How does pre stretch amount affect playability (e.g., 10% vs 20%)

ryohazuki222

Professional
Finally convinced myself to go even deeper into the rabbit whole of strings and got a WISE.

I’m pretty tuned in to strings / tension etc that I like but this is on a neos lock out.

Going to mess around with constant pull w/o pre stretch next. But I also plan on comparing and contrasting pre stretching (using the machine) and the different amounts of pre stretch.

It hit be that I’ve never seen much discussion on the pros/cons of machine pre stretching various amounts. Example: I was going to try 5% (lowest I think) against 25% pre stretch (highest I think).

I’m doing this more for my curiosity than anything else but i would like to learn more about what “should” be different — at least in theory or others experiences.

Share your thoughts!

Note that I’m only really interested in polys. But if any learnings from syn or nat gut might be relevant, I’m curious about what I could learn from that.
 

esgee48

G.O.A.T.
I don’t like machine prestretch. Prestretch removes permanent elongation from polyester strings. The issue is the section of string between the clamp and the tension head which gets pulled again on the next string. Now you have a section of string which gets prestretched twice and a section prestretched once. With an eCP, I prefer not to machine prestretch and just pull longer until I am sure the machine no longer makes adjustments.

Prestretching will deaden the string bed so you have to reduce ref tension. Like anything else, you have to find the right ref tension.
 

kkm

Hall of Fame
With machine prestretch you'll want to think about moving reference tension down, by about the % of machine prestretch. If you string at 50 without prestretch, but you want to try prestretch, say 10%, you could string at 45 with 10% prestretch.
 

MathieuR

Hall of Fame
The issue is the section of string between the clamp and the tension head which gets pulled again on the next string. Now you have a section of string which gets prestretched twice and a section prestretched once.
Yes, a piece is prestretched twice, and a piece once. But both at the same tension. And if that prestretchtensioning-time is long enough, that should not make much difference.

Edit: I string with a Stringway. For prestretching I just put an extra badminton-weight on the bar, at the end, adding 12kg to the ref.tension. I remove it when "equilibrium" is reached.
 

matt33

New User
Personally I do not like prestretching poly because it is already a relatively dead string, so removing what little elasticity there is doesn’t seem right.

On the other hand I really like prestretching nat gut which I find significantly reduces the variability in how it plays in the first few hours. Because the guy is so “alive”, it doesn’t really take away any of the guy qualities, it just gets it to a more stable place sooner IMO.

My racquet setup is 100” Gravity Pro and I hybrid gut/poly at 62lbs 10% pre on the gut and 58lbs on the poly (use ghostwire, a very soft poly). Strung on Neos 1000 + Wise.

Hope this helps

Matty
 

MathieuR

Hall of Fame
because it is already a relatively dead string, so removing what little elasticity there is doesn’t seem right.
Huge misunderstanding: prestretching does NOT remove the elasticity. It "pre-creates" (a part) of the lasting elongation that you would create with every hit against the ball.

But you are right, you get a different string; you should change (lower) your ref.tension.
 

ryohazuki222

Professional
Huge misunderstanding: prestretching does NOT remove the elasticity. It "pre-creates" (a part) of the lasting elongation that you would create with every hit against the ball.

But you are right, you get a different string; you should change (lower) your ref.tension.
based on my first hit, I agree with this more than the rest I’ve read.

Nothing dead about the feeling of the setup I had. Definitely very firm… but I switched from lockout to constant pull and then also pre stretched.

So far really noticeable how consistent playability is in the first 4 hours
 

ryohazuki222

Professional
Combining Internet research with first hand experiences (so far) and a healthy dose of chat gpt prompting to boot… I feel like I’ve got an answer to my question that aligns across theory/reality from my perspective.

As you increase the machine pre stretch from 0-20% ; you’re essentially trading power and comfort for control and firmness. In addition, you’re improving the tension maintenance as you pre stretch more.


Interestingly, this also shows up on an ERT 300 measurement. I strung a racket at 41.6 pounds with 20% pre stretch. (Peak 50lbs tension). I forget exactly where it landed but the conversion from DT to tension was at around 47 pounds.

