STROKE TIMING … A Complete MythBusting Study of Stroke Acceleration Effects

Dr. Dave debunks many common myths and misconceptions concerning stroke timing and acceleration and their effects on cue tip contact time and shot action.
Contents:
0:00 - Intro
0:24 - Common Myths
1:58 - Tip Contact Time
3:22 - Stroke Acceleration
5:47 - The Study
6:30 - Results and Conclusions
8:45 - Wrap Up
Supporting Resources:
- stroke “best practices” technique advice: billiards.colostate.edu/faq/s...
- stroke acceleration resource page: billiards.colostate.edu/faq/s...
- stroke timing resource page: billiards.colostate.edu/faq/s...
- stroke “type” and “quality” resource page: billiards.colostate.edu/faq/s...
- tip contact time resource page: billiards.colostate.edu/faq/c...
- cue tip hardness resource page: billiards.colostate.edu/faq/c...
- European stroke acceleration study: www.sciencedirect.com/science...
- Barry Stark Snooker Coach “timing” videos:
---- part 1: • 109. Timing - What is ...
---- part 2: • 146. Timing part 2 - I...
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[@DrDaveBilliards]

*Contents:* 0:00 - Intro 0:24 - Common Myths 1:58 - Tip Contact Time 3:22 - Stroke Acceleration 5:47 - The Study 6:30 - Results and Conclusions 8:45 - Wrap Up *Supporting Resources:* - stroke “best practices” technique advice: billiards.colostate.edu/faq/stroke/technique/ - stroke acceleration resource page: billiards.colostate.edu/faq/stroke/acceleration/ - stroke timing resource page: billiards.colostate.edu/faq/stroke/good-timing/ - stroke “type” and “quality” resource page: billiards.colostate.edu/faq/stroke/type-and-quality/ - tip contact time resource page: billiards.colostate.edu/faq/cue-tip/contact-time/ - cue tip hardness resource page: billiards.colostate.edu/faq/cue-tip/hardness/ - European stroke acceleration study: www.sciencedirect.com/science/article/pii/S1877705815014976 - Barry Stark Snooker Coach “timing” videos: ---- part 1: kzbin.info/www/bejne/sHmVgXuXfNFrf80 ---- part 2: kzbin.info/www/bejne/apbGf5mpeKxofJo *Subscribe to Dr. Dave's KZbin Channel:* kzbin.info

[@cvajda]

Have you ever thought about Venom's masse shots or Chinesese strike through? They puss the ball insanely

[@DrDaveBilliards]

@@cvajda A masse shot is different since the CB gets “trapped” between the tip and the table. FYI, I have actually filmed a bunch of stuff with Venom, including masse shots. See the playlist here: kzbin.info/aero/PLH9d4KFY28XvjfavLkmw8nIcWOiDH2GYc&si=d7SaCEDppuwuZa69

[@darkerdelirium]

Love when you use actual data and the scientific method to disprove "established knowledge" of the game. In any field, people like you Dr.Dave are tremendously important!

[@DrDaveBilliards]

I'm glad you think so. Not everybody agrees, but hopefully videos like this will help in that regard.

[@pawegrzanka5494]

@@DrDaveBilliards These videos are very much needed in pool community. "[...] to disprove "established knowledge" of the game." - IMO it's an ignorance thing - we tend to search for a "silver bullet", when all we need is practice and proven fundamentals, we tend to believe when someone gives us the mind-comforting statements. Whenever I've heard of accelerating(through the CB) producing a different effect than hitting the ball with the same exact velocity of the cue tip at the contact point, I found it strange that people think this way. Ultimately, we can believe in anything as long as our ignorance lets us, like multiple tip contacts (it being debunked by you is also a gift of knowledge for some). Thanks again for your work

[@seamusmcfadden994]

"Not everybody agrees" True. I like some of his ideas, even though he is definitely a little (lot) quirky but..... This guy who goes by two initials and last name rhymes with "Miley" lol apparently is not a fan of yours. Did you guys have some kind of beef before? I took a lesson with him and he brought you up out of the blue. It wasn't just you either. He seems to like to blow other people's candles out so his is brighter.@@DrDaveBilliards

[@DrDaveBilliards]

@@pawegrzanka5494 Thank you for the comments. You're welcome. I aim to swerve. :)

[@DrDaveBilliards]

@@seamusmcfadden994 Many "established people" in the pool world dislike me because I have documented and demonstrated many things that "go against" what they "teach."

[@ZSharkPH]

I can imagine a lot of time and effort went into this video. Thanks for the hard work Dr.

[@DrDaveBilliards]

You are correct. You're welcome. Pubo and I aim to swerve. :)

[@keyboardkevin5949]

LOVE THE PHYSICS BEHIND ALL THIS STUFF! Never stop!

[@DrDaveBilliards]

I don't plan to stop anytime soon. It is too much fun, and I keep learning stuff.

[@terrythomas4407]

The high speed camera shot was very interesting to witness. Thanks.

[@DrDaveBilliards]

Super slo-mo pool videos always teach so much. FYI, many more can be found here: billiards.colostate.edu/faq/video/slow-motion/ Enjoy!

[@Zombies8MyPizza]

I have a few different interests and it's crazy to see stuff that was once seen as fact, getting debunked by new technology. Extremely interesting!

[@DrDaveBilliards]

I'm glad you think so. I agree. :)

[@jamesnewcomer5963]

It's great to see explanations of the importance stroke timing, not due to the physics of the interaction between stick and ball, but because we humans are imperfect machines who need best practices to achieve consistency. It's more about physiology than physics in this case.

[@DrDaveBilliards]

Well stated.

[@lanternman13]

That's an important point. This is also my perspective. I always try to understand both sides. The measuring scientist and the teaching instructor. The scientist looks more at the measurement of the transfer of physical forces to the material, while an instructor describes the feeling of how this has to be executed motorically in order to achieve consistency in stroking. The topic of “timing” is quite controversial, as is “contact time”. Because of the lack of measuring instruments, I focus on feeling the strokes I apply on the ball. In my arsenal is a 10.5 mm carbon fiber shaft (Cuetec Cynergy). This is the first shaft where I could clearly feel the contact and, with a soft hit, the "contact time" of an appropriate follow-through. I was then able to transfer this experience to the other tip sizes and had better results (e.g. Drawshot). When it comes to the methodology, you also have to differentiate between the speed characteristics of the cloth and how well the balls are polished. Rough balls and rough cloth should certainly increase the "contact time". (another topic) Due to the fast cloths, a lot of conditions will have changed over time, and the knowledge of the older players and coaches probably also comes from earlier conditions and times.

[@DrDaveBilliards]

@@lanternman13 Good points. As an instructor, I like to strive to say things properly and correctly from a physical perspective, but I also offer technique advice in a way that is most useful to my students, even if it might sometimes not be technically correct. For example: “Accelerate through the ball.”

[@DrDaveBilliards]

BTW, check out my follow-up video dealing with draw shots, which supports the myth busting even further: kzbin.info/www/bejne/b4itpIJma7mqd68

[@xeyedsurfer]

The best in the world have coaches, the coach is not better than the player, they just evaluate the information in a logical way to help them further.

[@DrDaveBilliards]

Agreed.

[@davekat4680]

……the best ‘real’ information anywhere 🙌🏼 thank you for your time Dr. and happy new year 🎉

[@DrDaveBilliards]

Happy New Year!

[@user-zt6lf6er4m]

Great study and analysis! Thank you and best wishes for the New Year!

[@DrDaveBilliards]

Thanks! Ditto!

[@trailerwookie]

Thank you for settling this definitively. I have read statement like ones you mentioned and I just couldn't wrap my head around what they were saying. Turns out it was nonsense. Thanks!

[@DrDaveBilliards]

Well stated.

[@dispoflection]

I love pool for many reasons, one of which being a great canvas for scientific exploration. Well done!

[@DrDaveBilliards]

Agreed. Thanks!

[@IamKlaus007]

This is the best explanation of cue/cueball control I've ever seen. Would appreciate your definition of the difference between a push shot and double hit.

[@DrDaveBilliards]

Push shots are covered in detail here: billiards.colostate.edu/faq/foul/push/ and double hits are covered in detail here: billiards.colostate.edu/faq/foul/double-hit/

[@420jacksonian]

love your videos ! happy swerve year

[@DrDaveBilliards]

I'm glad to hear it. Ditto!

[@ngsaichin1]

Thanks Dr. Dave for this useful clarification. I heard that there is so-called "AK Timing" but it is difficult to get its scientific understanding because the contact time is so short (less than 2 msec)

[@kirillernandez8838]

Thank you, men. It is a very comprehensive research

[@DrDaveBilliards]

You're welcome. We aim to swerve. :)

[@NefariousMinds]

I always thought this. It is simply a transfer of energy, but I can understand why people think the tip is holding on to the ball. This is why the action must be performed before tip contact, and perfect timing would be just before tip contact. On another note, it would be cool to see a study like this with mechanics. Like the different muscle sets used on the backswing vs forward swing. It would show exactly why you need a smooth transition. Also, I have heard a couple pro teachers say there is no need for a delivery with the wrist on the forward stroke. I have tried both ways, but I have found that the wrist delivery with perfect timing of the swing of the forearm is superior. What is your thoughts on this Dave?

