New TWU Experiment: Spin and String Pattern

[TW Professor]

Does string pattern make a difference to spin? How? Why? It is all here in the new TWU experiment/article "Spin and String Pattern." (There are many movies so it may load slowly on older machines.)

http://twu.tennis-warehouse.com/learning_center/stringpattern.php

 

[Centered]

It is safe to say that pattern makes a difference. But questions remain as to how to maximize or optimize that difference.

The racquet pattern tests in Section 7 inconclusively suggest that lower tension might also help. Also, how much difference in string spacing is enough or not enough to make a meaningful difference? There was very little comparative spin production with the 16x18 pattern compared to the 14x9. What about 16x16, 16x14, 16x12? And where the spaces occur matters also, especially as demonstrated in the 8Mx6X pattern in the pattern-rig tests. The pattern contained a lot of strings, but the impact zone was left open and the pattern generated a great deal of spin.

I am rather surprised that you were unable to determine whether or not string tension makes a large difference or not and that you were unable to determine which string pattern is the most optimal. Or, was 14x9 the most optimal?

The shape of the racquet head (and perhaps its stiffness) should make a difference, too. Some racquets have shapes that are much different than the typical oval.

There is also the issue of string thickness.

Perhaps, in this way, spin, control, and feel can be better customized to each player.

There seem to be so many questions still that I wonder how one would go about such customization in a fairly efficient manner.

Choosing strings with a low coefficient of friction will help.

Have you yet tested hybrid setups with gut mains and nylon crosses, since some nylon strings had a lower COF than VS Team in your chart?

Also, while the gut oil hypothesis is interesting, have you determined why nylon strings would have a lower COF given that they have no oil to exude?

What is responsible for a string's COF? If oil is what makes gut "super slippery" when it's used for the mains in a hybrid (despite it being less slippery than some nylon strings by itself), should slicker surfaces, like Teflon, be used for synthetic strings? Should oil be applied to strings?

 

[Kevo]

Very interesting, thanks for taking the time to put that up. What I would like to see is something closer to real world conditions. Something akin to a swing machine with variable swing speed and a ball launcher that will send in a ball at a relatively stable speed. That's a tough ask, I know, but from my experience swing speed is the biggest factor.

Anecdotally I've gotten surprising spin from two very different setups. I played a Kevlar hybrid once in an RDX 500 mid at 60lbs. The setup was very low powered, but I got tremendous spin out of that one. I have two theories as to why. The first is that I was swinging faster to compensate for the low power. The second is that the compression of the ball on the strings was storing energy in the ball itself which was affecting spin.

The other setup was a very mushy multi in the RDX 500. That one felt like the ball was on the strings forever and I got the feeling of holding the ball in the strings. It was also low powered and I could swing very hard and get huge spin. I don't think the ball was compressing much, so I attribute the spin to the dwell and stretch of the strings inline with the string bed.

With either of these setups I could swing less aggressive and spin reduced to more normal levels. Since I switched to the PSL with an 18x20 pattern I feel I can get as much spin as I ever could except with those two particular setups. I think the reason is that they let me swing harder while being able to keep the ball in play.

My take away from personal experience is that swing speed is by far the most important factor, and optimizing your equipment to allow the greatest swing speed will yield best results for spin with other factors like string type and pattern being secondary contributors.

 

[Centered]

If swing speed is the most important thing, consider a racquet with no strings in it. No matter how fast you swing, the ball will go through the racquet. There won't be any spin applied.

So, based on that thought experiment alone, it seems to me that there's more involved than swing speed.

I'm no physicist, so I'll leave the testing to the TW Prof.

 

[Gasolina]

So wait.... after reading all that... it does say that an open pattern might generate more spin?

 

[Kirko]

I don't think so >>

So wait.... after reading all that... it does say that an open pattern might generate more spin?

I use 18x20 redondo mid and 1st time user to luxilon after years of nat.gut and get the best topspin ever and I'm convinced "strings" that locked in like luxilon give me 1st time ever the most "english" i put on a ball, before i used topspin as an alternate shot eg. passing shot & moonball. different story now. tension helps too, that is the right one for "you".