The above racket set up felt stiffer and played more controlled, with better tension maintenance than the same except strung at 52 lbs on a crank.

Same exact machine and stringer… just different tensioning device and technique. — manual crank vs constant pull.
 

ryohazuki222

Professional
I also hit the same DT by stringing mains at 48 and crosses at 44 with 10% pre stretch.

Both variants of pre stretch experiments played quite similarly.
 

Wes

Hall of Fame
Combining Internet research with first hand experiences (so far) and a healthy dose of chat gpt prompting to boot… I feel like I’ve got an answer to my question that aligns across theory/reality from my perspective.

As you increase the machine pre stretch from 0-20% ; you’re essentially trading power and comfort for control and firmness. In addition, you’re improving the tension maintenance as you pre stretch more.


Interestingly, this also shows up on an ERT 300 measurement. I strung a racket at 41.6 pounds with 20% pre stretch. (Peak 50lbs tension). I forget exactly where it landed but the conversion from DT to tension was at around 47 pounds.

The above racket set up felt stiffer and played more controlled, with better tension maintenance than the same except strung at 52 lbs on a crank.

Same exact machine and stringer… just different tensioning device and technique. — manual crank vs constant pull.

I also hit the same DT by stringing mains at 48 and crosses at 44 with 10% pre stretch.

Both variants of pre stretch experiments played quite similarly.

Due to my feeble brain, I may be the only one finding it difficult to extrapolate the pertinent info. from your experiments.

Perhaps it would be easier to discern the variables/results of scenario A versus scenario B (and later, C, D, E, etc., if/when completed) if the info. was presented more like a chart/graph. :unsure:

Maybe something similar to this...
(BTW, please let me know if I've even translated this data correctly)

A. Mains: 41.6 Pre-stretch: 20%
Crosses: 41.6 Pre-stretch: 20%
DT: ??
DT to pounds conversion: 47

B. Mains: 48 Pre-stretch: 0%
Crosses: 44 Pre-stretch: 10%
DT: ??
DT to pounds conversion: presumably 47 again?
 

MathieuR

Hall of Fame
I don´t have much experience with pre-stretching myself, but see the advice from Head:
Agree. You should be aware what's happening.
The "DANGER" is certainly there if you prestretch, and don't go down in ref.tension.

Normally I use mains/crosses 20/18kg, DT34.
Prestretching at ~30kg, then 18/16kg, DT34

It is the stringbedstifness you feel at balcontact, that can give shock to wrist and elbow.
 

travlerajm

Talk Tennis Guru
So much misinformation on this thread.

Prestretching a poly makes it livelier (more elastic), not deader.

Don’t confuse tighter effective tension with deader.
 

ryohazuki222

Professional
So much misinformation on this thread.

Prestretching a poly makes it livelier (more elastic), not deader.

Don’t confuse tighter effective tension with deader.
Personally I’m struggling with words a lot on this topic.

For example, so far I’ve noticed that something can feel stiffer (ie, less comfortable) to my arm while it is, in fact, less stiff (ie, lower stringbed stiffness, as measured by some device).

And to your point, many use “feels dead” as a description of high stiffness. But “feels dead” could also refer to just lost elasticity.

I’d like to know what you mean by “livelier/more elastic” in terms of playability.

TWU has some pretty good research on how the science happening can be true and a “conflicting” experience can also be true when it comes to strings. Basically because of the players reaction and adaptations to the physics of the string changes.
 

travlerajm

Talk Tennis Guru
Personally I’m struggling with words a lot on this topic.

For example, so far I’ve noticed that something can feel stiffer (ie, less comfortable) to my arm while it is, in fact, less stiff (ie, lower stringbed stiffness, as measured by some device).

And to your point, many use “feels dead” as a description of high stiffness. But “feels dead” could also refer to just lost elasticity.

I’d like to know what you mean by “livelier/more elastic” in terms of playability.

TWU has some pretty good research on how the science happening can be true and a “conflicting” experience can also be true when it comes to strings. Basically because of the players reaction and adaptations to the physics of the string changes.
A string made from plastic polymer starts out viscoelastic. That is, when you stretch it, it will deform both elastically and plastically. The elastic deformation is 100% energy return, returning to its original length. The plastic deformation is permanent, doesn’t bounce back.

