I need a clear answer, when receiving, when does the ball has LESS spin? Off the bounce? Or after it reached its apex?

[kaisersoze]

The law of conservation of angular momentum states the following:
1. Rotation will not speed up unless additional force makes it speed up. So the spin will be slower at the apex as compared to immediately after the bounce. Especially since some of the spin is eaten up by contact with the table and changing the momentum (direction) of the ball.

2. HOWEVER, Newton, Decartes, Bernoulli, Euler, and Einstein all do not play TT. Otherwise they would have added the exception: due to special relativity, the spin speeds up the moment it hits your racket in an amount inversely proportional to your ITTF rating (the lower your rating, the more it spins faster, because the ball hates you).

Best answer ever thanks

 

[NextLevel]

I have to disagree with you here (agree on the front part).

I understand what you are saying, and how it is not applicable to lower level players, but the amount of spin and how much of the spin to override or to use/borrow, is part of service return and the useless things that you claim from great coaches does have a purpose and this all comes to the finer quality of the return. For example, BH flick, you can choose so many parts of that incoming position to flick the ball, and there is a meaning for each of the so called point of contact and we often have these conversions with players when working on service returns.

But now I'm going into territory not applicable for the forum but because it isn't applicable to the forum, it doesn't mean those statement from coaches are useless. It should be not applicable.

You don't understand my point so let me explain it again, hppefully better. Some coaches might say something like wait for the ball to drop because the spin is less and you can attack more easily. Or counterspin later because the spin is less. My point is none of those things are really about the quantity of spin on the ball. They are usually about how easy it is to execute a stroke and hit a certain contact point and swing trajectory relative to how the ball is travelling. Taking the ball later allows you to get more information about the ball 's rotation from the travel path. The absolute amount of spin is not the key. Playing upwards on a ball is easier when the ball is falling.

There are many examples of this in all kinds of situations. Some people say one should block off the bounce because it is easier to control the spin blocking off the bounce and the spin is more after the ball travels to a higher point. Some say block at the highest point or before the ball is falling to borrow power (which is not spin based and actually makes more sense but still isn't absolute). There are good and bad reasons to block off the bounce but the amount of spin is not one of them. My main point is that quantity of spin explanations are almost always wrong in explaining why a technique is deployed when it is. Ease of deploying the technique because of other factors like how the ball is travelling at the point in the trajectory it is contacted ate usually better. There is nothing wronf with good coaches having bad physics I am sure we all have our own pet ideas that we have never seriously tested. We play table tennis vs running physics experiments. They are very different things. And it doesn't reflect on the quality of the instruction or the player. It's often just good advice tied to bad logic.

 

[Tony's Table Tennis]

You don't understand my point so let me explain it again, hppefully better. Some coaches might say something like wait for the ball to drop because the spin is less and you can attack more easily. Or counterspin later because the spin is less. My point is none of those things are really about the quantity of spin on the ball. They are usually about how easy it is to execute a stroke and hit a certain contact point and swing trajectory relative to how the ball is travelling. Taking the ball later allows you to get more information about the ball 's rotation from the travel path. The absolute amount of spin is not the key. Playing upwards on a ball is easier when the ball is falling.

There are many examples of this in all kinds of situations. Some people say one should block off the bounce because it is easier to control the spin blocking off the bounce and the spin is more after the ball travels to a higher point. Some say block at the highest point or before the ball is falling to borrow power (which is not spin based and actually makes more sense but still isn't absolute). There are good and bad reasons to block off the bounce but the amount of spin is not one of them. My main point is that quantity of spin explanations are almost always wrong in explaining why a technique is deployed when it is. Ease of deploying the technique because of other factors like how the ball is travelling at the point in the trajectory it is contacted ate usually better. There is nothing wronf with good coaches having bad physics I am sure we all have our own pet ideas that we have never seriously tested. We play table tennis vs running physics experiments. They are very different things. And it doesn't reflect on the quality of the instruction or the player. It's often just good advice tied to bad logic.

So don't you think calling them (great coaches statement) useless is a bit far stretch?

any ways, I can sense you also don't understand my post, but its okay, as I said it is probably not applicable, so I'm not too bothered.

at the end of the day, spin needs to be your friend and you need to learn to use it, not to fear it.

