TT Myth Busters

A higher rubber rating make you faster or spinner. No, thats what the manufacturers say most of the time unless someone makes their own.

The part on rubber tickness is far more complicated than what is explained (in fact, it depends of the stroke and I suppose that the OP only speaks for common offensive backsides here....and it is still not true).

The part on the blade weight makes no sense. the ratio Cinetic energy/mass is LINEAR, speaking about a non linearity above 160 gramms makes no sense. Why people don't play with 300gr blades ? Because the speed is also part of cinetic energy (the ratio is not linear btw) and if you lose much speed, despite the increased mass, you will lose cinetic energy.

Also, it is not like the players are looking for the fastest blade, else most pro players wouldn't play with ALC or Clipper blades, since there are much much faster blades.

What we usually call "control" is the sensitivity to incomming speed/spin and the linearity of a blade/rubber (linearity is not the good word here, the idea is that a small change of the stroke doesn't result in a big change on the result), but also for blades it is linked to the sweet spot of a blade (same idea here : a small change to the impact point doesn't result in a big change on the result).

The is why, usually, slower blades are are rated with better control.

you right about everything BUT... a lot of this stuff is just a matter of terminology. if SP rubbers have on average a different trajectory with the same stroke as inverted (and of course they do because there is less spin), one can say that they do have a "sink ball effect" compared to inverted.

different blades give different feedback every time you hit the ball. you feel the blade vibrate and some blades feel harder or softer than others. this feedback can make you get used to hitting the ball at different speeds sooner and your consistency goes up because your brain has more variables to work with. also the slower a blade is the easier it gets to land shots on the table. so subjectively speaking you can say some blades have better control than others.

as for sponge thickness, i would say a thicker sponge gives the topsheet more room to distort so at least it should cause an increase in spin.

the wobble effect is quite interesting for me, because almost every player i know claims to have seen it a lot of times when playing against long pips. "DID YOU SEE HOW THIS ONE FLEW LEFT AND RIGHT?!" being the usual example just after they miss a ball... except nobody else has seen it but them and it has never been caught on camera.

so how come? i believe it's a trick that the brain plays on us when we play. on most shots we don't actually follow the ball with our eyes during it's whole flight, but our brain predicts the path based on our opponents stroke and the beginning of it's flight path. this can only come with experience after thousands of different situations that our brain gets used to. so when LP rubbers come into play, a same pattern creates a different result (because of different spin) but our brain still tries to predict the way it's used to... i believe the "wobble" is actually an illusion that results from our brain making the split second correction when our eyes catch the ball flying or bouncing differently than our brain was telling us it would based on experience.

For offensive backsides only : more tickness will result on faster top spins & higher arc but it will be slower on flat hits.

Wobble ball he is correct in his explanation it is when you hit a ball with no spin and the turbulent air currents in the room move it. If you don't believe it look up football knuckle balls. It's the same idea but the bigger ball and larger movement is easier to see

passifid said:

Wobble ball he is correct in his explanation it is when you hit a ball with no spin and the turbulent air currents in the room move it. If you don't believe it look up football knuckle balls. It's the same idea but the bigger ball and larger movement is easier to see

Click to expand...

nope, table tennis balls would have to travel at very high speeds for that to happen and usually there are no air currents in closed halls. if your theory were true you could produce a wobble ball fairly consistently just by hitting the ball around with no spin.

Its not easy to generate no spin. If you have some basis in physics, read some litterature about the magnus effect. The table tennis ball is submit to magnus effect and (almost) everything about the relation between trajectory and spin is caused by the magnus effect for our beloved table tennis balls.

LP still don't make balls wobble though. i will believe that such a thing happens when someone gets it on camera or even if i hear about someone witnessing it who WASN'T playing at that moment.

If the ball is not round, it can. Else not.

1. rubbers or blades have power. They don't. You do. Blades and rubbers are inanimate objects that won't move without some outside force. People generate power.

This is half myth. The nearest I can think for power is Coefficient of Restitution. Blade and rubber have C.O.R., but no one measure it officially for a moment

2. rubbers or blades have control. They don't. You do. You control the stroke.

Yes. I prefer to measure control as, number of player that says this blade or rubber controllable per 100 player.

3. SP have a sink ball effect. Well they do but you can duplicate the same effect with inverted rubbers. There is no force or impulse a SP can generate that an inverted rubber cannot.

Yes

4. hard rubbers are faster than soft rubbers or the other way around. It is more complicated than that. People talk about how springy a sponge is and that is a good indications of how fast the rubber is but it is really the internal damping. If there are any mechanical engineers here they know about the mass on a spring with a dashpot for damping. No one mentions the damping and damping is important..

Yes, ironically.

5. Thick rubbers are faster than slower rubbers. Rubber doesn't generated energy. It absorbs energy. Given the same stroke a thinner rubber will be faster.

Yes.

6. LPs generate wobble balls. There is no wobble force generated by a paddle or rubber. LPs do generate a higher percentage of dead balls than inverted but basically there is no force an LP can generate that an inverted rubber cant. Inverted rubbers should be able to generate wobble balls too but there is no wobble force. If a ball appears to wobble it is caused by the ball being moved by air currents or eddies around the opponent. It has nothing to do with the rubber or blade because the paddle has no effect on the ball after it has left the paddle.

Yups, this about ?games? from eye and mind. Terminal velocity of 40 mm ball is quite high, so I dont think current crop of player able to attain that.

7. Dwell time is not long. Dwell time is very short. It is on the order of a millisecond to millisecond and a half. I have high speed videos to prove it.

