Spin theory

[blahness]

[color = red] wrong !! compare continuation (your term) looper vs chop in a 3 shot sequence
continuation (looper vs chop)
1
incoming chop
20 rev
outgoing top stroke
21 revs
result 21 revs going towards chopper
2
chopper. returns
22 revs
outgoing top stroke
23 revs
result
23 revs going towards chopper
3
chopper returns
24 revs
topstroke
25 revs
result 25 revs going towards chopper

Now consider top vs top where on both. sides the surface of the ball is rotating towards the approaching brushing rubber
1
incoming top effort
20 revs
outgoing top stroke effort
20 revs
result 40 revs (x)
2
incoming top effort 20 (effort +x)
60 revs
outgoing top stroke effort 20
20 revs + 60 revs = 80 revs
result
80 revs

3
incoming top effort 20 (effort + x)
100 revs
outgoing top stroke effort 20
20 revs. + 100 revs = 120 revs
result
120 revs

these conservative numbers show how spin in top v top rallies can increase exponentially compared with top v chop
[/color]
a reality check: the above is a theoretical idealised example players on both sides are executing pure brushing strokes on both sides. The real numbers will be more conservative.
In fact in reality most strokes are combinations of brush and more solid impact.
Also in practical match situations the need to be sure of winning points preempts the desire to produce maximum spin. Which is why when you see two amateurs having a blast going fh to fh for hours with the ball arcing more and more with each brushing impact its well to realise that its worthwhile to practice other skills as well. Its not always a spines

You completely ignored that there's a max limit to the rubber friction capacity and exceeding it means you can't control the ball well.

But this theoretical discussion is really out of topic from the original discussion, which is about how to deal with different spin situations and selecting the best way to deal with strong incoming spin.

 

[pingpongpaddy]

[ color= blue]

Let me clarify, all I wanted to express was that no matter if it's topspin or backspin arriving at the racket, the amount of topspin you can genarate is (almost) equal according to Spinsight's numbers. [ /color]

When serving we have a special case because the rotation entering our racket is always zero (or very close to it).

To your points, I've made different observations than you.
I can't speak for others but for me personally it is easier to "kill" a backspin serve with an attackable length than a topspin serve.
Thinking about this objectively I realized that the spin arriving at my racket has less impact on the succesfullness of killing a serve than other factors as height and speed of the ball because the racket angle on that shot is quite vertical (I hope we have the same definition of "killing" in that sense).
When comparing two serves with the same amount of (high) spin and given speed by the racket but one with backspin and the other with topspin, the topspin one will arrive at the receiver with a bigger speed and lower arc which makes it more difficult to kill. Not to mention the impact of the magnus effect the ball will experience into the air.
Furthermore the serve with topspin will have lost less of its starting rotation when it arrives at the receiver.
To remember - the effect of the ball losing spin due to friction with the table is even more important on a serve because the ball has two contacts with the table instead of one.
Also I've never heard about the saying "even a fool may kill a good topspin serve".

Regardless of what percentage of the input spin arrives at the receiver, the question if we can put more maximum spin on backpin or topspin serves (or the same) isn't easy to answer.
In my mind the maximum on backspin serves is higher because when trying to put the same maximum of spin on topspin serves as it is possible to put on backspin serves, the ball presumably would go into the net or out behind the opponents' side after the first bounce due to the low arc and speed generated as the result of its contact with the table.

Sorry for my long post...

creative writing based on "even a fool can do x ..." based on advice from one of my first coaches why at deuce in the fifth, it makes sense to do a tight serve that is difficult to hit unless you have 100% confidence that your opponent will misread your topspin

I am not yet familiar with Spinsight so I have just applied to be a beta tester. it sounds interesting

