Dr. Dave's answers to frequently-asked questions (FAQs), mostly from the AZB discussion forum
for more information, see Section 2.05 in The Illustrated Principles of Pool and Billiards
How does the speed and acceleration of the cue vary during a typical stroke?
See the following video that I worked on with Bob Jewett:
Bob Jewett also has an article with a good example plot here (see page 9).
All stroke types create acceleration during the forward stroke. They just do so different amounts at different times. With a typical pendulum stroke, acceleration occurs during the entire forward stroke, but diminishes to zero as you approach the ball. Acceleration is the rate of change of speed. If there is no (or very little) acceleration just before CB contact, the speed is no longer increasing as the tip hits the ball. Therefore, the cue is not accelerating "into" the ball. This is typical with a pendulum stroke. The speed levels off just before CB contact. This might make it easier to control shot speed because the speed isn't changing as you hit the ball; otherwise, slight changes in stroke "timing" can result in different speeds. So there might be an advantage to not accelerate "into" the ball. People who drop their elbow before CB contact are most likely still accelerating (the speed is still increasing) at CB contact, especially with power shots, so they are accelerating "into" the ball.
What people usually mean when they say "accelerate into the ball" or "finish the stroke" is: "don't decelerate into the ball" (i.e., don't slow the cue before cue ball contact). Decelerating into the ball can result in very poor speed control.
For more info on the effects of speed and acceleration, see: follow through.
See also: TP B.4 - Stroke speed and acceleration vs. distance. Here is the summary from the analysis:
With typical pendulum (p) strokes, the speed is more constant (i.e., leveled-off) at CB impact, possibly making it easier to control shot speed, because the speed is less sensitive to variations in bridge and stroke length. With typical "accelerate into the ball" (a) strokes, the force increases and levels off during the stroke, and force is being applied all of the way up to ball impact. With a classic pendulum stroke, it is natural to coast into the ball with no force at impact. The peak force is typically lower with an "accelerate into the ball" stroke than with a pendulum stroke (for the same shot speed) because force is applied over a larger distance. Therefore, for some people, this type of stroke might seem to require less effort for a given speed, and higher speeds might be possible. A typical "accelerate into the ball" stroke usually involves more of a "piston-like" stroke, with shoulder motion and elbow drop, allowing some people to generate force more easily throughout the stroke. One disadvantage of a piston stroke is that tip-contact-point accuracy might be more difficult to control.
TP A.9 - Cue accelerometer measurements shows accelerometer measurements and describes cue reactions during strokes and CB impacts. The blue curves in the top three plots (red curves in the bottom two plots) represent forward acceleration. A positive acceleration implies slowing in the backward direction (e.g., at the end of the back swing) and/or speeding up in the forward direction (e.g., during most of the pre-impact portion of the forward stroke). A negative acceleration implies slowing in the forward direction (e.g., in the later part of the forward warm up strokes) and/or speeding up in the backward direction (e.g., at the beginning of the backstroke).
The relatively flat portion of Andreas' curve, before impact, corresponds to the second half of his back-swing. Notice how it is nearly identical to the shapes in the warm-up strokes (which I think are fairly firm). I think the entire forward stroke, before impact, is represented by the tall peak. The final forward stroke is much faster and more forceful than the warm-up strokes. After the peak, and before impact, the acceleration appears to go negative a little, implying he was actually decelerating a little before impact (if you trust the sensor, its calibration, and the data acquisition). At impact, the signals go wild due to shock waves and vibration.
In the first two plots (softer strokes), the acceleration is still positive at impact, implying that the cue stick is speeding up during the entire forward stroke (e.g., he is accelerating into the ball). Both of Pizutto's plots show slight slowing (negative acceleration) just before impact.
Andreas does not appear to have a distinct pause at the transition between the back and forward stroke because the acceleration curve would be flat (at zero) if there were a deliberate pause.
The spike before impact represents the entire forward stroke, not any weird wrist action. Note that the time scales are very different between the two sets of plots. Pizutto's plots are just showing the final forward stroke and the resulting shock and vibration immediately after impact. Andreas' plots show a much large time interval, including warm-up strokes.
Are there commercial products available that use accelerometer measurements to diagnose stroke issues?
Yes. The Digicue training aid from OB, and the QMD Stroke Analyzer.
If I accelerate into the CB, will I get more "juice" on the ball?
In principle, the cueball will ... have more speed and spin ... when you apply a force during impact. It's just that since the impact period is so short (mainly), the effect is essentially negligible. If you had a really, really soft tip such that contact lasted, say, a second, that would be a different story. So would being able to apply something like 100 lbs of force, as opposed to what we actually apply, about 15-20 lbs at the peak of a power stroke (much less throughout most of the rest of the stroke).
That aside, "accelerating through" can, in theory, give you noticeably more ["juice"] by generating more cue speed before impact commences. One impact begins, virtually nothing short of a superhuman effort can alter things. And the term "accelerate through" is a misnomer. You can continue to apply force, but the impact will inevitably slow the cue down unless you can muster something on the order of 400 lbs.
[The cue] does sense force, but the force doesn't last long (it takes force acting over time to get things moving). And the entire force that you might be applying with your grip hand is not what the cueball sees; it's only about 1/4'th of that. The force that really gets its attention is the one generated by the impact of the already moving cue, and this can approach 300-500 lbs. That's why cue speed is important, not the relatively meager force generated by our stroking arm.
What is the advantage of having a low stance with the chin close to the cue?
Having you eyes closer to the cue helps you more easily visualize the alignment of the cue with the desired aiming line. With your head low, it might help to use an open bridge (see Diagram 3 in "Fundamentals - Part IV: bridge length" - BD, December, 2008) Most snooker players, who require tremendous accuracy, use an open bridge and have there chin just above (or even touching) the cue.
I find that my "chin height" varies with the shot. For shots where the CB and OB are a reasonable distance apart, I am fairly low on the cue. For cut shots with the OB close to the CB, my stance raises a little to facilitate visualizing the contact point and the alignment of the balls at contact. For straight-ins, I don't raise as much as for cuts.
Is it recommended to drop one's elbow during the stroke?