 

[NextLevel]

So don't you think calling them (great coaches statement) useless is a bit far stretch?

any ways, I can sense you also don't understand my post, but its okay, as I said it is probably not applicable, so I'm not too bothered.

at the end of the day, spin needs to be your friend and you need to learn to use it, not to fear it.

The issue is more with your ability to understand what I am saying than anything I actually said. I said the statements and explanations based on the quantity of spin are useless fron a physics standpoint. The coaches are giving good technical advice but are explaining it with dubious physics.

In fact I suspect I can find the video or one of the videos that prompted OP to ask his question. But the technical advice is not about the physics. It is about the utility of the technique regardless of whether the physics is right or wrong. You can do the right thing for wrong reasons and in a results driven world, many people may not care. It is only if the actions are *driven* by the reasons that a real problem exists. But in may cases, they are not, if people are told that the physics is wrong, they will do the same things and just find different or better explanations.

It is more important to be helpful than to be correct sometimes.

 

[Tyce]

I think when some coaches say there's less spin on a ball and right after the bounce, they mean there's less spin working in the wrong direction for your stroke.

 

[The Omega Man]

In fact I suspect I can find the video or one of the videos that prompted OP to ask his question.

Here is a video from 3 days ago, from professional player Andreas Levenko explaining the Banana Flick technique, around the 2:32 minutes mark, he explains when to take the ball, and he says that it has to be when the ball is descending because it has "the least amount of spin" so he uses the word SPIN to convey the ideal point to engage with the ball, then if the ball doesn't really change most of the spin force like MANY has stated here, and does not to make a difference, why is He using the words "THE LEAST SPIN" as a determining factor for when to engage the Ball? Shouldn't he be using just "ball height" instead? If the spin is not really changing at any point in time to make a difference, and what matters is the ball's height to make a quality stroke for a quality receive, why are professional players and coaches still propagating this so-called "lie"?

Food for thought

 

[Colestt]

Maybe he's talking about how much spin you can put on the return at those times?

 

[The Omega Man]

Maybe he's talking about how much spin you can put on the return at those times?

No, He literally says that's the moment when the ball has the least amount of spin from the serve, just watch the video I time-stamped it exactly when He explains this.

 

[Dr Evil]

No, He literally says that's the moment when the ball has the least amount of spin from the serve, just watch the video I time-stamped it exactly when He explains this.

He does (incorrectly) imply that the ball has the least amount of spin at the moment it starts to drop. But I'm pretty sure he's just being imprecise. He really means that the ball has less spin on the fall compared to off the bounce or at the peak of the bounce.

His main point is that you should try to contact the ball for a banana flick around the moment it starts to fall. This is good advice. Although you could wait for the ball to fall almost to the table, this would make the shot more difficult because -- although you would be dealing with marginally less spin -- the table would now be more in the way of generating a low to high racket trajectory, and you'd have to lift the ball at a sharper angle. Of course you could get help lifting the ball by taking it off the bounce (when the momentum of the ball is lifting it up most energetically), but then you have the opposite problem of adding enough topspin to get it to dip back down so it doesn't fly long.

 

[Colestt]

To me the higher you take the ball the less likely you are to net it

 

[NextLevel]

I think when some coaches say there's less spin on a ball and right after the bounce, they mean there's less spin working in the wrong direction for your stroke.

You can give charitable interpretations for sure. While i don't think this gets to the point, the main thing is they know human beings usually need reasons for what they do, so they are trying to provide one they may have heard from someone else or come uo with themselves, but its objective value as a physics answer/comment on the amount of spin on the ball is dubious. One could argue that the spin to speed ratio might be higher layer in the ball's travel path but it doesn’t mean much, what we really care about is wherher the technique works or not, the science of it is not really actionable to most people.

