Ball Pocketing, Dwell Time, Spin Potential

tlm said:

That makes some sense, but I am not so sure that poly can really exceed kevlar in spin potential let alone be far superior. I feel that because poly puts more power on the ball that many players will see a better hop off the court because of the polys power not spin, so then many would think they are getting more spin but actually it is more power.

If we are talking about just spin I think that kevlar actually produces more spin than poly.

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But it doesn't. TWU has tested strings extensively and poly is always top of the charts across materials.

So what's the final verdict? "Does increased ball pocketing and thus dwell time equal more spin potential?"

pvaudio said:

But it doesn't. TWU has tested strings extensively and poly is always top of the charts across materials.

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Well maybe so, but are we talking about tests with rackets hooked to machines and pressure-less balls? Some of these lab tests are not the same as players hitting the ball.

tlm said:

Well maybe so, but are we talking about tests with rackets hooked to machines and pressure-less balls? Some of these lab tests are not the same as players hitting the ball.

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Well, just as one example, Agassi played with Kevlar for much of his career. The first time he tried poly, he said, in my paraphrasing, that the spin was akin to cheating.

pvaudio said:

Well, just as one example, Agassi played with Kevlar for much of his career. The first time he tried poly, he said, in my paraphrasing, that the spin was akin to cheating.

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I remember him saying that poly was like cheating but I don't remember him saying that the spin was the main factor. The comparison of the pro players using poly and us amateurs is not very good to me. These guys use a fresh string job every half hour or so.

And I will say that I love fresh poly, it is hard to beat. But even after an hour or so I can tell a difference in the playability, spin and control of poly, let alone a few days. But with the kevlar main and poly cross I am using right now the consistency is way better than a full poly job, no comparison in my opinion.

Fair enough. Regardless, given how spin-reliant today's game is, I don't think it's coincidence that poly is the dominant string material whether in hybrid or in full. Now if the argument is about rec players vs. the pros, that's missing the point entirely because this is about spin potential. If you can generate the RHS required, the poly wins. I don't think it's coincidence that Kevlar has more or less become obsolete as a string material. And actually, Kevlar has the highest rate of tension loss of all string materials.

akamc said:

ChicagoJack, that is a very interesting video clip! It certainly looks more extreme than my mental picture of a typical shot and would change how I visualize ball-string interaction, except that I wonder how fast the ball was traveling and how the racket was anchored. Also, isn't that a pressureless Tretorn Micro-X ball which may not react like a normal ball? Most slow-mo clips of pros hitting do not appear to show so much ball deformation, but they are also not so detailed.

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Hi akamc -

Yeah I know, pretty dramatic stuff. Of all the slow mo vids and photos I've seen, that one shows the most extreme ball deformation. Ball compression to about 45% original size is much more typical. I'm curious about the ball velocity, and impact conditions as well. Regarding the Tretorn Micro X balls, they aren't the limp noodles that the phrase "pressureless" might imply. Rather than being gas injected like typical balls, that lose pressure every second of every minute, they are filled with millions of balloon like microcells, that don't leak. While you might find the Tretorns sanctioned for use once in a blue moon for tournament play, they are mainly used for ball machines, because they stay playable for a very long time. Based on the user feedback right here at TW, they play a bit like stiff, extra duty balls. Pure conjecture on my part, but I'm guessing that the ITF chose these balls for their tests, because they needed a tough felt to stand up to the machines that fire the balls, and they needed a ball that offered a solution to the problem of regular balls losing pressure so quickly.
http://www.tennis-warehouse.com/feedback-tretpress.html
http://www.tennis-warehouse.com/Tre...less_Tennis_Balls_x72/descpage-TRETPRESS.html

-Jack

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UCSF2012 said:

So what's the final verdict? "Does increased ball pocketing and thus dwell time equal more spin potential?"

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Hi USCF2012 -

Yeah cool, sorry I cant give you the short answer you are looking for. That's actually like four separate questions all tangled up into one question. Some basic distinctions are needed first.