In this thread we are discussing the Pure application of brushing impacts on producing spin so easy balls high balls don't really come into it. we are not talking about that
In particular I have taken a relativist approach to consider the result of a pure brushing in two opposing cases.
first lets consider two kind of car crash:-
1:- a car crashes at 10 kmh into brick wall. we can see that the impact speed is 10 kmh
2:-two cars each moving at 10 kmh collide into each other. We can see that the impact speed is 20 mph
now brushing a tt ball to produce spin which may be rotating or not
give the racket an upward speed of 10 and a forward speed of 0
now the possibilities for the rotation:
1:- the ball may not be rotating. So after the brush impact the ball gain rotation of 10 (result of adding racket speed 10 to the speed the surface of the ball is moving relative to the racket surface which is 0)
2:-the balls surface may be rotating away from the racket surface at a speed of 5. so both surfaces are moving upward at different speeds. In this case the relative speed of impact of impact is only 5 so as a result the balls rotation is increased by 5 to 10
3:- the balls surface may be rotating toward the racket surface at 10, so in this case the speed of brushing impact is doubled to 20 resulting in a rotation speed of 20
the incoming topspin rotation of the ball towards for racket with the topspin motion would mean that the ball would have a more pronounced arc. so going upward over the net, but then due to the Magnus effect dipping down onto the table thus giving more margin for error for strong attacking shots
sorry for my long post its fun to try to involve tt in illustrating Relativity

 

[pingpongpaddy]

You completely ignored that there's a max limit to the rubber friction capacity and exceeding it means you can't control the ball well.

is "max friction capacity" a meaningful thing ?
Its not clear to me that this is not just something which people try to apply without having a means of quantifying it

My gut is that high quality rubbers have a pretty adequate capacity for player to apply rotation to the ball which after all is very very light

 

[pingpongpaddy]

Very interesting discussion, which makes a lot of sense. Key is being able to control position of the return when using incoming spin.

I play a good level player regularly who uses a very light touch on the side of the ball when returning my pendulum, and it comes back loaded with my spin, which requires me to adjust (or try to double down again) if I am to avoid the ball flying off the table side..

does he try touching only one side of the ball ? If he were to touch the opposite it would be interesting to analyse. When you say "loaded with my spin" do you just mean spinning strongly or is the ball rotating with same direction and axis as you applied in your serve.
depending on which side he contacts he may be using the energy you expending to change the rotation

 

[brokenball]

Now consider a good backspin serve. This may win a point on occasion but its less vulnerable to opponents attacking shots.

This is true if the ball is long enough to loop. One of my practice partners is very good at this since he gets lots of practice looping long back spin serves. The serve needs to double bounce. to be safe.

So a good server must exercise judgement as to whether risking the topspin is justified.

Rarely, only to try to catch the opponent off guard and it must be fast and low.

 

[brokenball]

I also doubt the max friction statement. Do you have any idea what the coefficient of friction is? It is very high for most inverted rubbers. Do you know what the of impact is? NO! You need to know this and multiply it by the coefficient of friction to find what the frictional force is. If the stroke is eccentric, not through the center of the ball, then this frictional force is multiplied by the distance between the center of the ball and the vector if the direction of force applied to the ball to get torque. Torque is what makes the ball spin. Rotational impulse determines how much the spin changes.

 

[Wrighty67]

does he try touching only one side of the ball ? If he were to touch the opposite it would be interesting to analyse. When you say "loaded with my spin" do you just mean spinning strongly or is the ball rotating with same direction and axis as you applied in your serve.
depending on which side he contacts he may be using the energy you expending to change the rotation

He is touching the right side of the ball very gently and so adding a little to my spin in the same axis and direction - I have yet to manage to try the same to this return but instead tend to go against the spin to control it.

 

[pingpongpaddy]

This is true if the ball is long enough to loop. One of my practice partners is very good at this since he gets lots of practice looping long back spin serves. The serve needs to double bounce. to be safe.

Rarely, only to try to catch the opponent off guard and it must be fast and low.

i was bit lazy about this I meant a good backspin that was short and therefore difficult to attack. of course I agree there are good long backspin serves which can easily be returned with a loop

I also doubt the max friction statement. Do you have any idea what the coefficient of friction is? It is very high for most inverted rubbers. Do you know what the of impact is? NO! You need to know this and multiply it by the coefficient of friction to find what the frictional force is. If the stroke is eccentric, not through the center of the ball, then this frictional force is multiplied by the distance between the center of the ball and the vector if the direction of force applied to the ball to get torque. Torque is what makes the ball spin. Rotational impulse determines how much the spin changes.

perhaps Blahness can show his expertise on "max friction" then

 

[pingpongpaddy]

You completely ignored that there's a max limit to the rubber friction capacity and exceeding it means you can't control the ball well.

