Do pros pre-stretch their poly strings?

Discussion in 'Stringing Techniques / Stringing Machines' started by jord123, Feb 23, 2016.

  1. Rabbit

    Rabbit G.O.A.T.

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    Pre-stretching string, specifically the practice of adding a percentage of reference tension to a pull, does exactly that and that is its only intention; to remove elasticity of a string and thereby take away some of its power.

    I really shouldn't ask, but what do you think pre-stretching is for?

    Personal experience can be disputed when the method used to replicate an action is flawed or if the nomenclature used is different. You say you use a drop weight and "add weight" to the pull. You state you're using 20 kg of extra weight on each pull?

    Clearly there is a disconnect. One must consider if they are the only voice in the wilderness that maybe they are wrong? I'm certainly not in the league of some of the stringers who've refuted your misguided interpretation of one video, but I do string and I string for a WTA tournament. I have never been asked to pre-stretch poly using the aforementioned definition of pre-stretching. I have, by two or three players, been asked to pre-stretch natural gut. The percentage they requested was 10%.

    I have to say that asking a question, getting the answer you don't want from people who know, and then continuing to argue is the definition of trolling.
     
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  2. MathieuR

    MathieuR Professional

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    I am an engineer, and will never dispute a proven fact. And then I mean fact as eg the earth is a sphere rotating around the sun.

    Again, I will only "draw out any argument" when I am not convinced it is a "fact"

    According to Wikipedia ( for what it's worth): In Internet slang, a troll (/ˈtroʊl/, /ˈtrɒl/) is a person who sows discord on the Internet by starting arguments or upsetting people, by posting inflammatory,[1] extraneous, or off-topic messages in an online community (such as a newsgroup, forum, chat room, or blog) with the deliberate intent of provoking readers into an emotional response[2] or of otherwise disrupting normal on-topic discussion,[3] often for their own amusement.
    I don't mean to "troll"; might be there is an "emotional response", but that is not my intention.

    Please first give me your definition of "elasticity". See the graph I posted last monday.

    Agree. I did mean eg "I like this string"/I like this type of machine/ I like a heavy racquet/etc.

    Yes, I did that. Can easily be done on a dropweight by adding an extra weight on the bar. So, I pre-tension with the extra weight, take the extra weight off, slack the string, and pull reference-tension ( and that for every string). But, my reference-tension is minus 2 kg compared with "non-prestretched". Normally 19.7kg, now 17.7kg. My SBS is then ~same.
    Yesterday I "only" added 10kg extra (ref.tension 18.8kg); will find-out this evening how this plays.
    It is still in the "experimental phase".
     
    #52
  3. MAX PLY

    MAX PLY Hall of Fame

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    ^^^

    Actually, the earth revolves around the sun while it rotates on its own axis--but enough about facts. ;)

    I think the point is that despite your own scientific research, the fact is that in the experience of many professional stringers, pre-stretching poly is rare. End of story. I actually don't think many players care about anything but how the stringbed "feels" and can the stringer consistently produce that "feel" on every racquet that comes off the machine. Your personal experience may differ and that's fine but I think you begin to run into trouble when you try to impose your views as "fact" and that imposition comes across as condescending to highly skilled and experienced professional stringers--even if you are right, it doesn't seem persuasive or collaborative. I hope you keep contributing as some of your posts have made many of us consider new ideas--and whether we agree with you or not is not an indictment--it's just a different view and that should be ok.
     
    #53
  4. Rabbit

    Rabbit G.O.A.T.

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    Great post. I couldn't agree more and very, very well stated.
     
    #54
  5. MathieuR

    MathieuR Professional

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    racquet: Yonex Ultimum RDTi42, 98sq,inch, 16*19, 335gram, 12pntsHL.
    strings used: Kirchbaum max.power 1.25 mains, supersmash 1.25 crosses
    Stringway Tension-Advisor gives for DT28 21.1 kg-mains, 20.6kg crosses. I know from experience I can go much lower: 19.1/18.6 gives with non-prestretched strings a DT of ~36 (drops to 33 after 3 hrs play)

    Now I pre-tensioned each string at ref-tension + 10kg, and used 18.1/17.6kg. Result right after stringing: DT36.1. Yesterday evening I played 2 hrs single-match. Measured this morning: DT 35.1. (and I liked the tension, string-bed-response).

