Spin Theory

Will Wilson

Semi-Pro
I am an analytical type person and am wanting to more fully understand the various theories regarding how spin is produced. First of all, I am not referring to stroke production, rather what generates the most spin and why, assuming technique and racket are the same.

Specifically, the gut main, poly cross setup is generally regarded as the best setup for "snap back". The mains can slide easily over the crosses and the snap back generates spin. I understand this, and assume it is correct based on people who have done scientific research.

My next question is, if this is the optimal set up for spin, why the plethora of shaped strings and textured strings that obviously are produced as such to increase spin but cannot produce a more "slippery" surface to encourage snapback. The theory here is that the shaped or textured surface grabs the ball better producing more spin.

Which is correct or are both? Can anybody help me understand the apparent contradiction?
 

ricardo

Hall of Fame
TWU - All you need to know about strings and spin...

http://twu.tennis-warehouse.com/learning_center/articles.php#string

Why Is String Stiffness So Important To Power?
String Stiffness: The Alpha and Omega of String Performance
String Stiffness — How It Works
Spin and String Movement (includes video)
Which String Generates the Most Spin? (includes video)
Spin and Static Friction Between Strings (includes video)
Spin and Sliding Friction Between Strings
Spin and String-to-Ball Friction (includes video)
Spin and String Pattern (includes video)
Spin and String Snap-Back (includes video)
Spin and String Stiffness (includes video)
Spin and String Lubrication (includes video)
Spin and Impact Location and Twistweight (includes video)
How Tennis Strings "Go Dead" — Part 1
How Tennis Strings "Go Dead" — Part 2

All of the above topics are here:
http://twu.tennis-warehouse.com/learning_center/articles.php#string
 

Aretium

Hall of Fame
I am an analytical type person and am wanting to more fully understand the various theories regarding how spin is produced. First of all, I am not referring to stroke production, rather what generates the most spin and why, assuming technique and racket are the same.

Specifically, the gut main, poly cross setup is generally regarded as the best setup for "snap back". The mains can slide easily over the crosses and the snap back generates spin. I understand this, and assume it is correct based on people who have done scientific research.

My next question is, if this is the optimal set up for spin, why the plethora of shaped strings and textured strings that obviously are produced as such to increase spin but cannot produce a more "slippery" surface to encourage snapback. The theory here is that the shaped or textured surface grabs the ball better producing more spin.

MOST of the shaped strings are just marketing.
Which is correct or are both? Can anybody help me understand the apparent contradiction?
There are contradicting theories. For me, I have very fast strokes and full strokes, the time on the stringbed is negligable therefore round slick poly holds the maximum control at such speeds. However, I do find loads of spin with all poly strings. Tour bite impressed me in spin production as did RPM blast which are both shaped. Of the round polys Alu has as much spin as I want as does Head Hawk, Solinco Outlast (we are talking impressive spin)

So IMO

FAST strokes - Gut/Poly or slick ROUND full poly

Med Strokes - Shaped

In the end of the day there is very little difference.
 

TimothyO

Hall of Fame
I am an analytical type person and am wanting to more fully understand the various theories regarding how spin is produced. First of all, I am not referring to stroke production, rather what generates the most spin and why, assuming technique and racket are the same.

Specifically, the gut main, poly cross setup is generally regarded as the best setup for "snap back". The mains can slide easily over the crosses and the snap back generates spin. I understand this, and assume it is correct based on people who have done scientific research.

My next question is, if this is the optimal set up for spin, why the plethora of shaped strings and textured strings that obviously are produced as such to increase spin but cannot produce a more "slippery" surface to encourage snapback. The theory here is that the shaped or textured surface grabs the ball better producing more spin.

Which is correct or are both? Can anybody help me understand the apparent contradiction?
Simple: for years it was conventional wisdom that shaped polys enhanced spin by "biting" the ball. Even TW reviewers still fall into that category.

Old habits die hard. In the USA huge numbers of people believe that the earth is 6,000 years old, that climate change isn't happening, and evolution isn't real.

There is no contradiction Just old habits...
 
while the snapback is certainly important you still need to "bite" the ball to create the spin. if there was no string to ball friction the racket would just slip on the ball with no spin created.

the question is just how much friction is needed and whether a shaped string really bites the ball better.
 

Clintspin

Professional
It's always assumed that the edges are only for gripping the ball however, the head stringer/engineer for Babolat said they are designed to put less string against the other string. So you have a very thin amount of material holding the string from snapping back. A very small amount of actual contact.
 