1. Although you have verbalized it as such, increased ball pocketing and increased dwell time are not always synonymous, in fact they are often inversely related. See my post #41, Para 1C for greater detail.

2. Ball pocketing, or more properly said, string bed deflection, is defined as the amount of deflection perpendicular to the string plane. This is not associated with spin enhancement. See my post #41 2A for greater detail.

3. Spin enhancement has been shown in recent years to be a product of two factors, ball-string friction and inter-string friction. Low inter-string friction promotes slide and snap back, parallel to the string plane. This happens while the string bed is deflecting/pocketing, but the deflection backwards is not what generates the additional spin. The additional spin is generated by the string brushing up the back of the ball in the vertical plane (on a groundstroke). See links in Post #41 2B for greater detail.

-Jack

[..] ......................

tlm said:

If we are talking about just spin I think that kevlar actually produces more spin than poly.

Click to expand...

tlm said:

Well maybe so, but are we talking about tests with rackets hooked to machines and pressure-less balls? Some of these lab tests are not the same as players hitting the ball.

Click to expand...

Hi Tlm

I don't ever argue what people feel/observe on the court. However, with regards to Kevlar offering more spin enhancement than poly, I invite you to consider that:

1. The 3 most credible racquet technicians on the planet, ie. the Holy Trinity of Roman Prokes, Nate Ferguson, and Warren Bosworth, all say otherwise.

2. The select few who study, and publish racquet physics for a living... Brody, Cross, Lindsey, all say otherwise.

3. Then there is the pro tour. Not many supporters there. As Pv Audio has noted, Agassi was the last Kevlar user of any note.

4. I used Kevlar myself for a few years circa 2001-2002. I was too was pretty convinced at the time I'd found the ultimate spin machine. I think I understand now why I thought that. There is a very plausible explanation to why you feel what you feel with Kevlar, why you might perceive it to be more spin friendly than poly. It isn't texture, or dwell, or increased ball grip. Perhaps it's just that it's very low powered. It's very stiff, in fact, 2-3 times stiffer that the stiffest poly. This just means you have less fear of hitting long. You swing faster when you don't fear hitting long. Swinging faster creates more spin. Your stroke has changed because of the string, but the additional spin is coming from your stroke, not the string itself. In lab experiments, they have proven conclusively that irrespective of player technique, certain strings produce more spin than others. That's the central issue at hand. Kevlar is no where near the top of that list. Pretty consistently, it's slippery textured poly as a full bed, or Gut/Poly that tops the spin charts.

5. What's ironic, is that for years following the The University Of Sheffield testing done by Goodwill and Haake circa 2004, the entire racquet physics community (excepting our very own TravlerAJM, who knew better) came to the conclusion that strings don't make any difference at all with regards to spin. That conclusion was 180 degrees opposite from what we were all experiencing on the court. More recent testing has only validated what players have known all along, that strings do make a difference with regards to spin. Even though we now have lab testing which validates the player experience, players are still skeptical of the dudes in the white lab coats, and perhaps rightly so.

-Jack

[..] ......................

corbind said:

Great work Jack. You're a man after my own heart!

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Hi Corbind

I'm no braniac, I can barely add and subtract. Just know where to find the answers, just a dumb jock who prefers reading racquet physics to prescription sleep aids, and it works really well for that purpose. Haha.

-Jack

ChicagoJack said:

Hi akamc -

Yeah I know, pretty dramatic stuff. Of all the slow mo vids and photos I've seen, that one shows the most extreme ball deformation. Ball compression to about 45% original size is much more typical. I'm curious about the ball velocity, and impact conditions as well. Regarding the Tretorn Micro X balls, they aren't the limp noodles that the phrase "pressureless" might imply. Rather than being gas injected like typical balls, that lose pressure every second of every minute, they are filled with millions of balloon like microcells, that don't leak. While you might find the Tretorns sanctioned for use once in a blue moon for tournament play, they are mainly used for ball machines, because they stay playable for a very long time. Based on the user feedback right here at TW, they play a bit like stiff, extra duty balls. Pure conjecture on my part, but I'm guessing that the ITF chose these balls for their tests, because they needed a tough felt to stand up to the machines that fire the balls, and they needed a ball that offered a solution to the problem of regular balls losing pressure so quickly.
http://www.tennis-warehouse.com/feedback-tretpress.html
http://www.tennis-warehouse.com/Tre...less_Tennis_Balls_x72/descpage-TRETPRESS.html

-Jack

[..] ......................