Here is a video from 3 days ago, from professional player Andreas Levenko explaining the Banana Flick technique, around the 2:32 minutes mark, he explains when to take the ball, and he says that it has to be when the ball is descending because it has "the least amount of spin" so he uses the word SPIN to convey the ideal point to engage with the ball, then if the ball doesn't really change most of the spin force like MANY has stated here, and does not to make a difference, why is He using the words "THE LEAST SPIN" as a determining factor for when to engage the Ball? Shouldn't he be using just "ball height" instead? If the spin is not really changing at any point in time to make a difference, and what matters is the ball's height to make a quality stroke for a quality receive, why are professional players and coaches still propagating this so-called "lie"?

Food for thought

Yes and in my experience, the main reason you wait longer is not because the spin is less, but because you subconsciously gain more information about what is on the ball the longer you wait if you have watched serves and balls often enough. If we were allowed to let the ball bounce twice on our sides before returning, most of us would get the spin right every time. Waiting longer also gives you a bigger distance to the net which can be helpful if returning more actively. It is also easier to keep the ball low chopping at a lower point in the trajectory. But wherher any of that is meaningfully about the ball having less spin is for others to decide. @canonFH discussed this well so I wont repeat what he wrote too much.

 

[NextLevel]

To me the higher you take the ball the less likely you are to net it

The banana had an upward element it is hard to add topspin to a ball that isnt falling. There are many reasons to adapt or take the ball earlier or later but less spin is a confusing way of communicating any of them.

 

[NextLevel]

He does (incorrectly) imply that the ball has the least amount of spin at the moment it starts to drop. But I'm pretty sure he's just being imprecise. He really means that the ball has less spin on the fall compared to off the bounce or at the peak of the bounce.

His main point is that you should try to contact the ball for a banana flick around the moment it starts to fall. This is good advice. Although you could wait for the ball to fall almost to the table, this would make the shot more difficult because -- although you would be dealing with marginally less spin -- the table would now be more in the way of generating a low to high racket trajectory, and you'd have to lift the ball at a sharper angle. Of course you could get help lifting the ball by taking it off the bounce (when the momentum of the ball is lifting it up most energetically), but then you have the opposite problem of adding enough topspin to get it to dip back down so it doesn't fly long.

The technique works so he can say anything he wants but you are being too charitable here. It is easier to lift a falling ball and the contact points after the peak are more forgiving to certain swings. Describing that as "less spin " is not insightful.

 

[The Omega Man]

The technique works so he can say anything he wants but you are being too charitable here. It is easier to lift a falling ball and the contact points after the peak are more forgiving to certain swings. Describing that as "less spin " is not insightful.

Exactly my point, if SPIN doesn't meaningful change, and it is not the deciding factor, but ball's height is, or in this case waiting for the ball to descend from its apex, then the word SPIN should not even be mentioned at all and that's what perpetrates this confusion at so many levels when you have coaches and professional players saying this.

 

[BlopChock]

He does (incorrectly) imply that the ball has the least amount of spin at the moment it starts to drop. But I'm pretty sure he's just being imprecise. He really means that the ball has less spin on the fall compared to off the bounce or at the peak of the bounce.

His main point is that you should try to contact the ball for a banana flick around the moment it starts to fall. This is good advice. Although you could wait for the ball to fall almost to the table, this would make the shot more difficult because -- although you would be dealing with marginally less spin -- the table would now be more in the way of generating a low to high racket trajectory, and you'd have to lift the ball at a sharper angle. Of course you could get help lifting the ball by taking it off the bounce (when the momentum of the ball is lifting it up most energetically), but then you have the opposite problem of adding enough topspin to get it to dip back down so it doesn't fly long.

This physics is not correct!

 

[NextLevel]

Exactly my point, if SPIN doesn't meaningful change, and it is not the deciding factor, but ball's height is, or in this case waiting for the ball to descend from its apex, then the word SPIN should not even be mentioned at all and that's what perpetrates this confusion at so many levels when you have coaches and professional players saying this.

Don't blame players who were coached from a young age too much, you believe almost everything you hear from the authorities you trust while growing up. Very few traditions would survive otherwise.

 

[NetProphet]

Pretty sure it's obvious to say that the longer the ball travels, the less spin it will have because energy doesn't come from anywhere. Racket gives the initially energy, everything after only slows it down. After a ball change, the ball loses spin incredibly quickly. Let's say you hit a good backspin serve that rolls back — by the time it hits opponent's side and starts rolling back, it barely has any spin

Yeah but that's after more bounces on the table. Spin after one bounce on receiver side, measured just after bounce and again before it hits the floor, what's the difference? How much spin has it lost?

