Prestressed Shaft and Impact Deceleration

[Mike O]

I would have thought so too, and if only a good shaft fitting were that simple, but I probably should have added:

Wishon, "The Search for the Perfect Golf Club", 2005
Chapter 4 Myths-
Myth #3 - "The third myth to bury is that the forward flexing of the shaft just before impact (which some people mistakenly call "buggy-whipping" or "kicking") increases the speed of the clubhead"......

I started this thread by saying I'm much more up on clubfitting than TGM (trying to change that) and that is probably evident in my posts, but I think there's opportunity for incorporating concepts from both to increase one's ability to teach and/or learn to play this game.

Absolutely!-- There's always room for growth and improvement in anything- that's what it is all about.

[ThinkingPlus]

2)Jorgensen, "The Physics of Golf", 1994
See Fig 12.1, also last paragraph of Chapter 12 - "...I think the flexing of the shaft forward as the clubhead comes into the ball is a general characteristic of the golf swing. Photographs made with the use of a focal plane shutter must be ignored in this context. There are few photographs in golf literature made with stroboscopic light sources, but of those I've examined, all of them show clubs flexed in this manner."

One thing to keep in mind specifically with Jorgensen and very likely with the others is the model swing on which their analysis is based. Jorgensen found footage of a particular PGA tour professional (unnamed) and used various images to create a mathematical model. He tweaked his model until it matched up well with that single subject. He may also have commented that his model matched reasonably well to other photographs. At this point he played parametric games with his model to see how the various parameters affected swing speed and other swing features.

What is not known with Jorgensen's human test subject, or possibly with the others as well, is whether the golfer was following the impact principles of TGM or not. Just because someone plays professionally or is a top amateur does not mean they swing in the most optimal fashion in the book. Nothing definitive, therefore, can be said about shaft flex before, during, or after impact unless we have a test subject who unquestionably is retaining maximum on plane lag pressure at impact with flat left wrist and bent right wrist.

BTW, I know the above sounds like some mad lady on a soapbox lecturing the crowd. It is not meant to be that way. I tend to get preachy unintentionally. This thread discussion has been very fun and one I have wanted to start for a long time. You just beat me to it! I think the video footage Yoda referred to will be definitive (one way or another). I also agree that whatever the outcome, the FLW & BRW hands leading clubhead at impact with maximum lag pressure golf stroke will always produce the most ball compression and speed. This is too much fun!!!!

[Daryl]

Steph, Thank you for your insight. As a club maker yourself, you've dealt with these issues before and will probably again.

Hmm? Is it possible that someone can do research, get published, and still be wrong? If one then many. Certainly the equipment makers (not the ball makers) with all of their technology have not advanced a players improvement in recent years quite as much as their investment and profits. I don't know that they actually have any interest in improving swing mechanics. I'm sure that they recognize the shortcoming of most teaching professionals and the general population of golfers to make permanent swing mechanic improvements and thus have adopted game improvement equipment to compensate. Certainly they didn't invest million and millions of dollars so that just a few Tour Pro's can make a few more bucks. And certainly, with millions in profits at stake, they aren't going to wait for teaching professionals and the general public to get the job done any time soon. If they can make a shaft, so that anyone can pick up a club and play respectable golf, they certainly would. And maybe that's not as far away as one might think. I think all that is holding them back is the PGA's Club Spec guidelines and the R&A. Until the general golfing public improves their mechanics, and teachers learn the real cause and effects of golf mechanics then game improvement technology will be their crutch, and maybe their savior. Everyone wants to build the ultimate golf club. Besides, historically, equipment makers have sucessfully redefined the game. Four wedges, Metal Drivers, Cavity back irons, graphite shafts. And Golf Course designers seem to be keeping up too. In fact, the only segment that's falling behind is the GOLFER.

Homer Kelley was, and still is, ahead of his time. Something that I have observed in browsing through golf books this evening is that many players exhibit the prestressed clubshaft at impact with shorter clubs and less with longer clubs. This may be due to longer shafts or possibly the difficulty of getting the Pivot to Transport the Power Package fully into the Release area in order to maintain the Prestressed Shaft.

Even Annikan Skywalkers recent thread with pictures of his swinging and hitting Stroke Patterns demonstrate a Prestressed Clubshaft before impact with his Swinging Pattern even more than his Hitting Pattern, though Yoda's comments may lead you to believe the opposite is more likely to be true. The Young man that Annikan illustrates further into the thread exhibits the same tendency. Could these videos be an optical illusion? The mistake would be to abstract these two swings and say that all of his swings work this way. I think that they always want a prestressed shaft but that kind of precision isn't always going to happen in every swing.