When you prestretch a string, it removes the plasticity so that it becomes closer to 100% elastic.

The more elastic a string is, the livelier it will feel at a given stringbed stiffness.

Prestretching a string means that it won’t lose as much tension while stringing it. So the stringbed will come out much higher tension and stiffer if you use the same reference tension. You need to compensate by stringing at lower reference tension.
 

10shoe

Professional
Prestretching a poly makes it livelier (more elastic), not deader.
Interesting assertion.

This is certainly not my experience with nylons and guts. Is poly different or are you saying this holds true for any material? Your subsequent post seems to suggest that you would include any thermoplastic.
 

travlerajm

Talk Tennis Guru
Interesting assertion.

This is certainly not my experience with nylons and guts.
It’s easy to mistake increased stiffness with lower energy return, because the ball has lower energy return than the strings.

The ball typically has 50% energy return, the strings 95%. So stiffer or tighter strings mean less elasticity of the impact because more energy gets lost in the ball deformation, even though the strings themselves might have more elasticity.
 
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10shoe

Professional
Well, I have a 3 day backlog of racquets to work my way through so as much as I'd like to participate in this thread I need to get back to stringing. My machine has pre-stretch capability and I pretty much never use it unless specifically asked to by a customer. My feeling is that unless you are willing to use cross string weaving tools like John Gugel, machine pre-stretch is really just poorly controlled overtensioning.
 

ryohazuki222

Professional
Well, I have a 3 day backlog of racquets to work my way through so as much as I'd like to participate in this thread I need to get back to stringing. My machine has pre-stretch capability and I pretty much never use it unless specifically asked to by a customer. My feeling is that unless you are willing to use cross string weaving tools like John Gugel, machine pre-stretch is really just poorly controlled overtensioning.
Pre stretching also serves the purpose of enabling stringaholism in a relatively under explored way!
 

travlerajm

Talk Tennis Guru
The real advantage of prestretching poly thoroughly (and by thoroughly I’m not just talking about the machine prestretch function), is that it makes it playable with consistent playing characteristics until breakage, as long as it’s a poly that doesn’t notch in the crosses.
 

ryohazuki222

Professional
The real advantage of prestretching poly thoroughly (and by thoroughly I’m not just talking about the machine prestretch function), is that it makes it playable with consistent playing characteristics until breakage, as long as it’s a poly that doesn’t notch in the crosses.
This is consistent with my “research”.

It changes the initial playability characteristics and also the “playability curve” throughout the life of the string.

Why I’ve been trying to figure out the expected cause/effect, is to prioritize which experiments to go run.

What I was surprised to find via AI prompting and experiments is that the peak tension pre stretched, the pre stretch amount, and the base reference tension all matter.

A poorly copied table for those interested after a pretty intentional round of prompting, inputting, and conversation with ChatGPT:

Racket,Peak Tension (lbs),Pre-stretch (%),Base Tension (lbs),Playability Characteristics

Racket A,42.5,0,42.5,Most natural elasticity; balanced feel with moderate power and control.

Racket B,42.5,5,40.5,Slightly firmer feel; enhanced control with good comfort and less power.

Racket C,42.5,10,38.6,Firmer stringbed; increased control, good tension maintenance, less comfort.

Racket D,42.5,15,37.0,Very firm stringbed; maximized control, excellent tension maintenance, lower comfort.

Racket E,42.5,20,35.4,Firmest setup; highest control, superior tension maintenance, least comfort.


The part that was most surprising to me (it’s not just the prompting but that the prompting aligned to a couple experiences I had the week before) is that racket e above (strung lowest) would feel the firmest.

SPECIFICALLY, I’m trying to isolate the pre stretch to understand what that does and more importantly — how I like or don’t like it to play with.
 

ryohazuki222

Professional
Due to my feeble brain, I may be the only one finding it difficult to extrapolate the pertinent info. from your experiments.

