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Shaft Behaves Like A String At High Clubhead Speeds


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#1 WILDTHING

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Posted 12 February 2018 - 09:34 AM

Seeing that the moderators decided to delete my previous thread and I have confirmation that they are volunteers and really don't have any time to police these forums, here we go again (so welcome little trolls out there).

At high enough clubhead speeds, the shaft can be regarded as behaving like a string in your hands. That is , no matter what you do with your hands with regards creating any clubhead rotation , in plane, out of plane , or along the shafts axis, will have no effect on the clubhead. So basically for an optimal swing, you will need to assert actions on the club, quite a distance from clubhead to ball (if the clubhead speed is very high) and judge/predict where you need it to be for your intended shot. So you may as well just let the clubhead 'go' where it wants to go because, even if you can feel its going wrong, there is nothing you can do to retrieve the situation (especially during impact).

But

There is one force that can keep up with the clubhead up to and during impact and that is the tension along the shaft (ie. the pull factor). And if that force is not aligned along the whole length of the shaft can create 'A Moment of Force'  that can increase or decrease clubhead speed.

So my point is trying to actively 'wrist extend/wrist flex/flat left wrist/bowed left wrist'  during the period where the shaft acts like a string will have no affect on the clubhead. It might be good golf instruction to create wrist extension through impact (while still in flexion) as a secondary effect of other body movements but I think it has the added benefit of preparing the wrists for the sudden jarring forces caused by ball collision (especially for an off-centre strike).


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#2 SomedayScratch

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Posted 12 February 2018 - 09:38 AM

View PostWILDTHING, on 12 February 2018 - 09:34 AM, said:

Seeing that the moderators decided to delete my previous thread and I have confirmation that they are volunteers and really don't have any time to police these forums, here we go again (so welcome little trolls out there).

At high enough clubhead speeds, the shaft can be regarded as behaving like a string in your hands. That is , no matter what you do with your hands with regards creating any clubhead rotation , in plane, out of plane , or along the shafts axis, will have no effect on the clubhead. So basically for an optimal swing, you will need to assert actions on the club, quite a distance from clubhead to ball (if the clubhead speed is very high) and judge/predict where you need it to be for your intended shot. So you may as well just let the clubhead 'go' where it wants to go because, even if you can feel its going wrong, there is nothing you can do to retrieve the situation (especially during impact).

But

There is one force that can keep up with the clubhead up to and during impact and that is the tension along the shaft (ie. the pull factor). And if that force is not aligned along the whole length of the shaft can create 'A Moment of Force'  that can increase or decrease clubhead speed.

So my point is trying to actively 'wrist extend/wrist flex/flat left wrist/bowed left wrist'  during the period where the shaft acts like a string will have no affect on the clubhead. It might be good golf instruction to create wrist extension through impact (while still in flexion) as a secondary effect of other body movements but I think it has the added benefit of preparing the wrists for the sudden jarring forces caused by ball collision (especially for an off-centre strike).

What is the said period?

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#3 WILDTHING

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Posted 12 February 2018 - 09:55 AM

View PostSomedayScratch, on 12 February 2018 - 09:38 AM, said:

View PostWILDTHING, on 12 February 2018 - 09:34 AM, said:

Seeing that the moderators decided to delete my previous thread and I have confirmation that they are volunteers and really don't have any time to police these forums, here we go again (so welcome little trolls out there).

At high enough clubhead speeds, the shaft can be regarded as behaving like a string in your hands. That is , no matter what you do with your hands with regards creating any clubhead rotation , in plane, out of plane , or along the shafts axis, will have no effect on the clubhead. So basically for an optimal swing, you will need to assert actions on the club, quite a distance from clubhead to ball (if the clubhead speed is very high) and judge/predict where you need it to be for your intended shot. So you may as well just let the clubhead 'go' where it wants to go because, even if you can feel its going wrong, there is nothing you can do to retrieve the situation (especially during impact).

But

There is one force that can keep up with the clubhead up to and during impact and that is the tension along the shaft (ie. the pull factor). And if that force is not aligned along the whole length of the shaft can create 'A Moment of Force'  that can increase or decrease clubhead speed.

So my point is trying to actively 'wrist extend/wrist flex/flat left wrist/bowed left wrist'  during the period where the shaft acts like a string will have no affect on the clubhead. It might be good golf instruction to create wrist extension through impact (while still in flexion) as a secondary effect of other body movements but I think it has the added benefit of preparing the wrists for the sudden jarring forces caused by ball collision (especially for an off-centre strike).