It's always assumed that the edges are only for gripping the ball however, the head stringer/engineer for Babolat said they are designed to put less string against the other string. So you have a very thin amount of material holding the string from snapping back. A very small amount of actual contact.
but then you would need to make sure that the edges of the strings meet and not the long sides. if the edges meet the contact area is smaller but if the long sides meet it is larger than with a round string.

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Clintspin

Professional
I am only telling you what the main guy at Babolat said. I wish I knew where I read it. However it would be true most of the time if you used a round string for the second string.
 

Clintspin

Professional
http://www.tennisindustrymag.com/articles/2012/07/19_the_stringers_file_lucien_n.html

Q: How much do geometrically shaped strings contribute to additional spin on the ball?

A: Geometric strings such at Babolat RPM Blast and Pro Hurricane Tour do help with additional spin on the ball but the reason is different than what most people actually think. The additional spin doesn’t come from the strings gripping the ball more, but rather from an octagonal cross section string that allows the main strings to “slide” with less effort over the cross strings, which increases the spin. The spin comes from the movement of the main strings rather than the texture of the string.
 

Will Wilson

Semi-Pro
It's always assumed that the edges are only for gripping the ball however, the head stringer/engineer for Babolat said they are designed to put less string against the other string. So you have a very thin amount of material holding the string from snapping back. A very small amount of actual contact.
I think I may have read that article but I think you have it backwards. The more surface area of string to string actually reduces pressure as the tension is spread out over a larger surface. In this theory, a flat sided string sliding against another flat sided string will allow greater snapback. A thin gauge poly against a thin gauge policy would restrict snapback because the string tension is concentrated in two very small, relative sharp surfaces.

I think that is why tourbite is so popular: it is four sided so they can easily slide against each other while also providing a "corner" of the string to bite the ball.

Does this make sense?
 

Clintspin

Professional
The article link is posted and the answer is copied and pasted in my last post. Sounds to me like he is saying it the way I thought he did.
 

Will Wilson

Semi-Pro
Reading more carefully, I think we are referring to the same article and are saying the same thing.

The flat surface of a shaped string will slide more easily against another string,especially against another flat surface string.
 

anubis

Hall of Fame
Topspin is generated by four distinct factors:

1. Technique. This cannot be overstated enough. Proper mechanics, more than anything else, affect spin production. I won't go into all of it because I don't understand it fully myself. However, I'm fairly certain that this is a fact and can be vetted by many other talented coaches both on these boards and in the real world.

2. String pattern. Generally, more open string patterns generate more spin. A 16x19 frame will generate more spin than an 18x20. This does not mean the 18x20 cannot generate much spin, on the contrary: the 18x20 can generate quite a lot of spin (see note #1 above). Be that as it may, with the same strings and technique, a 16x19 will generate a little more spin than the 18x20. Not by leaps and bounds, but there's enough of a delta factor that should influence your decision.

3. Mains string movement. The mains need to snap-back into place quickly in order to maximize spin. This can only be done if there is a low coefficient of friction between the mains and the crosses, and enough room (tension-wise) for the mains to move in the first place.

3a. Coefficient of friction. See this link for more info. Essentially, it is in your best interests to have the cross strings to be as slick as possible in order to maximize spin. The mains should be slick too, but the crosses are more important. As long as the cross strings are very smooth, then the mains will be able to move freely. If the cross strings are rough, then they will lock the mains in place, preventing string movement, inhibiting spin potential.

3b. Tension considerations. If the cross strings are too tight, then they will exert too much force on the mains, which inhibits them from moving. This is irregardless of coefficient of friction. It doesn't matter how slick your strings are: if you take an 18x20 pattern frame and string it full poly @ 65 lbs all the way around, then those mains aren't moving at all. They're so locked in place that your spin production will be negligible. Instead, for tight 18x20 patterns string the crosses 3 lbs (or 1 kg) looser than crosses. For open string patterns such as 16x19, 2 lbs looser should be sufficient. For "spin" technology frames such as 18x16, 16x15, etc., string mains and crosses @ the same tension.

4. Strings: Poly vs. nylon vs. gut. Just because you've got a smooth poly in the crosses doesn't mean you can put a synthetic gut (nylon) in the mains and expect crazy spin, because you won't. Nylon doesn't "snap back" like poly does. The strings will be moved out of place upon ball impact, but the strings aren't going to force themselves to "snap back" to their original positions before the ball leaves the string bed. They will after the ball leaves, but that is after the fact and does not help with spin production.

However, if you put a smooth poly in the cross, and then put almost any other poly OR natural gut in the mains, the mains WILL snap back before the ball leaves the string bed. This is what affects spin the most: the fact that the mains are so hell-bent on returning back to normal that they literally take the ball with them in the process. This forces the ball to rotate even faster.