[@DrDaveBilliards]

All my thoughts on wrist action are here: billiards.colostate.edu/faq/stroke/wrist/

[@ethanletzer3507]

Dr. Dave your the best. It's all about the facts with you and that's hard to find in a person. You demystify and simplify the game of pool in such an eloquent and easy to understand way that let's even amature players like me understand. Take out the opinion and all you have is the truth and that's the way it should be!

[@DrDaveBilliards]

Thank you for the supportive comments.

[@sociologie4507]

Dr Dave! You a legend! I have a PhD too and a healthy dose of "skepticism" in practice is what it looks like under your microscope.

[@DrDaveBilliards]

Thanks.

[@gregaclark2]

Hi Dr. Dave, thanks for another useful video, your timing was perfect! ;-) I'm working towards achieving a sub-20-min mighty x drill, and the small details about my stroke, especially draw shots, has become a recent obsession of mine. Videos with scientific detail like this one make it much easier for players like me to understand, which turns into confidence at the table. On a side note, something of interest to me is the prevalence of "cheating" with performance-enhancing drugs. Is it possible that you could delve into social and scientific review/commentary of PEDs? I know it's a touchy subject, but any objective commentary or scientific research (as it pertains to pool) would be extremely interesting. Similarly, techniques like fasting or having alcohol to calm nerves (or abstaining from alcohol until after a match as a reward system), or other clever ways that athletes try to gain an edge (e.g. abstaining from sex) could be of interest.

[@DrDaveBilliards]

Sorry, but I don't really have any interest in PEDs and their effects, nor do I have expertise in this area. I'm not that kind of doctor. :)

[@diesvenja9623]

Looking through the video of Barry again: he was using a 35k FPS camera and came to a difference of 200 microseconds difference. You were using an 8k FPS camera where, if I am not mistaken, a difference of 200 microseconds would be only 1-2 frames. You were also talking about 11-12 frames contact time which would include the difference that Barry saw. So I’m wondering if there is maybe a difference that is just not clearly visible with an 8k FPS camera?

[@DrDaveBilliards]

We have also filmed stuff close to 30,000 FPS, but we couldn’t get the wide view we needed at the faster frame rate. It is possible Barry’s tiny differences were due to slight changes in cue speed and tip offset from center, but we don’t know.

[@SliceNdicez]

Possible, but his room for error was literally 0.0001s, which is probably too little to make any significant impact on how the cue ball moves.

[@SenseiNatePlaysPool]

Love it!

[@EhBitTV]

I think of stroke timing as having more to do with the speed and spin matching up to what you want to happen, for example a long stop shot, the backspin running out just at the time of contact would be good timing etc.

[@DrDaveBilliards]

That sounds more like "shot timing." But I agree that good stroke timing is required to be accurate and consistent with stop and controlled draw shots. For more info, see my recent "DRAW SHOT CONTROL" video: kzbin.info/www/bejne/qGrXmZehlq6ssNU

[@stateliker]

Great video. I love it

[@DrDaveBilliards]

Thanks. I'm glad you love it. I hope others do also because it involved lots of work.

[@anthonykeller5120]

Your video here came at an auspicious time. I have one billiard comment and one very off base physics comment. I recently heard a female player describing a new training regimen on which she embarked. Part one of the regimen spent a month on her stroke with no ball she could learn the difference between stroking the cue so that it pushes the cue ball versus striking the cue ball. According to her there is a significant difference. During the discussion on ‘time on the ball’ I wondered about this in relation between pushing and striking. On top of that I just watched the finals of the Chinese Heyball tournament where a female played a male opponent. It seemed as if you could hear the difference (as well as see the difference) when the female stroked a push instead of when she struck the cue ball (she missed a number of the push shots). My mind concluded the cue did spend more time on the ball to the detriment of the accuracy. Four days ago I watched a video about two moveable objects on a frictionless plane next to an immovable wall. If the objects contain the same mass and the outside object hits the object between it and the wall, 3 collisions occur (inside object, wall, outside object). If you increase the mass of the outside object from 1 by powers of 100, 10,000, 1,000,000 you get 3 collisions, 31, 314, 3141 respectively. As you increase by powers of 100, the number of collisions matches pi. I’ve always used a 21 ounce cue until a couple of years ago when I added a six inch extension in the middle since I’m 6’3” and it now weighs close to 26 ounces. Now I’m wondering if I’m going to cause my cue mass to stay on the ball longer or cause unwanted double hits with the cue when the cue is close with the object ball. Not sure why the video popped into my mind here, but I thought you might find it interesting. My engineer son said pi is in a lot of unexpected places, it is not just round object relationship.

[@DrDaveBilliards]

I'm glad you like the "timing" of my video. :)

[@DrDaveBilliards]

Concerning cue weight, too much weight can lead to bad hits at large tip offsets. For more info, see: billiards.colostate.edu/faq/cue/weight/ billiards.colostate.edu/faq/draw/cue-weight-effects/ Enjoy!

[@valentenicoletti3622]

Thanks ! Really Good Video

[@DrDaveBilliards]

You’re welcome. I’m glad you liked it.

[@slicergears657]

I love science! Thank you Dr. Dave.

[@DrDaveBilliards]

Me too! You’re welcome.

[@keijokettu3309]

These myth busting videos are brilliant! Just for the entertainment value it would be fun to see a compilation of smaller and more irrelevant myths. For example, there seems to be a collection of habits that transfer from player to player. One of these I myself picked up was: When I have ball-in-hand I often roll the cueball against the rail as if to clean it. I see pro players do this all the time and even saw the ref at the Derby City Classic quickly do this instead of properly cleaning up the ball. That raised up the question in my mind: does it actually do anything and if so, how well?

[@DrDaveBilliards]

Good idea about small or even silly myths. I'll think about it. Concerning rubbing the CB on the cushion nose and table, it does help clean chalk marks off the ball. Using a glove or towel is obviously better. BTW, I have a lot more pool myth busting videos and info here: billiards.colostate.edu/myths/

[@ShortstopOnPool]

Nicely done. All I can say is, amen, brother, amen. But now I suggest research be done to determine what features actually produce the best or desired "action". I would think a computer controlled piston to precisely set cue tip acceleration and speed at impact would be required. Huge project!

[@DrDaveBilliards]

Thanks. I think the "best practices" for a good stroke, to create the "best action," are already well understood. They are summarized and demonstrated in the videos and via the info here: billiards.colostate.edu/faq/stroke/technique/ The European study also validated that most top players reach maximum speed with no acceleration at tip contact (except with a break shot). Here's the link: www.sciencedirect.com/science/article/pii/S1877705815014976

[@coderman1]

i think he did mention it. cue tip position and speed and cue direction. nothing else matters. i have thought for a long time, why dont cue manufacturers have a cue swing machine? how else do they quantitatively prove their cue/shaft is better than any other?

[@DrDaveBilliards]

@@coderman1 Cue testing machines have been used over the years, but many things can and have gone wrong with machine testing. See: billiards.colostate.edu/faq/squirt/robot-test-results/ Careful cue testing with actual players can be just as good (if not better) when done properly. See: billiards.colostate.edu/faq/squirt/published-data/

[@seamusmcfadden994]

Excellent video!👍

[@DrDaveBilliards]

Thanks!

[@keyboardkevin5949]

What is the most updated size guide for your t-shirts? I'm seeing one that says a small is 19in width but another that says its 18in width. How "small" is a small... Not sure if the shirts run big or small. Thanks!

[@DrDaveBilliards]

If you click on the "Size Guide" link on the ordering page of any shirt, it will provide accurate information. The shirt sizes run average.

[@KarlsCracklingCottonMouth]

Another awesome vid

[@DrDaveBilliards]

Thanks. I'm glad you think so.

[@permickichristensen]

Amazing video :)

[@DrDaveBilliards]

Thanks!

[@Arclight24]

Great topic! ❤ thanks Dr. D! ❤ Recently Carlo Biado played 8 ball in South America with a heavy handicap against the allegedly best player there. “Reyes Gomez” He needs to pocket the 8 ball with the same pocket as the last ball. 🎱 this is a good video to analyze hope you can find the time to dive deep into this 🙏🏼🙏🏼🙏🏼 Happy new year Dr.D! ❤

[@DrDaveBilliards]

I’m glad you like the video. Thanks for the info, but my list is topics to film is already extremely long (and it keeps growing). FYI, if you are interested in classic match analysis videos, I have some here: billiards.colostate.edu/videos/pool-matches/

[@AVR-88]

Is there a difference in "timing" due to hardness of a tip, like a hard break tip vs a very soft playing tip? I believe that the prolonged tip contact feeling has more to do with the stroke timing leading to contact and the vibrations of the cue reaction. There must be a difference of wave lengths between accelerating, normal, and de-accelerating strokes. Is there a way to test that?