But this theoretical discussion is really out of topic from the original discussion, which is about how to deal with different spin situations and selecting the best way to deal with strong incoming spin.

its certainly in conflict with some of the ideas that you expressed, but imo that is what makes for a good discussion and enables us all to improve our understanding

 

[blahness]

its certainly in conflict with some of the ideas that you expressed, but imo that is what makes for a good discussion and enables us all to improve our understanding

Nah you aren't even here to learn or discuss anything and completely missing the point of this whole thread which is an understanding and methods of how to handle spin safely in match situations, not some stupid theoretical discussion with brokenball or yourself whom I'm gonna add to my ignore list.

Btw friction depends on many things most importantly normal force. But I'm not gonna give you any direct answer here in the interest of keeping this thread on track.

 

[pingpongpaddy]

Nah you aren't even here to learn or discuss anything and completely missing the point of this whole thread which is an understanding and methods of how to handle spin safely in match situations, not some stupid theoretical discussion with brokenball or yourself whom I'm gonna add to my ignore list.

Btw friction depends on many things most importantly normal force. But I'm not gonna give you any direct answer here in the interest of keeping this thread on track.

A forum is about give and take. Being intolerant of those that politely disagree with you is a little childish and counter productive to the spirit of the forum

 

[blahness]

Spinsight did some investigations about Spin numbers.
They measured the amount of spin some pros could generate on different shots.
Here's a translated snipped from an interview Spinsights' Hermann Mühlbach did with german magazine mytischtennis.de:

"myTischtennis.de: And it is probably also decisive whether you play the topspin with the forehand or the backhand?

Hermann Mühlbach: In fact, the average values for the four topspin variants - i.e. forehand, backhand, against block or undercut - were the same across all professional players! Despite the very different movements and conditions of these variations, the average number of revolutions was the same. This means that there is basically no advantage or disadvantage to one of the techniques. In principle, the same stroke quality can be achieved. [...]"
source: https://www.mytischtennis.de/public...--Je-hoeher-der-TTR-Wert--desto-mehr-Spin--p/

There's to note that a block on topspin also generates a small amount of topspin arriving back at the player who played topspin, not only coming from the racket itself but also from the friction the ball has with the table.

This is very interesting indeed. Although I would think that topspin vs chop is quite different compared to topspin vs push, and topspin vs strong topspin is quite different with topspin vs block. Because push and block typically generate relatively low spin returns in general.

But maybe sometimes it's an illusion caused by differences in the speed/spin ratio. Fang Bo's channel did some spin measurements, and spins from loopkills were consistently the highest, even though a slow spinny loop felt spinnier to the receiver.

 

[blahness]

Very interesting discussion, which makes a lot of sense. Key is being able to control position of the return when using incoming spin.

I play a good level player regularly who uses a very light touch on the side of the ball when returning my pendulum, and it comes back loaded with my spin, which requires me to adjust (or try to double down again) if I am to avoid the ball flying off the table side..

In the context of this thread - he is going against the spin and using the properties of the inverted rubber to invert the spin of the ball. If you think about it - a FH pendulum sidespin serve rotates clockwise - he touches the ball on the right, the return ball (from your perspective) will be rotating anti clockwise - which is equivalent to a reverse pendulum serve from your perspective. When you touch the return ball its gonna fly to the left if you dont compensate for it. You can either touch the left side of the ball to compensate (going against the spin), or rotate it anticlockwise (going with the spin or spin continuation, but you need to be active in the brush to achieve this)

I'm guessing that this is side backspin FH pendulum not sidetopspin FH pendulum, he won't be able to get away with lightly touching the ball against sidetopspin (as now this becomes more of a spin continuation scenario)

 

[Wrighty67]

In the context of this thread - he is going against the spin and using the properties of the inverted rubber to invert the spin of the ball. If you think about it - a FH pendulum sidespin serve rotates clockwise - he touches the ball on the right, the return ball (from your perspective) will be rotating anti clockwise - which is equivalent to a reverse pendulum serve from your perspective. When you touch the return ball its gonna fly to the left if you dont compensate for it. You can either touch the left side of the ball to compensate (going against the spin), or rotate it anticlockwise (going with the spin or spin continuation, but you need to be active in the brush to achieve this)