There is a lot of misunderstanding and misrepresentation in the "elbow drop" arena. The general "don't drop the elbow" advice is not as rigid as some people think. Obviously, for an extreme power shot, the elbow will want to drop naturally during the follow through (due to the momentum of the arm and cue). The problem lies with dropping the elbow too much or when it is not intended, especially if the elbow is dropped unintentionally before cue ball contact. For most (almost all) shots, and for most people (especially beginners), accuracy and consistency will be better if the elbow is not dropped before (and maybe after) cue ball contact. A potential problem with dropping the elbow after cue ball contact (e.g., when it is not required based on shot power) is that if one's timing is a little off, the elbow might drop a little before contact, which can affect tip contact point accuracy. A complete list of both advantages and disadvantages of dropping the elbow during the stroke can be found below.
Here's a video demonstration of a non-elbow-drop pendulum stroke:
Elbow drop and pendulum vs. piston stroke are also discussed in:
Elbow drop advantages:
An advantage of dropping the elbow during the stroke is it can allow more power by involving the shoulder muscles. Having a slightly "choked up" grip, where the forearm is forward of vertical at CB impact, and using a more upright stance can also help add power. Related discussion and demonstrations on how to add power to a break shot can be found here: power break technique advice.
Other possible advantages of dropping the elbow during typical (non power) shots include:
Here's a video by Max Elberle that demonstrates a well-executed elbow-drop stroke. As Max points out, the key is to not drop the elbow and hand before contact with the CB; otherwise, the cue tip will hit the CB higher than you might think it will.
If you want to experiment with a pure pendulum stroke with a still elbow, and if you have difficulty doing so, one thing that can help is to focus on keeping the shoulder joint totally still and locked during the stroke. The upper arm and elbow can drop only if the shoulder joint moves.
Elbow drop disadvantages:
Here are some possible disadvantages of dropping the elbow:
Some people use what is called a "J" stroke, where the grip hand follows the pendulum motion on the back swing and forward swing into the ball, and then the grip moves in a straight line (with elbow drop) after CB contact and during follow through. If you trace out the path of the grip hand, it looks like a "J" turned sideways. This is a combination of a "pendulum stroke" and a "piston stroke." If done well, this gives the benefits of the pendulum stroke tip contact point accuracy, and the follow through of a piston-stroke, but some people might have trouble with dropping the elbow at the right time and right amount consistently. For more information, see follow through.
I personally believe that most people would be more accurate and consistent if they didn't drop their elbow (although, dropping a small amount or after the hit is fine, especially if the drop is not exaggerated and doesn't involve "chicken wing" motion). In other words, I think the potential disadvantages associated with dropping the elbow outweigh the potential advantages, for most people. However, obviously, if one has always been an "elbow dropper" and has countless hours of practice and successful experience under their belt, and one is a top player, it probably wouldn't help one to attempt to change. Anybody can master any technique if it is practiced and reinforced enough. However, I agree with most top instructors, that people first learning the game should consider limiting or eliminating elbow drop.
Could you show some video examples of top pros executing fixed-elbow pendulum strokes?
from DTL (in AZB post):
Hunter Lombardo uses a pendulum stroke.....although the shot below is a soft shot, he does this on all shots except maybe a power draw.
Darren Appleton uses a pendulum stroke.
Alex Pagulayan uses a pendulum stroke.
Chris Melling uses a pendulum stroke. He takes some of the arc out of the back swing by pulling the cue more straight back which causes a slight elbow drop at the end of the back swing.
Niels Feijen has a pendulum stroke......no video needed.
The quality of players coming out these days just keep getting better and better. The winning play is trending toward the player with the best fundamentals. Soon, players like Busty/Efren/Frost with their loopy/loosey goosey strokes, will be a thing of the past. In 20 years if you don't have a laser-like straight stroke with rock solid, near text book fundamentals (see snooker players below), you'll have no shot at winning major tournaments.
Below is S. Frost. Notice on this quick front on shot the up/down motions of his grip hand/elbow..........this is all provided by flexion/extension of a fixed shoulder (the shoulder and head are stationary, the movement is from rotation of the head of the humerus in the joint space).
Busty is similar but with a lot of added wrist action. Notice the up/down elbow during the stroke.....disappears on the last stroke.
Comments from others:
from Bob_Jewett (in AZB post):
In the second and third articles in this PDF http://www.sfbilliards.com/articles/2004.pdf are some thoughts and observations on what the elbow does during the stroke.
In my experience, players often have two distinct strokes. On soft shots their upper arms are motionless and the stroke is restricted to the forearm. The shoulder is frozen in place and moves not at all. On power shots, the elbow drops at the end of the stroke. In my view, this drop is essential on power shots to keep the arm happy and not hurt. I've tried a still elbow on such shots and it hurts. The drop is typically the thickness of the upper arm, so a few inches.
This observation applies to players as diverse as Allison Fisher and Nick Varner. Well, they're not that diverse since they are both Hall-of-Famers.
In the case of snooker players, keeping the chin on the shaft forces a piston stroke, mostly. That will naturally lead to some elbow drop on power shots from the simple mechanics involved.
What is one of the main keys to playing good? Repeatability. So, what do you think the first thing an instructor is going to teach someone? Yes, repeatability. Now, the instructor can stick around for a few years and watch his student shoot thousands of balls until his mind finally gets trained to do it the same way, no matter what way that is, OR, the inst. can teach a simple way to be repeatable and accurate in the stroke. And, do it in a few hours. Which should he do?? (If you really don't know the answer to that, stop reading now, you are too stupid to play pool, or to do much else.)
The pendulum stroke is easily taught, and is extremely repeatable and reliable. When set up properly, you hit the cb with a level stroke at impact, and right where you want to hit it. You are not hitting the cb while on an upswing as some have stated. If you are, you aren't doing it right, go see an instructor.
It has been mentioned numerous times that you seldom see the top pros not dropping their elbow. This is true. You also seldom see them drop BEFORE contact, although some do. It seems to be the consensus on here that that means that you should drop your elbow. Let's think about that for a minute..... when did the pendulum swing really come into play? Not very long ago. When did the top players start playing? A long time ago. This wasn't even an issue when they were learning! So, how did they learn? By shooting thousands and thousands of shots. You can learn the same way too. (not a very time efficient method, though)
They, the top pros, have learned repeatability the hard way, over time. Doing that, they each have little and some have large idiosyncrasies to their stroke that works FOR THEM. To try and repeat their strokes, can easily be a HUGE waste of time. If we should only copy them, why don't more people try and play like McCready or Bustamante, arguably two of the best players?
Many of the top players also jump up in the air when they break. Does anyone really think that is a good thing to do? It has been proven over and over that it is not, and adds NOTHING to the break. (except a lot of problems if you don't have your timing just perfect.) Remember what your mothers taught you? Just because Timmy is jumping off a bridge doesn't mean you have to do it too! There's a lot of wisdom in that if you bother to think about it.