Perhaps it would be easier to discern the variables/results of scenario A versus scenario B (and later, C, D, E, etc., if/when completed) if the info. was presented more like a chart/graph. :unsure:

Maybe something similar to this...
(BTW, please let me know if I've even translated this data correctly)

A. Mains: 41.6 Pre-stretch: 20%
Crosses: 41.6 Pre-stretch: 20%
DT: ??
DT to pounds conversion: 47

B. Mains: 48 Pre-stretch: 0%
Crosses: 44 Pre-stretch: 10%
DT: ??
DT to pounds conversion: presumably 47 again?
See my post above if that helps. In my previous posts I’m mixing and matching different scenarios.
 

devoker

Rookie
Personally I do not like prestretching poly because it is already a relatively dead string, so removing what little elasticity there is doesn’t seem right.
That elasticity will be removed within the first hour of hitting anyway though.

What I was surprised to find via AI prompting and experiments is that the peak tension pre stretched, the pre stretch amount, and the base reference tension all matter.

A poorly copied table for those interested after a pretty intentional round of prompting, inputting, and conversation with ChatGPT:
Lol, AI didn't do any of the experiments. It just writes a meaningful conversation based on the data it was fed. It doesn't need to be true.
 

MathieuR

Hall of Fame
That elasticity will be removed within the first hour of hitting anyway though
Elasticity is NOT removed by prestretching, and not by playing.

Prestretching creates (a part of) the lasting elongation, which you would otherwise "create" by playing during the break-in phase with fresh strings.
 

devoker

Rookie
Elasticity is NOT removed by prestretching, and not by playing.

Prestretching creates (a part of) the lasting elongation, which you would otherwise "create" by playing during the break-in phase with fresh strings.
It is true that it creates lasting elongation. I think when people talk about elasticity they mean the stiffness of the string. Intuitively, they think a softer string is more elastic.

However, plastic deformation occurs during prestretching. After plastic deformation has occurred, the material no longer possesses its original elasticity. Any subsequent stress applied to the material will not follow the same elastic behavior as before. The material has undergone structural changes that impair its ability to revert to its original form elastically. So we can say that loss of elasticity occurs after plastic deformation.

On the other hand, same deformation keeps happening everytime the ball is hit.
 

MathieuR

Hall of Fame
So we can say that loss of elasticity occurs after plastic deformation.
No.
Just do a simple test:
- put a piece of poly under mild tension, say 5kg
- mark a piece on this string, ~25cm
- tension/prestretch using 30kg
- measure the length of the marked section under tension
- go back to 5kg
- measure the section. Now you can calculate: lasting elongation in cm en %, same for the elastic elongation at 30kg, in cm and %.
- repeat with same string, but now tension first at 20kg, measure, and again at 30kg. The string will hardly have lasting elongation, but same elasticity.
On the other hand, same deformation keeps happening everytime the ball is hit.
No, because this "deformation" was already created while prestretching.
 
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fritzhimself

Professional
This is consistent with my “research”.

It changes the initial playability characteristics and also the “playability curve” throughout the life of the string.

Why I’ve been trying to figure out the expected cause/effect, is to prioritize which experiments to go run.

What I was surprised to find via AI prompting and experiments is that the peak tension pre stretched, the pre stretch amount, and the base reference tension all matter.

A poorly copied table for those interested after a pretty intentional round of prompting, inputting, and conversation with ChatGPT:

Racket,Peak Tension (lbs),Pre-stretch (%),Base Tension (lbs),Playability Characteristics

Racket A,42.5,0,42.5,Most natural elasticity; balanced feel with moderate power and control.

Racket B,42.5,5,40.5,Slightly firmer feel; enhanced control with good comfort and less power.

Racket C,42.5,10,38.6,Firmer stringbed; increased control, good tension maintenance, less comfort.

Racket D,42.5,15,37.0,Very firm stringbed; maximized control, excellent tension maintenance, lower comfort.

Racket E,42.5,20,35.4,Firmest setup; highest control, superior tension maintenance, least comfort.


The part that was most surprising to me (it’s not just the prompting but that the prompting aligned to a couple experiences I had the week before) is that racket e above (strung lowest) would feel the firmest.

