PDA

View Full Version : tension question >>>>>

Kirko
12-15-2006, 03:33 PM
lets say you string a racket with basice prince syn. gut or wilson extreme 17 ga. at 72 lbs. how much tension does it lose before it stablizes. I have heard it loses about 4 lbs. over night even if you don't use it. Thanks in advance!

lude popper
12-16-2006, 11:41 PM
in NY, when we tested string jobs (strung at a reference tension of 60) on an RDC, the initial 24hr tension loss -- with no play -- seemed to average at 10%> polys losing a little more, natural a little less.

alu16L
12-17-2006, 07:59 AM
in NY, when we tested string jobs (strung at a reference tension of 60) on an RDC, the initial 24hr tension loss -- with no play -- seemed to average at 10%> polys losing a little more, natural a little less.

I second that

th____44
12-17-2006, 10:24 AM
oh....that sucks!!!!
imagine how much tension they lost when you play....

ChicagoJack
12-17-2006, 11:23 AM
lets say you string a racket with basice prince syn. gut or wilson extreme 17 ga. at 72 lbs. how much tension does it lose before it stablizes. I have heard it loses about 4 lbs. over night even if you don't use it. Thanks in advance!

Agree with the commentary so far, but the word "stabilizes" in your OP caught my eye. Tension loss is a moving target. It is never the same from hour to hour, minute to minute, or year to year. It's kind of a mind blowing concept when you think about it.

-Jack

alu16L
12-17-2006, 12:10 PM
Agree with the commentary so far, but the word "stabilizes" in your OP caught my eye. Tension loss is a moving target. It is never the same from hour to hour, minute to minute, or year to year. It's kind of a mind blowing concept when you think about it.

-Jack

Yeah, I just got a brain cramp thinking about how much tension my strings loose with every shot I hit.....

racketrx
12-17-2006, 07:48 PM
Ok, everyone step back from the RDC for a second.

All strings lose tension based on time as well as play. So when we get used to a new stick freshly strung at 65 lbs., it's not really 65 lbs by the time we get to a court.

This issue is how much does this string lose vs that string. This data is available on-line in the USRSA's string database.

Warning: Science Content!!

The next problem is that they also lose tension according to the curve that describes their material properties. Some are fairly linear over time and use and others like poly lose quite a bit at first and then "lock In" and keep their tension almost all the way to failure.

Don't get a headache over it, just get the data to compare and factor this in as one of the many criteria in choosing a string.

ChicagoJack
12-17-2006, 10:42 PM
Hi racktrx -

Just out of curiosity, what data sources are you using to conclude the following :"... and others like poly lose quite a bit at first and then "lock In" and keep their tension almost all the way to failure."

The nature of USRSA testing is to measure initial tension loss after stringing. The string bed is allowed to sit for 200 seconds, then is hit with a force similar to that of a 120 mph serve 5 times. Just wondering if there's another scource for longer term tension loss data available. That would be cool to have.

Thanks,
-Jack

Kevo
12-18-2006, 05:44 AM
The nature of USRSA testing is to measure initial tension loss after stringing. The string bed is allowed to sit for 200 seconds, then is hit with a force similar to that of a 120 mph serve 5 times.

This is all true, except it is only 1 string not an actual strung racquet. I find the numbers to be a good general guide, but you kind of need to build in your own personal fudge factor. I mean I could hit 20 of those high power serves in the first hour. Of course they might not make it in, but for purposes of string bed stiffness my personal experience won't match up exactly with the RSA's numbers, because I am using a whole string bed and experiencing it's stiffness, not just a single string. So for individual strings, you're own results will vary, but it does give you something you can use to decide what strings you may be interested in. Also keep in mind that the test is done at 62lbs. so your string may perform quite differently at different tensions.

racketrx
12-18-2006, 05:53 AM
ChicagoJack: In 2003 when Poly was starting it's rapid rise in popularity there were some articles in Racquet Tech Magazine that published curves of tension loss over time. I will see if I can find the article or curve for reference.

racketrx

ChicagoJack
12-18-2006, 06:08 AM
ChicagoJack: In 2003 when Poly was starting it's rapid rise in popularity there were some articles in Racquet Tech Magazine that published curves of tension loss over time. I will see if I can find the article or curve for reference.

racketrx - That would be a cool find. I've been crawling in the cupboards of that site since 2001, and must have missed that article somehow. Thanks for the investigation effort.

Kevo - I didn't know it was only one string, thanks for that. I did know tension was 62. You and I have discussed before the short term nature of the testing. My point then was the same as it is now. You either assume that the strings that loose lots of tension early, continue to do so - or you assume they settle in. This I why racketrx's above statement caught my eye, I am intrested in getting longer term testing data on tension loss. Thanks again.

-Jack

Kevo
12-18-2006, 11:15 AM
CJ,

I have seen some of the curves as well but can't remember where. I think it may have been a German version of Tennis Magazine. They tested the DT value of the stringbed over time on some of their string tests and the curves were pretty flat after the initial loss. The initial loss is fairly high, and then the loss after that is fairly steady over time. The steepness of that flat section is what most people notice as poor tension holding I think. If it's too steep then you feel like it loses tension all the time. If it's shallow you think it's holding tension because the change isn't dramatic enough to notice.

racketrx
12-18-2006, 07:32 PM
ChicagoJack: I didn't find the charts or article I was looking for. I know they are out there, but Racquet Tech and RSI and not easy to search. When I did a google search I did come up with a post of yours from 2004 discussing tension loss. Too funny.

Racketrx

ChicagoJack
12-18-2006, 07:46 PM
Hi racketrx -

Boy, If I had a nickle for everytime I came up with a google search that ended right back at TW. I really do believe you and Kevo are being earnest with your recollection, it's just a pity we cant find it. The USRSA seems to keep stuff linked back to 2004, and the rest of the stuff falls out of reach after a certain point.

Thanks again for trying, best regards
-cj

fastdunn
12-19-2006, 11:16 AM
in NY, when we tested string jobs (strung at a reference tension of 60) on an RDC, the initial 24hr tension loss -- with no play -- seemed to average at 10%> polys losing a little more, natural a little less.

Does this 10% include the tension loss due to a stringing process itself?
(friction, clamp drawback, plain sloppiness... etc)

There's also supposed to be difference between dynamic vs static tension
loss. AFAIK, kevelar has excellent static tension maintenance but has
horrible dynamic tension maintenance, for example...

The curve of tension loss (dynamic, meaning while you hit with it)
seems to be different depending on materials.

I do not have fancy tension meter( just a string-o-meter).
From my experience, right after stringing nylons at 60 lbs on constant pull,
I get stringometer reading of low 50's. Then by the time I hit with it,
it hovers around 50. Then it slowly goes down from high 40's to low 40's
over 20-40 hours of hitting. I usually re-string if it drops below 45.

Valjean
12-19-2006, 11:47 AM
There's already another source: when a string is playtested at the USRSA, the review gives an RDC reading immediately after stringing and 24 hours later, then compares those to similar readings for a control string, Prince Original Synthetic Gut.

VGP
12-19-2006, 12:01 PM
Do people just not get the difference between reference tension and actual tension?