    (edit Thursday 24 March: after + 3 double-matches the DT is 34.85)

    I think, that for pros pre-stretching is not that interesting, as they change rackets after 9 games. But for me, simple amateur, it helps to prolong the time between string-jobs. And think about all those amateurs that have a re-string once every year ;)
     
    Last edited: Mar 24, 2016
    #55
  6. diredesire

    diredesire Adjunct Moderator

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    No need to go on a crusade and bring up peoples' personal info and/or non-public conversations. Please keep the discussion civil and on topic.
     
    #56
  7. drakulie

    drakulie Talk Tennis Guru

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    Actually, once you take the "stretch" out of the string, it has nowhere to go. In other words, it's dead, so the tension loss is less.
     
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  8. MathieuR

    MathieuR Professional

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    The elasticity of a pre-stretched string is not necessarily gone; see the graph that I gave before:

    If you would have a string with no or hardly any elasticity, it will be very difficult to get it tensioned. But a pre-stretched string does have elasticity. But you did remove the "permanent elongation" with the pre-stretch; that's why it keeps its tension when playing.
     
    #58
  9. Irvin

    Irvin G.O.A.T.

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    That being the case, are you saying it is very difficult to tension a stiff poly and almost impossible to tension Kevlar?

    EDIT: If you want a permanently elongated string why not just play Kevlar?
     
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  10. MathieuR

    MathieuR Professional

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    A stiff poly and kevlar both have elasticity.


    The permanent elasticity of Kevlar is 3-4 times smaller as of poly.

    edit: the goal of pre-stretching is NOT to kill elasticity, but to kill tension-loss caused by the permanent-elongation.
    If you use a "standard" string, at reference-tension of 20kg, then every time you hit a ball, the string gets a tension a very short moment higher as the reference-tension. And with every hit you get a tiny bit of permanent elongation (that stays there, and causes tension-loss).
    If you pre-stretch that string at say 40kg, and use it at same reference-tension of 20kg, then, when you hit a ball, the string gets also a tension a very short moment higher as the reference-tension. But, the string did already loose the permanent elongation "till 40kg". So that elongation "will not happen", so, no or less tension-loss.
     
    Last edited: Mar 24, 2016
    #60
  11. Irvin

    Irvin G.O.A.T.

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    I will agree with that. So instead of doing all that stretching on strings why not just use Kevlar?
     
    #61
  12. MathieuR

    MathieuR Professional

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    Cause a stretched poly is still 4 times more elastic as Kevlar ( I think it is even more for some poly's); so plays completely different. I like a stretched-poly (at lower-as-my-normal-reference-tension), I don't like kevlar.
     
    #62
  13. ricardo

    ricardo Hall of Fame

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    Stretchability and elasticity are two different things

    Stretchable
    A stretchy material does not imply a return to its original lenght once you remove the tension.
    An example would be a Spaghetti Noodle.

    A stretchy material cannot hold tension because it does not want to return to its original lenght when stretch. It will just keep stretching until it breaks.

    Elastic
    An elastic material implies a return to its original lenght once you remove the tension.
    An example would be a rubber band or a tennis string.

    An elastic material can hold tension because it wants to return to its original lenght when stretched. The more you stretch it, the harder it is to stretch it.
     
    #63
  14. Irvin

    Irvin G.O.A.T.

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    Well we disagree again. I like Kevlar (for some strange reason) I don't like poly. If only Kevlar had more power.
     
    #64
  15. MathieuR

    MathieuR Professional

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    Exactly. Try a pre-stretched poly ;) You will have a string with more elasticity (-> power) and no/little tension-loss.

    Edit: I played with natural gut in the mains for some time. Loved the feel, but I could not control the ball; too much power. So for the moment back to pre-stretched poly
     
    Last edited: Mar 24, 2016
    #65
  16. jim e

    jim e Hall of Fame

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    I would suspect that you most likely strung the nat. gut at a relatively low tension. For myself and my nat. gut customers, ( I string a fair share of nat. gut) , the gut is typically strung low to mid 60 lb. range for most of my gut players, as gut hits very nice at high tensions giving good control.
    I have had one customer that had his gut strung at 70 lbs. You have to use a quality gut at those tensions as cheap guts cannot tolerate high tensions.This is for all gut set ups.
     
    Last edited: Mar 24, 2016
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  17. drakulie

    drakulie Talk Tennis Guru

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    The "elasticity" that was there before you pre-stretched it, is not the same. Period. This is why the tension drop is not the same as a string that was not pre-stretched.
     