[@DrDaveBilliards]

All tip hardness effects are summarized and demonstrated here: billiards.colostate.edu/faq/cue-tip/hardness/

[@mike1why]

Good job with the video and the explanations. I still find it unsatisfying, despite understanding and agreeing with the concept. It still leaves the question of _why_ a `good' stroke has that particular feel and better action. I look forward to your next enlightening installment. Best regards.

[@DrDaveBilliards]

To me, a "good stroke" has "good timing" (mostly no deceleration), as described in the video.

[@richardbarabe4863]

​@@DrDaveBilliards yes, but now after watching this video, I wonder how does the timing matters. I understand it's not the contact time, but what is it then that a good stroke have more action ?

[@DrDaveBilliards]

​@@richardbarabe4863 See the videos here: billiards.colostate.edu/faq/stroke/good-timing/

[@Bozebo]

I felt sure of this already from your earlier videos :)

[@DrDaveBilliards]

Me too. Unfortunately, some people still won't "buy" it.

[@MrJdsenior]

You can NEVER confuse some people with actual data and logic. In fact, in my experience, the more you try, the harder they hold onto their preconceived notions, especially if they have some stake in the outcome. You know the type. :-) @@DrDaveBilliards

[@DrDaveBilliards]

@@MrJdsenior This is a major problem with the “human condition” (and “social” media) in today’s society.

[@bjbjup]

Dr Dave, am you fans, love your videos. I have some suggestions in your analyst. 1. Barry and Joe Davis, claimed that prolong the contact time, at power screw shot. If you want to mythbust their claim you should analyze power screw shot, same as their claim. 2. Pubo Huang study. If the cue ball does not stop in the area/distance, the shot was not included. That means the study is about the speed of the cue ball, but not the speed of the cue itself. An example: at the impact, if the speed of the cue(or cue tip) is the same, but the cue ball goes further, out of the area limited, the shot will not included! We should measure the speed of the cue, not the speed of the cue ball.(You might say they are the same thing. But what if they are not?) 3. From Barry and Joe Divis, they said, if you do the right thing, there will be more back spin on a power screw shot. It is all about the spin, not about the speed of the cue ball.

[@DrDaveBilliards]

1. We're on it. 2. If you look at the plots, the cue speeds matched also. Again what happens to the CB depends only on the tip position and speed of the cue at impact. 3. You get more spin by hitting the CB lower or having more cue speed at impact. That's it. Nothing else matters (for a given cue).

[@bjbjup]

@@DrDaveBilliards Barry and Joe Divis both mentioned "power screw shot". Barry's video measured screw shot. Barry channel invited professional player to test power screw shot. So it is all about power screw shot. Snooker experienced players, when they use power screw shot, their back hand fingers will have a soft feeling(like a spaceX landing), while they feel an impact for a stun shot. And this happen only on a power screw shot. Prolonging of the tip on the CB is their explaination(maybe right maybe wrong) If we want to prove it by experiment, better use the same conditions as a in a snooker game, lighter and smaller balls, longer table,(these two factors make the shot much hard, means much more spin is needed, compare to the pool game), lighter cue, 17~18oz(this can make the speed of cue faster), and a snooker cue without any leather cover, touch directly to the wood or the paint on it, will increase in the feel at impact. (An experimental particle physican said, photon has zero mass theoretically, experimentally we are not sure yet.)

[@DrDaveBilliards]

@@bjbjup We have plans to do a draw/screw shot video also. I strongly suspect the answer will be the same: All that matters is the tip contact point and the speed of the cue at impact. Having a good stroke (with good "timing") helps one be consistent and accurate with these things: billiards.colostate.edu/faq/stroke/good-timing/ billiards.colostate.edu/faq/stroke/technique/ PS: Snooker cues and balls are different, but the physics of the tip/CB collision (and many other physical aspects of the games) are the same.

[@dansass1353]

Hey DrDave, love your analysis, thank you for sharing this with us. I had a question about grip strength at time of contact. It stands to reason that a tight grip would effectively be adding mass to the stick at time of contact vs a loose or sliding grip. Could grip strength effect tip contact time?

[@DrDaveBilliards]

A non-human "death grip" could effectively add mass to the cue, but I don't think this is the case with typical pool strokes by typical humans. Most top players actually have a relaxed grip, even on power shots.

[@TheSnookerGym]

‘Death grip’ lol - I will have to use that if I can! Happy to quote you!

[@bjbjup]

@@DrDaveBilliards A tight grip could add mass the cue when impact(would it?), but it will make the accelerating harder(as Bruce Lee said). A loose grip makes less mass but easier to accelerate. So where is the balance?

[@DrDaveBilliards]

@@bjbjup It would need to be a ridiculously tight grip by somebody with very bony hands. Otherwise, grip tightness is really not a factor. See: billiards.colostate.edu/faq/grip/light-vs-tight/

[@cristianmunteanu8765]

Awesome!🎉

[@DrDaveBilliards]

Thanks.

[@Kmuggle]

Two questions ... 1. Does this information disprove the claim that the grip of the cue hand should be loose? If the only things that effect the cue ball are tip speed at impact, cue tip offset and cue direction ... it seems to me that given the short cue tip impact time ... that anything the shooter does ... except for that one instance ... can have no effect. 2. When we say "Man, that guy has a stroke!" ... given the short cue tip impact time ... what that is measurable ... determines a that guys good "stroke"?

[@DrDaveBilliards]

1. Correct. Nothing the shooter does has an important effect on tip contact time (for a given cue tip and cue speed at contact). 2. A good stroke has good timing with smooth acceleration (and over a long stroke length for more power). For more info, see the video and info here: billiards.colostate.edu/faq/stroke/technique/

[@vivekarulnathan9446]

Great video. The only defense I will make for Barry (the first youtube instructor to help me after I took up the game) is that while the exact words (such as the tip holding on to the cue ball) might be factually wrong, the desired outcome of his instruction is likely similar to what one could conclude from your video - having a cue action that is consistent, smooth, and peak acceleration before contact. Assuming Barry is someone who's coaching foundations were formed before the days of such video technology, those words are a means of ensuring players have good fundamentals. If you watch all of Barry's videos, he emphasizes more than anything else that having a consistent stroke (and routine) that you can rely on all the time is the key to developing your game. I am sure you will agree with that.

[@DrDaveBilliards]

I agree that sometimes instructors say things that might help a student even if those things are not "technically correct." For example, I often tell students to "accelerate through the ball" even though this is not what actually happens. It just helps them not "decelerate" into the CB, which is a bad thing. However, the problem I have with Barry's presentation is he is seemingly stating his opinion as unequivocal fact (which is inappropriate and incorrect). It is fine to say "imagine you are keeping the tip on the CB" or "think about trying to keep the tip on the ball; but it is not OK to say "better stroke timing makes the cue tip contact time longer." (which is not true). I instead prefer to give the advice: "Accelerate smoothly and completely while staying still and relaxed, and use a longer stroke length when you need more power." That gets the job done. BTW, "acceleration" does not peak at the CB ... "speed" does. The acceleration is actually zero at peak speed.

[@markusaurelius6725]

You're missing the point. Barry went out of his way to use a high speed camera to prove his theory. However, the data he himself recorded was messy and didn't support his argument due to measurement and/or process errors. So clearly, he has gone above and beyond just "using words to ensure players have good fundamentals". He's out to _prove_ this is physically what is happening during tip/ball contact. Barry entered the area of science, and so Dave's response was perfectly proportional.

[@DrDaveBilliards]

@@markusaurelius6725 I like it ... "proportional."

[@vivekarulnathan9446]

@@markusaurelius6725 What point am I missing? Did I question any of Dave's findings or claim Barry was right? Or did i say Dave's video wasn't an proportional response? I was merely pointing out that watching Barry's channel makes it clear it is not a place to seek information on the physics of the game and that pretty much everything he says (including the wrong claim on tip contact) is an effort to emphasize good fundamentals. That's what I take from his channel.

[@blandcircle4402]

How does the timing of the stroke impact the quality of spin imparted on the cue ball? Is it all the same because of the similar contact time? Does the consistency rate at which you can put maximum draw or top spin change depending on stroke type?

[@SliceNdicez]

Used to have a decelerating stroke when doing straight draw shots because I was afraid of the cue ball drawing back into the cue. The action of decelerating (by pulling the cue back) was an additional motion that caused unintentional sidespin causing my straight draw shots to be very inconsistent. I think the reason why a normal stroke is good is because it is done with one action which requires less subconscious coordination/causes less mistakes which makes it very consistent.