Hi USCF2012 -

Yeah cool, sorry I cant give you the short answer you are looking for. That's actually like four separate questions all tangled up into one question. Some basic distinctions are needed first.

1. Although you have verbalized it as such, increased ball pocketing and increased dwell time are not always synonymous, in fact they are often inversely related. See my post #41, Para 1C for greater detail.

2. Ball pocketing, or more properly said, string bed deflection, is defined as the amount of deflection perpendicular to the string plane. This is not associated with spin enhancement. See my post #41 2A for greater detail.

3. Spin enhancement has been shown in recent years to be a product of two factors, ball-string friction and inter-string friction. Low inter-string friction promotes slide and snap back, parallel to the string plane. This happens while the string bed is deflecting/pocketing, but the deflection backwards is not what generates the additional spin. The additional spin is generated by the string brushing up the back of the ball in the vertical plane (on a groundstroke). See links in Post #41 2B for greater detail.

-Jack

[..] ......................





Hi Tlm

I don't ever argue what people feel/observe on the court. However, with regards to Kevlar offering more spin enhancement than poly, I invite you to consider that:

1. The 3 most credible racquet technicians on the planet, ie. the Holy Trinity of Jay, Nate, and Warren, all say otherwise.

2. The select few who study, and publish racquet physics for a living... Brody, Cross, Lindsey, all say otherwise.

3. Then there is the pro tour. Not many supporters there. As Pv Audio has noted, Agassi was the last Kevlar user of any note.

4. I used Kevlar myself for a few years circa 2001-2002. I was too was pretty convinced at the time I'd found the ultimate spin machine. I think I understand now why I thought that. There is a very plausible explanation to why you feel what you feel with Kevlar, why you might perceive it to be more spin friendly than poly. It isn't texture, or dwell, or increased ball grip. Perhaps it's just that it's very low powered. It's very stiff, in fact, 2-3 times stiffer that the stiffest poly. This just means you have less fear of hitting long. You swing faster when you don't fear hitting long. Swinging faster creates more spin. Your stroke has changed because of the string, but the additional spin is coming from your stroke, not the string itself. In lab experiments, they have proven conclusively that irrespective of player technique, certain strings produce more spin than others. That's the central issue at hand. Kevlar is no where near the top of that list. Pretty consistently, it's slippery textured poly as a full bed, or Gut/Poly that tops the spin charts.

5. What's ironic, is that for years following the The University Of Sheffield testing done by Goodwill and Hawke circa 2004, the entire racquet physics community (excepting our very own TravlerAJM, who knew better) came to the conclusion that strings don't make any difference at all with regards to spin. That conclusion was 180 degrees opposite from what we were all experiencing on the court. More recent testing has only validated what players have known all along, that strings do make a difference with regards to spin. Even though we now have lab testing which validates the player experience, players are still skeptical of the dudes in the white lab coats, and perhaps rightly so.

-Jack

[..] ......................


Hi Corbind

I'm no braniac, I can barely add and subtract. Just know where to find the answers, just a dumb jock who prefers reading racquet physics to prescription sleep aids, and it works really well for that purpose. Haha.

-Jack

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Okay Jack fair enough, I just get hooked on the great spin I get with a kevlar main and poly cross. But more than that this set up plays so much more consistent than a full poly job does.

I love poly when it is fresh, but it come nowhere near kevlar when it comes to maintaining pinpoint control with its built in restricted flight even after a few hours of use. I hit a high trajectory with a lot of top spin and when the poly starts to lose some tension I have a harder time with shots going long.