What is the said period?

Good question . I have asked the same and haven't received an answer (yet!).

But according to Tutelman's website , if a clubhead is swinging at very high speeds the typical force generated by a clubhead on a ball at impact is 2000 Ibs force.  To actually implement a change in that force by 1%  (ie. 20 Ibs -which is generally used as a noticeable change) the shaft would have to bend 10 inches.  That does not happen in a real golf swing .

So my guess , for really high speed swingers, the shaft is acting like a piece of string when the clubhead is quite a distance from the ball. The actions being done to predict where the clubhead will be 'at /during impact' will all have to be completed for a longer period of time before impact (than say ball strikes at baseball, tennis , etc). All trained and ingrained into the subconscious.

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#4 Golfrnut

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Posted 12 February 2018 - 10:05 AM

I think you are talking a lot more on the discussion of human reflexes than shaft performance no?

As for how the swing is working...the GEARS information that is coming out now is helping to clarify a lot of what exactly is taking place, how the hands are decelerating, shaft going to lead bend, etc.


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#5 Stuart G.

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Posted 12 February 2018 - 10:21 AM

View PostWILDTHING, on 12 February 2018 - 09:55 AM, said:

Good question . I have asked the same and haven't received an answer (yet!).

But according to Tutelman's website , if a clubhead is swinging at very high speeds the typical force generated by a clubhead on a ball at impact is 2000 Ibs force.  To actually implement a change in that force by 1%  (ie. 20 Ibs -which is generally used as a noticeable change) the shaft would have to bend 10 inches.  That does not happen in a real golf swing .

So my guess , for really high speed swingers, the shaft is acting like a piece of string when the clubhead is quite a distance from the ball. The actions being done to predict where the clubhead will be 'at /during impact' will all have to be completed for a longer period of time before impact (than say ball strikes at baseball, tennis , etc). All trained and ingrained into the subconscious.

For impact, the "period" is ~ 1/2 millisecond.   The amount of time it takes the club head to move maybe 3/4". So the consequences of the impact forces and the responsiveness of the club to forces applied by the player during the swing are two VERY different time scales.

But the actual general rule is that as the momentum increases, so will the delay between when the club responds to the forces input at the grip end of the shaft.  The amount of elasticity also plays a part - which is why the axial forces will have a quicker response (because the shaft is less flexible in that axial direction).   Just realize that linear and rotational momentum are independent.   So a fast club head speed means higher linear momentum and would make the path control less responsive - but it doesn't mean that the rotational momentum would necessarily be high and the face control less responsive.

And of course, as mentioned above, the nervous system itself will add some delays as well. From what I've read, is optimally somewhere around 20 milliseconds from the brain to the hands (~3 ft of club head travel distance).

Edited by Stuart G., 12 February 2018 - 10:28 AM.


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#6 Solidstrike

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Posted 12 February 2018 - 03:47 PM

I’m not sure what the point of this topic is or even why I’m chiming in.

I don’t know about you guys, but I start the downswing by rotating and letting my hands drop into the slot, whatever happens through impact... just happens.  Trying to control the forces through impact is probably hazardous to your health.  

I can see how the instruction is to extend through impact to make sure you’re fully releasing the club down the line but that’s more of a direction to release to and not an attempt to control the wrists.

Edited by Solidstrike, 12 February 2018 - 03:47 PM.


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#7 juststeve

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Posted 12 February 2018 - 03:59 PM

We may be talking about different things here but it is certainly possible to manipulate the club face at impact with hand action. I can quite easily deliver the face, closed, open, turned down and turned up by manipulating it with my hands, whether the shaft acts like a string or not.

Steve  .

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#8 WILDTHING

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Posted 12 February 2018 - 07:02 PM

---------------
I think you are talking a lot more on the discussion of human reflexes than shaft performance no?

As for how the swing is working...the GEARS information that is coming out now is helping to clarify a lot of what exactly is taking place, how the hands are decelerating, shaft going to lead bend, etc.
-------------

No , not really. I am basically saying that when the club shaft starts behaving like a string  (and we don't know exactly when that happens in the downswing) , there is very little one can do with the hands to influence the clubheads motion (except maybe in the the axial direction). We definitely cannot influence the clubhead during impact as Stuart G has posted above because the response time from hands through shaft to clubhead takes longer than the duration through impact. I've just received a reply from  a golf scientist to some of my questions about when does the shaft become a string , and does it behave like string with regards tension and torque (around its axial length) . He provided me an answer below. Note the section I made bold and underlined which suggests he thinks that it might also behave like a string leading up to impact.