[@DrDaveBilliards]

Timing can affect the cue speed at contact, which does affect the shot. However, for a given cue speed at contact (for a given tip position), the quality, type, or timing of the stroke has no effect. For more info, see: billiards.colostate.edu/faq/stroke/type-and-quality/

[@KK-sg5gl]

We need slow motion video on a full table power draw shot, as well as a force follow shot, and maybe a powerful 10 ball break shot.

[@DrDaveBilliards]

I have super slomo videos for pretty much every type of shot here: billiards.colostate.edu/faq/video/slow-motion/ Check it out.

[@CocoboloCowboy]

People who would be considered bright,if they apprieciate Dr. Dave’s information. But his info is 100% Truth. If you want to find out Dr. Dave info practice what he preaches. People can only learn to play pool better with practice.🥳

[@Gotwired]

Imho, the simplest way to explain it is that if cue tip contact time was longer than an instant, any spin on the ball would result in a chalk mark that looks like a line or multiple chalk marks rather than a single dot.

[@DrDaveBilliards]

Good point. A good example of that is the tip riding the CB with an elevated follow shot. See the "elevated follow shot" videos about halfway down the page here: billiards.colostate.edu/faq/foul/double-hit/

[@logic368]

I think most people are capable of a smooth accelerating stroke when they’re not nervous. But what the good players have is their own method for achieving the right speed and direction of the cue. I personally think direction of the cue is one of the hardest things to get right (it’s really hard to get the cue to travel in a perfectly straight line)! Some use a slip-stroke, some use a punch, others use a good old-fashioned pendulum. But on that final stroke forward, all the top players manage to make the cue travel very, very straight. Would you agree with that?

[@DrDaveBilliards]

Good point. It takes a good stroke to be consistent and accurate with everything.

[@pmayh3m]

Awesome!!! More ammo to argue with the pool myth perpetuators out there.

[@DrDaveBilliards]

Thanks! Unfortunately, sometimes more ammo just makes the "war" more violent.

[@filip000]

Regardless of elders, time spent, traditions, respect, emotions and everything else.....science always wins.

[@DrDaveBilliards]

Facts are definitely better than "alternative facts."

[@colincolenso]

Brilliant video Dave. So many of us have presumed so many powers to the STROKE which are mostly fallacious. Upon re-reading, specious is probably a better descriptor. Bridge positioning is far more of a challenge than stroke execution. There's a saying that race isn't everything, but it's not nothing. The stroke isn't everything, but it's not nothing. Players assume their bridge placement is somehow anointed by God to be perfect. It rarely is, and its imperfect placement is the main cause of poor stroking and the peri-stroke adjustments (swiping) that afflict and restricts the progress of almost all players.

[@DrDaveBilliards]

Well stated, Colin. I would add “consistent and accurate personal vision center alignment” as another thing just as important as a repeatable stroke: billiards.colostate.edu/faq/eyes/vision-center/

[@TaSk1o4]

So what is going on, or what might be making the difference, when you can feel that you struck a ball exceptionally well, and get a surprising amount of action? When you can even hear the sound of a perfectly struck cue ball? What is the difference when some players can get more out of the cue ball, with less effort? If everything comes down to tip speed and placement at contact, why do subtleties in grip make such a big difference? Or is perfect speed and accuracy just that difficult to attain, when a stick is swung by a human arm? I feel like there are still so many mysteries behind what is happening when a cue ball is beautifully struck.

[@DrDaveBilliards]

When you hit the ball well and it sounds and looks good, that just means you hit the ball where you wanted with the speed you wanted. Simple as that. Now, to do this with consistency and accuracy takes skill. It also helps to have all the solid fundamentals explained and demonstrated here: billiards.colostate.edu/faq/stroke/technique/

[@japanesemaytree8982]

There is also the "timing" that people use when accounting for the fact that it is very difficult to deliver a perfectly straight stroke from backswing to contact to finish. As a result, players often have to one extent or another on line and off line variations through the coure of the stroke. From this perspective, a player's timing is "right" when the cue is on line at the time of impact. Accordingly, it's typical for a player's timing to be good at some speeds and hits (say a long stop shot, e.g.), but completely off for others (slow speed follow shot, e.g.) This is not the "timing" issue you address here obviously. But is a legitimate "timing" consideration, reflecting the reality of what is perhaps typical.

[@DrDaveBilliards]

Agreed. “Timing” usually refers to the smooth acceleration of the stroke into the ball and has nothing to do with tip contact time. For details on this topic, see the videos here: billiards.colostate.edu/faq/stroke/good-timing/ billiards.colostate.edu/faq/stroke/technique/

[@ThichNhatHanh23]

Do you know the method with which you hold the cue at its center of gravity with your thumb and forefinger in one hand and let it swing until it stops?The muscles of the body must be relaxed except for the two fingers. After swinging out, the cue is in a position that is unique to your body. This is the position in which your body can most easily hit an object in a straight way because every body, lats and shoulder muscle is different which causes a different angle of the arm .We often say that we aim with our feet in billiards but the lats and shoulder muscles can push the cue of line. My angle from the cue to my feet is almost a 90 degree angle. I stand very sideways to the table, almost like Albin Oshian.

[@DrDaveBilliards]

I honestly don't think that method is very useful unless it is done in your pool-stance body position (not in a upright standing position). FYI, a good way to find your "personal best" stance position is covered in the videos here: billiards.colostate.edu/faq/stance/

[@ourniche]

This is great Dr. Dave. Just for fun I "ran the numbers" comparing a 16 oz and 19 oz cue while assuming a cue ball mass of 4.5 oz (which I think is pretty close for a snooker ball?). With a simple center ball head-on collision the more massive cue will result in a 13% reduction in cue ball speed which is modest but not insignificant. This is assuming that the force the player generates is the same in both cases - so the heavier cue will not be moving as fast as the lighter cue (but this is partly offset by the heavier cue otherwise causing a greater energy transfer).

[@DrDaveBilliards]

It is not that simple. See: billiards.colostate.edu/faq/cue/weight/

[@ourniche]

@@DrDaveBilliards I believe my approximation is valid over the "typical range" of cue masses - it seems to match exactly what you have referenced for center ball collisions. If the force a person exerts is not influenced by the cue mass - a reasonable and very close approximation, then the difference in acceleration and final cue speed will be linearly proportional to the cue's mass - ie twice the mass, half the acceleration and half the speed at contact - or very close to it. The difference in mass as you noted also alters the CB speed - the greater the mass, the greater the CB speed. I just did the calculations with both of these factors taken into consideration. Results - when you increase cue mass the lower cue speed has a greater influence than the greater cue mass. Again assuming the player applies the same force to the two cues.

[@DrDaveBilliards]

@@ourniche Check out the following analysis that you might find interesting: billiards.colostate.edu/technical_proofs/new/TP_A-30.pdf

[@ourniche]

@@DrDaveBilliards thanks - will do when I get a chance. I did find an error in my math already though - realized I didn't account for increased time of stroke when the cue mass is greater - ie you apply the same force so a slower acceleration with the heavier cue but then of course you have the benefit of accelerating the cue for a longer time. So my result (accounting for both slower cue and more massive cue) is only a very small decrease in final cueball speed with the heavier cue. I'm happy about that because I'm 6'2 and use a long and therefore "heavy" cue :-)

[@DrDaveBilliards]

@@ourniche Also, the force applied during a stroke is not constant. See: billiards.colostate.edu/faq/stroke/acceleration/ And it also depends on the weight of the cue, muscle physiology, and level of effort.

[@youtubesux6361]

You should try one of those things that baseball guys put on the bat butt to get all the bat telemetry. It would work on a cue I bet

[@DrDaveBilliards]

That's a good idea. It has been done before. See the last section at the bottom of the page here: billiards.colostate.edu/faq/training/teaching/

[@Mozac01]

I don't think its about the actual contact time and more about the way the cue ball is struck which tends to feel like a longer contact time. Its something similar to striking the cue ball with your finger while trying to either add maximum spin to the cue ball forward motion or very little from the same contact point maintaining the same speed. While both shots may have the same contact time, the way one approaches them will be instinctively different and both will feel different to the touch. In cue sports this feel is generated not at contact time, but what the fingers are doing just before, during and right after strike. This might have something to do with how fingertips touch system works.

[@DrDaveBilliards]

Agreed. Tip contact time has nothing to do with a good stroke. But the “type” of “quality” of the stroke also has no effect on the action of a shot (assuming the tip contact point and cue speed is the same in any comparison). See: billiards.colostate.edu/faq/stroke/type-and-quality/

[@SPM310]

Does this mean tip contact time is the same for beginner to pro? Does this mean it's not tip contact time, but where and how the tip hits the CB that makes the difference between beginner to pro? What is it that makes pros - pros?

