylan Frittelli
  • Billy Horschel
  • Brooks Koepka
  • Martin Laird
  • Scottie Scheffler
  • Charl Schwartzel
  • Adam Scott
  • Cameron Smith
  • Jimmy Walker
  • Matt Wallace

That leaves the following 23 players who can win the Masters:

  • Paul Casey (45/1)
  • Stewart Cink (450/1)
  • Corey Conners (80/1)
  • Bryson DeChambeau (11/1)
  • Sergio Garcia (50/1)
  • Tyrrell Hatton (45/1)
  • Viktor Hovland (33/1)
  • Sungjae Im (40/1)
  • Dustin Johnson (9/1)
  • Si Woo Kim (125/1)
  • Marc Leishman (110/1)
  • Shane Lowry (110/1)
  • Hideki Matsuyama (45/1)
  • Rory McIlroy (18/1)
  • Collin Morikawa (30/1)
  • Louis Oosthuizen (75/1)
  • Ryan Palmer (150/1)
  • Jon Rahm (12/1)
  • Justin Rose (80/1)
  • Jordan Spieth (11/1)
  • Justin Thomas (12/1)
  • Bubba Watson (55/1)
  • Gary Woodland (150/1)

Here are my personal top-10 picks

  • Paul Casey (45/1)
  • Corey Conners (80/1)
  • Bryson Dechambeau (11/1)
  • Sergio Garcia (50/1)
  • Viktor Hovland (33/1)
  • Dustin Johnson (9/1)
  • Rory McIlroy (18/1)
  • Collin Morikawa (30/1)
  • Jon Rahm (12/1)
  • Jordan Spieth (11/1)
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On Spec

On Spec: The unexpected lesson from Jordan Spieth’s win | Plus ANWA & ANA Inspiration coverage

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In what can only be called the busiest week in golf so far in 2021, host Ryan breaks down the Augusta National Women’s Amateur, the ANA Inspiration on the LPGA Tour, the Drive, Chip, and Putt, and of course Jordan Spieth’s comeback win in Texas.

All of this is leading into the Masters, and Jordan’s win comes with a very important lesson for those golfers who might be struggling with their own game.

 

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