    #67
  18. Irvin

    Irvin G.O.A.T.

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    A quote from the very same article the graph came from:
    But there's another factor that peppers players' descriptions of string death — loss of elasticity due to an internal fatigue and breakdown of the string.

    EDIT: here is another quote from that article, "Elasticity is the ability of the material to return to its pre-stretched length." If you permanently elongate a string it does not have the ability to return to its pre-stretched length. All string will loose some or most of it elasticity depending on what tension was used to tension the string, whether or not it was pre-stretched, how long the string is held in a stretched state, and normal use.
     
    Last edited: Mar 25, 2016
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  19. Irvin

    Irvin G.O.A.T.

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    @MathieuR just out of curiosity what is the difference in DT of a frame strung without the string being prestretch as opposed to one that has been pre stretched. Assuming the same tension is used to string the rackets.
     
    #69
  20. Irvin

    Irvin G.O.A.T.

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    The article @MathieuR got the graph from was an interesting article but I think it can all be summed with with a portion of the conclusion section:

    "Pre-stretching has a significant influence on energy return. Pre-stretching increases stiffness and energy return while decreasing deflection and dwell time. This is because the previous stretches realign the polymer chains in the axial direction, removing some of the viscous play normally evident in the unfolding and sliding of chains.
    Although the decrease in energy return does not affect ball velocity much, it probably amplifies the effect of increasing friction between strings. Lateral movement of the mains is inhibited by the increased friction and the decreased energy available to overcome that friction. The combined effect is what players experience as the increased stiffness and decreased response of the stringbed."

    I'd prefer a responsive stringbed.
     
    #70
  21. ricardo

    ricardo Hall of Fame

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    Very interesting question, Teacher.

    I would assume that the DT would be the same initially.
    However, the pre-stretch string will retain/maintain the DT much longer than the non-prestretch string.

    I further assume that the DT of the non-pre-stretch string will plummet drastically while the DT of the pre-stretch string will go down very, very gradually.
     
    #71
  22. Irvin

    Irvin G.O.A.T.

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    I think that's a bad assumption.
    Possible but that would depend on many factors.
     
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  23. MathieuR

    MathieuR Professional

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    Agree. There is a change, depending on the type of string. See this graph of "a" poly:
    [​IMG]
    1st stretch, start 200mm/0N -> 227mm/350N -> 216mm/0N: plastic deformation = 16mm (= not recoverable) 8%, elastic deformation 11mm = 5.5%
    2nd stretch (stretching the pre-stretched string again): start 200mm/0N -> 216mm/350N -> 206mm/0N: plastic deformation 6mm = 3%, elastic deformation 10mm = 5%


    I think it is more what is stated elsewhere: "This is because the previous stretches realign the polymer chains in the axial direction, removing some of the viscous play normally evident in the unfolding and sliding of chains"
    This is what happens when you hit a ball AND when you pre-stretch.

    Agree. See graph and you see the elasticity of a pre-stretched string (+ still a part lasting, non-recoverable elongation)

    Correct, this is the plastic deformation, non-recoverable, lost forever.

    I have to use a lower reference tension: normally 19.1kg for the mains, pre-stretched till 40kg, then ref.tension is 17.1kg. Both give DT ~36.

    That is why you have to use a lower reference tension. Then the dwell-time will increase again.

    Same for me.
     
    #73
  24. ricardo

    ricardo Hall of Fame

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    I think that's a bad assumption.

    I assume that DT is based on tension.

    When you tension a specific string @50lbs, then 50lbs is applied to that string whether it is pre-stretched or not.
    At this point, both will have the same DT.

    But as soon as you clamp, both strings will lose tension.
    However, the pre-stretched string will lose less tension than the non-prestretched string on a given timescale.

    When you hit with that string, both strings will again lose tension but at different rates.

    So in summary, since the non-prestretched string loses more tension faster, so would the DT.

    I hope I pass the test Teacher.
     
    #74
  25. Irvin

    Irvin G.O.A.T.

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    DT is what the player feels if it is based on tension all strings would feel the same if the tension were the same.

    EDIT: Notice above where @MathieuR drops his tension on pre-stretched strings. Why would you assume he does that?
     
    Last edited: Mar 25, 2016
    #75
  26. ricardo

    ricardo Hall of Fame

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    You are right again as usual.

    Even if DT stands for dynamic tension,
    what a player feels is more important than the tension itself.