 

[canonFH]

I would like to add one more thing that its easy to forget that these guys are young people who have spent most of their life only doing one thing: repetitively practicing their strokes. I doubt any of the top players would have had an engineering degree. They just present the technique they think is most reasonable for most people.

So I would take their advice on the what and the how but the why would be dubious at best. Many things in table tennis are counterintuitive, so there might be minor inefficiencies in the pros strokes as well. But we can trust that there won't be glaring holes in their techniques, and if a top 100 rank says I should hit the ball while falling, I should take it as a starting point and then try to figure out the why myself by doing different things. Besides being wrong about the physics, pro players also don't know my level and their advice may not be applicable for me.

For example, after making a short pendulum serve to my opponent's FH, I am ready for the ball to come to my FH and make a strong attack. If the ball is returned to my BH, I am only able to make a weak push due to my position. A high level coach noticed this and asked me to be in a neutral position to be ready for both the balls. After some practice, I was able to open up on both but neither well.

At the end, I ended up not taking his advice because I'd rather make a strong attack on some of the balls than make a relatively weak attack on all of the balls. But the coach's advice is not wrong. It just requires me to move faster, which I'm not able to do right now.

Ultimately, table tennis is a sport where knowing is not sufficient, you have to be able to do the things. Even if you know that taking the ball right at the bounce is most optimal due to whatever physics, if you're not able to do it, its useless. The things that hold us back are not the why but the how.

 

[XpingpingpongpongX]

Spin doesn't really change in a fraction of a second. If you do a side spin serve, and just watch it bounce, the spin is still very strong after like 5 seconds. It's because bouncing on a surface does not slow down a side spin much, and the air drag force isn't really that much to slow it down. When people say it's less spin, it's more of a subjective feeling than a physical truth.

The real difference is the vertical velocity of the ball, the angle and normal force of the ball when it hits your paddle, and the location (relative to the table) of the hit. With these 3 elements, you can figure out what works better for each scenario. Hitting early is usually harder for amateurs because of the small window of timing. You need to be very focus and have quick footwork.

 

[NetProphet]

I would like to add one more thing that its easy to forget that these guys are young people who have spent most of their life only doing one thing: repetitively practicing their strokes. I doubt any of the top players would have had an engineering degree. They just present the technique they think is most reasonable for most people.

So I would take their advice on the what and the how but the why would be dubious at best. Many things in table tennis are counterintuitive, so there might be minor inefficiencies in the pros strokes as well. But we can trust that there won't be glaring holes in their techniques, and if a top 100 rank says I should hit the ball while falling, I should take it as a starting point and then try to figure out the why myself by doing different things. Besides being wrong about the physics, pro players also don't know my level and their advice may not be applicable for me.

For example, after making a short pendulum serve to my opponent's FH, I am ready for the ball to come to my FH and make a strong attack. If the ball is returned to my BH, I am only able to make a weak push due to my position. A high level coach noticed this and asked me to be in a neutral position to be ready for both the balls. After some practice, I was able to open up on both but neither well.

At the end, I ended up not taking his advice because I'd rather make a strong attack on some of the balls than make a relatively weak attack on all of the balls. But the coach's advice is not wrong. It just requires me to move faster, which I'm not able to do right now.

Ultimately, table tennis is a sport where knowing is not sufficient, you have to be able to do the things. Even if you know that taking the ball right at the bounce is most optimal due to whatever physics, if you're not able to do it, its useless. The things that hold us back are not the why but the how.

And do you just magically know what to practice?
As in, no info about the 'why' needed, you just know 'what' to practice without any explanation given or needed?
The why is what helps peoples understanding of the game and feeds alot of things from analyzing the opponent and forming tactics to knowing where to focus your own training for improvement.
Your post suggests the explanation and understanding of things is pointless, I couldn't disagree more.
And if you think that top players don't understand the physics of the game without an engineering degree I'd say your completely crazy!