Yes

8. Accelerate through the ball to increase dwell time or hold the ball on the paddle. Yes, it does increase dwell time but on the order of a few micro seconds.

Yes

9. Heavier blades are faster all other things being equal. Yes but after the paddle gets to be about 160 gm the increase per gram diminishes rapidly. If a heavier paddle is faster then why not play with a 300 gm paddle.

Err, no, the other way around. Lower mass raise hand speed, ultimately raise momentum.

While true that momentum is speed * mass, player need force to move the blade, speed ^ 2 * mass, and there is a ceiling for force that can be applied. That is why in golf we concern to lower mass, cause the increase in swing speed raise momentum more than weight. This should also goes true for table tennis.

10. The flooring under the table makes a difference to the bounce. It does but like myth 9 the effect is so small that one couldn't measure it.

Yes

11. Rubbers are tensioned. What a joke.

Yes, this is quite an old superstition. But yes, the C.O.R. may be changed by boosting or any other process.

Let the heated discussions begin!!!!
The rest should just sit back and enjoy the thread.

passifid said:

Wobble ball he is correct in his explanation it is when you hit a ball with no spin and the turbulent air currents in the room move it. If you don't believe it look up football knuckle balls. It's the same idea but the bigger ball and larger movement is easier to see

Click to expand...

The wobbling ball phenomenon is also very well known in soccer/ football (edit: or even better: volleyball) You can go ask any goalkeeper (or volleyballplayer). Most oft them know this very well.... And couple of weeks ago i played vs a LP Player and a teammate watching the match came to me after the game, that he had never seen a ball behave and fly like this before.... I didn't even realize, cause i was so focused in playing.

Why do we have to worry so much about physics in table tennis???
I prefer playing and experiencing the above first hand,even if it contradicts some of the above statements.

I believe that the more mass a blade has,the more momentum,given the equation(P=m.v),therefore faster.

I think you seriously missunderstand something. I don't know where to start to explain it and I'll try to be as simple as possible without entering the details. You are speaking about the formula giving va and vb when knowing the COR (Cr) and the mass of various objects..........

this one :


........changing the mass is changing also the COR, why are you assuming that the COR will be unchanged ? This makes no sense, of course a 95gr viscaria will have higher COR than a 80gr one (most of time, you will always find me a 95gr ultra soft viscaria with a low COR).

Yes you are right, if you find me a bat of 160gr that has the same COR than a 200gr one, indeed the increaseof speed wont be as much as the weight increase............but........this is assuming that the two bats have the same COR, why do you think that the COR of a 95gr viscaria is the same as a 80gr one ? Because I tell you : it's not, not the same at all.

I hope I made it clear, because it's not easy to explain some simple things sometimes.
But this formula is showing you that even if you find a viscaria of 60gr with an insane COR, matching the COR of a 100gr viscaria blade, you will still LOSE speed. This formula derivated from the concervation of momentum is showing use the very high importance of the mass indeed.

The absolute most expensive equipment is the best stuff haha, many really believe that.

I wont even speak about the fact that the COR, for a given blade, is absolutely not a constant. For, taking measures at slow speed, a Calibra LT speed will have higher COR than a calibra LT+, but at high speed the COR of calibra LT+ is of course higher.

COR is not a constant for our table tennis rackets. And here we are absolutely not speaking about the real cinetic energy of the ball, taking in account spin....we must add 0.5j*teta? to the equations and using models of collisions without frictions like those previous formulas, it's formulas for collision between particules, indeed without any friction.........it's indeed wrong from the start since friction is so much important in table tennis.

edit, here is an article I have actively participated to write (not finished yet), speaking this time of the rebound on the table (and thuus determine how to "exploit" it), but its written on French and of course far from being completed : http://fr.wikiversity.org/wiki/Tennis_de_table/Annexe/Mod?lisation_du_rebond_sur_la_table

Der_Echte said:

The absolute most expensive equipment is the best stuff haha, many really believe that.

Click to expand...

I believe if you wear expensive TT socks you will be a better player.

izra said:

you right about everything BUT... a lot of this stuff is just a matter of terminology. if SP rubbers have on average a different trajectory with the same stroke as inverted (and of course they do because there is less spin), one can say that they do have a "sink ball effect" compared to inverted.

different blades give different feedback every time you hit the ball. you feel the blade vibrate and some blades feel harder or softer than others. this feedback can make you get used to hitting the ball at different speeds sooner and your consistency goes up because your brain has more variables to work with. also the slower a blade is the easier it gets to land shots on the table. so subjectively speaking you can say some blades have better control than others.

as for sponge thickness, i would say a thicker sponge gives the topsheet more room to distort so at least it should cause an increase in spin.

the wobble effect is quite interesting for me, because almost every player i know claims to have seen it a lot of times when playing against long pips. "DID YOU SEE HOW THIS ONE FLEW LEFT AND RIGHT?!" being the usual example just after they miss a ball... except nobody else has seen it but them and it has never been caught on camera.

so how come? i believe it's a trick that the brain plays on us when we play. on most shots we don't actually follow the ball with our eyes during it's whole flight, but our brain predicts the path based on our opponents stroke and the beginning of it's flight path. this can only come with experience after thousands of different situations that our brain gets used to. so when LP rubbers come into play, a same pattern creates a different result (because of different spin) but our brain still tries to predict the way it's used to... i believe the "wobble" is actually an illusion that results from our brain making the split second correction when our eyes catch the ball flying or bouncing differently than our brain was telling us it would based on experience.

Click to expand...

The 'wobble balls' are nu illusion. If the ball has little to no spin at all it wil wobble through the air. Just like a wobble ball in football.