------------------------------------
I am talking about the shaft being a string DURING impact. Not leading up to it. (I might make a case below for that too, but it's not the point I was making.) Sasho is talking about getting the clubhead speed ENTERING impact. So two completely different things.

But as I said, there are a couple of other interesting points:

When Sasho talks about the moment overcoming the couple around club parallel, he is saying the hands' torque can't keep up with the clubhead speed, so only the moment of force will. "Can't keep up." What I'm saying is: even if the hands could keep up, it wouldn't matter during impact.

A string transmits tension just fine; it can't transmit compression or shear, which are necessary to develop resistance to a lateral force. But resistance to an axial force is tension. So the moment of the force WILL be transmitted to the clubhead, even during impact, because the force in this case is mostly along the axis of the shaft. (I haven't looked in enough detail to know if the small angle between force and shaft matters in this conclusion. And I am not intending to do that analysis.)

It is also a string in torque. Not as radically as in deflection; you can come close to the 1% torque number with the deflection that actually happens during impact but it's still a factor of 2 or 3 off.
-----------------

The reference to Sasho McKenzie was related to his video below (which can get a bit complicated unless you remember some of your old Physics lessons). When Sasho mentions the 'in plane couple'  goes to zero or negative when club is approx parallel to the ground in the downswing, I may have mistakenly thought that is when the shaft might behave like a string because the hands just can't keep up.  But on reflection , maybe it can't keep up from P6 ( from an 'in plane coupling' perspective) but that doesn't mean the shaft has become a 'string'  . Maybe the hands can still influence clubhead rotation around the axial shaft a lot closer to impact but then has zero effectiveness during impact.

https://vimeo.com/158856998

Anyhow , this is just a post to discuss the academic side of the golf swing , so maybe I shouldn't have created this Topic in the  'instruction section' .

PS. I'm wondering whether any measurements/graphs have been made that compares 'handle twist velocity' vs 'clubhead twist velocity'  in the downswing and through impact?  Wouldn't that show the 'hand influencing  clubhead' response time interval and prove when a shaft becomes a string from an axial torque perspective?

Edited by WILDTHING, 13 February 2018 - 03:56 AM.


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#9 WILDTHING

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Posted 13 February 2018 - 04:27 AM

View PostStuart G., on 12 February 2018 - 10:21 AM, said:

View PostWILDTHING, on 12 February 2018 - 09:55 AM, said:

Good question . I have asked the same and haven't received an answer (yet!).

But according to Tutelman's website , if a clubhead is swinging at very high speeds the typical force generated by a clubhead on a ball at impact is 2000 Ibs force.  To actually implement a change in that force by 1%  (ie. 20 Ibs -which is generally used as a noticeable change) the shaft would have to bend 10 inches.  That does not happen in a real golf swing .

So my guess , for really high speed swingers, the shaft is acting like a piece of string when the clubhead is quite a distance from the ball. The actions being done to predict where the clubhead will be 'at /during impact' will all have to be completed for a longer period of time before impact (than say ball strikes at baseball, tennis , etc). All trained and ingrained into the subconscious.

For impact, the "period" is ~ 1/2 millisecond.   The amount of time it takes the club head to move maybe 3/4". So the consequences of the impact forces and the responsiveness of the club to forces applied by the player during the swing are two VERY different time scales.

But the actual general rule is that as the momentum increases, so will the delay between when the club responds to the forces input at the grip end of the shaft.  The amount of elasticity also plays a part - which is why the axial forces will have a quicker response (because the shaft is less flexible in that axial direction).   Just realize that linear and rotational momentum are independent.   So a fast club head speed means higher linear momentum and would make the path control less responsive - but it doesn't mean that the rotational momentum would necessarily be high and the face control less responsive.

And of course, as mentioned above, the nervous system itself will add some delays as well. From what I've read, is optimally somewhere around 20 milliseconds from the brain to the hands (~3 ft of club head travel distance).

Considering your comment about the 20 ms delay from 'brain to hands'. Yes , I've read an article below which was quite interesting.

https://theconversat...a-thought-42392

"Surprisingly, people typically judge the onset of their movement to occur 75-100 ms prior to when it actually began. This difference cannot be accounted for simply by the time it takes for the movement commands to travel from the brain to the arm muscles (which is on the order of 16-25 ms). It’s unclear exactly why this misperception occurs, but it’s generally believed that people base their judgment of movement onset on the time of the decision to act and the prediction of the upcoming movement, instead of on the movement itself. These and other findings raise important questions about the planning and control of action and our sense of agency and control in the world – because our decision to act and our perception of when we act appear to be distinct from when we in fact do."

