View Full Version : Poly/Gut Hybrid Tension
Hi,
After a lot of reading (TW Forums, Babolat, StringingForum; special thanks to Joe, JayCee, JayPro) I’ve come to this conclusion:
Mains Tension:
1)-10% - Poly Mains
2)-0.1-0.3kg per Cross - Mains increase (no crosses when stringing)
PS85: ~=0.17kg per cross * 16 PS85 Crosses = -2.72kg
Crosses Tension:
3)+10% - Crosses show higher (friction with mains when stringing)
4)-x% - Mains are longer than Crosses
PS85: 33cm/25.1cm = -24%
Formula(PS85 Poly/Gut): Crosses = Mains + 2.72kg - 4%
I would appreciate your comments about it. Especially about point 2 - it’s too inaccurate.
Thanks
Hi Antontd,
My message is relatively simple as far as differences in tensions on mains and crosses are concerned yet a very large number of stringers feel that it is too complicated. :confused:
I'm just a stringer and by no means a mathematician, and if I have found that putting the tension in the crosses at +4lbs over the tension in the mains it is nothing more than experience and "trial and error" testings over the years. :o
If you are intent on developping a "formula" to demonstrate or explain what we are doning, or should be doing that's fine with me, but personally I have a lot of difficulty in understanding what you have written in your posting. If you care to enlighten me I would appreciate it, at least I won't feel that I am stupid, or less stupid than I feel today. :(
If I can grasp the fundementals I will try to comment on your findings, but actually I'm lost. Keep it simple, I'd like to have a chance to understand it all. :)
Cheers,
JC :cool:
JayCee,
You need to go back to Antontd's very first line, in fact the last credit within parenthesise, to understand what might have influenced the formulaic conclusions :eek:
Jaypro - How ya doin mate ? Long time.
cheers,
kwick
I am not sure who wrote this, I think it was Joe. but I found it here. It will explain better:"
Regarding string length: The difference between a short and a long string, both under the same tension, is that the long string will deflect more on impact than the short string. Therefore the ball deformation is less, resulting in decreased loss of energy and thus more power. The aim of a good string job is to obtain a uniform string bed deflection. But I am not sure if we are allowed to view it like that. I think it would be true if the strings weren't woven into each other but instead we had two separate string planes. But since the cross strings are woven into the mains, the result is a connected string bed in which the deflection of one string influences the deflection of many other strings in the string bed.
Regarding tension loss of the cross strings: Totally right, this is mainly due to the friction at the main strings. The tension loss due to friction during pulling the cross string has been measured by Cross & Bower in 2001. They measured an actual pull tension of about 10% less than the reference tension. That means if I pull the cross string with a reference tension of 25 kg, the resulting tension on the string is about 22.5 kg. But of course these values strongly depend on the surface of the string.
Another correct point is that during the cross string installment, the tension on the main strings is increased. A measurement of Dr. Carl Love showed that the tension on the central main string increased by about 0.1-0.3 kg per additional cross string that was installed. So in a racquet with 18 cross strings the tension on the mains would be increased by approx. 2-4 kg.
So, to sum it up, there is proof that if I string the crosses 2 kg tighter than the mains, I will most probably still end up with a higher tension in the mains than in the crosses, in the best case equalizing for the different length of the strings."