[@DrDaveBilliards]

The tip contact time is no different for different players hitting the CB at the same speed with the same tip hardness. Everything that separates pros from others is summarized here: billiards.colostate.edu/faq/advice/pro/

[@MrJdsenior]

I'm assuming it included about 20,000+ hours of determined and well observed practice. @@DrDaveBilliards

[@the_pirates_den]

"Ladies and gentleman"

[@DrDaveBilliards]

"Peanut Butter and Jelly."

[@lesterweinheimer665]

Now I've got the munchies!

[@DrDaveBilliards]

@@lesterweinheimer665 That's what happens when you smoke pot and watch awesome pool videos. :)

[@MatthewKirkum]

I agree with the things you said, but to anyone else reading this, Barry Stark is still one of the best coaches I've ever come across. His channel is an absolute wealth of knowledge and good technique, and my game improved quite a lot after watching just a few of his videos.

[@DrDaveBilliards]

Agreed. I watch Barry’s videos also.

[@zanethind]

Another good video Dave. Always appreciate these debunked videos

[@DrDaveBilliards]

Thanks. I'm glad to hear it.

[@meravids6740]

Science and mathematics and technology right there.

[@DrDaveBilliards]

DAM right.

[@DeanWhipper]

I don't know what it is specifically about Snooker, but it always seems to generate the most outlandish ridiculous myths. Maybe it's the high level of difficultly? People struggling and willing to believe just about anything if they think it will help their game. The vast majority of advice I see online is just straight up unscientific nonsense.

[@DrDaveBilliards]

There does seem to be more "rubbish" conspiracy theories in the snooker world than in the pool world, but the pool world has its share also.

[@DeanWhipper]

​@@DrDaveBilliards English sports are quite often filled with old wives tales.

[@dnbmania]

4:39 Dave i find it curious that the green line that is shown to be ideal has the shape it does. We can see that the cue is accelerating at impact (shown by a positive gradient), however the rate of change of acceleration is decreasing (the gradient is flattening out). In my head an exponential graph would be more ideal. What do you think?

[@puboh]

The graph is time vs speed. So the green graph shows the cue reaching maximum speed right at impact, so the cue isn't acclerating at impact.

[@DrDaveBilliards]

The green graph, with maximum speed (and no acceleration) at cue tip contact is "ideal." It is what most top players do, as validated by the European study mentioned in the video. Acceleration at tip contact is actually difficult to achieve with a smooth stroke, and deceleration is a speed-control killer.

[@kenbarr4386]

I have a question: why does a good draw shot require a pronounced follow thru? I thought the follow thru was the best way to accelerate through the shot and impart the most spin. But you are now saying the acceleration does not matter. So you have only 1/2 busted the myth, can you prove an accelerating and decelerating shot imparts the same draw spin? Or at least explain what I am missing? Why does a punch shot feel like it produces less draw spin then a follow thru shot if not acceleration at point of impact?

[@DrDaveBilliards]

If you generate the cue speed necessary for good draw, and if you stay relaxed, a good follow through cannot be avoided. See: billiards.colostate.edu/faq/stroke/follow-through/ To get good cue speed, a long stroke with smooth acceleration is the best approach, but most good players have no acceleration at the point of contact (where they have already reached maximum speed). See: billiards.colostate.edu/faq/stroke/acceleration/ For lots of good draw shot technique advice, see: billiards.colostate.edu/faq/draw/advice-and-drills/

[@puboh]

Yes, in fact, as long as you are hitting the ball at the same speed and same contact point, accelerating and decelerating cues at impact produce the same result on the cue ball (that said, if there's any difference, it is not to an extent that matters in the game of pool). Please wait for DrDave's new video where we have video proofs for this

[@DrDaveBilliards]

@@puboh Well stated. I can't wait for the new video to be posted! :)

[@kenbarr4386]

@@DrDaveBilliards I agree with what constitutes a good draw shot. My point is that if I hit the draw shot properly I get more draw than if I hit with a jabby punch shot, even if I hit the punch shot harder, ie. the target ball moves faster. If acceleration has nothing to do with results as you suggest, the the likely answer is with proper stroke I am likely able to hit lower on the cue ball without miscue because I can get the cue flatter.

[@DrDaveBilliards]

@@kenbarr4386 … or you are generating more speed than you think since a longer and smoother stroke requires less effort to generate the same cue speed.

[@poppajretired410]

Now comes the “Yea, but what about”•••••••••😂

[@DrDaveBilliards]

You can never satisfy the true Myth Believers.

[@NameName-ji6wv]

Problem with this info: Im so bad at pool, no one will believe me if i tell em this lol.

[@DrDaveBilliards]

Then just tell them to watch the video instead. Problem solved. :)

[@Krushard]

Was mentioned before but it's time to build a ball-striking machine. It's very puzzling to go through a very thorough experiment procedure, use expensive and high-precision equipment, and then... put the human into the equation. Probably didn't matter much for this particular case, the evidence is pretty convincing but why give skeptics food for thought.

[@DrDaveBilliards]

FYI, human testing can be just as good, if not better, than machine testing if done carefully. For more info, see: billiards.colostate.edu/faq/squirt/robot-test-results/

[@JerryLee..]

Much respect to Barry but people used to believe the earth was flat.

[@DrDaveBilliards]

Some still do. I know … it’s frightening.

[@robert5726]

If two balls are hit together, soft and then hard, the contact time might be the same, but the pressure is dramatically different. Could the type of stroke (accelerating, decelerating) affect the pressure, resulting in increased ball rotation in a screw shot, even if contact time is the same? Maybe an accelerating stroke simply imparts more energy and that is why it imparts more spin rotation, regardless of contact time or pressure.??? If you're going to bust a myth, you need to conjure a new one!

[@DrDaveBilliards]

The "impulse" (sum of the force over the contact time) is different based on shot speed, but it has nothing to do with the stroke. It depends only on the speed of the cue at impact (creating the "impulse" based on the cue's "momentum" due to its mass and speed).

[@deanmckenna7641]

I bet the way to achieve maximum acceleration before contact is to try to accelerate through the ball. After all most pros believe this is what they do and they must have good timing

[@DrDaveBilliards]

Pretty much no pro actually "accelerates through the ball," but it can certainly help some people to think that. What they definitely don't do is decelerate into the ball (like many amateurs). For more info, see: billiards.colostate.edu/faq/stroke/acceleration/

[@deanmckenna7641]

@DrDaveBilliards I did not claim they did. Only that thinking that is what you are doing helps you to have an accelerating stroke.

[@DrDaveBilliards]

@@deanmckenna7641 Understood. FYI, they are not reaching “maximum acceleration” at contact. Proper acceleration (and no deceleration) helps them achieve “maximum speed” (and good speed control) at contact. For more info, see the link.

[@deanmckenna7641]

@DrDaveBilliards neither of us can get action like this and by his own words he believes he needs to go "through" the ball. Again I stress it is a belief only: kzbin.infoJO9Ch4ULvKQ?si=70Ck5G0EAteh_F6e

[@georgemathiellis5486]

Yet it feels like if follow through effects the hit. Players with poor stroke cannot play certain shots. Not even by accident. If the only thing effecting the shot is tip position and cue speed it would be possible for a rookie player to make a long draw shot even if it took 20 attempts.... in my experience seeing a rookie make a long draw shot happens really really rarely.

[@DrDaveBilliards]

People who cannot execute long draw shots do not have proper technique: billiards.colostate.edu/faq/draw/advice-and-drills/ It is as simple as that. Concerning follow-through effects, see: billiards.colostate.edu/faq/stroke/follow-through/

[@albertofuentesr9236]

I'd repeat the experiment with draw instead of center ball contact, maybe as part of the inertia is transferred in rotation the time that the tip push the ball differs with different accelerations

[@DrDaveBilliards]

I've done many super slow motion videos with all sorts of hits, and I have not noticed any important differences in tip contact time. For examples, see: billiards.colostate.edu/faq/video/slow-motion/

[@pawelmiechowiecki7901]

There is a certain speed of the cue when the cue has enough momentum to shoot with enough energy (without pushing the cue, squeezing it, pulling it back, etc.), and the speed should be exactly when the tip hits the cue ball. That's the timing.

[@DrDaveBilliards]

I disagree based on the info and data in the video and at the linked resource pages.

[@Nonesandiego]

Very interesting and informative, I was wondering if tip hardness could cause any variation in the data based on the tip impact absorption , e.g hard tip versus soft tip. The video didn’t take this into account. Everyone here who has played for enough years can definitely tell you there is a difference in feel and playability based on tip construction.

[@DrDaveBilliards]

Tip hardness definitely has an effect on the efficiency of the hit and the tip contact time. I cover this in great detail here: billiards.colostate.edu/faq/cue-tip/hardness/

[@SPM310]

What I'd like to see is a real professional pool/snooker player hit the ball in high speed. All we've seen are amateur's hitting the CB on high speed cameras.