SPECIFICALLY, I’m trying to isolate the pre stretch to understand what that does and more importantly — how I like or don’t like it to play with.
So at 42 pounds you can't speak of a firm stringbed - that's a hammock in my eyes.
With these reference weights, it really doesn't matter how you string the thing - it will always suck to play. :rolleyes:
 

ryohazuki222

Professional
That elasticity will be removed within the first hour of hitting anyway though.


Lol, AI didn't do any of the experiments. It just writes a meaningful conversation based on the data it was fed. It doesn't need to be true.
Duh. I’m using AI to “predict” and “converse” with chat gpt but ultimately I’m stringing up a stick myself and taking it to the court. The latter is the “experiment” part.
 

ryohazuki222

Professional
So at 42 pounds you can't speak of a firm stringbed - that's a hammock in my eyes.
With these reference weights, it really doesn't matter how you string the thing - it will always suck to play. :rolleyes:
This is the fascinating part. You WOULD think that. I thought that.

But it’s not that simple. 41.6 constant pull with 20% pre stretch feels stiffer and has more control than 52 strung on a spring based lockout tensioner. Now 45 on a lockout is the lowest if gone with this set up for comparison and that IS very very trampoline like. Fun on its own when but not really for me to play with for real.

If you’re stuck on the “reference tension”. You’re missing the entire point of this thread. Additionally, it’s worth reading some of the TWU material on stiffness. Note that the above I’m testing on not-that-stiff poly.
 

Tan Tennis

Rookie
So much misinformation on this thread.

Prestretching a poly makes it livelier (more elastic), not deader.

Don’t confuse tighter effective tension with deader.
That’s exactly what I thought, but the outcome is the opposite on what I tested. I just pre-stretch Sync 10% at 48 lbs on Gravity MP and it’s stiffer than another Gravity MP I strung Sync at 50 lbs. It’s more boardy and has lower power.

My pro stringer friend explain to me that pre-stretching 10% at 48 lbs is like you strung a racket at 53 lbs and play until tension drops to 48 lbs. The plus is it doesn’t drop much further so it remains playable at a desired tension longer, but in a less elastic form. Stringing normally at 50 lbs will be softer as poly can stretch out when you play, and you could be end up playing at 42-45 lbs in the end.
 

fritzhimself

Professional
This is the fascinating part. You WOULD think that. I thought that.

But it’s not that simple. 41.6 constant pull with 20% pre stretch feels stiffer and has more control than 52 strung on a spring based lockout tensioner. Now 45 on a lockout is the lowest if gone with this set up for comparison and that IS very very trampoline like. Fun on its own when but not really for me to play with for real.

If you’re stuck on the “reference tension”. You’re missing the entire point of this thread. Additionally, it’s worth reading some of the TWU material on stiffness. Note that the above I’m testing on not-that-stiff poly.
Well - a lot of apples and oranges are being compared here.
You can NEVER calculate the DT value (measured with an ERT 300) back to a previously applied tension force - that is NONSENSE!
So far I haven't read which string you used for this experiment.
Even on which frame and size you have strung does not appear here.
I like to use the word reference weight - that's the best way for me to deduce what kind of DT or SBS might arrive at the frame.
But you wrote above that you even forgot the DT value.
Well - I don't really care how you try to breathe (longer) life into a dead poly with pre stretch.
What makes me curious is at what level do you play tennis?
 

ryohazuki222

Professional
Well - a lot of apples and oranges are being compared here.
You can NEVER calculate the DT value (measured with an ERT 300) back to a previously applied tension force - that is NONSENSE!
So far I haven't read which string you used for this experiment.
Even on which frame and size you have strung does not appear here.
I like to use the word reference weight - that's the best way for me to deduce what kind of DT or SBS might arrive at the frame.
But you wrote above that you even forgot the DT value.
Well - I don't really care how you try to breathe (longer) life into a dead poly with pre stretch.
What makes me curious is at what level do you play tennis?
Ya. This is true.

Don’t consider anything I’m doing scientific (in terms of the scientific method). Just some intentional anectodal information that might or might not be interesting.