So maybe as golfers, we should be thinking of doing  'release' a lot earlier than we actually do.

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#10 Stuart G.

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Posted 13 February 2018 - 05:04 AM

Yes, we are thinking of doing things a lot earlier then we might think we are.

I might not have said it explicitly but in this context you can forget the "shaft as a string" theory, it doesn't really apply.

The whole idea (or science behind) making corrections during the swing is an interesting one but (IMO) the most important question is really when does the player first realize that a correction might be needed and the process to make a correction actually start?   I don't know, but I suspect that the better the player, the earlier in the swing they realize that something isn't quite right.  Likely even as soon as the start of the transition.


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#11 WILDTHING

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Posted 13 February 2018 - 12:12 PM

View PostStuart G., on 13 February 2018 - 05:04 AM, said:

Yes, we are thinking of doing things a lot earlier then we might think we are.

I might not have said it explicitly but in this context you can forget the "shaft as a string" theory, it doesn't really apply.

The whole idea (or science behind) making corrections during the swing is an interesting one but (IMO) the most important question is really when does the player first realize that a correction might be needed and the process to make a correction actually start?   I don't know, but I suspect that the better the player, the earlier in the swing they realize that something isn't quite right.  Likely even as soon as the start of the transition.

So basically , it is irrelevant whether the shaft is acting like a string or not , because by the time we've acted on a thought to use our hands (maybe from P6.5 onwards at a guess) to try and influence the clubhead, it has already probably moved about 3ft and through impact?

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#12 Stuart G.

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Posted 13 February 2018 - 12:54 PM

View PostWILDTHING, on 13 February 2018 - 12:12 PM, said:

So basically , it is irrelevant whether the shaft is acting like a string or not , because by the time we've acted on a thought to use our hands (maybe from P6.5 onwards at a guess) to try and influence the clubhead, it has already probably moved about 3ft and through impact?

While that scenario is a possibility it's not really what I meant by it not applying.   It doesn't apply because the time frame is relatively long enough that it (the shafts ability to transfer force to the head) is not really the limiting factor in how much we can control the club head. e.g. IF the correction starts early enough in the swing relative to the reaction time, the shaft likely isn't going to prevent the correction from getting to the club head.  But that also  depends a bit on the specific nature of the correction.

No hard data on this but I suspect one would have to start the correction shortly after P4 to have any chance of that correction having any effect on the ball flight.

For those pro's that have reported being able to hit a shot shape their instructor/coach calls out in the back swing - how late in the swing can that call get and still have the player hit the called shot?  Any videos of this?

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#13 gvogel

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Posted 13 February 2018 - 12:55 PM

Bobby Jones thought of the shaft as "an imponderable medium."

I don't know if that adds anything at all to the discussion, but I always enjoy reading Bobby Jones.
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#14 glk

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Posted 13 February 2018 - 01:42 PM



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#15 Etzwane

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Posted 14 February 2018 - 05:08 AM

View PostWILDTHING, on 12 February 2018 - 09:34 AM, said:

Seeing that the moderators decided to delete my previous thread and I have confirmation that they are volunteers and really don't have any time to police these forums, here we go again (so welcome little trolls out there).

At high enough clubhead speeds, the shaft can be regarded as behaving like a string in your hands. That is , no matter what you do with your hands with regards creating any clubhead rotation , in plane, out of plane , or along the shafts axis, will have no effect on the clubhead. So basically for an optimal swing, you will need to assert actions on the club, quite a distance from clubhead to ball (if the clubhead speed is very high) and judge/predict where you need it to be for your intended shot. So you may as well just let the clubhead 'go' where it wants to go because, even if you can feel its going wrong, there is nothing you can do to retrieve the situation (especially during impact).

But

There is one force that can keep up with the clubhead up to and during impact and that is the tension along the shaft (ie. the pull factor). And if that force is not aligned along the whole length of the shaft can create 'A Moment of Force'  that can increase or decrease clubhead speed.

So my point is trying to actively 'wrist extend/wrist flex/flat left wrist/bowed left wrist'  during the period where the shaft acts like a string will have no affect on the clubhead. It might be good golf instruction to create wrist extension through impact (while still in flexion) as a secondary effect of other body movements but I think it has the added benefit of preparing the wrists for the sudden jarring forces caused by ball collision (especially for an off-centre strike).