It has been stated that you can't get proper follow through with a pendulum stoke. Again, if you can't follow through for 1/1000 of a sec, (all the time the tip is on the cb) you better quit now. The ONLY reason for any follow through is to not stop the stroke. You want the tip going smoothly until contact. All the pendulum stroke does is alter where your follow through goes AFTER contact. It does not minimize it in the least.
If you drop your elbow BEFORE contact, you are much more prone to not hitting the cb where you intend to. Hence, the up and down swings in play that many players suffer from. If one muscle is a little tight, it changes where you hit the ball. Dropping your elbow before contact introduces the shoulder muscles into play. Just something else that can go wrong. Why not eliminate as much as possible that can go wrong??
What many of the top players have learned over trial and error is that if you extend your cue along the shot line on the follow through, it really helps you keep the stroke straight on the way to the cb. The mind finds it easier to make everything work properly with a longer line to work with than just the few inches to the cb.
NO ONE is saying that method doesn't work, or is bad. If it works for you, great! However, there is an easier way to achieve the same results, yep, the pendulum stroke. The top players are not going to change what took them many years to ingrain into their subconscious to achieve the same results. That would be rather foolhardy. But, when you are learning, or even if you have been playing a long time and DON'T have a repeatable stroke, the pendulum stroke is an easy way to get one. The fewer moving parts you have, the less can go wrong.
It has been wrongly stated that you can't get enough power with a pendulum stroke. And that you can't get anything put a dog-break with it. Baloney. I have make 8 out of 9 balls on the break with a pendulum stroke. When Scott and I played, right after the first break of mine, he started laughing and said "And people say you can't get a good break with a pendulum stroke!" First off, the break is not so much about power, as it is about accuracy and a good rack. Just ask Donnie Mills, or Corey Duel. And, you can get all the power you need for ANY shot that comes up during a game.
Many times, when you have an experienced player, and he/she tries to shift over to a pendulum stroke, they have problems. ANY time you try and learn something you are used to doing a new way, you have to give it time to erase the old way of doing it, and ingrain into your subconscious the new way. How long that takes, varies with the individual. Even after you have the new way ingrained, sometimes the old way still creeps in. It took me the better part of a year to finally let my subconscious go and trust it enough to stroke correctly when I switched over to a pendulum stroke. And, the old way still creeps in now and then and messes me up.
Once you get to the point of NOT thinking about your stroke, but letting your subconscious stroke it, the pendulum stroke is a VERY effective tool! Many players reach a plateau, and can't seem to get any better. I feel there are two main reasons for this- they do not have a repeatable stroke, and/or they really don't pay attention to just what is happening when they shoot a shot. The don't know just where they hit the cb, where the cb hit the ob, and where the cb went after contact with the ob, and what speed was used. Not KNOWING those things, you can't possibly duplicate and expand on them.
Another thing you will see a number of top pros do, is to do their warmup strokes with the tip on the cloth well before the cb. They have the natural talent, and years of experience to bring the tip up precisely to where they want it on the final stroke. If you don't have their natural talent, or years of experience, good luck with that. So, is that also something we should all do just because they do it? Are there better ways to accomplish the same end result? Busty looks like he is using an old water pump when he strokes. Should we copy that move too? Why not? The pros do it. Mainly, because we aren't them.
We don't have the natural talent, or the time to invest as they have done. We have to use whatever methods we can to shorten the time it takes, and to make things as easy as possible. The pendulum stroke really helps the fundamentals and repeatability. Aiming methods can really help in their area. Kicking systems in theirs, etc.
But for some to get on here, and make statements that they have about the pendulum stroke, only shows how little they do know about it, and about the general concepts of pool, what works and why it works.
Nobody is saying that dropping your elbow is bad, or that you can't play good that way. If it works reliably for you, keep doing it your way. But, if you find that you are not reliable, try the pendulum stroke. It is a much easier way to get repeatability. And, that is what this game is all about. There's not much point in learning how to get the cb to do what you want it to do if you can't hit it where you want to. Thinking you hit the cb in one spot, and actually hitting it in another only puts into your subconscious something that is wrong. Then, when you DO hit the cb where you want to, you get a different reaction out of it, and get all confused and lose confidence in yourself.
...the vast majority of students who come to me are looking for consistency. The best way to achieve this is SPF and no elbow drop. There are select shots where dropping the elbow may allow more power, but that same majority would be giving up a lot of accuracy to gain the power. In my opinion, accuracy is more critical than power. There are always going to be players at the top of the game who can control a full arm stroke with accuracy and consistency. They would be in the minority.
I have had very good success helping students improve their control by using the pendulum stroke. As an instructor, I have to consider each student as an individual, so I can't say I would ever say that a student MUST not drop their elbow. But so far, whenever I have had a student try the pendulum stroke, they have shown very quick improvement in accuracy. I have one student who uses this stroke on his break! He regularly makes something (often multiple balls) and almost always lands the cue ball in the center of the table. I don't see any reason to introduce a full arm swing to a player who would be better served from an accuracy standpoint by developing a simpler motion. When the student comes to me who can consistently make controlled contact with a full arm stroke, I don't think I would suggest any changes. Until that student appears, I think this is the best method to teach. There are going to be exceptions, but I suspect they are few and far between.
from Mike Page:
If you were to install webcams in a hundred poolrooms throughout the world and view 1000 random elbow drops on pool strokes, those 1000 strokes might be divvied up as follows:
990 strokes: category A elbow drops
9 strokes: category B elbow drops
1 stroke: category C elbow drop
category A elbow drops--
the vast majority of them--are plainly and simply bad mechanics. This person's elbow is moving during the stroke, as perhaps is his or her head, making strokes inconsistent, making strokes rely on carefully choreographed timing of different motions, and encouraging the addition of other compensating motions. These people absolutely will benefit from learning good mechanics like those Randy and Scott and Steve and others advocate so well. These people should heed the advice of instructors like those I just mentioned and practice it until one nipple is as calloused as the bottom of a foot, imo.
category B elbow drops--
These are solid players whose elbow is still at the time of contact. The stroke is a simple pendulum stroke until after the cueball is gone. The impetus for dropping the elbow in the follow through perhaps comes from the desire to have a long, exaggerated follow through, or perhaps it comes from wanting a level, horizontal follow through (instead of the tip approaching the cloth as in the pendulum stroke). These people don't necessarily need to change anything. The biggest problem they cause is for others. They embolden the category A folk--who don't recognize the difference--thus providing a disincentive for the category A folk learning good mechanics.
