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-   -   NEW TWU (3-21-13): How Strings "Go Dead" (http://tt.tennis-warehouse.com/showthread.php?t=458365)

TW Professor 03-21-2013 09:04 AM

NEW TWU (3-21-13): How Strings "Go Dead"
 
There is a lot of talk about how polys "go dead" and there are a lot of contrary opinions of what going dead means. I asked playtesters at TW and some say the ball flies and control is lost and others say the string hits like a board -- two seemingly contrary opinions.

So what really happens? This experiment set out to find out and the results are reported here:

How Strings Go Dead

McLovin 03-21-2013 09:29 AM


ChicagoJack 03-21-2013 09:32 AM

Mr. Lindsey -

Wow. Thank you. Thank you. Thank you. Thank you. You've correctly identified an issue that has needed serious consideration for quite a while. While the effect of strings, racquets, and inherent rebound power / ACOR is given careful study in your book, the going "dead" issue is given only a brief mention. This in depth study is truly appreciated!

-Jack

newyorkstadium 03-21-2013 09:40 AM

Thanks TW Professor.

I'm confused by this article. So all strings lose spin potential, but nylons lose less then poly's? Although, in your words the "decrease in tension should also decrease the friction between strings"

I'm guessing the increase in stiffness is the dominant factor. The main thing I read is that dead strings "hurt your arm".

kaiser 03-21-2013 10:15 AM

Thanks Prof, great experiment with very intreguing results, much appreciated!
I'm trying to get my head around how these findings can be reconciled with the increased spin with no concomitant loss of control reported for sub-40 lbs tensions in the "Low, low tensions" thread.

You conclude in this paper:
"The lower tensions and perpendicular stiffness of many polyesters leads to longer dwell times and greater deflection. This keeps the ball on the racquet for a longer arc of the stroke, potentially creating "power" problems with the ball going deeper, wider and higher than desired. The decrease in perpendicular stiffness also contributes to the sensation that the strings get "mushy" or behave like a trampoline. A loss of control is the end result."

Following this line of reasoning, shouldn't we expect to see the same phenomena and resulting loss of control when stringing at very low tensions in the first place? I don't observe this in my own rackets.

Sander001 03-21-2013 10:23 AM

Quote:

Originally Posted by newyorkstadium (Post 7293087)
Thanks TW Professor.

I'm confused by this article. So all strings lose spin potential, but nylons lose less then poly's? Although, in your words the "decrease in tension should also decrease the friction between strings"

"Should" is a key word in science which is used as a preface for the next phase of the experiment.

TennezSport 03-21-2013 10:38 AM

Nice work, thanks.....
 
This is a very nicely done string baseline analysis and explanation. It makes it clear to see how complicated it gets when you add in racquet size, string pattern, weight and playing styles to the string life, but at least you have a place to start understanding poly string. Thanks for the data.

Cheers, TennezSport :cool:

arche3 03-21-2013 10:46 AM

Puts all the ttw wanabe scientists to shame. Good job!

Overdrive 03-21-2013 10:59 AM

So a low-tension co-poly lasts less than a high-tension co-poly?

Just for verification.

fgs 03-21-2013 12:36 PM

kaiser,

i think you don't see the difference between stringing low from the start and getting to the same tension by repeated impact on the string. after several hundreds of impacts, the strinbed will behave differently than a fresh stringbed installed at a lower tension.

TW Professor 03-21-2013 01:00 PM

Quote:

Originally Posted by kaiser (Post 7293148)
Thanks Prof, great experiment with very intreguing results, much appreciated!
I'm trying to get my head around how these findings can be reconciled with the increased spin with no concomitant loss of control reported for sub-40 lbs tensions in the "Low, low tensions" thread.

You conclude in this paper:
"The lower tensions and perpendicular stiffness of many polyesters leads to longer dwell times and greater deflection. This keeps the ball on the racquet for a longer arc of the stroke, potentially creating "power" problems with the ball going deeper, wider and higher than desired. The decrease in perpendicular stiffness also contributes to the sensation that the strings get "mushy" or behave like a trampoline. A loss of control is the end result."