I have never seen the shaft being described as acting as a string at any moment in the swing. During the impact interval, only the lower part of the shaft responds to impact (given the collision time and the speed of propagation of deformations in the shaft), so I would not call that acting like a string. Clearly the player cannot detect nor react to what is happening during the time of contact but the club path and face rotation changes during impact according to the forces the player applied before contact.


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#16 Stuart G.

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Posted 14 February 2018 - 06:52 AM

View PostEtzwane, on 14 February 2018 - 05:08 AM, said:

I have never seen the shaft being described as acting as a string at any moment in the swing. During the impact interval, only the lower part of the shaft responds to impact (given the collision time and the speed of propagation of deformations in the shaft), so I would not call that acting like a string.

Several scientific papers have validated that it is actually is largely the case so it's actually a fairly well established concept.  The influence of the shaft, is pretty much negligible with respect to the physics that determine the ball flight from the impact conditions and the 'string' behavior assumption results in generally accurate results. The only questionable exception seems to be when it comes to vertical gear effect - and even those that think the shaft does have some influence admit that while maybe not completely negligible, the influence is still extremely small.

Edited by Stuart G., 14 February 2018 - 07:00 AM.


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#17 Etzwane

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Posted 15 February 2018 - 12:51 AM

View PostStuart G., on 14 February 2018 - 06:52 AM, said:

View PostEtzwane, on 14 February 2018 - 05:08 AM, said:

I have never seen the shaft being described as acting as a string at any moment in the swing. During the impact interval, only the lower part of the shaft responds to impact (given the collision time and the speed of propagation of deformations in the shaft), so I would not call that acting like a string.

Several scientific papers have validated that it is actually is largely the case so it's actually a fairly well established concept.  The influence of the shaft, is pretty much negligible with respect to the physics that determine the ball flight from the impact conditions and the 'string' behavior assumption results in generally accurate results. The only questionable exception seems to be when it comes to vertical gear effect - and even those that think the shaft does have some influence admit that while maybe not completely negligible, the influence is still extremely small.

Thanks for the information but even if the shaft has negligible effet effetg impact intervalle that does not make it look like a string in the sense of the OP. It still transmit the golfer action to the clubhead, with a delay that is sizeable compared to impact duration but negligible compared to human perceptions/reaction.

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#18 Stuart G.

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Posted 15 February 2018 - 06:19 AM

View PostEtzwane, on 15 February 2018 - 12:51 AM, said:

Thanks for the information but even if the shaft has negligible effet effetg impact intervalle that does not make it look like a string in the sense of the OP. It still transmit the golfer action to the clubhead, with a delay that is sizeable compared to impact duration but negligible compared to human perceptions/reaction.

Correct - which is exactly why I said the same thing in a couple of my previous posts.

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#19 Man_O_War

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Posted 15 February 2018 - 09:09 AM

View PostWILDTHING, on 12 February 2018 - 09:34 AM, said:

Seeing that the moderators decided to delete my previous thread and I have confirmation that they are volunteers and really don't have any time to police these forums, here we go again (so welcome little trolls out there).

At high enough clubhead speeds, the shaft can be regarded as behaving like a string in your hands. That is , no matter what you do with your hands with regards creating any clubhead rotation , in plane, out of plane , or along the shafts axis, will have no effect on the clubhead. So basically for an optimal swing, you will need to assert actions on the club, quite a distance from clubhead to ball (if the clubhead speed is very high) and judge/predict where you need it to be for your intended shot. So you may as well just let the clubhead 'go' where it wants to go because, even if you can feel its going wrong, there is nothing you can do to retrieve the situation (especially during impact).

But

There is one force that can keep up with the clubhead up to and during impact and that is the tension along the shaft (ie. the pull factor). And if that force is not aligned along the whole length of the shaft can create 'A Moment of Force'  that can increase or decrease clubhead speed.