Category C elbow drops--
This is, for example Mike Masséy. These people are capable of a good pendulum stroke and perhaps employ a pendulum stroke on most of their shots. However, on power strokes, e.g., a break shot or a power draw shot, you will see an elbow drop. These players' elbows are moving at contact because the point is to add some speed by pivoting about the shoulder. In fact focusing on the elbow drop is like focusing on the thunder instead of the lightning. The lightning here is the elbow raise on the backstroke. Then pivoting about both the shoulder and elbow on the forward stroke increases speed. Most players, imo, should never do this for, say, a draw shot. The reason is that while the speed increases a bit, the bigger effect is our precision in where we contact the cueball goes down by a more significant amount. So I would say if you can't consistently draw one and a half table lengths with a pendulum stroke, then there's no way you should be futzing with this stuff. And if you CAN consistently draw one and a half table lengths with a pendulum stroke, then...well...you're more or less good to go!
Does an extended follow-through add power, draw action, or accuracy to a shot?
This is a question of cause and effect. The follow-through strictly has no influence on the cue ball because the cue ball is gone before the follow through takes place. What the grip and stroke does during cue tip contact is also unimportant because the tip is in contact with the cue ball for only a very short amount of time (approximately 0.001 seconds). However, the follow-through is usually a good indicator of the quality and nature of the stroke into the ball (before tip-ball contact), which does matter quite a bit. For example, if the follow-through is very short, it could indicate a decelerating or over-constrained stroke into the ball, which can adversely affect speed control. Also, if the follow-through involves tip lift (e.g., due to grip tightening and/or elbow drop), steer (e.g., due to a flying "chicken-wing" elbow), or exaggerated forward extension (e.g., due to excessive shoulder and elbow motion), these motions might be starting before tip contact, during the stroke into the ball, and this could definitely affect cue-tip-contact-point and aiming accuracy. To summarize, a good and appropriate follow through is not the "cause" of a good hit, but it is often a strong indicator of a good stroke into the ball (before tip-ball contact) ... which does affect the hit.
All the cue ball "cares" about is tip contact point, cue speed, and cue angle and elevation at the moment of impact. Follow-through is just a symptom of your stroke and has no direct affect on the action of the shot. Now, when you follow through, maybe you are doing something different with your stroke to get a different cue speed or a different tip contact point, or maybe your stroke is straighter. To detect this, you can videotape your stroke changes and look at the chalk mark on the CB. It helps to use a ball with markings (e.g., a striped ball or a Jim Rempe ball) when checking the chalk mark. If two shots have the same cue speed and tip contact point, but have different amounts of follow through, the action of the shots should still be the same. If you are getting different action, you are not hitting the CB with the same speed, tip-contact point, or aiming line. With an elbow-drop (long follow-through) stroke, there might be a tendency for the player to drop the elbow slightly before CB contact. If this happens, the tip will hit the CB slightly higher than the player thinks. Likewise, with a shorter follow-through, a player might have a tendency to tighten the grip slightly, which would cause the cue tip to lower some. Also, different cue speeds will result from variations in the stroke. For more information, see stroke "type" and "quality."
Concerning the break shot, the only thing that significantly affects the power for a given break cue and tip contact point (and cue angle) is cue speed at impact. However, if a powerful stroke does not exhibit a long follow-through, it is either not very powerful, or effort is being made to limit the follow-through. If one tries to constrain the follow-through, one will probably not achieve maximum speed at impact.
Follow-through can also be important in achieving good action on draw shots (although, not always for the reasons people think). For more info, see "Draw Shot Primer - Part V: how to achieve good draw action" (BD, May, 2006). In particular, see item "b" under "other advice" and item "5" under "suggested best practices." I think these points apply equally well to both a power break and a power draw.
For more information on topics related to follow-through, see:
forearm perpendicular to cue
Why is it usually recommended to have the forearm perpendicular to the cue at CB impact?
With a non-elbow-drop stroke, and with the forearm perpendicular to the cue, the cue tip will be moving exactly straight in the cue direction. If the grip is forward, the tip will be moving down into the ball; and if the grip is back, the tip will be moving up at impact. Also, there is a natural tendency to reach a constant maximum cue speed when the forearm is perpendicular to the cue at cue ball address. This can make it easier to control your shot speed, because the speed of the cue won't be changing much just before contact. For more info, see:
pendulum vs. piston stroke
What is the difference between a pendulum stroke and a piston stroke?
A "pendulum stroke" is where you keep your upper arm still during the stroke. The only motion is from the elbow down. Some people refer to this as a "pinned elbow" stroke. With a pendulum stroke, the upper arm is considered part of your body, which should remain still during the stroke.
A "piston stroke" is one where you coordinate motion of both the elbow and the shoulder to keep the cue tip moving in a straight line during the entire stroke (just like a piston in the cylinder of an internal-combustion engine). This type of stroke is common among snooker players who guide the cue on the chest and chin during the stroke, forcing the cue to move in a straight line.
For more information on the differences and advantages of each type of stroke, see: elbow drop.
Here's a video demonstration of a non-elbow-drop pendulum stroke:
A "J" stroke is a combination of a pendulum and piston stroke, where the grip hand follows the pendulum motion on the back swing and forward swing into the ball, and then the grip moves in a straight line (with elbow drop) after CB contact and during follow through. If you trace out the path of the grip hand, it looks like a "J" turned sideways. If done well, this gives the benefits of the pendulum stroke tip contact point accuracy, and the follow through of a piston-stroke, but some people might have trouble with dropping the elbow at the right time and right amount consistently.
Many pros seem to be close to a "J" stroke, but some pros drop their elbow before CB contact, on some shots more than others. Also, some lift the tip after CB contact, especially with follow shots, and some finish with the tip down (with an almost-pendulum-like stroke finish). Some even swoop their stroke on some shots (usually only shots with english), moving the tip sideways during the stroke (before and after CB contact). Some drop their elbow just a little after CB contact on many shots, and some drop their elbow a lot (mostly after CB contact) on most shots. The one thing that can said for sure is that most pros drop their elbow after CB contact, especially with firmer shots. Some seem to do this purposefully; and for others, it just seems like a natural side-effect of the forward momentum of the cue and arm after CB contact.
For more info and advice, see stroke technique advice, elbow drop, and follow through.