I’m a weak 5.0 / strong 4.5 level wise. Using an ezone 98 2022 customized to 340g and 340 sw that’s fairly polarized. I’ve got very spinny strokes. Strings: poly tour rev mains 1.25; bab rpm rough crosses 1.25. Hitting mostly with a ball
Machine and Wilson triniti pro balls. But also with humans with us open or Dunlop atp balls.

Not giving all that detail to be funny. But because it’s interesting how it changes the perception.

Wilson triniti pro from a ball machine are a stiffer ball. Makes “harshness” more apparent. This is one reason I started stringing lower. I’m mostly playing for exercise these days - not competition. But the Dunlop is very squishy in comparison. Us open is in between.

Last year doing a different experiment I learned that there’s a difference between feeling the strings compress and feeling the ball compress (different topic for a different day).

Very interested in what you’re saying about DT from ert300. Not following your comment. Im only really using DT to see if it matches to my playing experience. As in: I hit and it feels really firm. Then I measure and it comes up as (what I know to me) is pretty firm. Also have been using for a while to monitor tension loss and it’s weird how consistent my feeling of “I don’t like this racket anymore” to what the DT number is.
 

ryohazuki222

Professional
That’s exactly what I thought, but the outcome is the opposite on what I tested. I just pre-stretch Sync 10% at 48 lbs on Gravity MP and it’s stiffer than another Gravity MP I strung Sync at 50 lbs. It’s more boardy and has lower power.

My pro stringer friend explain to me that pre-stretching 10% at 48 lbs is like you strung a racket at 53 lbs and play until tension drops to 48 lbs. The plus is it doesn’t drop much further so it remains playable at a desired tension longer, but in a less elastic form. Stringing normally at 50 lbs will be softer as poly can stretch out when you play, and you could be end up playing at 42-45 lbs in the end.
This is eerily similar to my experience. The difference for me though is that - based on feel of hitting the ball - the racket strung without pre stretch and the racket strung with, feel very very different even though they arrived at the same place (albeit through two different methods).
 

fritzhimself

Professional
Ya. This is true.

Don’t consider anything I’m doing scientific (in terms of the scientific method). Just some intentional anectodal information that might or might not be interesting.

I’m a weak 5.0 / strong 4.5 level wise. Using an ezone 98 2022 customized to 340g and 340 sw that’s fairly polarized. I’ve got very spinny strokes. Strings: poly tour rev mains 1.25; bab rpm rough crosses 1.25. Hitting mostly with a ball
Machine and Wilson triniti pro balls. But also with humans with us open or Dunlop atp balls.

Not giving all that detail to be funny. But because it’s interesting how it changes the perception.

Wilson triniti pro from a ball machine are a stiffer ball. Makes “harshness” more apparent. This is one reason I started stringing lower. I’m mostly playing for exercise these days - not competition. But the Dunlop is very squishy in comparison. Us open is in between.

Last year doing a different experiment I learned that there’s a difference between feeling the strings compress and feeling the ball compress (different topic for a different day).

Very interested in what you’re saying about DT from ert300. Not following your comment. Im only really using DT to see if it matches to my playing experience. As in: I hit and it feels really firm. Then I measure and it comes up as (what I know to me) is pretty firm. Also have been using for a while to monitor tension loss and it’s weird how consistent my feeling of “I don’t like this racket anymore” to what the DT number is.
Thank you for your explanation.
I have been involved in stringing for a good 30 years and have also had international experience.
I mainly string for people who play tournaments and championships, so I didn't have people like you on my radar.
So all's well and good luck for the future. (y)
 

drakulie

Talk Tennis Guru
when pre-stretching ANY string, you are essentially taking the elasticity (life) out of the string. the higher degree of stretch, the more life taken from the string.
 

MathieuR

Hall of Fame
when pre-stretching ANY string, you are essentially taking the elasticity (life) out of the string. the higher degree of stretch, the more life taken from the string.
No! Why is this repeated over and over again. It is NOT true.
Yes, you change the string. By prestretching you create (a part of) the lasting elongation that you would get with every hit against the ball.

Just try the little test as described in my post #28.
 

drakulie

Talk Tennis Guru
No! Why is this repeated over and over again. It is NOT true.
Yes, you change the string. By prestretching you create (a part of) the lasting elongation that you would get with every hit against the ball.