This is why dead poly isn't as effective as fresh poly is: the main strings lose some of their elasticity and they don't return back to their original position before the ball leaves the string bed. Any time the mains become sluggish and slow and don't want to return back to their original position, you're losing spin potential on your frame.
 

Shroud

G.O.A.T.
Topspin is generated by four distinct factors:

1. Technique. This cannot be overstated enough. Proper mechanics, more than anything else, affect spin production. I won't go into all of it because I don't understand it fully myself. However, I'm fairly certain that this is a fact and can be vetted by many other talented coaches both on these boards and in the real world.

2. String pattern. Generally, more open string patterns generate more spin. A 16x19 frame will generate more spin than an 18x20. This does not mean the 18x20 cannot generate much spin, on the contrary: the 18x20 can generate quite a lot of spin (see note #1 above). Be that as it may, with the same strings and technique, a 16x19 will generate a little more spin than the 18x20. Not by leaps and bounds, but there's enough of a delta factor that should influence your decision.

3. Mains string movement. The mains need to snap-back into place quickly in order to maximize spin. This can only be done if there is a low coefficient of friction between the mains and the crosses, and enough room (tension-wise) for the mains to move in the first place.

3a. Coefficient of friction. See this link for more info. Essentially, it is in your best interests to have the cross strings to be as slick as possible in order to maximize spin. The mains should be slick too, but the crosses are more important. As long as the cross strings are very smooth, then the mains will be able to move freely. If the cross strings are rough, then they will lock the mains in place, preventing string movement, inhibiting spin potential.

3b. Tension considerations. If the cross strings are too tight, then they will exert too much force on the mains, which inhibits them from moving. This is irregardless of coefficient of friction. It doesn't matter how slick your strings are: if you take an 18x20 pattern frame and string it full poly @ 65 lbs all the way around, then those mains aren't moving at all. They're so locked in place that your spin production will be negligible. Instead, for tight 18x20 patterns string the crosses 3 lbs (or 1 kg) looser than crosses. For open string patterns such as 16x19, 2 lbs looser should be sufficient. For "spin" technology frames such as 18x16, 16x15, etc., string mains and crosses @ the same tension.

4. Strings: Poly vs. nylon vs. gut. Just because you've got a smooth poly in the crosses doesn't mean you can put a synthetic gut (nylon) in the mains and expect crazy spin, because you won't. Nylon doesn't "snap back" like poly does. The strings will be moved out of place upon ball impact, but the strings aren't going to force themselves to "snap back" to their original positions before the ball leaves the string bed. They will after the ball leaves, but that is after the fact and does not help with spin production.

However, if you put a smooth poly in the cross, and then put almost any other poly OR natural gut in the mains, the mains WILL snap back before the ball leaves the string bed. This is what affects spin the most: the fact that the mains are so hell-bent on returning back to normal that they literally take the ball with them in the process. This forces the ball to rotate even faster.

This is why dead poly isn't as effective as fresh poly is: the main strings lose some of their elasticity and they don't return back to their original position before the ball leaves the string bed. Any time the mains become sluggish and slow and don't want to return back to their original position, you're losing spin potential on your frame.
Really good post Anubis! You pretty much covered it.

Though I would say that 16x19 vs 18x20 is pretty meaningless. Its a general rule that might work most of the time but its possible to have an 18x20 that is actually more open than some 16x19. String bed density is a better determiner than just the string pattern.

Under 3b, I would mention different tensions greater than 3lbs as a way to generate more snap back.

Also "irregardless" should be replaced by "regardless" :)
 

anubis

Hall of Fame
Really good post Anubis! You pretty much covered it.

Though I would say that 16x19 vs 18x20 is pretty meaningless. Its a general rule that might work most of the time but its possible to have an 18x20 that is actually more open than some 16x19. String bed density is a better determiner than just the string pattern.

Under 3b, I would mention different tensions greater than 3lbs as a way to generate more snap back.

Also "irregardless" should be replaced by "regardless" :)
Thanks for the grammar tip! As to string patterns, I forgot anther crucial piece of information: string bed size. A 16x19 string pattern in a 90 square inch frame should really be considered just as "tight" or "closed" as a 98 square inch frame with an 18x20 string pattern.

In other words, string pattern is relative to the size of the frame. The size of the squares of the string patterns become larger as you increase the square inches of the frame.
 

Shroud

G.O.A.T.
Thanks for the grammar tip! As to string patterns, I forgot anther crucial piece of information: string bed size. A 16x19 string pattern in a 90 square inch frame should really be considered just as "tight" or "closed" as a 98 square inch frame with an 18x20 string pattern.

