'accelerating' stroke

swest said:

Greetings,

This isn't really an aiming question, but I think this forum is getting the attention of a few people that Know, so I'm going to ask it here.

I have apparently been laboring under, and teaching fellow players, a misconception. I have also spouted it here in one of the other threads on aiming.

I thought that by striving for a smoothly accelerating stroke through the cue ball I was increasing the spin effect that I was imparting to the CB. By smoothly accelerating, I mean that if you were to measure the velocity of my cue stick's tip from just before CB impact to just after the CB is no longer in contact with the tip, that the velocity would be continuously increasing.

I thought that this acceleration was increasing the contact time of the tip with the CB, and that that increased contact time was increasing the spin effect (particularly w.r.t. the draw shot).

Reading some of the comments from this forum, and now some of the info on Dr. Dave's site (at http://billiards.colostate.edu/threads/cue_tip.html#contact) I am becoming disabused of that misconception.

Nevertheless, I'm seriously confused. Why does it feel like this is what is happening? Also, I've always taught my fellow players to 'stroke' not 'poke'. I would have said that I was more likely to miscue when 'poking' than when 'stroking'. This new information would seem to contradict that fundamental principle.

Insights?

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I believe this is why it is so important to "accelerate" through the cb and not to poke or decelerate on the way to the cb-

While many of our actions of the stroke can be done with our conscious mind, many are also done with our subconscious. Our subconscious pays close attention to what actually happens, and adjusts accordingly. Hence, an experienced player quickly being able to adjust to the speed of the table.

When you stroke, your mind is counting on an even speed stroke, or even an "accelerating" stroke and then gauges the results of what happened. And, then can make those minute adjustments in where you are hitting the cb to get the results you intended on the next shot without you even realizing it is happening.

However, when you decelerate to the cb, you will naturally get much less action, or spin and speed on the cb than intended. So, your subconscious then makes you actually hit much farther out on the cb than you think you are to get the action you wanted.

Many times you will hear an amateur say "wow! Where did that stroke come from?" What actually happened, is they properly hit the cb (accelerating stroke) and then they still hit it with much more english than they needed, thereby getting much more spin and action on the cb than they thought they could.

Even hitting as far out on the cb as you can, while slowing down, or poking the stroke, you will not get the same action as you can hitting only half way out on the ball with a proper stroke. (last statement is not set in stone, but an approximation)

When reading those results, ask yourself what does slow,medium, and fast mean to you when your are playing. Is the same slow speed used the same slow speed for everyone?

Also consider that 1 m/s is 39.3 inches per second.

With using subjective quaniltes about speed, the test results are in question as to being truely representative of everyday pool playing.

Consider this. You can have a cue going a steady speed yet to the cb, the cue will appear to be accelerating through it since the cb is not moving at time of impact.

Also, you musy have follow through or the cb would never move.

duckie said:

When reading those results, ask yourself what does slow,medium, and fast mean to you when your are playing. Is the same slow speed used the same slow speed for everyone?

Also consider that 1 m/s is 39.3 inches per second.

With using subjective quaniltes about speed, the test results are in question as to being truely representative of everyday pool playing.

Consider this. You can have a cue going a steady speed yet to the cb, the cue will appear to be accelerating through it since the cb is not moving at time of impact.

Also, you musy have follow through or the cb would never move.

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You NEED approximately 1/8" of followthrough to get the action you want on the cb.

Ummm...why does a stroke matter if we can only hit the cue ball for 1/1000th of a second? Twisting and pivoting and all other gyrations are futile in changing the hit on the cue ball. Why does a good stroke matter? Scientifically speaking, of course.

Best,
Mike

swest said:

I thought that this acceleration was increasing the contact time of the tip with the CB, and that that increased contact time was increasing the spin effect (particularly w.r.t. the draw shot).

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This is exactly how I stroke the ball, and I'm pretty sure it's the best way.

A lot of people have a misconception about follow through. They think of making contact with the CB, and then extending the tip past the CB's original location. This isn't the case though.

A proper follow through/accelerated stroke is one where the tip, in a way, pushes the CB towards the target. All in one fluid motion. Whether or not the tip is actually staying in contact any longer is irrelevant to me. It works.

Watch Efren shoot in this video. Don't watch his patterns, his stroke, his stance, or any of that. Just pay attention to his tip.

http://www.youtube.com/watch?v=oRvwlX3ihRg

swest said:

Yeah, that's kinda what's got me squirming for a rationale here...

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re-read what I wrote. The only reason it really matters is in correlating what we are thinking we are doing to what we are actually doing. If you consistently decelerate, you won't notice anything until you actually "stroke the cb good". At that point, your subconscious will be lost and not really know what is going on. In other words, with a proper stroke, you can hit a lot closer to center and still get good "action" on the cb than you can with a decelerating stroke. Decelerating, you have to hit farther out on the cb to get the same action as hitting closer to center with a non-decelerating stroke because you won't get the same rpm's on the cb otherwise.

swest said:

I'm with you now. I thought you were strictly referring to shot-to-shot consistency. You are saying that by insuring that we are not actually decelerating, we are guaranteeing our maximum (and, as a side effect, consistent) effectiveness for a given shot speed.