Good thinking Kwick,
Nice to see your input, seen all of your thoughts on GSS and as usual am inclined to say "amen" to most of your opinions. It would be nice to hear something from JayPro, but he neglected his offer to send me a few of his JayPro plastic bags to me (and probably DF) for Xmas, so I think he may be a little wary of our reactions if he shows up. Hey Jason, we miss you mate. :(
So, back to the findings of Antontd, admiably backed up by Cross & Bower (in 2001) and Dr. Carl Love. I'm, as I said previously, just a stringer, a string freak, and have managed to contribute a few ideas in string conceptions some time ago, and with the passing years these ideas tend to have been proven. My work on poly/multi and poly/gut hybrides in the 80's and my opinion at the time that this was going to become the basis of competition player's strings in the future is now starting to become true (it took 15 years!!). :)
In trying to understand how we could combine totally different materials, we needed to understand how and why each string reacted under play conditions, and for it took us a long time to realise that most of the theories on the real tension on the mains and crosses were quite wrong. In fact, the differences between the tension on the mains and the crosses are generally between 25% and 35%, (depending on the type of string and the surface, a very low coefficient of friction between the strings leads to a better string tension in the crosses). On the average , when strung at the same tension mains and crosses, the difference is 33%. Which means if you string at 23/23kgs, you will get 24kgs in the mains and 16kgs in the crosses. I can explain this, demonstrate to any one that it is true and yet 00% of the stringers on this earth will dispute this. Perso I don't care who thinks what, if anyone makes a basic read out with a "Stringmeter" which permits us to mesure comparative tensions on the same strings in the same racquet, the majority of stringers will say that the meter doesn't work. So where do you go? :confused:
I am not going to change the world, and the stringer that tried to get exactly the same tension in the crosses as the mains started by deforming the racquet and finally breaking it, he was trying to put 12kgs more in the crosses to "equalise" the tension on the stringbed. :eek:
When we make a racquet, the construction of the frame and the concept of the string pattern allow for an average difference in real tension of about 30% and the tollerences above and below this difference are quite large, most of the shock and the work in the string bed is being done by the mains, but the way the that the strings "feel" and the quality of play will be delivered by the crosses. With loose crosses the mains are free to move laterally, its softer, more comforable and less precise. When you (progressively) increase the tension on the crosses, compared to the tension on the mains) the stringbed becomes tighter, you get better control and as the mains move less then the notching is reduced and the strings last longer. If the tension in the crosses goes up to 4kgs more than the mains, it becomes too hard and unplayable, yet if you measure the real tension on the crosses, they will still be about 6 kgs less than the mains ??? In fact the more tension you put on the crosses, the more you force the main strings out of line and the more you increase the tension on the mains. So to get to the same tension mains and crosses is impossible. :p
As for the relative length of the strings, the effect of this is insignificant, the other variables in stringing (loss of tension because of clamp movement, strings slipping in the clamps, loss on the knots and the elasticity of the strings, the ability of the stringer, etc. etc.) are infinitely more important and have a huge influence on the quality of the string job. ;)
So, if all this garble interests someone, then fine, I really don't want to get into endless discussions on the topic, it's a take it or leave it posting and whether anyone wishes to agree or disagree with me then so be it. I think that as of the moment a player starts to try to explain to himself that his problems with his game can be assimilated to different ways to string his racquet, by tweeking this and that to improve something else, the guy in in for a nightmare. It's like player who start adding on and taking off lead tape on the frame. Once you find a good balance between power and control with your racquet and your strings, keep it constant and learn to play with it as it is. The material is important, but to be right in your head, to understand that a player that is confident in himself and his material will play a good game of tennis, and a player who is constantly trying to change his material to compensate his own failings, will never overcome his problems, he will just keep asking himself questions, and rarely find the right answers. A bad senario. :(
That's enough, sorry to bore you all, but keep it simple and you will get it to work out for the best :)
Cheers,
JC
JC,
Thank you for your long and bor… well, long and comprehensive post;))
I am not trying to equalize the tension, but to find the perfect combination.
So you say 33% difference? That’s fine, because the mains are longer – they need higher tension to give equal response. As you can see in my PS85s, the difference is 24%. What we get is Crosses=Mains*1.09(9%).
25kg * 1.09 = 27.25
Here is another question: people say that 80% of the power and the touch come from the mains. Babolat says crosses give power and comfort, mains give durability and spin. My opinion is that tighter strings will be more important when we measure power. What do you think about it?
Anton
ps: I will test 25/27
@ Anton,
Wow, this is a very difficult subject to comment on, because there are lots of opinions that are not only opposite but it is difficult to demonstrate clearly what actually happens when the ball is in contact with the string, which is for a very short time (in a freshly strung racquet), it varies between 0.004 and 0,007 of a second, about 5 thousanths of a second, I have tried to take a close look, but the ball comes and goes before I can see anything at all. We call the time of contact with the ball "dwell time", which in itself is a subject which can lead to very passionate debates, which if possible I prefer to avoid. :p
Please read the following post, written by Tim Strawn, who in my opinion in one of the most knowledgeable gentlemen in Tennis, and not only I find what he says to be most interesting, I tend to agree with him as well. With sincere thanks to Tim, I quote the following :
Quote :Forum Admin
GSS Administrator
Grand Slam Stringers!!
