Agree. . . Maybe I should have said, ‘Research validates Erickson.’ LOL! BTW, I have a set of bulletback staff irons in my bag. . . direct from my good friend Mike Rees. They are not as flat at John’s but they are pretty flat.
I believe if the launch monitors would take into account clubhead mass, the data would be more accurate. So much of the data is just estimated. For example, with a radar system, can the system actually read the spin of the ball, or is it just calculated per the launch angle and peak height?
I’ve got a set of them buttonbacks too. X200 shafts bent to John’s specs and backweighted to my preferred weights.
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This is something I never really understood. . . until recently. Now I get it. Once again, Kwon claims the same thing. I think it would really find it interesting to have you (who have actually put these ideas into tour level performance), Homer Kelley who described the swings mechanical options and Dr Kwon that can describe the dynamics/physics of virtually any swing on a panel discussion. Of course Homer is no longer with us. . . .maybe Bobby Clampett?? And the discussion would not be on ‘what is the best way to swing a club,’ but on how to best communicate proper swing concepts to golf students. (A man can dream.)
Yea, I switch back and forth between old Staff irons and Hogan Apex or Channel Back irons. First year 8813 putter also. Just something about those old clubs that make golf. . . GOLF>
CFH
Their method for spin is explained in the link below - they claim it’s accurate within 20 rpm.
Club mass data would have no change on accuracy of ball measurements/calculations. Ball data is king - if that’s accurate you know where the ball is going without knowing anything about the club.
Club mass data would be interesting for someone that wants to study relationships between the mass and ball flights (distance, dispersion, etc…), but not important in accuracy of a launch monitor.
I not bashing these machines… I am calling out their shortcomings and why they are giving misleading results.
For example… if clubhead A is 10 ounces moving 100 MPH and clubhead B is 16 ounces and moving 100 MPH there will be a significant change in compression and ball speed and depending upon the loft of the club and point of contact, these numbers will be VERY different.
These machines focus exclusively on path, spin rate, loft, trajectory and will give the golfer data that would suggest they do certain things with their swing. There is no data that would suggest the player change the mass of their clubhead… and it has no way of knowing if the golfer was holding shaft flex… or what their lie angle is… and how that affects ball flight.
A more massive clubhead that is holding shaft flex … the golfer will NOT have to rotate as fast as a player using a very lightweight club void of shaft flex.
These are VERY critical elements… I am not bashing… I am waiting for science to get their act together and start looking at some of the most critical details of superb ball striking. These machines are causing harm to a lot of golfers who are focusing a square path and ball speed which has very little to do with playing quality golf.
Why? Because very few shots in a round of golf would favor maximum ball speed. Golf is about hitting the ball a SPECIFIC distance on most shots. Square path is not taking into account where the player is aiming, or the options available for the player to rotate their base lines, and also shot shaping and trajectory control.
This is not about good if they agree or bad if they disagree… these are simply objectives shortcomings of these machines that so many worship as a pillar of scientific golf rhetoric.
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Heavier mass requires less rotational speed for the same ball speed. So the swing is slower and more manageable. It puts more FEEL into the hands… AND it slows down acceleration rates.
CRITICAL! STUFF!
NOT TO BE OVERLOOKED
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My gamers are the Buttonbacks and my Hogan Precisions with the same X200 shafts and very similar weights using the grip weights (Tour Lock Pro).
Dr Kwon’s website shows he is not a physics professor, but he’s probably very good at both maths/physics as well as a world-renowned biomechanics expert.
It’s a very good website and has lots of information.
Dr. Kwon’s Bio (drkwongolf.info)
Ph.D. (1993): Exercise & Sport Science (Specialization: Biomechanics, Minor: Mechanical Engineering), The Pennsylvania State University, University Park, PA
M.Ed. (1986): Physical Education (Specialization: Biomechanics), Seoul National University, Seoul, Korea
B.S. (1984): Astronomy, Seoul National University, Seoul, Korea
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Lagpressure
There have been several research studies done on the influence of increasing clubhead mass. Here is the link to Dr Sasho Mackenzie’s research article (free to download) but it can be technical reading.