[@DrDaveBilliards]

I agree that would be nice, but I am confident it would not change the results. The CB doesn’t care what the stroke looks like or who is stroking. All it cares about is the cue speed, contact point, and cue direction at impact. We were able to create different accelerations at the same speed. The results would be the same for another shooter also creating different accelerations with the same speeds at tip contact.

[@shch5098]

test with center ball hit ??

[@DrDaveBilliards]

Yes, and also at fairly slow speed to make it easier to be consistent with shot speed and tip contact point with the different accelerations of interest. FYI, tip contact times are actually shorter with faster speed. And contact times change very little with different tip offsets. For more info and examples, see: billiards.colostate.edu/faq/cue-tip/contact-time/ billiards.colostate.edu/faq/sidespin/maximum/

[@shch5098]

@@DrDaveBilliards IMO, no meaning to discuss a stroke or tip difference with a center ball hit.

[@DrDaveBilliards]

@@shch5098 Obviously, per the info and links in my previous post, I disagree.

[@blindi6326]

I do not actually know if you hold a doctorate degree, but just judging on how you read cited information, refer to sources and judge research, it sure seems like it.

[@DrDaveBilliards]

I have a PhD in Mechanical Engineering and a Doctorate of Pool (DP) from the Billiard University.

[@CertifiedSlamboy]

I’d love to see a scientific look at the recent Stephen Hendry video filmed with the Sight Right founder (and his actual methodology and claims). Lots of people calling him a snake oil salesman

[@DrDaveBilliards]

You don’t need any gizmos to accurately find your personal vision center position. See the 1st video and other info here: billiards.colostate.edu/faq/eyes/vision-center/

[@JeffKernsTheArtist]

These videos are filmed with the cue almost parallel to the bed of table. A common thing that is taught. In reality very few shots are shot like that. Watch any pro or semi pro match before wasting time disagreeing with me. Most strokes are struck with some downward angle. I would be very curious to see the difference in contact time on those types of strokes.

[@DrDaveBilliards]

Tip contact time is no different over a wide range of cue elevations. Highly elevated power masse shots with a really soft tip are another matter.

[@JeffKernsTheArtist]

@@DrDaveBilliards thanks for letting me. I think that you facing an extremely uphill battle busting this myth. Mostly because on certain shots it feels like the contact time is longer. I can't explain the science of this. But believing that you can alter the contact time seems to be effective. 😊🤣😃 Maybe the real difference is that the actual contact time is different but the mind and bodies reaction to impact of different types of strokes.

[@DrDaveBilliards]

@@JeffKernsTheArtist Different types of shots certainly feel different, but it has nothing to do with tip contact time changing.

[@JeffKernsTheArtist]

@@DrDaveBilliards What I meant to say was even if the contact time is NOT different, the mind and body feel that it is different. Until someone can explain what is going on I will continue to use the theory that the contact time changes. After all I don't shoot pool with a high speed camera and a graph! 😃😂😀 I do enjoy your videos. Thanks!

[@DrDaveBilliards]

@@JeffKernsTheArtist There is nothing mystical about it. When you stroke the cue well and hit the spot you want on the CB with the speed required for the shot, you get a good result. Now, to do this with accuracy and consistency requires skill. Solid fundamentals also helps: billiards.colostate.edu/faq/stroke/technique/

[@vyacheslavboyko6114]

7:30. In case of the acceleration it is a pretty straight line for a human. *sceptical. You don't controll acceleration here properly - it is effectively an exchange of impulse. To see an effect one needs to get in to the scale of the contact. One needs to change the velocity at much higher rate. The study only shows that it is irrelevant for the game and not that you debunked the Idea. Thanks for the study, very interesting.

[@dustinp26]

The idea he debunked is specifically within the context of the game.

[@DrDaveBilliards]

The data from the slo-mo clips and the resulting plots do not include the entire forward stroke ... only the portion of the stroke close to tip contact. Regardless, the point of the video was to show the difference between accelerating and decelerating at tip contact. That was certainly done.

[@john_vin]

​@@DrDaveBilliardsI don't know why I can't post a comment but can only reply..but great job as always. Goes to show not all experienced players are necessarily accurate with what really happens. They're leaning on what follows after the shot (aftermath) but not necessarily what's actually happening in there.

[@vyacheslavboyko6114]

Could you please share the raw data? The 3 Videos of ball contact with full time resolution.

[@DrDaveBilliards]

@@vyacheslavboyko6114 Pubo is working on a research paper. We can share the “data” when he is done.

[@MrJdsenior]

Pubo's table, or whomever that table belonged to, needs to do some leveling. Either that thing rolled off a TON at 6:14, or there were some nasty lensing and or geometry effects showing up. I realize that this has nothing to do with the point of the video, but just sayin'. I know that when you watch a pool match on video, it is often impossible to judge angles correctly, even for the pros watching their monitor while commentating, when they can't physically see the table. Maybe that is what's going on? None of the results of this video surprise me much, and I'm not even totally convinced that if you could maintain contact longer, that it would have much effect on imparted spin amounts. I might however, believe that a soft tip might give some marginal benefit in that regard, but I expect if it does, it is very little.

[@DrDaveBilliards]

Agreed. The table is not level, but it is what Pubo had convenient access to. I also agree that it has nothing to do with the results and conclusions of the video.

[@puboh]

Yes the table isn't level. Unfortunately I can't do anything with it as it's not mine 😢

[@MrJdsenior]

Yes, I wasn't saying that it did, it was just an observation, in general. :-)@@DrDaveBilliards

[@MrJdsenior]

Cool, never expected a response from you. Thx for your work on the video, it was enjoyable and I learned a lot. :-) @@puboh

[@stephenlawrence4903]

Dr Dave I'm not convinced yet. I view it like table tennis. To get the spin you're told to brush the ball. If you look at Barry Starks video it's the same sort of thing. You see the tip slide down the ball. Your videos are not like for like. It would be interesting to do a furthur test with screw back.

[@DrDaveBilliards]

I’ve done slo-mo videos of all types of shots (screw back shots included). Stroke timing has no effect of tip contact time or spin action on those either. For more info and examples, see: billiards.colostate.edu/faq/video/slow-motion/ billiards.colostate.edu/faq/sidespin/maximum/

[@dazmill697]

Again its all about feel isn't it? The follow through isnt the real issue but if you didn't follow through you'd just quit on contact and wouldn't have any feel of the shot at all. In defence of Joe and Barry I think ots that feel there trying to describe.

[@DrDaveBilliards]

It would be fine if they mentioned “it should feel like,” but Barry seems to be making unequivocal factual statements (which is not appropriate since they are incorrect). Good points about the follow through. See: billiards.colostate.edu/faq/stroke/follow-through/

[@dazmill697]

@@DrDaveBilliards excellent read that link, my perspective is from snooker but I do enjoy your vids. All the different opinions and ways of playing make cue sports so fascinating to me. My favourite player growing up was Alex Higgins and he followed no rule book, with his twitching and moving on the shot he did things his way but you couldn't take your eyes off him.

[@DrDaveBilliards]

@@dazmill697 It is best to follow "best practices;" but with enough dedicated practice, almost any technique can be mastered.

[@dominikz.1376]

I think timing is b.s., and also I think tip timing is not b.s. None of this helps in becoming a terrific pool player

[@DrDaveBilliards]

Depending how you define "timing," it can be very important. For the reasons why, see: billiards.colostate.edu/faq/stroke/good-timing/

[@sam29mill2]

Have you told Barry he's wrong?

[@DrDaveBilliards]

I have not. I only included clips from his video because many people have referenced it trying to convince people that tip contact time can be extended with stroke timing.

[@DrDaveBilliards]

I should have attempted to contact him before I released my video, as a courtesy, but there really isn't much to discuss. The videos speak for themselves, IMO.

[@sam29mill2]

@@DrDaveBilliards hi DrDavebilliards, thanks for reply. I will leave him a comment telling him there's an interesting slo mo video to watch on stroke timing.

[@DrDaveBilliards]

@@sam29mill2 Thanks.

[@sam29mill2]

Hi, I've left a link to your video on the Barry stark video.

[@snerbsnerb2454]

Love your channel Dave and a big fan of your evidence-based approach! However I was a bit surprised to hear you rebuke Barry's theory so rudely, only to then fall so short of adequately disproving it. All your tests involved centre-ball striking. The main purpose of a well-timed stroke is to impart high spin relative to the cueball's speed, so naturally Barry's experiment focused on off-centre striking. I'm not sure there was any point measuring the contact time on a centre-ball hit. But much worse, the frame rate was hopelessly inadequate in your tests. You said the contact duration was consistently "10 or 11 frames" which is nowhere near precise enough, given that Barry's experiment produced just a fractional increase in contact time on a 'well-timed' shot. I'm still on the fence about the contact time theory, but this vid has done nothing to change that. I always enjoy and admire your content though and remain a big fan, keep them coming!