 

[Netspirit]

So wait.... after reading all that... it does say that an open pattern might generate more spin?

yeah. lol.

 

[fuzz nation]

I use 18x20 redondo mid and 1st time user to luxilon after years of nat.gut and get the best topspin ever and I'm convinced "strings" that locked in like luxilon give me 1st time ever the most "english" i put on a ball, before i used topspin as an alternate shot eg. passing shot & moonball. different story now. tension helps too, that is the right one for "you".

Well, the trouble with the Redondo is that there isn't a model with an open pattern to compare it with, right?

A lot of the spin access in a racquet like the Redondo is due to its flex. Since it's so soft, it puts all the spin on the ball from the same angular contact that the player would generate using their ingrained swing with any racquet of similar weight and balance. The extra flex makes less inherent linear velocity at contact, so there's ultimately a higher ratio of spin to velocity from that racquet than we could expect from a stiffer option.

Add some less resilient poly to the equation, and there's even less linear velocity at contact, but the same spin given the same rate and angle of swing. That layout should make for a spin-meister extraordinaire!

I believe that an open pattern can contribute a little to the spin potential and when combined with a very flexible racquet, it can get bananas... actually, the ball's flight can start resembling bananas. Two softies with open patterns that I've tried in the past include the Flexpoint Radical Tour and the Prince Original Graphite OS. Those two racquets seemed to churn out circus shots.

 

[TW Professor]

I am rather surprised that you were unable to determine whether or not string tension makes a large difference or not and that you were unable to determine which string pattern is the most optimal. Or, was 14x9 the most optimal?

The experiment was primarily about pattern and spin. The result was quite definitive that pattern affects spin. Determining "optimal" depends on the definition of the word. If you mean the most spin, then the patterns with no cross strings win. Clearly, you don't want that. "Opimality" is a personal choice. There is no ratio or coefficient of pattern to spin to control to launch angle to power to whatever that is going to dictate the best setup. But we do know that spacing between strings influences spin, and so does friction between strings, and the one tension test performed also indicated that tension matters. (But an extensive tension experiment is for another day--one thing at a time.) But, ultimately, the player has to experiment and choose what feels best. But, based on what we know, the player doesn't have to waste time experimenting with strings or patterns that are not likely to enhance a desired performance.

However, experimentation has to abide by the ITF rules:

"a. The hitting surface, defined as the main area of the stringing pattern bordered by the points of entry of the strings into the frame or points of contact of the strings with the frame, whichever is the smaller, shall be flat and consist of a pattern of crossed strings connected to a frame and alternately interlaced or bonded where they cross. The stringing pattern must be generally uniform and, in particular, not less dense in the centre than in any other area.

The racket shall be designed and strung such that the playing characteristics are identical on both faces. The racket shall be free of attached objects, protrusions and devices other than those utilised solely and specifically to limit or prevent wear and tear or vibration or, for the frame only, to distribute weight. These objects, protrusions and devices must be reasonable in size and placement for such purposes."

This rule specifically disallows making the center of the stringbed less dense than any other area. That certainly limits your options.

Have you yet tested hybrid setups with gut mains and nylon crosses, since some nylon strings had a lower COF than VS Team in your chart?

We have not done any more COF tests yet. However, there was one gut main and nylon cross hybrid tested. The results are on the Hybrid Graph on this page: http://twu.tennis-warehouse.com/learning_center/COF.php.

What is responsible for a string's COF? If oil is what makes gut "super slippery" when it's used for the mains in a hybrid (despite it being less slippery than some nylon strings by itself), should slicker surfaces, like Teflon, be used for synthetic strings? Should oil be applied to strings?

COF is determined by the shapes/fit of the two surfaces and the atomic attraction between the materials. Lubricants, coatings, etc. change the atomic attraction of the surfaces.