(PDF) The Influence of Clubhead Mass on Clubhead and Golf Ball Kinematics (researchgate.net)
Here is the conclusion which is easier to understand:
Conclusions
This study has provided novel insights into the understanding of how the mass of a driver’s clubhead influences driving performance. Increasing clubhead mass within a commercially available range was found to decrease clubhead speed, but have no meaningful influence on ball speed. Similarly, increasing clubhead mass had clear influences on dynamic loft, angle of attack, and spin, but there was no net influence on carry distance and only a relatively small effect on the total predicted distance. Collectively, this suggests that manipulating clubhead mass to increase driving distance is not likely a worthwhile exercise. Clubhead mass did a have a meaningful influence on where the ball finished laterally due to differences in both launch angle and spin. Increasing clubhead mass tended to create more fade spin as well as start the ball further to the right, which resulted in meaningful differences in the average lateral finish location among conditions. This finding has important implications for club fitters and manufacturers. When adjusting the clubhead center of gravity location to manipulate ball flight tendencies, it would seem important to only ‘move’ mass, while keeping the total clubhead mass constant, so as to avoid confounding mechanisms. Finally, there appears to be some evidence to suggest that golfers with higher clubhead speeds may perform more consistently with heavier clubheads.
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Some more from that research article:
The results from this study demonstrate that as clubhead mass increased the clubface was pointed significantly more to the right during impact (Figure 3a). Lead deflection and toe-down deflection act in opposition to influence face angle, with toe-down deflection tending to open the face (MacKenzie & Sprigings, 2009). Notably, with current drivers, the amount of toe-down deflection at impact typically exceeds that of lead deflection; therefore, a heavier clubhead generating more deflection in general would tend to be associated with a more open face. Face angle, as measured by TrackMan, is also influenced by the same factors as dynamic loft noted in the previous paragraph. So, for example, a systematic change in impact location toward the toe could also be responsible for some, or all, of the more open face angle with the heavier clubhead. Regardless of the mechanism, the face angle results corresponded to equivalent differences in horizontal launch angle between conditions, with the ball launching more right as clubhead mass increased (Figure 3b). Acting in synergy with launch angle, to separate the finish positions between conditions, was the spin axis tilt of the ball (Figure 3c). For example, the heaviest condition tended to launch the ball the farthest right with a fade spin, while the lighter conditions were associated draw spin. The end result of these interactions is quite clear as the heaviest condition had an average finish location approximately 20 yards right of the lightest condition
(Figure 3e). Interestingly, while manufactures have designed clubheads so that the center of gravity location can be moved to manipulate ball flight, it would seem that an overall change in clubhead mass has a meaningful influence.
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Here’s some more that I found:
Here is another useful article regarding ‘Rate Of Closure’ . The ABS technique might be able to theoretically keep the clubface squarer to the path and create smaller clubhead speed (with a greater clubhead mass while ball velocity unchanged) but the swing plane angle is probably non-negotiable.
What is ‘rate of closure’ and can it help your golf swing?
ABS -Driver Swing
- Swing slower = less ROC
- Less grip roll = less ROC
- Swing Plane Angle (Non negotiable) = 1200 deg/sec
Note what is stated at the end
Does Rate of Closure actually matter?
It would seem beneficial to be on the low end of the Rate of Closure spectrum. Wouldn’t it be tougher to ‘square-up’ a faster closing face? However, there is currently no evidence to suggest that players with lower RoC hit more fairways or hit their approaches closer to the hole. For example, in his PhD Thesis, Dr. [Phil Cheetham found no relationship between shaft twist speed and driving accuracy in a group of 70 PGA Tour players.]
In the studies that have been conducted, it is possible that the influence of RoC was obscured by other golfer characteristics, such as hand-eye coordination and course management.
Ping measured many golfers to check dispersion of golf ball vs Driver Closure Rate and here is their graph.
Obviously, the results could be questioned, for instance, how they measured dispersion of a golf ball plus other possible variables like ‘weak/neutral/strong grips’ . It might be non-intuitive, but one cannot assume that a low ‘Rate Of Closure’ (or any technique for keeping the clubface squarer to the path through impact) will guarantee less ball dispersion.
This article is a fantastic read. Thanks
There is only a 3-3.5 yard average drop in driving distance for the heaviest head as compared to the lightest. This was for a 26 gram increase.
More interesting - heavier heads were more likely to produce a right miss and lighter heads a left miss (for right handed golfers).
Heavier heads appeared to give high swing speed players more consistency (but not statistically significant).