Just try the little test as described in my post #28.
try stretching a plastic straw at mcdonalds and let us know how long it takes to go back to its original form. HINT: it wont.
 

MathieuR

Hall of Fame
try stretching a plastic straw at mcdonalds and let us know how long it takes to go back to its original form. HINT: it wont.
- in the Netherlands plastic straws are a thing from the past ( environmental polluting)
- your answer is a straw man fallacy. Stick to the subject, do the test and be surprised.

Edit: if elasticity should be destroyed, I would not be able to string my racket; it is the elasticity that holds the tension.
 
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10shoe

Professional
No.
Just do a simple test:
- put a piece of poly under mild tension, say 5kg
- mark a piece on this string, ~25cm
- tension/prestretch using 30kg
- measure the length of the marked section under tension
- go back to 5kg
- measure the section. Now you can calculate: lasting elongation in cm en %, same for the elastic elongation at 30kg, in cm and %.
- repeat with same string, but now tension first at 20kg, measure, and again at 30kg. The string will hardly have lasting elongation, but same elasticity.

No, because this "deformation" was already created while prestretching.

Could you please post a video of you doing this?
 

MathieuR

Hall of Fame
Here is a link to a test I posted:
 

drakulie

Talk Tennis Guru
- in the Netherlands plastic straws are a thing from the past ( environmental polluting)
- your answer is a straw man fallacy. Stick to the subject, do the test and be surprised.

Edit: if elasticity should be destroyed, I would not be able to string my racket; it is the elasticity that holds the tension.
well, the string doesn't disintegrate. it simply will NOT hold its original length. once it is stretched, it will become longer. after that. once it is hit over and over, it will continue to lengthen. it will no longer rebound like a "trampoline". hence, it is "flat".
 

MathieuR

Hall of Fame
it simply will NOT hold its original length. once it is stretched, it will become longer.
Yes, prestretching will make the string longer (with the "permanent elongation part" linked to that specific prestretch-tension. The higher that tension, the longer).
But then you use this "changed" string to string at your ref.tension.
after that. once it is hit over and over, it will continue to lengthen. it will no longer rebound like a "trampoline". hence, it is "flat".
Every "hit" will increase the stringtension; it will be higher as the ref.tension used.
But as long as this "hit-tension" is less as the prestretch-tension, the string will NOT (or minimally) lengthen; you have already given this length-increase while prestretching.
 

drakulie

Talk Tennis Guru
Yes, prestretching will make the string longer (with the "permanent elongation part" linked to that specific prestretch-tension. The higher that tension, the longer).
But then you use this "changed" string to string at your ref.tension.

Every "hit" will increase the stringtension; it will be higher as the ref.tension used.
But as long as this "hit-tension" is less as the prestretch-tension, the string will NOT (or minimally) lengthen; you have already given this length-increase while prestretching.
Every hit will DECREASE the string tension, not increase it.
If what you state is true, every player in the history of the game will have ruptured the racquet after a few hitting sessions as a result of the string increasing in tension after every hit. LOL
class over.
I'm out.
 

travlerajm

Talk Tennis Guru
There is some confusion in this thread because people tend to misuse the word “elasticity.”

Elasticity is the ability for a material to return to original length after being stretched.

But some people misuse the term Elasticity, thinking that it means how easily it can be deformed. A better term for this is Plasticity. Pre-stretching removes Plasticity. Removing Plasticity improves Elasticity (using the formal definition of Elasticity).
 

10shoe

Professional
There is some confusion in this thread because people tend to misuse the word “elasticity.”

Elasticity is the ability for a material to return to original length after being stretched.

I'm going to disagree with this and put it in the terms that I recall reading in the USRSA's monthly publication. Tennis strings are not unlike rubber bands. A fresh rubber band will not stretch very far but when released snaps back to it's original shape. A worn out rubber band can stretch much further but when released does not snap back like the fresh one. The ability to stretch is elasticity and the ability to return is RESILIENCE. According to the USRSA, as strings age they become more elastic and less resilient, just like the rubber bands above. The ball sinks into the string bed more as the strings age and is propelled out less, leaving you with a racquet that feels dead.
 
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