In other words, string pattern is relative to the size of the frame. The size of the squares of the string patterns become larger as you increase the square inches of the frame.
Yes but its a bit more than that really:

http://tt.tennis-warehouse.com/showpost.php?p=8495873&postcount=16
 

KYHacker

Professional
Well, as I continue to improve my technique and demo racquets with different string patterns, weights, headsizes, etc., there is one fundamental determinant for me with regard to spin-- CONFIDENCE.

I can only generate my maximum spin when I am confident that the ball will go where I want to hit it. So, choose according to what allows you as an individual to be confident enough to maximize racquet head speed as everything else is meaningless in comparison.
 

scotus

G.O.A.T.
I usually leave theories simply as that -- theories.

They are interesting findings, but usually not something that I consider "truths."

My approach to strings is simply this. Demo some strings that get fairly high reviews either based on these theories or simple anecdotal experience from fellow posters, and then I decide if something works for me.

Having said this, I have a couple of questions about the snap-back and how a smooth, round co-poly is supposed to enhance this snap-back.

(1) On TWU data, the string combo with the lowest string-to-string COF is the gut mains and MSV Hepta-Twist crosses. The Hepta-Twist is a shaped and twisted string, not at all smooth and round. How does this result in the lowest COF and how does it square with all these posters pushing for smooth round co-poly in the cross?

(2) Babolat Origin is a monofilament, which according to the TWU data has one of the lowest string-to-string COF. Yet both the TW review team and the public feedback on TW find this string to be completely mediocre in spin production. Perhaps it doesn't grip the ball well? But even a reviewer who used it as a cross to a poly did not see much in the way of spin production.
 

SpinToWin

Talk Tennis Guru
(1) On TWU data, the string combo with the lowest string-to-string COF is the gut mains and MSV Hepta-Twist crosses. The Hepta-Twist is a shaped and twisted string, not at all smooth and round. How does this result in the lowest COF and how does it square with all these posters pushing for smooth round co-poly in the cross?
We recommend round and smooth polys for the crosses because they do not cut into the mains quickly and because the playability is very consistent. You get the better bang for your money with round and smooth poly strings in the crosses.

(2) Babolat Origin is a monofilament, which according to the TWU data has one of the lowest string-to-string COF. Yet both the TW review team and the public feedback on TW find this string to be completely mediocre in spin production. Perhaps it doesn't grip the ball well? But even a reviewer who used it as a cross to a poly did not see much in the way of spin production.
Babolat Origin has a slick coating which disappears faster than you can blink. After the coating is gone, the strings really stick to each other, so spin and string movement is pretty bad.
 

scotus

G.O.A.T.
We recommend round and smooth polys for the crosses because they do not cut into the mains quickly and because the playability is very consistent. You get the better bang for your money with round and smooth poly strings in the crosses.
Thanks for the reply.

So your recommendation has more to do with longevity of string life and possibly longevity of spin production than the best possible spin production for one or two hitting sessions, right?

Babolat Origin has a slick coating which disappears faster than you can blink. After the coating is gone, the strings really stick to each other, so spin and string movement is pretty bad.
Here, if what you say is true, it seems that TWU's COF data are based on the first few minutes of "hitting" with a brand-new string and has little bearing on how the string would behave in the next 10 minutes, let alone next 10 sets of tennis.
 
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SpinToWin

Talk Tennis Guru
Thanks for the reply.

So your recommendation has more to do with longevity of string life and possibly longevity of spin production than the best possible spin production for one or two hitting sessions, right?

Here, if what you say is true, it seems that TWU's COF data are based on the first few minutes of "hitting" with a brand-new string and has little bearing on how the string would behave in the next 10 minutes, let alone next 10 sets of tennis.
Yes on both accounts.
 

Clintspin

Professional
Certainly strange to me that natural gut ranks so high as a main for spin production. If you look at gut under a microscope I am fairly sure the stuff looks anything but smooth after a few hits. Gut just grabs the ball nicely, not helps strings snap back.

Did Nadal's spin rpm go up after he made the switch from 15g nylon to poly? If not, I would have to say how you swing at the ball has 99% to do with topspin.

TW poster are going to drive themselves crazy trying to find the perfect string setup. There was a time when most of us played with something like Leoina 66 and played fine from week to week. We also didn't blame it on our racquets and change racquets every other month. I don't know how many times I read that a player has found the perfect racquet or perfect string job and then a few weeks later are searching again.
 

moonballs

Hall of Fame
Here, if what you say is true, it seems that TWU's COF data are based on the first few minutes of "hitting" with a brand-new string and has little bearing on how the string would behave in the next 10 minutes, let alone next 10 sets of tennis.
For mono filament string like poly, Syn gut and ZX there friction is stable as the string wear down. The notch of the mains does increase friction moderately.
 
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