So my point is trying to actively 'wrist extend/wrist flex/flat left wrist/bowed left wrist'  during the period where the shaft acts like a string will have no affect on the clubhead. It might be good golf instruction to create wrist extension through impact (while still in flexion) as a secondary effect of other body movements but I think it has the added benefit of preparing the wrists for the sudden jarring forces caused by ball collision (especially for an off-centre strike).

not a new  concept but well captured.   It's not just a string, it's a string with a weighted ball on the end of it and rotates around the wrist.  Dan Martin and other physic buffs have all kinds of terms to describe this action and doesn't just apply to high speeds if you include the weight on end of string thought...because that introduces center of mass to the equation, which would be somewhere lower on the string in the case and the center of mass has to be in line with shaft...where force is applied.
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#20 WILDTHING

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Posted 15 February 2018 - 07:01 PM

View PostStuart G., on 13 February 2018 - 12:54 PM, said:

View PostWILDTHING, on 13 February 2018 - 12:12 PM, said:

So basically , it is irrelevant whether the shaft is acting like a string or not , because by the time we've acted on a thought to use our hands (maybe from P6.5 onwards at a guess) to try and influence the clubhead, it has already probably moved about 3ft and through impact?

While that scenario is a possibility it's not really what I meant by it not applying.   It doesn't apply because the time frame is relatively long enough that it (the shafts ability to transfer force to the head) is not really the limiting factor in how much we can control the club head. e.g. IF the correction starts early enough in the swing relative to the reaction time, the shaft likely isn't going to prevent the correction from getting to the club head.  But that also  depends a bit on the specific nature of the correction.

No hard data on this but I suspect one would have to start the correction shortly after P4 to have any chance of that correction having any effect on the ball flight.

For those pro's that have reported being able to hit a shot shape their instructor/coach calls out in the back swing - how late in the swing can that call get and still have the player hit the called shot?  Any videos of this?

Just for a bit of fun  I looked at the example of a pros swing on the video below (using 3D Technology - Gears I think)

https://www.youtube....h?v=j6SkUz3bxUY


I've looked at the stopwatch in the video and plotted the approx times for the following approx positions:

P-Position time    Time Constant (if I assume 5-iron in video)
P4 : 0.80 secs 0.031 secs
P5 : 0.86 secs 0.031 secs
P6 : 0.93 secs 0.031 secs
P7 : 0.97 secs 0.031 secs

I got the  'Time constant' figure from Tutelmans site below for a 5 iron.

https://www.tutelman...hp#timeConstant

He summarised the following about how 'Time Constants'  could be used:

***   If the interaction lasts more than about 3-6 time constants, then the object's elasticity has time to respond. The impinging object will "feel" the whole object respond.

*** If the interaction lasts less than about 1/3-1/6 of a time constant, the impinging object will only "feel" the immediate fragment of the object that it touches. The rest is too "loosely coupled" to the point of impact.

So from P4- P5 it took 0.06 secs  . The actual interaction time felt in the hands  is about 2 time constants (ie. 2 x 0.031 secs).  So I am assuming the golfer would only be feeling a little more than the fragment of the club in his hands.

From P5- P6 it took 0.07secs  (but obviously over a longer distance) . The actual interaction time is about 2  time constants.  So the golfer is feeling a little more than the fragment of the club in his hands.

From P6-P7 it took 0.04 secs (again maybe over a longer distance) . The actual interaction time is less than 1 time constant and the golfer would still be feeling a little more than just a fragment of the club (but less than the previous positions).

So lets assume he has one overall thought to do something with the club from P4- P7  (0.17 secs) .  The interaction time would be about 5 time constants . In the latter scenario he should theoretically feel the whole object respond (at least for some part of the 0.17 secs)

So maybe the golf swing is decided by a specific thought to do something from P4 to at least P7  if a golfer actually wants to feel the whole club respond (in the way he intended). If he thinks about doing something later in the downswing , he is going to feel less in terms of clubhead response.

Straitjacket time :fie:

PS. So quite simply, the result of your golf swing is primarily dictated in the slowest part of your downswing.

Edited by WILDTHING, 15 February 2018 - 08:13 PM.


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#21 Etzwane

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Posted 16 February 2018 - 01:07 AM

Research in neuroscience show that the entire downswing to impact is programmed and there is no time for a human to feel what is happening, let alone act. Swing corrections happen no later than transition as a reaction to backswing feels.

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#22 Stuart G.

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Posted 16 February 2018 - 04:33 AM

View PostWILDTHING, on 15 February 2018 - 07:01 PM, said:

He summarised the following about how 'Time Constants'  could be used:

It's an interesting application of that concept but there are a few flaws in how you are applying it.

1) It assumes no preload on the shaft.  For most of the transition and first half of the down swing, there tends to be a significant amount of longitudinal load on the shaft and that would make a big difference in the response time.