[@DrDaveBilliards]

Thanks for the honest feedback. FYI, we chose the center-ball hit and slower-speed shots to more easily create the same cue speeds and tip contact points with the different stroke timings. Regardless, I think the results are still valid and apply to other shots based on other videos and results here: billiards.colostate.edu/faq/cue-tip/contact-time/ billiards.colostate.edu/faq/cue-tip/hardness/ Best regards and Happy New Year!

[@snerbsnerb2454]

@@DrDaveBilliards Happy New Year Dr Dave! Having rewatched a few of your other excellent videos, I think you must be right about contact time not being a significant outcome of a well-timed shot. I've no doubt that good timing generates more spin, but maybe not by this mechanism. The fact the tip type changes the contact time so much more seems to give it away. Thanks again for all your great work!

[@RoboKubik8]

This gives perception of a scientific study, but has so many flaws there. You should be using some machine to move/accelerate the cue to get consistent repeatable results. And even faster camera speeds to capture the exact time interval. In your other video you were able to capture the difference between hard and soft tips. Even if a difference might appear small, it has a big impact on the game. Sorry, I'm not convinced about your theory, that acceleration doesn't have an impact on tip contact time.

[@DrDaveBilliards]

Using a testing machine would not change the results. In fact, cue testing machines can create a whole host of problems. For examples, see: billiards.colostate.edu/faq/squirt/robot-test-results/ Using a higher frame rate would give more precision, but I honestly don't think precision beyond what we measured is important to the question. If you include enough decimal places, you can always find differences (even for "identical" shots with a machine).

[@RoboKubik8]

@@DrDaveBilliards But when you are trying to prove something, it's not enough saying you don't think the precision you measured is enough. You should prove, it does not have an effect on the cueball. This video doesn't prove anything. It just shows you were unable to even measure the contact time precisely. I'm pretty sure the contact time must be longer when you're accelerating through the cueball, it's just basic physics. If it has only negligible effect on the cueball is another question. But nothing was proven in this video. Would be nice to see a video with a machine playing a deep power screwshot with and without accelerating through the cueball, if there would be a difference. A human can only do it when accelerating through, I believe.

[@DrDaveBilliards]

@@RoboKubik8 I look forward to seeing your video presenting what you are recommending.

[@cosmicraysshotsintothelight]

"These small differences" are the difference and are important. Even if it is measured in microseconds or less. I make shots that prove it. I can post one, but it was not specifically to outline this feature, but shows the successful shot, which I can only do with my soft tip cues. Jacking up also increases tip time as the elevated stick contact event compresses the ball into the cloth of the table surface... for a brief moment. A moment you seem constantly eager to dismiss. I shoot the cue ball "out" to the right end of the end rail and my soft tip will spin the ball, That spin I "pinch" onto the ball brings it all the way "back" to the left side pocket. Doing it with a level cue and a hard tip is nearly impossible. This one was only to the center of the end rail, but the claim is the same. kzbin.info/www/bejne/e6XOkqB3qKaEabssi=3NLPz3coNbXTYurX And another one... kzbin.info/www/bejne/pIOYqnukr5mHnNUsi=WiqofpNmpsHEoEF_ It appears to leave the tip at the same time, but even if it is measured in nanoseconds, Mr. Physicist, the "bite" effect is real, not mythical. I reference modulus of elasticity. You *should* know that it is not instantly "released" from the contact event with *any* tip. Please try observing again using an actual soft tip and one thick enough to illustrate the effect instead of one hard and thin enough to illustrate your "instant release for both tip types" claim.

[@DrDaveBilliards]

The best example of a shot where tip hardness and cloth compression are important are the jump shot. See: billiards.colostate.edu/faq/cue/jump/

[@aimprobilliards1009]

Good work with the collaboration and putting this together. Thank you. BUT, you claim more than you prove here, as I see it. Your claims seem to be based on your theoretical understanding of the physics of the impact. What we all care about is putting spin on the ball and you have no data here about spin vs stick acceleration. I look forward to future experimental DATA that does prove your conjecture about tip position and cue momentum. As a point of reference, in other videos, you suggest that tip hardness has no effect on the ability to do a power draw shot or that we can experiment at the miscue limit to test sidespin and should get the same results as you. Trust me, I've done MANY attempts at power draw and NEVER get your results, while having many miscues. The logical conclusion is that there's something different about either your equipment or your stroke, including speed. You deny that it's the equipment, so therefore, must it not be the stroke or stroke speed? Does a power draw shot require special athletic skill (e.g. young, fast twitch muscles). How to prove I can get enough stroke speed? And if I can get that speed, then all that's left is the stroke.

[@DrDaveBilliards]

The amount of spin created depends only on the cue speed, cue direction, and cue tip contact point. This is well understood. For those with math and physics backgrounds, a complete analysis can be found here: billiards.colostate.edu/technical_proofs/new/TP_A-30.pdf Good stroke mechanics and timing definitely help create good cue speed and an accurate tip contact point, both of which are necessary to generate desired spin.

[@aimprobilliards1009]

@@DrDaveBilliards Dr Dave: With all due respect, you missed my point entirely. All of what you just described is the theory of physics/mechanics. That's fine. But you are attempting to prove this with experiment. You can't then ignore that your experiment hasn't actually proven that and fall back on theory. Either you are giving the theory or you are giving the experimental proof. I was hoping for experimental proof. And you haven't responded to my second point, which is that I cannot do power draw ever, yet multiple of your videos suggest that if I just hit around the miscue limit enough, I'll do it no matter the equipment or stroke. I propose my experimental result refutes that.

[@DrDaveBilliards]

@@aimprobilliards1009 FYI, I have done some testing in the past and it agrees with the theory well. For example, see the article and links here: billiards.colostate.edu/bd_articles/2005/oct05.pdf

[@aimprobilliards1009]

@@DrDaveBilliards Great! I'll have a look at it another day. But what about negative evidence? At what point does it count? as I said, I don't get power draw at all. How many others have to have a similar report to constitute evidence that there's some other factor than cue tip position at impact and speed if many of us continue to fail continuously despite hitting hard and hitting near the miscue limit as confirmed by some percentage of miscues?

[@puboh]

You can position a stripe ball the same way (stripe horizontal) and shoot draw shots many times. The chalk marks tell you if you actually hit low enough. If you want to compare your hit consistency, don't remove the chalk mark, instead rotate the stripe ball so the previous chalk mark stays on the left side while keeping the stripe horizontal. Shoot again. You can see a streak of marks showing your contact points over the last, say 8 shots.

[@cosmicraysshotsintothelight]

There are still a few physical factors *you* makes assumptions on. As I see it, your "soft tip" is not soft at all. You assumed on that. And it is so thin there is no space for compression to occur. I happen to know that my hard stroke shots act differently if I use a hard tip or a soft tip and I *can* feel the compression at the moment of *my* strokes. And therefore, your declaration that it is "a myth" is actually your opinion, and a high speed video of what *you* claim is a soft tip is sullied by your obviously already biased opinion, which you then back up with a video that clearly does *not* involve a "soft tip" scenario.

[@DrDaveBilliards]

This video doesn’t deal with tip hardness effects. I cover that in detail here: billiards.colostate.edu/faq/cue-tip/hardness/

[@codrincodrin3439]

I don’t understand why don’t you get it and why can’t you accept a different way of saying it. If you try Joe Davis’s tips, you would be a much better student, sir. The “feel” method. Yeah, how about that? From a “feel” perspective, when you accelerate properly, your tip is glued to the cb much longer. It’s just a sensation, even though the amount of time that the cue is touching the cb is the same. I think you need to respect the guys before you that did a much better job without the technology that is nowadays.

[@DrDaveBilliards]

I appreciate how advice doesn’t need to be “technically correct” to be helpful. However, Barry seems to be presenting his claims as technically factual, and that is wrong and misleading, IMO.

[@oldmangoesdie8812]

It is all about the pulse or how the force is transfer (hard or soft) which the response make people feel like the cue stick to the ball. Make it too detail is almost no help to player than to guide how to achieve it. This game is simple. Don't make it complex.

[@cosmicraysshotsintothelight]

Even as you state "here is some recent high speed footage (footage is now an incorrect term)", as you post video of the tip compression TIME and then blatantly ignore the moment right there on the video. It IS there, you simply DISMISS it, and you also seem adamant about dismissing the effect. You can SEE it compress. THAT IS "TIME", whether you want to agree or not. Perhaps if you were an electrical engineer you would understand that any time other than zero is still of a definitive TIME period. The computer you toggle the ones and zeros of while making your videos sure knows it.