I'm guessing that this is side backspin FH pendulum not sidetopspin FH pendulum, he won't be able to get away with lightly touching the ball against sidetopspin (as now this becomes more of a spin continuation scenario)

I may have explained it incorrectly - he is returning my spin by touching the side of the ball on the left and letting my spin pass through

 

[blahness]

I may have explained it incorrectly - he is returning my spin by touching the side of the ball on the left and letting my spin pass through

Is it a righty vs righty match up? And is it FH pendulum or reverse pendulum? Sidetopspin or sidebackspin?

 

[Wrighty67]

Is it a righty vs righty match up? And is it FH pendulum or reverse pendulum? Sidetopspin or sidebackspin?

Right/righty - FH pendulum side/back

 

[blahness]

A forum is about give and take. Being intolerant of those that politely disagree with you is a little childish and counter productive to the spirit of the forum

Ok I'll bite.

You need to sink the ball into the sponge to generate an increasing normal force on the ball in order to engage it with high friction (similar to locking in gears) - after engaging it then the tangential force can spin the ball hard.

When going against the spin (topspin vs topspin), the problem comes when the ball already has an immense amount of spin on it and you're trying to forcefully brush it instead of allowing the rubber to do its job to reverse the spin. What this leads to is a very high amount of ball tangential speed relative to the racket (100 + 100 = 200) in your example, which happens before the ball is sinking into the sponge. Because there's not much normal force at this point, there is also not much friction capacity so it's easy for it to just slip off resulting in a bad contact. So for control, it's better to focus on a thicker contact to sink it into the sponge and let the inverted rubber invert the spin much like a tangential trampoline.

But however, if you're doing spin continuation and forcefully brushing (for eg with topspin against strong backspin), the tangential speed of the ball relative to the ball is low (105-100=5 for example), which reduces the frictional demands of the rubber at the beginning stages of the contact before the ball is sunk into the sponge. This allows you to brush hard and still maintain control of the ball.

The idea, of course is that if you're doing spin continuation with inverted rubbers you should be brushing hard to at least match the incoming ball spin, but if you're going against the spin it's better to let the rubber do its job of inverting the spin and focus more on controlling and carrying the ball to where it should be.

 

[blahness]

Right/righty - FH pendulum side/back

Interesting that he can touch it on the left - do you mean a right to left movement similar to a FH sideswipe? Normally contacting on left on a FH pendulum sidespin serve results in eating the sidespin full on and the ball missing the table on the right. But it also depends if it's backspin dominant or sidespin dominant. A FH sideswipe movement indeed will result in spin continuation against a FH pendulum serve which results in the ball coming back to you clockwise (same direction as how you served it), with extreme sidespin.

 

[Wrighty67]

Interesting that he can touch it on the left - do you mean a right to left movement similar to a FH sideswipe? Normally contacting on left on a FH pendulum sidespin serve results in eating the sidespin full on and the ball missing the table on the right. But it also depends if it's backspin dominant or sidespin dominant. A FH sideswipe movement indeed will result in spin continuation against a FH pendulum serve which results in the ball coming back to you clockwise (same direction as how you served it), with extreme sidespin.

I need to pay more attention, but my recollection is it is a gentle right to left touch that doesnt see the ball deflect as much as you would expect with a flatter blade contact, so the ball lands on my BH side but carrying all the original spin plus a little - he does it a lot and it makes a short third ball that is very difficult to play with any intent.

 

[blahness]

I need to pay more attention, but my recollection is it is a gentle right to left touch that doesnt see the ball deflect as much as you would expect with a flatter blade contact, so the ball lands on my BH side but carrying all the original spin plus a little - he does it a lot and it makes a short third ball that is very difficult to play with any intent.

I think if it is a right to left movement it has to contact the back of the ball, not on the left. But yes, understanding the spin behaviour also helps one to adjust for the incoming spin.

I used to do a lot of stuff by autopilot but imo knowledge is power. Knowing what the incoming spin is, and ways to handle the spin is already half of the battle won.