Also the mistake would be to take any stop action photo of your sources and conclude that all swings for all golfers demonstrate a similar trait. The majority of the pros can be wrong at the same time. But with time they improve. The Pro's have made some impressive improvements during the past 50 years, and I'm sure that improvements will continue far long after the research you quote fades into obscurity.

THE SECRET

6-C-2-B. ANGULAR ACCELERATION The Clubhead “overtaking” speed is governed by the Law of Conservation of Angular Momentum whereby the increased Mass resulting from any extension of the Swing Radius decelerates the Hands and unless they are supported by Power Package Thrust (6-B-1) or Throw Out Action (2-K), can result in great loss of Clubhead speed. Rely on Clubhead Lag to meter out the necessary support for the Primary Lever Assembly. Strictly speaking, any increase in the product of Mass times Velocity is Acceleration whether or not the speed has changed. But the formula for Kinetic Energy gives Velocity the Greater value. And, actually, the acceptable tolerance in the Ball-to-Clubhead weight ratio is quite small.

6-C-2-C. IMPACT CUSHION The prestressed Clubshaft will resist the added weight of the ball during Impact, instead of cushioning the Impact with an unstressed Clubshaft. See 2-M-1

Clubhead Lag Pressure normally remains constant regardless of the Velocity it has produced. And both #1 and #3 Pressure Points are the product of Accumulator #1.

6-C-2-D. LAG LOSS The very small degree of Clubhead Lag permitted by Clubshaft Flex, makes this procedure especially susceptible to Clubhead Throwaway. And the stiffer the Clubshaft the less margin.

Over-Acceleration is the menace that stalks all Lag and Drag. Here it allows the Hands to reach maximum speed before reaching impact and so dissipates the Lag. So, the length of the Stroke and the amount of Thrust should be adjusted and balanced to produce a “High Thrust-Low Speed” Impact-“heavy” rather than “quick.” Daintiness is dangerous.

[jmessner]

Steph - I agree this was fun. I knew it might be a tough crowd, but a honest debate can be a learning experience for everyone. Daryl mentioned some images from Anikan, and I'll have to check those out. It's a miracle sometimes to find some images where contact hasn't already been made. I did find one thread with a sequence of Tiger though caught right before impact that I thought was interesting:

http://www.lynnblakegolf.com/forum/s...ead.php?t=2476

It's probably my crooked straightedge but the clubhead looks bowed forward to me. Now to get ready for an early morning round tomorrow.....

[Daryl]

Steph - I agree this was fun. I knew it might be a tough crowd, but a honest debate can be a learning experience for everyone. Daryl mentioned some images from Anikan, and I'll have to check those out. It's a miracle sometimes to find some images where contact hasn't already been made. I did find one thread with a sequence of Tiger though caught right before impact that I thought was interesting:

http://www.lynnblakegolf.com/forum/s...ead.php?t=2476

It's probably my crooked straightedge but the clubhead looks bowed forward to me. Now to get ready for an early morning round tomorrow.....

I'm sure you have Tigers book. On page 138 the swing sequence shows it Bending the proper way, before contact. I'm sure you can invent a way to dismiss this one too. Interesting how you fail to mention photos that don't support your personal views.

[Daryl]

I think that I can move closer to a conclusion on the issue of Prestressed Clubshafts.

Images of golfers using shorter irons exhibit the Prestressed bend through impact that HK wrote about. Most of the pictures of longer shafted clubs did not.

One answer might be that shorter clubs have a greater downward force so that when a clubshaft is initially bent, it may be easier to maintain that bend through impact.

The two photos illustrated in this thread illustrate a reverse bend in the Clubshafts prior to impact but the players appear to be trying to hit up on the ball.

I will keep looking for pictures of a golfer, with a graphite shaft driver who hits down on the ball consistent with TGM theory.

[ThinkingPlus]

I'm not saying I have the proof regarding shaft flex, or if certain things can be done or not- and certainly there are alot of factors- throwaway etc. that would influence a forward bending shaft. But the above photos of these clubshafts do not necessarily have a forward bending shaft at this point in the swing- if both of these golfers are swingers- which I believe they are- and you have the natural clubshaft "bowing up" that a swinger's shaft has, then when you view that "bowing up" i.e. that upside down "C" from the side as in these photos- then it will appear that the clubshaft is bending forward when it is not. So with so little "bending forward" - and the angle of these photo's - I would think that, that bending forward could be completely attributed to the "bowing up" of the clubshaft- which is the result of the sweetspot lining up with the line of pull/center of gravity application.

