GEARS 3D Modeling System

Anyone interested in discussing GEARS we welcome your conversation or insights here…

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I have reached out to Tom in the East Bay area about their GEARS system.
Will wait for a reply…

Let’s try that again…

A respectful post about the benefits of GEARS and how it might be used to improve a golf swing for those interested in a substantial analytic inquiry of their golf swing…


Excited to see how this goes…

I’m interested in learning about it… and how it is set up.
Where are the pressure plates? What specifically is it measuring and in what direction?

Hopefully we can learn something here… and how it might benefit golfers.

My concerns with this thread are that:

  1. Any GEARS experts, that may come along to share insights on their experiences with the system, will be basing their insights on the golf swings they have been recording and studying

  2. These experts are likely to refer to PGA tour players’ swings (or swings of other players whom they consider to reflect the pinnacle of ball striking ability)

  3. In general those players are using a swinger’s release mechanism and I therefore expect that the swinger’s model will be the basis of the expert’s starting assumptions as to what is and isn’t possible.

As a result, my prediction is that this thread will descend into utter chaos in a similar fashion to the ‘science validates ABS’ one that preceded it, as those posters that seem intent on arguing that holding shaft flex is not possible, will not change their ‘base assumptions’ until John or someone else accepts their ‘challenge’ and gets on GEARS.

Should John get on GEARS? In my opinion, he does not need to. I am already comfortable with the fact that the physical laws of the universe do not prevent shaft flex from being held.

From the universe’s perspective, there is particularly nothing special about the length of backswing, a specific wrist angle (a ‘moment arm’) or the precise moment of impact. What it boils down to is if the grip end of the club is being accelerated (in terms of angular velocity) at a rate that is not less than that of the clubhead at any given moment, there be a force stressing the shaft.

My guess is that those that need to see John get on GEARS as further proof of this concept are unlikely to ever be fully satisfied.


I would agree with all you have said here.
We will no longer allow threads to turn into chaos… as it’s not what this forum is about.

We really didn’t have problems like this in the past as posters were generally considerate of one another… and conducted themselves respectfully.

I certainly have no problem with anybody questioning what is taught here, methodology etc… but when accusations of fraud, deceit, lying etc … it’s not how we do things here and that kind of behavior will simply not be tolerated.

As far as GEARS, I have interest in it, but also have questions about it and how it collects data, and certainly if it has the ability to measure pressures in the hands in a tangential direction. Also, does it have the ability to measure the opposing forces created within the shaft through the strike arena, similar to if I hung a weight from the clubhead and stressed the shaft with the grip in fulcrum. I believe this is called form 3 lever system.

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If GEARS is simply doing 3D modeling without the ability to measure pressures and forces, then I don’t see much benefit to it… similar to Trackman… not looking at what needs to be looked at.

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I am not a golf research scientist, but I’ve read a few of the papers published by Mackenzie, Kwon, and other people who are.

There are a few commercial systems which measure ground force pressures. Kwon uses these extensively.

Regarding measuring the forces and torques on the club, this is done by what I believe is referred to as inverse (or reverse?) kinematics.

The basis of this is as follows:

  1. Directly measuring something like how much force your hands are exerting is problematic and difficult. It would require some type of pressure or force transducer applied to the arm and/or the grip, and such devices would interfere with the swinging motion.
  2. However, since all mechanics are governed by Newton’s Laws of Motion, if you can measure the movement of things, you can work backwards and deduce what forces and torques were necessary to create the motions observed.
  3. GEARS and other 3-D systems provide such detailed measurement of motion.

Mike Jacobs in NY is one golf teacher using a combination of 3D motion capture and force/pressure plates to teach golfers. By using the same inverse kinematic approach, his software system can measure all of the things you reference - how much force are you applying to the aft side of the shaft, how much force are you pulling up on the grip, how much force are your hips unwinding, whatever it is.

So the answer is yes, with the proper software, GEARS ascertains pressures and forces. Nobody MEASURES hand forces directly, but with precise enough movement measurement, the forces are calculated by following Newton’s laws of motion.

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It certainly would need to take into account the mass of the clubhead, and whether or not the shaft has kinetic pressure loaded into it through impact. Big difference.

I would like to know what this is going to tell me that the ball would not tell me? I mean practical or relevant stuff… not just a pile of numbers that need to be interpreted.

Both Trackman and Flightscope were totally underwhelming when I went on those years ago.

Sounds like technology is improving but still might have a long way to go…

Depends what you want to know. Just outputs data - you might have some analysis or interest in certain data, you may not. It helps folks understand what is objectively and really happening to various parts of the body and club at various points in the swing. Whether that has any practical application depends on whose hands the data is in. It’s not something I would be too interested in, but I could see how others would.