2) That value only applies to control of the head in the longitudinal planes.  For face orientation, you'd need to get the natural torsional response frequency.  Never seen that measured so can't say what those values might be but I strongly suspect it's a much higher frequency.   It also doesn't include axial control - essentially where the hands are (relative to the head) at impact which might largely come from potential 'adjustments' to release timing or sequencing of the different body parts.

View PostEtzwane, on 16 February 2018 - 01:07 AM, said:

Research in neuroscience show that the entire downswing to impact is programmed and there is no time for a human to feel what is happening, let alone act. Swing corrections happen no later than transition as a reaction to backswing feels.

Links?  

Personally I would expand that to say back swing and transition feels.   No data to back it up,  but I would think corrections can be 'programmed' as well.  At least they are rarely the result of a purely conscious thought process from my (very limited) observations.  Not a lot different then the 'automatic' reactions one has to tripping on something and the resulting reactions/corrections to regain balance.   And just like tripping, the presence of the reaction or correction, and the success of those corrections are two very different things.

EDIT:  while I find this topic an interesting one, I must add that it's out of pure scientific curiosity.  The usefulness of any conclusions in the real world are highly questionable.  Will it change how we approach the game in any way?  equipment selection, shot selection, training and/or decisions on swing changes?   Not in any productive way that I can foresee.

Edited by Stuart G., 16 February 2018 - 05:18 AM.


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#23 Etzwane

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Posted 16 February 2018 - 08:09 AM

View PostStuart G., on 16 February 2018 - 04:33 AM, said:


Links?  


Unfortunately not, this was from a couple of seminar from a golf pro working with researchers on neuroscience applied to sports. Backswing is long enough to be in closed-loop (have time for proprioception and action in feedback) while downswing is in open-loop (motor action is programmed and executed, no time for feedback and action).

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#24 WILDTHING

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Posted 17 February 2018 - 08:02 AM

I'm sure that it will be useful as knowledge about the golf swing builds up over many more years. For example, the preloaded aspect in takeaway , at top of backswing and transition. We see many golfers starting their downswing while the club is still moving slightly into the top of the backswing , so doesn't that create more loading on the shaft and therefore the ability to feel the weight of the whole club through one's hands/fingers (rather than fragments)? Doesn't that offer a better opportunity for the club to respond quicker to any intended actions/corrections via our hands/fingers on the grip?  If proof were found that success in performing an intended golf swing depended on certain feels in the takeaway/transition , then maybe instruction could be concentrated more in perfecting those areas.

For example , one could create 'swing cues'  to improve the takeaway and transition if we knew for certain those were the primary areas where the golf club best responded to a golfers intent . Further, we know from scientific studies that 'external swing cues'  are  better for learning (and retention of learning) than internal swing cues.

Quote Dr Gabriele Wulf
“There are good swing thoughts and bad swing thoughts” says Dr Gabriele Wulf, a professor of kinesiology at UNLV and a leading expert on performance cue research.  “We have found that the swing cues that shift your attention away from your body, what we call external cues, are much more effective than internal swing cues, or those that focus on your body.  Dr. Wulf goes a step further and says, “In decades of research, I’ve never seen anyone improve by using internal swing thoughts.”

So I think we are slowly getting there in golf instruction where bits of the puzzle are slowly coming together from physics, biomechanics , neurology,, etc etc.

Edited by WILDTHING, 17 February 2018 - 08:05 AM.


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#25 Stuart G.

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Posted 18 February 2018 - 05:02 AM

View PostWILDTHING, on 17 February 2018 - 08:02 AM, said:

I'm sure that it will be useful as knowledge about the golf swing builds up over many more years. For example, the preloaded aspect in takeaway , at top of backswing and transition. We see many golfers starting their downswing while the club is still moving slightly into the top of the backswing , so doesn't that create more loading on the shaft and therefore the ability to feel the weight of the whole club through one's hands/fingers (rather than fragments)?

No.  The weights there for the person to feel irrespective of how much the shaft loads.  The only thing the amount of load does is change the time period over which the individual might feel the change in momentum or acceleration of the head.  e.g. softer or more load will just spread it out over a bit more time while a firmer shaft, the feel will be more abrupt.  But there is no "right" or "wrong" feel independent of the players own subjective interpretation of that feel.  And it's not going to be a limiting factor on what the player really can do or not (assuming the general stiffness of the shaft is in the right ball park for the individual's swing).