With a pendumlum stroke, the tip moves up and down during the stroke. Does that have any negative effects?
No. With a pure pendulum stroke into the CB, the tip returns to the exact spot aimed at on the CB, assuming the tip isn't too far from the CB at address. Also, the motion of the tip is very straight both a few inches before contact and a few inches after contact. For illustrations and example numbers, see:
TP B.18 - Pendulum Stroke Cue Tip Trajectory
What are some recommended "best practices" for the pre-shot routine?
See pre-shot routine.
What is SPF or SPFF?
SPF = set, pause, finish
SPFF = set, pause, finish, freeze
from Mike Page:
Many pool instructors refer to the simple pendulum stroke as an "SPF" stroke, where the letters refer to SET, PAUSE, and FINISH positions. The drills you do in the Foundations courses are designed to help burn the SPF sequence into your muscle memory. These drills pay particular attention to the SET and FINISH positions.
THE SET POSITION
As in many sports, the set position is key. It is from here that the fuse is lit for the final stroke. The player’s body is held completely still in the set position for at least three seconds. During the Foundations courses, students should hold every set position for at least five seconds. Here are some characteristics of the set position:
• Forearm is vertical.
• Tip is close to the cueball.
• Eyes switch focus from cueball to target location, with at least two seconds on target location.
From the set position, the player draws the cue back slowly to the PAUSE position. It is not necessary to actually pause at the PAUSE position. Some top players do; others don’t. What is necessary is the cue be drawn back slowly (not jerked back) and the transition from backward to forward motion be slow and smooth. The cue is accelerated forward from the PAUSE position. When the forearm becomes vertical again, the tip will be at the ball. At the tip-ball impact on the forward stroke, the player is passing again through the SET position.
THE FINISH POSITION
Instructors in many sports, including pool, stress the importance of follow through. We disagree. Follow through focuses on what happens to the front of the cue, i.e., the tip. When a player decides in advance where he or she would like the tip of the cue to finish, there is no guarantee a pendulum stroke can comply. So a player attempting to get the tip to a particular location likely will call upon the shoulder joint. Pivoting about the shoulder joint drops the elbow and raises the tip.
We prefer instead to focus on FINISHING THE STROKE. The stroke is finished when the grip hand reaches its natural finish position—the natural end of the pendulum stroke. Depending upon the player’s body type and stance, this could be where the forearm hits the biceps, or it could be where the grip hand hits the side of the chest. So instead of focusing on follow through, we focus on finishing the stroke, on the grip hand going home.
A consequence of finishing the stroke is the tip of the cue will reach a particular finish location—for many people this is four or five inches beyond the cueball with the tip touching the cloth. So have no fear, others will think you are dutifully following through.
Unless doing so would disrupt the balls in play, freeze for at least two seconds in the finish position. Note that you’ve gone home.
The "set" position occurs at the CB, after your warmup cycle is finished. It's the last conscious thought about, "Well? Are you ready or not?" With the tip at the CB, the "set" position is used to verify earlier decisions on angle, speed and spin. If it is a go, there are no more warmups, and the final backswing begins. The "pause" happens as we come to the end of the natural backward motion of the cue, so we can make a smooth transition to the forward swing. All strokes start from zero, and accelerate to whatever speed you're hitting the shot with. The "finish" ... The grip hand ends up in the armpit area, close to the chest; and the tip is on or close to the cloth, some distance past where the CB was sitting. The "freeze" is an opportunity for self-evaluation, that happens after the stroke is over, and you have remained motionless, except for your forearm. The freeze allows you to check components of your stroke, including the grip finish, tip finish, and speed control.
When do muscle transitions occur during the stroke?
if the real reason for a "pause" is to allow the "backswing" muscles to stop working before the "forward swing" muscles take over, then there is absolutely no need for a pause in MOTION, only a pause in acceleration.
When the "backswing" muscles relax, the stick is still moving backwards. There can be a finite period of relaxation before the "forward swing" muscles contract and apply force. AT THIS POINT, AND FOR A FINITE TIME AFTERWARD, THE STICK IS STILL MOVING BACKWARDS. It takes some finite time for the "forward swing" muscles to accelerate the stick to zero velocity. There will then be no finite time at zero velocity because the acceleration is continuous, so the stick progresses smoothly (semi-sinusoidally) from backward to forward velocity.
For this example, the "pause" was in acceleration, not velocity. This relaxation of backswing muscles and subsequent resumption of opposite force occurred entirely before the backwards motion ended.
What is the definition of "pause"?
Strictly, the word "pause" implies stopping for more than an "instant." When a player has an obvious "pause" between the end of their back-swing and the beginning of their forward-swing, I like to refer to it as a "deliberate pause" or a "distinct pause." Here, the implication is clear: the cue is held stationary (stopped) for more than an instant.
Strictly speaking, if the cue stops only for an "instant," there is no "pause." An "instant" does not involve any passage of time. A "pause" does imply a "stop" (zero speed) for a distinct amount of time. For example, when a free-swinging pendulum changes direction at is highest point, it does "stop" for an "instant," but it does not "pause." The speed gradually and smoothly changes from negative (in the backward direction) to positive (in the forward direction), through zero. The speed does not stay at zero for any amount of time. At the tiniest fraction of a second before the speed is zero, the pendulum is moving slowly in one direction (negative speed); and at the tiniest fraction of a second after the speed is zero, the pendulum is moving slowly in the other direction (positive speed). The speed is zero only for an "instant." Not even the smallest fraction of time passes during that instant.
This explanation applies to any speed (i.e., there is nothing special about zero). For example, consider the cue speeding up gradually between 1 mph and 5 mph. The speed hits 3 mph for only an instant during the acceleration, but there is no "pause" at 3 mph. Now, if you stop accelerating at 3 mph, and hold the speed constant at 3 mph for a period of time, then you could say there is a "pause" in the acceleration. Again, the smooth transition through a speed of zero is no different. If you don't hold the speed at zero for a distinct period of time, then, strictly speaking, there is no "pause."
People will interpret the word "pause" in different ways; but as long as one is clear and consistent with the meaning, and people know what you mean, that's all that matters. Again, I like to use the phrase "deliberate pause" when there is a distinct "pause" in the action (i.e., the stop occurs for more than just an "instant"). For example, both Allison Fisher and Buddy Hall (and others) obviously have a "deliberate pause" before their final forward stroke. The phrase "pause for only an instant" is also OK when there is no "deliberate pause"; although, it is strictly not proper. When somebody rushes or jerks the transition between back and forward motion, there still is a "stop for an instant" (because the cue still changes direction and has zero speed for an instant). I would call this a "pauseless and rushed" transition.