Re: Dwell time ?
« Reply #14 on: 27. Mar 2005 at 18:41 » Quote Modify
--------------------------------------------------------------------------------
Very interesting discussion indeed.....
I want to respond to this question primarily because I hold a different opinion as to why the pros like poly and what role dwell time plays here.
For quite some time the debate raged on about "string tight for power, loose for control" or visa-versa. It now appears that the general consensus is that stringing tighter increases control but we also know that in the process other things change. For example, in smaller head racquets where the sweet spot is at a minimum to begin with, you can actually reduce the existing sweet spot even more by stringing tighter in an effort to gain more control. So we know we have a delicate balance when working with such frames . We also know that the resulting control from stringing tighter is not because it produces more dwell time, it's actually the opposite.
As for dwell time and how it relates to control I would offer the following:
In the pro game where many are using smaller head size racquets with much more dense string patterns I'm of the opinion that the sooner the ball comes off of the string bed, the more control is enhanced. If the ball is staying on the strings longer this means that it remains there (although this is only miliseconds) as the racquet is in forward motion, creating more chance of an errant shot. If you are swinging at a slower pace then perhaps yes, it may be possible to control the ball more since the ball does not flatten out as much as with a much harder stroke as we see at higher levels of play.
I believe poly at the professional level is an enhancement to control because in combination with a more powerful (forceful) stroke, a smaller head frame with a more dense string pattern, a heavier frame, plus the additon of a stiffer string such as poly, you are reducing dwell time. The ball is flattening out (allowing for more topspin, thus increasing control) and coming off of the racquet face much faster than with natural gut or other synthetics. Refined strokes at this level dictate a situation where the player is not looking for the ball to stay on the strings any longer than necessary. The issue of power as it relates to poly is merely a byproduct of the player being able to hit out more freely due to the strings reduced elasticity. The pros can generate all the power they desire because of their ability to stroke the ball differently than the average club player--what they seek is control in the process
We know that the additional power received from natural gut is a direct by-product of how you strike the ball. If your stroke is less powerful you will not experience the full benefit of natural gut. However, if you can really strike the ball with great force (such as the pros do) you begin to see the real benefits of the elasticity of the natural gut string. Natural gut is much more elastic at tension ranges bewteen 55-70 lbs whereas nylon is less responsive in that area. Which takes me to this example which I have mentioned previously:
I use the example of Henman, a long time natural gut user, switching to a poly hybrid. In the smaller head size frame Henman was using they were working with a small sweet spot from the very start. As it was explained to me by Henman's stringer, he was having trouble controlling the ball --he couldn't take his natural stroke with the gut without the loss of control. When they tried to increase the tension the sweet spot was decreased so this solution was not that beneficial. By going to the poly hybrid Henman was able to use his natural stroke and gain the desired control. Because they were using poly and the poly was less elastic, they were also able to string at lower tensions and therefore increase the sweet spot a little bit in the process.
This is one of those subjects that can get very complicated. The combinations we typically see at the club level vary greatly from what we see at the tour level, ie; as it relates to the amount of power one can actually generate, no matter what string and racquet is used. I remain of the opinion that poly produces a quicker release from the string bed, thus increasing control given the factors I have described above as they pertain to the tour player. It's your serve
Tim
Unquote.
This does not reply to your question on the role of the mains and crosses, I will tackle that one the next time, but to be able to discuss such details, it is very important to be aware of the basics of "dwell time". Tim's posting is an excellent introduction. :)
Later,
JC :cool:
PS. If we get into real technical garble, boredom is guaranteed. :D
Once you find a good balance between power and control with your racquet and your strings, keep it constant and learn to play with it as it is.Quest for improvement through experimentation with materials is admirable but you wont find a better piece of advice than from the quotation above.
Thanks for keeping us honest JayCee :)
regards,
kwick
That reminds me of something a golf shop sales person told me. I was trying to find good clubs, asking all the questions, getting sucked in to all the marketing when he turned to me and said "It's the indian and not the arrow"
Quest for improvement through experimentation with materials is admirable but you wont find a better piece of advice than from the quotation above.
Thanks for keeping us honest JayCee :)
regards,
kwick
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