[@FishbrainMnt]

You are totally right, but (huge but here) if something is not true it doesn't mean it won't teach you to play better. Pool is mainly feel sport not some sport science thing (if it was you would be multiple world champion). The best coaches in pool will make you imagine stuff that really makes no sense (like in this video keep cue tip longer on the cue ball), but will make you accelerate and follow through better. So I agree it is rubbish in science sense but in no means rubbish when it comes to teach someone. Your videos are great from physics perspective but they are not the best when it comes to teaching someone HOW to play. No offense, I love your videos but only the science.

[@dustinp26]

The "no offense" should be unnecessary, DrDave certainly agrees with this and if you think you're arguing with the point of his video, then you've completely missed the point.

[@FishbrainMnt]

@@dustinp26 He is saying those claims are complete rubbish, but in reality they help people to get better, so they are not. I'm not trying to argue with the point of the video I'm arguing that his information will not make you the best player you can be.

[@dustinp26]

@@FishbrainMnt The claims aren't related to teaching, he said the claims about cue contact time are rubbish. As I said, you completely missed the point and you're practically trolling his page at this point.

[@FishbrainMnt]

​@@dustinp26 This comment is about his content as a whole not necessarily this video. But this video also, because he is not saying anything about the benefits of advice like this. I'm expressing my opinion, it is not trolling.

[@cj-ef1rp]

The “thing(s)” that make you better in any sport is to know what is true, what is rubbish, and focus on practicing the correct, accurate methods for improvement. If you follow advice that is incorrect, it can do far more harm than good. And the real problem is, those who espouse these myths believe them to be scientifically true. Now if someone said, “imagine your tip holding the ball longer” because that is a sensation you get with a proper follow through, then yes, your correct that it may not be true but it can be helpful.but these are “myth debunking” videos to demonstrate the factual, accurate effects. Never have I heard Dr Dave say “do this and you will instantly improve”. He always says practice these things to improve. And always has a disclaimers that your actual mileage may vary depending upon table conditions and equipment. Just the way a proper PhD should provide data from analysis.

[@djamo1969]

First, yet again! Lol

[@DrDaveBilliards]

Good job. I hope you actually watch the video after you are the first to click on it! :)

[@djamo1969]

Yes. I watch every one by the end of the day. Depends on how busy I am.

[@DrDaveBilliards]

@@djamo1969 There will be a quiz tomorrow. :)

[@haydenwalton2766]

dave, i have to say that this presentation has brought very little to the discussion. as a preliminary comment - stating that you disagree with joe davis and an english snooker coach demonstrates nothing ! there is so much to say on this topic (nearly all of which ive stated previously, which you have mostly ignored, misunderstood or dismissed without evidence) one quick point relating to your new video : in the shot of the three strokes in super slowmo, you can clearly see the object ball at top (the accelerating stoke) in greater rotation !!! (assuming, of course, that all three tips are the same distance from the centre of the cue ball, which it looks they are. ive plenty more to say on the topic if people are interested. but in short, you are wrong on this important aspect of the game dave. your analysis on all this in comendable, but your conclusions are way off the mark.

[@dustinp26]

He didn't just state he disagrees, the rest of the video demonstrated why he disagrees. Your quick point is not new, it's obvious that object ball is in greater rotation. I don't think you watched the section where he explained that study... spin was not controlled for as it was irrelevant.

[@DrDaveBilliards]

@haydenwalton2766 Obviously, I disagree with your "analysis." I think if you watch the video and read through and watch everything on the linked resource pages with an open mind (and with no preconceived notions), your opinion on the matter might change. But I know that it difficult to do. My analysis is not based on opinion ... only only carefully measured experimental data. The experiments might not have been perfect, but they are definitely good enough to draw the conclusions drawn.

[@haydenwalton2766]

@@DrDaveBilliards dave, as I stated, I think your inquiry into these topics on your channel is to be commended however, I think that your analysis on this fundamental area of the game is both incomplete and misdirected. furthermore, I think the conclusion that you draw from this analysis is incorrect. a general challenge - ask ten top pros their opinion on the matter. you might be interested in what they have to say.

[@davidbehrens4760]

​@@haydenwalton2766you still haven't given any actual reason for saying what you're saying, and Dave acknowledges from the beginning that what he is addressing is common perception among many players and enthusiasts including experienced pros. That doesn't mean they're right, hence the scientific analysis which you've thus far failed to address in any substantial way.

[@haydenwalton2766]

@@davidbehrens4760 that last point is a fair one, to some degree. as to my reasons - I've outlined them in depth several times in comments on dave's videos. I dare say I will again on this one shorrly.

[@danimal107]

Who are you going to believe? 1) A 20 time world champion 2) A KZbinr who has never won ANYTHING in professional pool. What is the logical choice,"DOCTOR" Dave?

[@dustinp26]

DrDave didn't ask you to believe him lol he literally presented the entire study for you to interpret on your own.

[@oneofthepeoplehere]

3) My own working eyes?

[@DrDaveBilliards]

2, because all of my results are backed up by careful experiments and logical explanations (which are supported even more at the links in the video description). BTW, even though I haven't won any pro tournaments, I am a professional instructor who has "done his homework." See: billiards.colostate.edu/dr-dave

[@dustinp26]

@@oneofthepeoplehere shhh, that'd require them to have a brain behind the eyes ;)

[@cj-ef1rp]

I’ll believe the guy who can prove what he says. Use science and measurements to confirm facts. Otherwise it’s anecdotal rhubarb… Always know the TRUTH of what you BELIEVE. To follow your logic, you should still believe in the Easter Bunny since hundreds of thousands of parents have told the tale for generations…. Yet with facts, you changed your belief. World Champion Egg Hunter title notwithstanding.

[@cosmicraysshotsintothelight]

If "Tip Time" and "Tip Compression" and "Tip Grip" were not a factor, then no off center strike on the ball would yield any spin. The very fact that English is possible means that tip time is real and dismissing it due to the time interval as "negligible" renders your entire claim to be devoid of facts. The only reason spin gets imparted is due to the coefficient of friction between the tip and ball. It is also the only reason leather tips AND chalk were introduced into the game. This stuff is real simple. Your dismissal of it has me flabbergasted, Doctor. Make a video of an UNCHALKED tip striking in the center of the ball straight inline with their paired axis. Then start walking off center with the stroke contact and note the point at which "slippage" occurs. Then do so with a chalked tip. The very elements of this experiment proves my claim. In order to impart the spin, there has to be tip time and tip grip. And an ACTUAL softer tip WILL impact for a slightly but effective longer moment. It really is that simple. You see the short duration as being negligible, but it is the exact thing that imparts the spin. Even the formula for it would show that zero tip time equals zero action. In order to impart spin, the tip has to have grip and momentary compression. Key word, Doc... momentary. It doesn't mean that it is negligible... Specifically, it means that it is NOT negligible. Your video, which you keep referencing is flawed because you did NOT use a soft tip and the tip you did use was milled too thin before it was attached, so your "soft tip" data is incorrect. Nice try though at continuing to deny it.

[@puboh]

Nowhere did he say the tip doesn't stay in contact with the ball, because 0 contact time is absurd. The ball has to accelerate continuously not instantaneously. The soft tip does stay on ball longer but it doesn't generate more spin. Just watch his previous videos.

[@cosmicraysshotsintothelight]

@@puboh I have watched them. I also have an issue with them. Again, if you are literate, then you would have noticed that I stated there was not soft tip data and why. Nowhere did you act as if you actually read what I wrote. Maybe a remedial English course is in order. What is absurd is the dismissal of the effect of contact time when it is the only thing that imparts spin on an off center strike.

[@puboh]

@@cosmicraysshotsintothelight you said "the only reason spin is imparted is due to friction" and "the only reason spin is imparted is due to contact time". These are two reasons. As far as billiard is concerned, I don't think there are any significant differences in friction

[@cosmicraysshotsintothelight]

@@puboh You don't think. Case closed. The coefficient of friction is what causes the tip to "grip" the ball. That "impact moment", being non-zero in length, is what is being discussed, as the amount of time that grip occurs in and has the "time" to apply itself to the ball with is exactly what is being discussed. Except with folks like you whom do not think.

[@puboh]

I said "I don't think" because we actually don't know how to model the tip grabbing the ball at impact with detail. We don't know if it is friction that cause the tip to grab the ball, or if there is mechanical coupling between the tip and the ball. If you know how to explain what happens to the tip during impact, please leave a reference and I'd love to read it. We can calculate the spin, speed of the ball right after impact using conservation equations, but we don't need any information about friction between the tip and the ball, let alone coefficient of friction. The analysis only assumes the tip doesn't slip on the ball during impact, which I believe it's true given the high-speed footage. So as far as the conservation equation is concerend, the tip contact time is not important, as long as it is not 0, and the friction is not important as long as the tip doesn't slide. Finally, my use of "friction" is to be taken with a grain of salt since we don't know if it is friction that makes the tip grab the ball.@@cosmicraysshotsintothelight