I really only care about dispersion. Small losses in distance are not a worry for me.
A lot of this is kinda intuitive, but cool to see some data it.
Glad to know today’s scientists are more concerned with commercially available ranges…
So about an ounce is their scope of experimentation.
Most modern drivers are around 11 ounces…
So what about 14 or 15 or even 16 ounces?
Then do the experiment with the same velocitiy for all weights…
Then do the experiment where the clubhead is gaining velocity into the strike.
Then the data might be of interest.
I’ve done a few calculations for clubhead speed which will create a ball speed= 148mph after impact, for a clubhead weighing 200 gm (ie. 7 oz) and also for a clubhead weighing 16 oz (454 gm).
I’ve assumed a perfect strike for each club and worked out the clubhead speed at impact.
200 gm - Clubhead speed 91 mph
454 gm - Clubhead speed 81.42 mph
So if you more than doubled the mass of the club you will still have to swing at 81.42/91 = 90% of the speed you swung with the 200gm clubhead.
You will not gain much clubhead speed for an acceleration through impact which lasts 0.5 milliseconds and I didn’t see any significant change in the dispersion of the golf ball for an off-centre strike (as per your video). I will double-check the clubhead acceleration through impact effect on dispersion with Dave Tutelman as he’s an expert on club technology. But as far as I am aware, nothing you can do with your hands on the grip will have an effect on the clubhead through the impact period (the club shaft may as well be a piece of string).
I think this is where the disconnect is (pun intended).
To swing a significantly heavier club requires a different technique, one that is much more connected and powerful through the strike. A technique where the shaft can’t be modeled correctly as merely a string.
As an analogy, we’ve all experienced using an inexpensive drill with a screwdriver bit to screw in all screw. It spins very rapidly, but if the surface into which you’re screwing presents a certain degree of resistance the result will be only that screw head gets stripped. If we try to overcome that by pressing hard into the surface we find that the cheap drill comes to a halt as it provides insufficient torque.
If you want to swing a very light club, a technique that mainly uses the arms, say, to generate speed may very well give you more distance than a technique that uses the body pivot. But if the club is much heavier the latter technique provides the torque that is needed to get distance. Moreover, and more importantly, using the latter technique with a heavier club can very well be much more accurate.
As another analogy, imagine you’re comparing swinging open a screen door (without any hydraulics) as fast as possible with opening a heavy bank door. You’d use very different techniques to do so in each case. And a superior technique for the super light screen door would not be the same as for the heavy bank door. But you’d have much more control with the heavy bank door.
That’s all to say, if you’re testing accuracy between swinging a light and heavy club, but you’re using the same (swingers) technique to do so in both cases, then you’re not testing what you claim you are.
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A swinger can also use his body pivot and core muscles to get the club swinging in the early downswing, whether the club is heavy or light, but it obviously depends on each golfer’s capabilities.
Yes it would be nice to see some evidence that golfers are ‘hitting’ vs ‘swinging’ but then you’d need to have a proper definition of each. I think TGM says that hitting is the thrusting of the trail arm using the upper torso as a foundation to push off .
Dave Tutelman defines it below:
Hitters and swingers
I’d like to take this opportunity to state very specifically what I mean later in these notes by the terms hitter and swinger. Most clubfitters and many instructors make this distinction, but it tends to be intuitive and imprecise. I believe that:
A swinger is a golfer who depends exclusively on centrifugal force for clubhead speed, and adds no wrist torque during the downswing except that needed to hold a 90º wrist cock.
A hitter is a golfer who depends to some extent on torque applied to the club’s grip via the hands and the wrists.
Of course, there are few pure swingers and no pure hitters. But, comparing two golfers, we now have a way to say which one is more of a hitter and which more of a swinger. And, in fact, we can tell from this whether a golfer is primarily a hitter or a swinger.
There is no agenda at all, and you can keep hitting as much as you want. Just questioning the physics behind the claims.
- Maintaining shaft flex into/through impact.
- Heavier clubs being accelerated through impact causes less ball dispersion for off-centre strikes.
- Clubface being squared with just torso rotation.
“Yeah, as we all know professors that teach business that never ran a business are worth about whatever they can sponge from state retirement funds for life”
That seems a bit of a harsh statement to say about people who have helped design your clubs to play this game.