If someone wanted to study the impact of retaining shaft flex into impact, for example, or whether that is even possible, they could use a system like this. The data would show which swings, if any, had shaft flex at impact. You can couple that with analysis of ball data to figure out what impact doing such a thing has on ball flight, ball speed, dispersion, etc… Again, whether that is practically that helpful, I don’t know as I’ve never used it, but it could be used for such purposes.

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Not sure what you mean by “interpreted,” but anything a video would tell you, GEARS can tell you, only more precisely and more completely.

Let’s say you hit 10 straight shots that draw 5 yards, but you were trying to hit a 5 yard fade. So something was causing you to deliver the club head closed to the path, instead of open to it.

The flight of the ball tells you only your impact conditions. The curve tells you the face and path relationship. If it flew low, you know you were either more de-lofted, or you hit it thin. But again, the flight of the ball is only telling you impact conditions, it’s not telling you what your body did to deliver the club head that way.

So, to use ABS terminology, let’s say you are wondering if maybe your hip rotation stalled and this caused you to flip the club head. Well, with GEARS, you can replay the swing with hip axis lines drawn, and look visually at exactly how fast and when your hips rotated. You can play this swing side by side with a recording of one of your good swings and compare the hips.

So let’s say you do that, and you find there is no difference in the hip rate…or even that, to your surprise, your hips turned slightly faster on the draw swings. Now, you can start looking at other things. Maybe you set the club a degree or 2 more closed than usual at the top. Maybe it was fine at the top, but you arrived at club horizontal with the face not open enough. Maybe all that was good, but your forearm rotation rate at the very bottom was faster in this swing than another.

It may be a pile of numbers, but to a person who understands golf, it’s a treasure trove of data that, without the technology, you can only guess at.

Regarding your first points about mass of the club head and kinetic pressure (I assume you mean stored kinetic energy) in the shaft, I’m not 100% sure I understand what you’re getting at, but I will take a shot at it.

3D motion capture systems measure the position of things in space. They don’t have force transducers to measure force or torque.

But as I mentioned in the previous reply, systems like GEARS are used to determine forces and torques. They are or can be calculated by Newton’s laws of motion. For a body to move from point A to point B with an acceleration R, we can calculate the force or torque acting on the body. To do that, you have to know the mass of the body in question, and all of the research on the kinematics of golf swings take into account the mass of the club heads, the mass of the golfer, the mass of the various body segments, and so forth.

And GEARS is superior to 2D video, because with 2D video you cannot determine precisely the speed or acceleration of something, because of parallax errors and so forth. GEARS is like a 3D movie, where you can see INTO the frame. The increased precision of measurement means that forces and torques can actually be determined, accurately, not just hypothesized as one might do looking at video.

If you are talking about a practical application of GEARS, you can make swings with club heads of various weights, and see the difference in how the shaft flexes, how the mass of the club head affects the rate that you rotate the face, or how it affects the plane the club travels on, etc. etc. A stiff shaft is good according to ABS, but how stiff? By looking directly at the shaft of the club at all points in the swing, you can determine the point where it is maximally flexed, and whether the flexion profile is more optimal with shaft A versus B.

With Trackman, you said you weren’t impressed, and in another thread you said that this was because you didn’t think Trackman was valid because it “didn’t account for club head mass.”

Trackman is a radar system. It’s like a police officer’s radar gun. It bounces radar signals off the ball and determines how fast the ball is traveling based on how long it takes the signals to be reflected back to the sensor. It doesn’t matter how much the club head weighs, just like it doesn’t matter how much a car weighs when it’s speed is measured by the cop’s radar gun.

Of course the mass of the club head is a determining factor in how fast the ball moves. Momentum is mass times velocity squared, and so of course nobody is arguing that Newton’s laws of motion don’t apply. If we were trying to CALCULATE the speed of the ball, yes, we would have to know the mass of the club head, it’s velocity, etc. etc. But Trackman doesn’t have to know that, because it is MEASURING the ball directly.

The same technology also allows trackman to measure the speed of the club head. Again, it’s a direct measurement, not a calculation.

Trackman does make many calculations. It calculates the distance and trajectory of the ball. For this, yes, it needs an algorithm, and the algorithm must account for the mass of the BALL, the spin axis and spin rate of the ball, the coefficient of friction of the ball, etc. etc. Trackman MEASURES most of these things, like spin rate, spin axis, etc., and then calculates the trajectory (distance, directory, height, carry, roll, etc.) based on all of these. It’s not any sort of new or untested or untestable technology. It’s basic engineering that has been in use for over a century. Trackman’s calculations of ball flight have been verified experimentally. It’s not hard to do. The device calculates a distance, and then you have a guy out there shagging the ball, and you see how accurate it was. It’s proven and it works.