My take away from personal experience is that swing speed is by far the most important factor, and optimizing your equipment to allow the greatest swing speed will yield best results for spin with other factors like string type and pattern being secondary contributors.

For a given set of inputs (ball speed, angle, spin, etc.), swing speed is the most important contributor to spin. But for a given swing speed, the racquet with the most spin friendly setup will produce the most spin.

 

[Kevo]

For a given set of inputs (ball speed, angle, spin, etc.), swing speed is the most important contributor to spin. But for a given swing speed, the racquet with the most spin friendly setup will produce the most spin.

OK, that makes sense to me. If I have two identical frames except for string pattern I should get more spin with the open pattern if I swing them the same speed. So is there a way we could quantify it. If the pattern is only 5% more open does that mean 1% more spin or 10% more spin.

Also, what happens to the power level of the frame with each pattern. Does the denser pattern let me swing harder and still keep the ball in? Does that mean the denser pattern frame has more spin potential? The spin question is a really tricky one in my mind because there are so many factors involved.

 

[Centered]

"The stringing pattern must be generally uniform and, in particular, not less dense in the centre than in any other area."

This rule specifically disallows making the center of the stringbed less dense than any other area. That certainly limits your options.

That's a stupid rule unless there's a good reason for it. Has anyone come up with a good reason for it? Merely allowing players to get a bit more spin doesn't seem to be an adequate reason given the wide range of head sizes, racquet stiffnesses, and racquet weights allowed. It's not like having fewer strings in the center is going to make a racquet behave like it's spaghetti strung.

 

[Centered]

However, there was one gut main and nylon cross hybrid tested.

Strangely, the nylon multi you used, Klip Excelerator, does not appear in the bottom chart so we can't see what its COF is.

Furthermore, some nylon multis, like X-One Biphase 16 had a much higher COF than VS Team gut (0.314 for Biphase versus 0.147 for VS Team). Yet, other nylon strings, as I've pointed out, had a lower COF than gut. Prince Synthetic Gut Original 16, for instance, has a COF of 0.124, which is lower than VS Team's.

This makes things still quite unclear.

If, for instance, you make a hybrid with X-One Biphase 16 and gut, it's likely to have a higher COF than one made with Prince Synthetic Gut Original 16 and VS Team. Klip Excelerator is a multi, like X-One Biphase and NRG2 16 -- both of which had much higher COFs than VS Team gut.

That nylon multis seem, based on the small sample in the chart, to have a higher COF than stiff nylon strings. Given that poly -- which is stiffer than nylon -- has a lower COF still, it seems to me that using a very stiff nylon string with gut mains is a worthwhile test.

 

[TW Professor]

Strangely, the nylon multi you used, Klip Excelerator, does not appear in the bottom chart so we can't see what its COF is.

Furthermore, some nylon multis, like X-One Biphase 16 had a much higher COF than VS Team gut (0.314 for Biphase versus 0.147 for VS Team). Yet, other nylon strings, as I've pointed out, had a lower COF than gut. Prince Synthetic Gut Original 16, for instance, has a COF of 0.124, which is lower than VS Team's.

This makes things still quite unclear.

If, for instance, you make a hybrid with X-One Biphase 16 and gut, it's likely to have a higher COF than one made with Prince Synthetic Gut Original 16 and VS Team. Klip Excelerator is a multi, like X-One Biphase and NRG2 16 -- both of which had much higher COFs than VS Team gut.

That nylon multis seem, based on the small sample in the chart, to have a higher COF than stiff nylon strings. Given that poly -- which is stiffer than nylon -- has a lower COF still, it seems to me that using a very stiff nylon string with gut mains is a worthwhile test.

Unless listed as a hybrid, the COF refers to the COF when both strings are the same. So whatever that COF is in that case will be different in a hybrid. So you are right, your test is worthwhile. With the small data sample collected so far, it is difficult to make generalizations about what kind of strings seem to interact to result in high or low COF. We will accumulate much more data as we proceed. The primary concern, though, will be to get data for each string on itself. Then to test hybrids. I will, however, intersperse the tests to keep it interesting.