    If a player feels that the racket is harsh, then that tension is too high for him.
    If a player feels that the racket is mushy, then that tension is too low for him.
    If a player feels that the racket is good, then that is the right tension for him.

    Yes, the player is at the center of everything.
    I will always remember that.
    The player trounces everything else.

    There is no best in anything except from the player's perspective.
     
    Last edited: Mar 26, 2016
    #76
  27. chjtennis

    chjtennis Legend

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    I really want the opinion from a real pro. Do you think club players need to pre-stretch their strings - Poly, gut or multi?
     
    #77
  28. Irvin

    Irvin G.O.A.T.

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    FYI Drakulie has not been on the forum for about a year now.
     
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  29. chrisingrassia

    chrisingrassia Professional

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    Not a single pro female player I strung for at Bank of the West wanted pre-stretch on anything, regardless of string type.

     
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  30. Rabbit

    Rabbit G.O.A.T.

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    I has one female pro last year that wanted a 10% pre-stretch using Head Sonic Pro at 60. A definite PITA to do.
     
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  31. esgee48

    esgee48 Legend

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    There is a thread talking about when pros ask for their frames to be strung based on when their next match is scheduled. Some want them close to match time. Others want 12-24 hours of tension relaxation to occur. If they want prestretch, they ask for the machine version. It is a personal issue and one should not argue that one way is best. 2 cents.
     
    #81
  32. chjtennis

    chjtennis Legend

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    That's a shame. Having tennis professionals here is awesome as we can get some insights from them. Hope he comes back!
     
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  33. uk_skippy

    uk_skippy Hall of Fame

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    If you are talking about professional stringers who work on the tour, then there are 2 others on this thread; myself and @jazar . We have both contributed to this thread, so may best to re-read the whole subject.

    Regadrs
     
    #83
  34. chjtennis

    chjtennis Legend

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    That's great. Thanks for helping out!
     
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  35. MathieuR

    MathieuR Professional

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    It is entertaining to re-read this thread. The pure aggression :mad::D:):mad:. And I thought we were all here to share and to learn.
    I myself did not do that much with pre-stretching and testing last months. With a fall a part of a shoulder-muscle-tendon got ruptured. Got a repair-operation early September, and now I am slowly re-starting playing.

    I think the answer is in line with the extra-tension you need when using a LO-tensioner, compared to a CP. On a LO the string gets virtually no time to stretch at reference-tension, so after clamping you have quit some tension-loss due to creep. With a CP the string has more time to stretch (elastically and plastically) under ref.tension before it is clamped; but still, there will be creep after clamping.
    When you pre-stretch with +20kg, there will be hardly any creep after clamping at reference tension. So if you would use same ref.tension as without pre-stretching, your resulting DT will be higher ( and stay there, as you already "destroyed" the plastic deformation)
     
    #85
  36. ricardo

    ricardo Hall of Fame

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    Do pros pre-stretch their poly strings?

    I pre-stretch to slow down tension loss.

    I use a string until it breaks (>50 hours with Babolat SS).

    Since most pros change rackets after a few games ( a few minutes, not hours),
    they are not that concerned in slowing down tension loss.

    Thus, I assume they see no need to pre-stretch.
     
    #86
  37. MathieuR

    MathieuR Professional

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    @ricardo , you were the one that "showed me the way" in re-use and pre-stretching. I do hope to experiment a lot more coming year now I'm back on track with my shoulder.

    It is just that, and nothing more. If you try it as a stringer/player you can test if it works for you. If you don't, you will never know ;)
     
    #87
  38. ricardo

    ricardo Hall of Fame

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    Hi Mathieu, glad to hear from you again.

    I am now using a different way of pre-stretching and I think it is more effective. I call it re-tensioning (https://tt.tennis-warehouse.com/index.php?threads/how-to-re-tension-a-string.558504/#post-10154243).

    I string at my regular tension (50-60lbs). After about 10 hours of use, I re-tension at a much lower reference tension. For example, from 55, I go down by 5 lbs increments until I get to the right tension.
    Sometimes, I re-tension 15 lbs lower. The more I re-tension, the lower the reference tension that I use. Otherwise, the SB is very stiff.

    Playability
    A retensioned string at the right tension plays much better than the initial stringing. Re-tensioning is like toning your muscles, removing all the sag and flabbyness. The SB feels firm, comfortable, responsive, and alive. It is like playing a freshly strung string that remains fresh until it breaks (>50 hours with Babolat Elastocross SS).
     
    #88

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