And even though I know kevlar loses tension quickly it does not lose its control anywhere near as quick as poly does. I am still experimenting with different poly set ups and hoping to find one that works. Because I would like to get away from the kevlar its stiffness can be hard on the arm. But like I mentioned its unmatched control and pinpoint accuracy is addicting.

By the way what club do you play out of, I play in the suburbs out of Park Forest and Homewood.
TLM

ChicagoJack said:

[What's ironic, is that for years following the The University Of Sheffield testing done by Goodwill and Hawke circa 2004, the entire racquet physics community (excepting our very own TravlerAJM, who knew better) came to the conclusion that strings don't make any difference at all with regards to spin. That conclusion was 180 degrees opposite from what we were all experiencing on the court. More recent testing has only validated what players have known all along, that strings do make a difference with regards to spin. Even though we now have lab testing which validates the player experience, players are still skeptical of the dudes in the white lab coats, and perhaps rightly so.

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Could you provide a link/reference to those more recent testing?

jmnk said:

Could you provide a link/reference to those more recent testing?

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Hi Jmnk - Sure, no problemo. See my links in post #41 section 2B. That's a good start. -Jack

tlm said:

Okay Jack fair enough, I just get hooked on the great spin I get with a kevlar main and poly cross. But more than that this set up plays so much more consistent than a full poly job does.

I love poly when it is fresh, but it come nowhere near kevlar when it comes to maintaining pinpoint control with its built in restricted flight even after a few hours of use. I hit a high trajectory with a lot of top spin and when the poly starts to lose some tension I have a harder time with shots going long.

And even though I know kevlar loses tension quickly it does not lose its control anywhere near as quick as poly does. I am still experimenting with different poly set ups and hoping to find one that works. Because I would like to get away from the kevlar its stiffness can be hard on the arm. But like I mentioned its unmatched control and pinpoint accuracy is addicting.

By the way what club do you play out of, I play in the suburbs out of Park Forest and Homewood.
TLM

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Great thread people....what I was looking for...

My question would be: When kevlar loses its tension, does it increase in power?
My experience of kevlar is that the older it gets, the rougher and looser the actual strings get, and the spin increases. Power, I am not sure. To me poly is great on flat shots, but not as great as kevlar with spin. Could anyone concur?

pvaudio said:

It's very odd. It's like it's braided almost. It's kinda lumpy rather than rough.

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Yeah, its definitely a strange feel...It's almost like they took alu power, and just cut small crevices into the string, somewhat like little spiral notches.

A lot of this is way over my head lol...But, for a While i was using the Kblade 98...Strung with Wilson Nat gut @ 56 lbs mains/Tec Black code @ 54 lbs cross. I had tried doing the same tension with the wilson nat gut mains and lux alu rough cross, but felt like the ball had a trampoline effect when making contact, and that same effect never happened with the black code. I used this hybrid for a few years and still like it to this day, but switched to all black code. Could you help me understand some possible reasons why i would have liked the black code hybrid more, based off of the information that you've provided previously? I currently string rackets for two different places and I string quite a bit, but still learning about the science of it all...so i find this quite interesting. Thanks Audio or whoever can enlighten me on this.

tennisnut123 said:

A lot of this is way over my head lol...But, for a While i was using the Kblade 98...Strung with Wilson Nat gut @ 56 lbs mains/Tec Black code @ 54 lbs cross. I had tried doing the same tension with the wilson nat gut mains and lux alu rough cross, but felt like the ball had a trampoline effect when making contact, and that same effect never happened with the black code. I used this hybrid for a few years and still like it to this day, but switched to all black code. Could you help me understand some possible reasons why i would have liked the black code hybrid more, based off of the information that you've provided previously? I currently string rackets for two different places and I string quite a bit, but still learning about the science of it all...so i find this quite interesting. Thanks Audio or whoever can enlighten me on this.

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For me on the kblade 98, the most success I had stringwise, was the thinner babolat pro hurricane (white)....second place was the pro hurricane tour (yellow)
I am not sure why though....the blade was also the lightest on strings compared to all my other rackets.