Why should I "pause"?
The pause at the set position allows your eyes to focus and verify both the tip contact point on the cue ball and the target aiming line (see quiet eyes for more info). For the "pause" at the end of the backstroke, see item 4 in the stroke "best practices" document. Adding a deliberate or distinct "pause" helps some people prevent themselves from rushing the final back stroke and from rushing the transition to the final forward stroke. Jerking this transition can cause stroking errors.
If you watch a hundred top players and also watch a hundred ball bangers, here is what I think you will notice:
set position: On average, the top players are stopped like an oak tree in the set position for a notably longer time. The bangers have variable set pauses that are often short and sometimes they don't pause at all.
final backstroke The top players--nearly all of them-- will bring the cue back slowly following the longish set pause. The bangers will bring the cue back faster.
backstroke pause Some of the top players pause; others don't. Some of the bangers pause; others don't. The differences you will note are not so much whether the players pause but rather how smooth and fluid the transition is. Part of the bangers problem with smooth transition is not really a problem with the backstroke pause/nopause. Rather it is collateral damage from the final backstroke problem. Bringing the cue back too fast encourages a jerky transition. Add a backstroke pause if it floats your boat. But if you're adding it to fix a jerky transition, then you may just be enabling the real (too fast backstroke) problem.
Because when there is a mechanical error in the stroke it usually happens in the transition from back stroke to forward stroke. Simply put, the end of your backstroke is the start of your forward stroke. So if the backstroke does not come back right, the forward stroke is adversely affected. A slow drawback, and slight pause eliminates this problem. Also the pause is when you re-focus on the ob's contact point. Yes "re-focus". During the practice strokes your eyes are scanning back and forth. When you are ready a back stroke and transition can for a split second distract your focus, even if you don't take your eye off the ball! A slight pause allows you to re-focus, or burn with intensity that vital little bit. It makes one simply react to the target from the trigger position without the distraction of having any moving parts going on at the same time.
Players with less experience get in a hurry to shoot a shot. Doing so they snatch the cue back. I have a phrase I like to use. "Finish Your Backswing".
"Gradually" bring the cue tip to the C/B and pause, let your focus go from tip placement to the O/B during this pause, "Gradually" start the cue back, (this is important because a snatch will make your backswing short) slight pause, then slowly start forward, no matter the power needed. This is the transition area. If you start forward fast, you just wasted the preparation needed to make a smooth stroke.
What you'll find, once you learn to slow down your stroke, you'll hit the cueball exactly where intended. The reason pool players never excel is they don't grasp the importance of these fundamental movements. You have to be accurate and quick movements will surely make you loose your focus.
shooting over a ball
What technique advice do you have when having to jack up to shoot over a ball?
when jacked up you have a smaller margin for error
so make smaller errors...
I shorten my stroke... shorten my bridge.. shrink it all up
in the most extreme case I'll begin with my back hand in my finish position and bridge as close to the shot as possible... and bridge as stable as possible
the entire forward stroke may only result in 2 or 3 inches of tip movement total...
sight the shot and line it up level...
and then shrink your stroke more and more as you are forced to jack up higher and higher...
smaller movements make smaller errors...
staying centerball axis is critical.. massé is a huge problem here... the higher you jack up.
to help relieve tension, I bend my elbow on my bridge arm. This also brings your body a little closer to the ball so you can choke up a little more comfortably on the butt w/ your stroking arm.
What is a slip stroke and why is it used?
Slip stroke -- The grip hand slips back on the butt just prior to the forward stroke at the cue ball.
Stroke slip -- As the forward stroke at the cue ball is executed, the cue slips through the grip hand to some degree (a "throw" or "release and catch").
Here is an article from Billiards Digest that describes several kinds of stroke including the slip stroke: http://www.sfbilliards.com/articles/2005.pdf (October)
And here is one that describes some other strokes: http://www.sfbilliards.com/articles/2005.pdf (November)
staying down on the shot
Why should I bother "staying down" after a shot?
from Andrew Manning:
Staying still helps for a few reasons.
1) If you're freezing at the finish of the shot, then you're certainly not jumping or moving during the final stroke, which I think everyone agrees is a bad thing to do.
2) When you freeze at the end of the shot, you can see where your cue finished. If you didn't stroke straight through the ball, this will be evident in your finish position, and you'll be able to observe it and use that feedback to improve your stroke.
3) Staying down and continuing to sight down your cue will keep a consistent frame of reference to observe the results of your shot. Your brain can record what the CB and OB do, versus what you wanted them to do, in great detail from this perspective. If you stand up before the shot is done, you have to adjust to looking at the shot from a different angle, and your brain will not be able to calculate what went right/wrong nearly as effectively. Getting the best possible visual feedback is crucial, since this feedback is drawn upon heavily by your subconscious the next time you're lining up a similar shot.
There may be other benefits as well, but I think those are the most important.
What is a swoop or swipe stroke, and should I use it to apply spin?
A swoop (or swipe) stroke is the technique of pivoting the cue during the forward stroke and follow through to apply spin to the cue ball. The swoop or swiping motion can be created by moving the entire arm (or even the entire body) during the stroke, or simply by flicking or twisting the wrist, or even by just shifting the bridge hand. The swoop stroke can be used to apply sidespin (with a sideways swiping motion) or top/bottom spin (with an up or down swiping motion during the stroke). The tip is usually swiped across the ball from the center outward, but it can also be swiped from the other side of the ball, creating contact closer to the center of the cue ball. The timing of the swoop is important. If you start it too early in the forward stroke, you won't have enough room to maintain significant swiping speed into the ball (and/or you might miscue). If you start it too late, you won't have ample acceleration time to generate enough swiping speed to make a difference (i.e., most of the swipe will occur during the follow through where it can have no effect). The swoop or swipe stroke technique has sometimes been referred to (mostly in reference to Philippine players in the past) as carabao english or a carabao stroke.
Alternatives to using stroke swoop to apply english include:
1.) Align the cue in the required direction (compensating for squirt, swerve, and throw intuitively) with the tip off center to apply the exact amount of english desired, and then use a straight stroke.
2.) Align the cue at the center of the cue ball along the desired aiming line (with the aim corrected for throw, where appropriate), and then use BHE or FHE or some other method to pivot the cue before the stroke to compensate for squirt and swerve (AKA "net cue ball deflection"), and then stroke straight along this new alignment.