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yep. Very important.

What about Alan Hopkins stroke...punch?

http://www.youtube.com/watch?v=hMJdV0kbUe8

LAMas said:

What about Alan Hopkins stroke...punch?

http://www.youtube.com/watch?v=hMJdV0kbUe8

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Believe it or not, it actually is an accelerating stroke. It's actually the best stroke out there. It is easily repeatable, and you hit the cb right where you intend to. Very accurate. I have used it for an extended period of time with great results. You just pull back an inch or two, and then accelerate forward. It looks like a punch, but actually is not when done correctly. Least wise, it is not what is normally referred to as a "punch stroke".

Neil said:

Believe it or not, it actually is an accelerating stroke. It's actually the best stroke out there. It is easily repeatable, and you hit the cb right where you intend to. Very accurate. I have used it for an extended period of time with great results. You just pull back an inch or two, and then accelerate forward. It looks like a punch, but actually is not when done correctly. Least wise, it is not what is normally referred to as a "punch stroke".

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It has to be very accurate for it doesn't have time or distance to alter it's intended course. It does take a bit of touch to get used to it in applying english...for me.

Neil:
...with a proper stroke, you can hit a lot closer to center and still get good "action" on the cb than you can with a decelerating stroke. Decelerating, you have to hit farther out on the cb to get the same action as hitting closer to center with a non-decelerating stroke because you won't get the same rpm's on the cb otherwise.

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Sorry Neil, but this is a rare misconception on your part. If you hit the cue ball on the same spot at the same speed it doesn't matter if the cue is accelerating or decelerating at the moment of impact - you'll get exactly the same amount of spin. The cue ball doesn't "know" if the tip was going faster or slower a moment before impact; it only "knows" the speed at impact (and contact is so brief and dominated by the dramatic slowdown of the tip that there are no clues during contact).

Like follow through, the benefit of a smoothly accelerating stroke is not its direct effect on the CB, but its lack of negative effect on the control and repeatability of your stroke's speed and accuracy. Conversely, a decelerating stroke doesn't have a direct negative effect on the CB, but is just likely the result of something that works against control and repeatability, like hitting the CB after the optimum point in your stroke's pendulum arc or because you're trying to stop it to avoid a double hit.

This is a perennial topic which comes up repeatedly over the years, with the same misconceptions and corrections each time. I feel a little nostalgic.

pj
chgo

swest said:

I'm with you now. I thought you were strictly referring to shot-to-shot consistency. You are saying that by insuring that we are not actually decelerating, we are guaranteeing our maximum (and, as a side effect, consistent) effectiveness for a given shot speed.

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If by shot speed you're referring to the speed of the cue just before impact, the cueball will react the same whether you're accelerating, coasting, or decelerating. All it cares about is how fast the stick is moving.

But of the three options, decelerating is nevertheless the worst. For one thing, you're wasting work already done in getting the stick up speed. For another, it's generally believed that jerkiness tends to introduce alignment problems. There are other disadvantages of a more technical nature having to do with the timing of the various phases of a stroke. By continuing to apply force throughout the stroke (i.e., the diametric opposite of poking), the final speed of the cue just before impact tends to be less sensitive to variations in the timing of those phases. This is also true with coasting, but less so. Final cue speed is most sensitive to timing variations when decelerating.

During a stroke, the force applied to the cue starts at zero, rises to some peak value, then subsides as the tip nears the ball. You get the most cue speed when the peak force occurs during the latter part of the stroke, roughly at the three-quarter mark, time-wise, or at about half the bridge length, distance-wise). More to the point for a typical shot, it takes less peak force to achieve some particular speed than when the peak happens early on. (I should note, though, that this depends somewhat on the shape of the force curve. I'm assuming a roughly sinusoidal profile, which I think is justified by the accelerometer measurements which have been done. Obviously, you would generate the greatest speed if you peaked early and then kept it there all the way until impact. But that's not realistic, based on those measurements.)

Coasting right before impact (i.e., the force level has subsided down to nothing), also has some advantages. It's more efficient, energy-wise, when getting the cue up to some particular speed, compared to accelerating all the way to reach the same speed. Final cue speed can also be more immune to variations in bridge length, particularly unnoticed variations.

As I think you've come to realize, tip contact time is irrelevant. It's irrelevant because the forces unleashed during impact are so much larger than those we apply to the cue, there's nothing we can do of any significance to alter it.

Jim

swest said:

This is, in fact, the answer I heard from Neil.

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Oops! Sorry if I misread you, Neil!

...Dr. Dave's page ... says basically what you said

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Yes, Dave's page is my auxiliary brain.

This is a prime example of what we were discussing in those other threads about knowing and understanding the principles behind what we do on the table.

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And a good example of how the simplest explanation is almost always the best bet. "Pool physics" gets a bad rap here as a difficult and complicating topic when it's really just common sense stuff that actually simplifies and demystifies the game.

pj
chgo