View PostWILDTHING, on 17 February 2018 - 08:02 AM, said:

Doesn't that offer a better opportunity for the club to respond quicker to any intended actions/corrections via our hands/fingers on the grip?  If proof were found that success in performing an intended golf swing depended on certain feels in the takeaway/transition , then maybe instruction could be concentrated more in perfecting those areas.

learning a swing - or the Intended actions is really a different topic.  While the feel from the shaft loading might be used by some in that context, it's not (IMO) really an ideal since it can be too variable and inconsistent and therefore unreliable.   Observations from many experienced and high quality fitters have shown us that.

Edited by Stuart G., 18 February 2018 - 05:04 AM.


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#26 Golfer827

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Posted 18 February 2018 - 08:31 AM

It’s certainly valid in the concept. However, I think this isn’t completely accurate. The shaft is like a string, but I feel it’s in more of a trebuchet type of operation.

As the weight of the club head is accelerated toward the ball, the shaft holds back until the club and head itself is parallel to the ground. At that point, the weight of the club head reacts to gravity and increases velocity faster than the kick point area of the shaft up to impact. Similar to a trebuchet after it releases its projectile of choice, only said projectile’s holster was around too much of the projectile.

The speed increase is minute, in relativity to overall acceleration, but that is where the bend profile of the shaft at those very high speeds comes into play. However, that is beyond my personal comprehension of the shaft at this time.

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#27 coops

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Posted 18 February 2018 - 08:47 AM

View PostEtzwane, on 16 February 2018 - 08:09 AM, said:

View PostStuart G., on 16 February 2018 - 04:33 AM, said:

Links?  


Unfortunately not, this was from a couple of seminar from a golf pro working with researchers on neuroscience applied to sports. Backswing is long enough to be in closed-loop (have time for proprioception and action in feedback) while downswing is in open-loop (motor action is programmed and executed, no time for feedback and action).

Just get a copy of "Search for the Perfect Swing" - Cochran & Stubbs, quite a famous golf instructional book... they describe this and an experiment that was done to prove it. ("It" being the idea that after transition it's too late to respond to anything - the testers were unable to miss the ball even when trying to when given a signal immediately after transition).

They also talk about the club at impact being pretty much a free body - club head and about 10 inches of shaft if i remember correctly - and again test it with a (persimmon) driver head made with a hinge in the hosel.

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#28 WILDTHING

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Posted 18 February 2018 - 10:23 AM

View Postcoops, on 18 February 2018 - 08:47 AM, said:

View PostEtzwane, on 16 February 2018 - 08:09 AM, said:

View PostStuart G., on 16 February 2018 - 04:33 AM, said:

Links?  


Unfortunately not, this was from a couple of seminar from a golf pro working with researchers on neuroscience applied to sports. Backswing is long enough to be in closed-loop (have time for proprioception and action in feedback) while downswing is in open-loop (motor action is programmed and executed, no time for feedback and action).

Just get a copy of "Search for the Perfect Swing" - Cochran & Stubbs, quite a famous golf instructional book... they describe this and an experiment that was done to prove it. ("It" being the idea that after transition it's too late to respond to anything - the testers were unable to miss the ball even when trying to when given a signal immediately after transition).

They also talk about the club at impact being pretty much a free body - club head and about 10 inches of shaft if i remember correctly - and again test it with a (persimmon) driver head made with a hinge in the hosel.

I think I'll take your advice and buy a copy of this book (I've read some of the reviews and they are all very positive).

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#29 Golfrnut

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Posted 18 February 2018 - 10:52 AM

View PostGolfer827, on 18 February 2018 - 08:31 AM, said:

It’s certainly valid in the concept. However, I think this isn’t completely accurate. The shaft is like a string, but I feel it’s in more of a trebuchet type of operation.

As the weight of the club head is accelerated toward the ball, the shaft holds back until the club and head itself is parallel to the ground. At that point, the weight of the club head reacts to gravity and increases velocity faster than the kick point area of the shaft up to impact. Similar to a trebuchet after it releases its projectile of choice, only said projectile’s holster was around too much of the projectile.

The speed increase is minute, in relativity to overall acceleration, but that is where the bend profile of the shaft at those very high speeds comes into play. However, that is beyond my personal comprehension of the shaft at this time.

Good swing thoughts or bad swing thoughts, we’re all at the mercy once we hit that proverbial point of no return.

It's not really gravity.  Club head/shaft behavior has a lot more to due with centripedal force, acceleration, hands/arms accelerating then decelerating before impact, etc.  The moment that the shaft goes from lag/lead deflection has a lot to do with the acceleration/deceleration of the hands/arms and timing of the wrist angles.

Edited by Golfrnut, 18 February 2018 - 10:54 AM.

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