Most (but not all) top players use technique "1." Technique "2" is good for people who don't yet have enough experience-based intuition to adjust for squirt and swerve intuitively. Stroke swoop is also an option for people who prefer a center-ball alignment before the final stroke.
Many "Old Timers" (and people who learned from "Old Timers") and even some "Young Guns" firmly believe that the swoop stroke provides an advantage. However, as described, illustrated, and demonstrated below, there is always an "equivalent straight stroke" that will send the CB in the same direction with the same speed and spin, and do so with better accuracy and consistency.
Tom Ross, with whom I created VEPS, was an accomplished player and an excellent swooper. He swooped his stroke on pretty much every shot with sidespin. While we were filming, this honestly bugged me because I thought it set a bad example to our viewers who might think this technique is required to be effective. This lead to many "heated" discussion between Tom and I during our filming.
Tom was a very effective swooper, but only because he had spent countless hours over 30-40 years perfecting his technique. Like many swoopers, Tom thought a swoop stroke was actually required to shoot those shots effectively because that's what he had learned from some of the top-playing "Old-Timer" mentors and idols he associated with when he was young.
During one of our filming breaks, Tom and I did several tests and experiments to try to determine if a swoop stroke could apply more spin to the CB (to help settle our "differences of opinion"). Before all of these discussions, tests, and experiments, Tom was a firm believer that the swoop stroke could apply more spin to the CB (seemingly defying the normal miscue limit). After the discussions, tests, and experiments, I finally convinced Tom that a straight stroke can do everything an equivalent swoop stroke can do. He also agreed that the straight stroke would be more accurate and more consistent for people who didn't spend the time and effort to master the swoop stroke. Did that make him change the way he plays? Absolutely not. That would be silly. He had already perfected the skill, despite its potential shortcomings, and that was what he what he always did, it came perfectly naturally, and it worked well for him.
Like many people who have learned and mastered the swoop stroke, Tom preferred aiming closer to center ball with the cue aligned in the direction he wants the CB to head, where it is easier to visualize the exact aim for the shot, and he preferred applying a pivot (to compensate for squirt or "cue ball deflection") during the stroke instead of before. He also used a non-LD solid maple shaft (as opposed to an low-cue-ball-deflection shaft), and the swooping motion provided even more squirt compensation (due to the sideways swiping motion, as illustrated in my diagrams) than a pre-stroke-BHE correction would (for his preferred bridge length). Also, some people learn to swoop because we all have a natural tendancy to want to use "body english" to steer the cue in the direction we want the CB to spin or go; and this habit can be hard to change, especially if one has reinforced it enough through extensive practice and repetition.
Here are some highlights from one of the experiments Tom and I did (with swooper Tom shooting the shots):
Now, if you twist the cue with your wrist while you swoop the stroke, you can do amazing things with the cue ball. I haven't mastered this technique yet, but I am still able to get tremendous curving action on the cue ball. For demonstrations, see:
There actually are several potential benefits of a swoop/swipe stroke for the people who can execute the technique accurately and consistently:
and from Cornerman (in AZB post):
Despite all of the potential benefits above, it can be difficult to be accurate and consistent with a swooping stroke (e.g., with the exact amount of english applied, or with avoiding a miscue when attempting to apply maximum english), unless one practices it a great deal. Most people will be more consistent and accurate (with actual tip contact point) with a straight stroke as compared to a swooping stroke; although, with enough consistent practice, any technique can be mastered. Some people (including some top players) can be quite effective with a swooping, swiping, or steering stroke.
A straight stroke (with appropriate aiming corrections for squirt, swerve, and throw, done either intuitively or using methods like FHE/BHE) is much more accurate and consistent (with the same spin-generating capability) than a swooping stroke, but some people will play better with a swooping stroke, especially if that's the way they've always done it.
For those who still think stroke swoop is a more effective way of applying sidespin than a straight stroke, see the results of the following experiment, and try it out yourself:
For more information, see "Swoop Experiment" (BD, August, 2015). If you want to compare the effectiveness of a swoop stroke vs. a straight stroke, try the test starting at the 6:34 point in the video. The test is not that difficult, and it doesn't take very much time. In setting up left obstacle ball on the 1st rail, be aware that the largest possible rebound angle varies with table conditions. It is best to place the left ball so the CB narrowly misses the left ball with an accurate hit and the maximum spin possible. After you determine the farthest point you can hit on the 2nd rail (through some practice shots with accurate hits on the 1st rail), just project back to the 1st rail to place the 2nd ball for a narrow miss of the CB for future maximum-spin shots. This will help ensure you don't "cheat" the experiment.
Note that in the diagrams that follow, squirt (cue ball deflection) is being neglected to focus on the effects of the swooping motion alone, which is exaggerated for illustrative purposes.
Below is a diagram from the video and article that shows that for a given swoop stroke, there is an equivalent straight stroke that will create the exact same CB motion (direction, speed, and spin). The cue alignment, tip offset, and swooping effects are exaggerated in the diagram so people can better understand what is actually going on with a swoop stroke. In the video, with the actual swoop stroke shots (starting at the 9:51 point in the video), the cue is aligned straighter and the tip contact point is closer to center; although the effects illustrated in the exaggerated diagram still apply (albeit to a lesser extent). It is clear in the video that the cue alignment (aim) must be different with the swoop stroke, as compared to the straight stroke, to have the CB head in the same direction.
The swoop stroke can create the same amount of spin with a slightly less perceived tip offset from center (exaggerated in the diagram for clarity); although, the cue alignment at contact must be different (exaggerated in the diagram for clarity) to achieve the same CB direction as the straight stroke. Much more explanation can be found in the article and video.
Some people have suggested it is possible to create maximum sidespin with a swoop (or swiping) stroke that contacts the CB close to the center of the ball (relative to the shooter), as shown in figure "a" in the diagram below. Unfortunately, this is not possible since the cue tip cannot create that much sideways force on the CB during a hit, where most of the force is along the "line of action" of the cue in the direction the cue is pointing (in this case, through the center of the CB). Even if this were possible, the CB motion would be extremely difficult to control and this would not be an effective technique for a real player on an actual pool table. The diagram below illustrates the proposed stroke along with an equivalent straight stroke, both achieving maximum sidespin.
