Yes, it's interesting to see pool players put the chin on the cue and pendulum stroke, invariably leading to head movement.
Johan Ruijsink stroke theory
- Thread starter Tennesseejoe
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Close is almost as good. Anyway, I think the head would have to be at least several inches, maybe a foot above the cue to have the shoulder as high as the elbow.
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Dell Hill advocates the 4 point stance. The grip, the bridge and chin make three. The chest to cue instruction is his final. His description of the pendulum stroke with the basic 4 point snooker stance is uncomplementary, “like chickens pecking”. The grip hand comes to the chest, rebounding back much like a peck. The effect of that peck over time, is that subconsciously, the body realizes it is being hit. The net result is that the body adjusts, lifting up. If the lift comes before the stroke, the chin ends up off the cue. If the pendulum is used for the forward half of the stroke many players lift up on the forward part of the shot to avoid the body contact. Hill didn’t fight the need for a downward plane, he set it as the norm. That way the head and cue are both up at address. The higher back of swing transition point allows the guarantee of a straight backswing using the bridge to chest wall, a strength of the 4 point method. Once in line at the back, the forward swing needs to stay in the same vertical plane going forward to stay on line. The wall is not used to guide the cue forward. The intent of the forward swing is still to go through straight but not to have the chest impede the stroke going forward. The cue comes down, not the head going up. The room to come down was created by the higher address position. The whole arm can initiate the forward move down and through. One side benefit is that the arm initiates the stroke, not the hand, and it slows down the transition. Since the cue should be on line at the back of the stroke the hand should stay quiet except for any needed pressure applied by a sideways squeeze.
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Isn't the longer lever length a source of additional power with identical tip speed? Just asking. Wouldn't it be the same as calculating torque? Length times Force?
Just speculating the shoulder can't move as fast as the elbow/forearm and the shoulder more or less hinders total speed and not a multiplier.
No. Measurements have shown that the flesh of the hand is much, much softer and pliable than the tip. By the time the hand, wrist, forearm, upper arm barely begin to influence the cue stick, the ball is gone. None of this stuff happens instantaneously so you have to take the different times of reaction into consideration.
It is the same for a golf club. Even though the amount of compression for a golf ball is much larger than for a tip/ferrule/shaft/butt during contact, because the speed is much higher, the contact time is only 0.5 milliseconds, or about half the time of tip-to-cue-ball contact. During that time, the bending wave from the club head to the grip does not have time to get to the grip hands. If a laser cut the golf club off at the bottom of the grip just before impact, the impact and shot would not be changed.
The important difference is the ratio of grip hand movement to joint movement - a full arm movement doubles it.
pj
chgo
Here is a link to a snooker coach demonstrating and talking about both styles. His analysis of the pendulum stroke being level throughout is incorrect. To keep the cue flat the elbow would need to drop during the backswing.
https://youtu.be/438vW9gkUYg
I like Dell Hills descriptions better.
Yes, and then it has to rise and then drop again during the forward stroke.
But to be clear, the “full arm movement” I spoke of is neither a pendulum or piston stroke.
pj
chgo
I agree. The model starts with a downward plane at address. From that address position, the cue is arced back like the first half of the pendulum stroke, fulfilling the snooker 4 point contact model. In theory the cue has now been drawn back in a straight line with the bridge and side of the chest constraining sideways movement. At the back, the cue plane is more elevated than is normal for a standard pendulum stroke. In theory the cue is vertically aligned with the shot line. In other words it is still lined up before moving forward. This is where the elbow starts down flattening the plane. While the elbow may lower slightly the entire arm is simply set in motion by the move.
A natural toss motion while standing uses the same dynamic. On the final back motion, in a toss, the elbow angle opens. Once the forward toss motion is initiated, the elbow remains open while the whole arm initiates the forward movement. The elbow now becomes part of a dynamic motion sensing the internally calibrated action needed to gauge velocity and trajectory, st the elbow closes.
You are absolutely correct, the whole arm stroke is neither a pendulum nor a piston stroke. Arm alignment is crucial to the stroke. That said once aligned it is harder to throw off line and allows a slower velocity to achieve the same momentum. From a motor skill perspective it should theoretically reduce errors.
The advocacy for a pendulum stroke is theoretical in nature as well. It starts with a level cue at address, and a vertical forearm at contact. The objective is a simple engine taking the cue through a level plane at contact. While it makes a good teaching model for neophytes, more advanced players need to realize that theory often doesn’t translate into practice. It’s a good first step, but it’s only AN ANALOGY. It’s like believing that a map is the actual road. A conceptual model is just a guide. When reality differs it can be a round hole/square peg scenario when context doesn’t match the analogy. Stick to the analogy when it it’s useful but be willing let it go when it’s not.
Are you saying it's not physiologically possible or not an effective pool stroke? I think it's clearly both.
pj
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I’m saying that trying to sell a flat stroke model for the pendulum stroke flies in the face of reality and you don’t disagree. As to the possibility of a circular arc being able to produce a horizontal contact through impact the answer is yes. There is only a single point in the arc where it would be truly level, in theory. Most pros don’t use it to the exclusion of other strokes. That suggests that when viewed situationally players are finding other methods a better choice, for them. Even Ronnie O’Sullivan, often pointed at as an elbow drop example, sometimes uses a pendulum stroke. Watch when he has shorter stun shots or soft draws, a pendulum suits his purposes, on a case by case basis. Are you saying that the arm is a true pendulum or is it just an analogous description of the motion and path?
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I don’t know what that means.
What’s a “true pendulum” if not the motion and path?
pj
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The video link I posted of the snooker coach comparing stroke types talks about the flat stroke of the pendulum swing. As you noted trying to keep the cue flat involves dropping then lifting the elbow dynamics to keep it flat. The pendulum stroke is different.
A pendulum by definition is a weight suspended and responding only to the force of gravity. A description in words is not the actual thing. An analogy uses the word “like”, that differentiates it from the actual thing. It’s a descriptive tool only.
That and a properly executed pendulum pool stroke both move along identical paths, regardless of what powers them.
So I still don't get your point...
pj
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