Very astute observation, Mike. If the camera is not perpendicular to the swing plane, in-plane bending cannot always be accurately seen by just observing displacement of the shaft and head in the image. Your explanation in this instance seems the most plausable.

[jmessner]

I'm sure you have Tigers book. On page 138 the swing sequence shows it Bending the proper way, before contact. I'm sure you can invent a way to dismiss this one too. Interesting how you fail to mention photos that don't support your personal views.

Don't have it - can you post? If it actually is before impact - then we have some conflicting data, but at least we have data.

[jmessner]

I'm not saying I have the proof regarding shaft flex, or if certain things can be done or not- and certainly there are alot of factors- throwaway etc. that would influence a forward bending shaft. But the above photos of these clubshafts do not necessarily have a forward bending shaft at this point in the swing- if both of these golfers are swingers- which I believe they are- and you have the natural clubshaft "bowing up" that a swinger's shaft has, then when you view that "bowing up" i.e. that upside down "C" from the side as in these photos- then it will appear that the clubshaft is bending forward when it is not. So with so little "bending forward" - and the angle of these photo's - I would think that, that bending forward could be completely attributed to the "bowing up" of the clubshaft- which is the result of the sweetspot lining up with the line of pull/center of gravity application.

Mike O - I missed this post from you earlier. What do you mean by "bowing up"? I think you basically reiterated the explanation given by the physics guys for the reason for the forward bend - the fact that the head sweetspot (center of gravity) lines up with the center of gravity of the shaft. Since the sweetspot is actually behind the face and shaft, there is a forward and downward bend (is this what you mean by bowing up?) of the shaft so the head CofG can line up with the shaft axis. For a driver (extreme case) the CofG is usually around 30mm behind the face.

[Mike O]

Mike O - I missed this post from you earlier. What do you mean by "bowing up"? I think you basically reiterated the explanation given by the physics guys for the reason for the forward bend - the fact that the head sweetspot (center of gravity) lines up with the center of gravity of the shaft. Since the sweetspot is actually behind the face and shaft, there is a forward and downward bend (is this what you mean by bowing up?) of the shaft so the head CofG can line up with the shaft axis. For a driver (extreme case) the CofG is usually around 30mm behind the face.

Actually, bowing up of the shaft was a reference to a vertical frame of reference- that is the Sweetspot is out on the clubhead somewhere- not at the end of the shaft- so the shaft has to bend up or I think Maltby or someone referred to it as clubhead droop. If you have that going on and are looking at it from an angle as in those photo's above-then that alone would look as if the clubhead was ahead of the grip- or bowing forward when really it was just bowing up.

Of course, you bring up a good point- that if the center of gravity of the clubhead is behind the shaft- due to the construction of the club - then that would create a situation for the Swinger who is using centrifugal force- where by during the swing/release -the shaft would be bowing forward.

In that regard, again the Hitter and Swinger are going to have different shaft motions- due to their acceleration methods- and that's why you have the Pre-stressed shaft for the Hitter and the Wallop of Centrifugal force.

For the swinger using centrifugal force (bowing up- to the degree the sweetspot is out away from the end of the shaft i.e. the longer your clubhead the more the shaft will have to bow up or the more the clubhead must droop down)for the Swinger. Likewise, the wider the clubhead/face the more the center of gravity is moved back in relation to the shaft and the more the shaft would have to bend foreward to line the center of gravity up with the #3 pressure point.

Here is the important distinction to make- for the swinger using a driver where the center of gravity of the clubhead is behind the shaft alignment based on the construction of the club. During release centrifugal force will want to line the #3 pressure point or grip end of the clubshaft with the center of gravity of the clubhead i.e. the longitudindal center of gravity of the club itself- thereby creating a situation where the shaft would bow forward. But that wouldn't mean that you don't have a lagging clubhead- if you're pulling/pulling/pulling and creating centrifugal force, you would have clubhead lag- in fact based on the construction of the club- if the shaft was straight and not bowed forward- that would be a situation where you did not have lag if you were Swinging the club!

P.S. pulling/pulling/pulling is more a mechanical description and not a procedural description- because I just invision someone trying to pull/pull/pull to make their movement- so don't go out and do that.