The physical reason why the shot shown in figure "a" in the diagram above is not possible can be explained as follows. Creating a sideways force on the CB with the tip requires friction, and friction requires "normal" force (in the direction of the cue, perpendicular to the CB surface). If you try to swoop or swipe with significant speed (in comparison to the forward speed of the cue), the normal force won't be large enough to create very much sideways friction between the tip and ball, and the CB won't move forward with much speed. And even if more friction were possible, the sideways or transverse "endmass" and stiffness of the shaft is not ample enough (as compared to the longitudinal effective mass and stiffness of the cue in the "line of action" direction of the shot) to support the sideways force over the incredibly short tip contact time. If it were, squirt (CB deflection) resulting from off-center hits would be much larger than it is with a typical cue, which would make it impractical to play shots with any sidespin at all, with or without a swoop stroke.
If anybody thinks it is possible to create maximum sidespin using a swoop stroke with the tip contact point being close to the "perceived" center of the CB, please try the experiment described in the article and starting at the 6:34 point in the video, being careful to check the chalk mark on the CB after each shot. It ain't possible!
Notice in the diagrams above that to create maximum sidespin, the effective force direction (in the case of a swoop stroke) and the actual force direction (in the case of a straight stroke) must go through the miscue limit, creating the largest possible effective (or actual) tip offset from center. To get more spin than what is possible with a straight stroke at the miscue limit (i.e., maximum sidespin), the "effective tip offset" with the swoop stroke would need to be beyond the miscue limit, which is not possible without miscuing (just as with a straight stroke).
Also notice that with a significant swoop or swiping motion, the cue needs to be aligned in a slightly different direction (as compared to an equivalent straight stroke) to have the CB head in the same desired direction. This slightly changes the "actual" or "perceived" tip offset from center, but the "effective" tip offset from center will be slightly larger due to the swiping motion, as shown in the diagrams (exaggerated for clarity). In the stroke comparisons in the video (starting at the 6:34 point), the slightly different aiming alignments required are clear. Regardless, to create the maximum possible sidespin with any stroke, and have the CB head in the correct direction, the chalk mark will be in the same place on the CB for all stroke types (as illustrated in the diagrams). The effective tip offset from center will also be the same (also illustrated in the diagrams).
from Bob Jewett AZB post:
So far as I know, no one has ever demonstrated that you can get more side spin by swooping. I think it is just a different -- and to me, a far less consistent -- way to do backhand english. Look at the players who really spin the cue ball, like Masséy, Sayginer and Trump. No goofy swooping.
Some players fear hitting off-center because of miscues. They barely spin the ball because their arms force them to hit near the center. If someone shows them this "new swoop-spin" technique to get side spin, they may actually rev up the ball for the first time in their lives. They will be true believers. They will also be layering on a mechanical monstrosity to fix a deeper problem in their mechanics.
Even though the tip is on the ball for only a very short time, it does not follow directly that the player could not possibly and under any circumstance affect the result of the shot by swooping the cue stick. Swoop can in fact be useful for shots when the cue ball is very close to the object ball; you swoop to avoid the second hit. However, think about how fast the tip will need to move to the side to have any significant effect. It should be moving to the side at a speed comparable to the forward motion of the cue stick. That's a 45-degee angle relative to straight ahead. Try very slow strokes in which the tip moves at a 45 relative to its normal path. I bet you can't.
Can you get more spin on the ball with stroke swoop?
Some people might be able to get an larger effective tip offset from center (and therefore more spin) by using a swooping stroke. For example, they might be uncomfortable aligning the tip as off-center as is possible with a straight stroke (maybe because they can't prevent themselves from swooping, which would cause a miscue with a large initial tip offset). If this is the case, a person might be able to get more spin with a swooping stroke.
For more information, see the info and videos above, especially: NV F.2 - Swoop Stroke Experiment - Can swooping create extra spin on the cue ball?
from Jal AZB post:
You can't get any more spin by swiping across the ball than with a straight stroke. Whatever stroke you employ, the maximum spin/speed ratio is limited by the coefficient of friction between the tip and the ball. This is a function of the materials involved, and not of the type of stroke.
It's true that if you swipe across the cueball and, say, make contact at centerball, you're going to put a little bit of spin on the cueball. This is, sure enough, spin you wouldn't have produced with a centerball hit and a straight stroke. But that doesn't mean that if you make contact near the miscue limit (~ 1/2 ball radius) while swiping, you're going to get some extra spin. You'll either miscue or end up with the same amount of spin as you would have obtained by cueing right at the miscue limit with a straight stroke.
You can test this by plopping the cueball down on the headspot and driving it straight to the foot rail while attempting to impart maximum sidespin using both techniques. I think you'll find that the only thing the swiping does is to increase the difficulty of accurate tip placement.
What are considered "best practices" for stroke technique?
Here is a good video demonstration of what are generally considered "best practices" of stroke technique:
The stroke "best practices" document provides a detailed summary of general recommendations for stroke preparation and execution. The pre-shot routine is also an important component of technqiue. Here's a good illustration from Jeremiah Gage summarizing important stroke routine "best practices":
For more info, here are some good resources:
"type" or "quality" of stroke
Can two strokes of different "type" or "quality" create a different outcome on a shot,
assuming the tip contact point, cue direction, and cue speed are the same with both strokes?
No. All the cue ball "cares" about is the hit, not what creates the hit. The important variables of the "hit" are cue speed, tip contact point, and the angle of the cue (left/right and up/down). Now, stroke technique obviously has a lot to do with how the cue is actually delivered to the ball. You might think you are delivery the cue the same way with different stroke "types" or "qualities," but this might not be the case.
Tom Ross, my partner on the VEPS project, and I had a big argument on this topic years ago. He thought the "type of stroke" made a difference on a particular shot he was demonstrating to me. He was totally convinced he was using the same speed and tip position with both stroke types, and yet he was getting two totally different results (which he could replicate consistently with his two "stroke types"). After using a Jim Rempe ball (with chalk mark evidence) and my high-speed video camera, I finally convinced him that the two stroke "types" were creating different "hits" on the CB. On one of the strokes, he was dropping his elbow a little more creating a higher tip position even though we was sure he was not. For more info, see Tom Ross' April '08 and August '08 BD articles.
Technique is important to create the desired cue speed, tip contact point, and cue angle; and if you change your technique, it will affect the outcome of the shot, but only if the cue speed, tip contact point, and/or cue angle are different as a result of the technique changes.
FYI, for more information on why grip, stroke acceleration, and follow through have no direct effect on the action of the CB, see the following:
effects of light vs. tight grip
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