Following this line of reasoning, shouldn't we expect to see the same phenomena and resulting loss of control when stringing at very low tensions in the first place? I don't observe this in my own rackets.

fgs is correct above. Strings behave differently depending on how they arrive at a given tension. I have done experiments where I get to and test a string, say at 40 lbs, in several ways. I might test the string freshly strung at 40, or strung to 60 and manually lowered to 40, or strung at 60 and raised to 80 (as if impacted) and then lowered to 40, or by stringing at 60 and repeatedly impacting until I get to 40. All the methods will arrive at different test data for the same 40 lbs. The tension is one thing, but how it gets to that tension is another.

TW Professor 03-21-2013 01:11 PM

Quote:

Originally Posted by newyorkstadium (Post 7293087)
Thanks TW Professor.

I'm confused by this article. So all strings lose spin potential, but nylons lose less then poly's? Although, in your words the "decrease in tension should also decrease the friction between strings"

I'm guessing the increase in stiffness is the dominant factor. The main thing I read is that dead strings "hurt your arm".

All strings that I tested increase in friction COF which will tend to decrease spin. However, the rate of that decrease and at what level you will notice it depends on the string. Most nylons don't have much string movement to begin with, so it doesn't matter much that the COF increases.

Yes, decreasing tension should decrease the friction between strings, but at the same time it is increasing due to wear. One or the other will win out. If you feel it getting stiffer, then the increasing friction due to wear is the winner.

newyorkstadium 03-21-2013 01:22 PM

Is it possible the lower tensions and perpendicular stiffness could balance out with the increased COF? So the playability stays the same.

If you find that a string ends up too stiff, can't you just string lower?

What happens to spin potential if the COF is going up, but the decreased tension also decreases the friction between strings?

DonBot 03-21-2013 01:36 PM

I notice a drop in playability when my full poly bed starts to etch really bad, I always assumed people complaining about a dead full poly string bed being boardy were victims of etching. I can't imagine the strings slide much at all when you have 16g poly etched half way to breaking.

JT_2eighty 03-21-2013 01:39 PM

Quote:

Originally Posted by TW Professor (Post 7293430)
fgs is correct above. Strings behave differently depending on how they arrive at a given tension. I have done experiments where I get to and test a string, say at 40 lbs, in several ways. I might test the string freshly strung at 40, or strung to 60 and manually lowered to 40, or strung at 60 and raised to 80 (as if impacted) and then lowered to 40, or by stringing at 60 and repeatedly impacting until I get to 40. All the methods will arrive at different test data for the same 40 lbs. The tension is one thing, but how it gets to that tension is another.

Great thread and responses!

Love it when the TWU prof gives us a new experiment to read.

I think the phenomena of 'string going dead' has been one of the most needed experiment out there; great stuff!!

pvaudio 03-21-2013 01:58 PM

I will just say this: that was absolutely fantastic. Thank you SO much for spending the time researching this topic. :)

lawrencejin 03-21-2013 02:10 PM

This is why I keep coming back to TW forums. Thank you for a great article!

tlm 03-21-2013 02:32 PM

Quote:

Originally Posted by kaiser (Post 7293148)
Thanks Prof, great experiment with very intreguing results, much appreciated!
I'm trying to get my head around how these findings can be reconciled with the increased spin with no concomitant loss of control reported for sub-40 lbs tensions in the "Low, low tensions" thread.

You conclude in this paper:
"The lower tensions and perpendicular stiffness of many polyesters leads to longer dwell times and greater deflection. This keeps the ball on the racquet for a longer arc of the stroke, potentially creating "power" problems with the ball going deeper, wider and higher than desired. The decrease in perpendicular stiffness also contributes to the sensation that the strings get "mushy" or behave like a trampoline. A loss of control is the end result."

Following this line of reasoning, shouldn't we expect to see the same phenomena and resulting loss of control when stringing at very low tensions in the first place? I don't observe this in my own rackets.

I sure do thats why I like higher tension because it gives better control than low does.

mikeler 03-21-2013 07:39 PM

Quote:

Originally Posted by McLovin (Post 7293067)

I've only had time to read the Conclusion but I agree so far!

Great job on this TWP.

ricki 03-22-2013 01:14 AM

So do I understand, that from polys you tesed here are best RPM Team and Luxilon Original?


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