Those statements apply to it’s utility as a measuring device. I am not making any judgement on whether trackman should be used to analyze a person’s golf swing, whether it is superior or inferior to video analysis, etc.

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Regarding forces and torques, I don’t think GEARS software itself has the ability to calculate torque. But the data can be input into other swing modeling programs like those developed and used by Dr. Kwon, Dr. Mackenzie, Mike Jacobs, etc., to determine those forces. This process is the entire basis of their research. Both Dr. Kwon and I think Mike Jacobs will analyze a golfer’s swing, usually requesting a small donation or fee. If you were interested in studying the forces and torques in your golf swing or comparing hitting and swinging methods, it could easily be done. Sounds like a great project for a grad student. )

Enough said…

As far as Trackman, if it is only analyzing the golf ball itself, then it doesn’t know where I am aiming. Doesn’t know what my lie was in the grass, doesn’t know the wind conditions, doesn’t know what club I am hitting, doesn’t know the mass of the clubhead, doesn’t know the temperature or the humidity, doesn’t know sidehill, uphill or downhill lie. Doesn’t know how flat or upright my clubs are, doesn’t know what kind of grooves I have or don’t have on my clubs, doesn’t know what kind of golf ball I am using, doesn’t know my grip pressure, cohesive body tensions, or the stiffness of my shafts. Doesn’t know if I am holding shaft flex or not, doesn’t know where on the club I hit the ball. Doesn’t know if my backswing is short and quick or long and flowing… doesn’t know if I am hitting or swinging.

Now if I am on the long drive circuit, and I live in Northern Ontario in the winter, and I am limited to indoor training sessions, then I think it could be quite useful.

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Trackman doesn’t only analyze the ball. It analyzes the ball and the club.

“then it doesn’t know where I am aiming”

Trackman is aimed. You pick a target using Trackman’s camera and it aligns to that target.

Trackman doesn’t know what lie angle your clubs are set to, but it measures the dynamic lie angle at impact. So it know what lie angle you’re impacting the ball at.

86general misstated a few things. Trackman, if used outdoors, does track the ball. It tracks the entire flight which would include how the wind is moving the ball. The flight can then be normalized which uses a ballflight algorithm to determine what would have happened without outside interference. GCQuad, however, only tracks the impact interval and uses a ballflight algorithm. But it has a built in barometer which can measure all sorts of things to set the conditions.

Trackman doesn’t “know” what your lie is or what the grooves look like or whatever else, but that stuff is measured in the launch conditions. If you have bad grooves and are hitting out of rough that will be reflected in measured spin rates and launch.

Flightscope measures shafts. Holding shaft flex would be irrelevant because the launch conditions are being measured. If you hold shaft flex and that does something to ball launch it would be within that measurement.


Thanks for posting…
I assume there have been a few releases of Trackman?

No, with respec, it wasn’t enough said; apparently you weren’t interested in reading the next paragraph, where I explained how the data from GEARS is used to determine all the forces and torques and “pressures” you are interested in.

It is not practical and probably not possible to DIRECTLY measure something like the flexing force applied to a golf shaft. You would have to design a force transducer that would fit in or on a club and not interfere with the swing. Whether it could be done or not I don’t know, but it’s unnecessary, because with GEARS and high school level physics, you can derive the forces with incredible accuracy. That’s what is done, over and over, in the academic work of people like Kwon, Mackenzie, Fenton, and others.

You CAN do this with GEARS or other 3D motion capture systems, because they can measure the position and movement of anything with incredible precision. You can’t do it with video. You can’t do it with following the golf ball.

Thank you Crankus for correcting me. I was aware that outside, Trackman follows the ball for a much longer distance than it does when used indoors, but I was not aware that it could be set up to track the entire ball flight.

Can the Trackman tell the difference between a low and high spinning ball?
If I make the exact same swing… but get two totally different ball flights based upon the construction of the golf ball… what would it be saying is different? Certainly the ball flight would be different. Would it assume I did something different or would it recognize that I was just using a different golf ball?

If I hit 10 shots in a row that have the same ball flight… a 5 yard piercing fade with a 1 iron…

Does Trackman tell me that I had essentially the same impact dynamics for all 10 shots?
I mean it would be confirming what I already know to be true?

Likewise, if I hit four balls, one fat, one thin, one pull slice, one rope hook… I assume trackman would tell me that these four shots happened.

It’s going to show OTT path for the pull slice with an open face… and an inside out path with a closed face for the rope hook.

Have I learned anything? I don’t think so.

Is it going to tell me how to fix my golf swing? Will it print out a discount coupon for a lesson with Butch Harmon or Bradley Hughes?

Will it tell me to flatten out my irons… ditch the frying pan and go with a 14 ounce persimmon driver? Maybe suggest I remove the offset on my irons?