Long term tension loss in polys is fake news

#1
In 2018 I strung my own racquets 25 times (all on an Eagnas Hawk 80). All racquets had full beds of poly except two which had natural gut in the mains and poly in the crosses.

In each case of a full poly stringbed the greatest drop in tension occurred after the first hit. Typically there was an 8% drop in tension from the tension off the machine (ex. Head Hawk Touch strung at 52.8lbs ends up as 48.6lbs after ~2hrs of hitting) with the most being a 13% drop and the least being a 3% drop. By the end of the second hit there was typically a 2% drop, and by the end of the third hit there was typically only a 1% drop. After ~6 hours of hitting tension loss was typically nonexistent or minimal at best. Tension was measured using RacquetTune which was deemed reliable here https://tt.tennis-warehouse.com/index.php?threads/racquettune-accurate-or-not.632950/.

My takeaway from this year long project is that anyone who says a poly's tension loss begins or is first noticeable after a week or two of hitting doesn't know what they're talking about. Playability may start to decline for certain polys after that amount of time but the string has settled into its final tension long before that point.

Something else I would add is that since the biggest drop in tension happens right after the first hit and that new tension stays pretty constant, most people are wrong about their tension preferences unless they happen to cut out their strings after one use. If you think a poly feels best when it's strung in the low 50's, you probably prefer the feel of it in the high 40's (like my example above).
 
#2
I don't think there's as much discrepancy as you think there is. I don't hear people disagreeing about initial tension loss being greatest, or playability dropping after the first 4-15 hours, depending on the player and the poly. People say their preferences based on what the machine should be set to in order for them to play well with it after. They understand that's not the exact tension in the racquet, and that's not what they're trying to say.
 
#3
This information is more for letting people know that when someone says they feel a poly's tension start drop only after one or two weeks into a playtest (which string reviewers say a lot), that person is incorrect and probably mistaking the drop in the string's playability for a drop in stringbed tension. Based on my observations, tension maintenance for poly strings applies to the tension after the first hit and not the tension off the stringing machine. I would wager a lot of people who have their racquets strung for them are not aware of this. Obviously they wouldn't need to change their preferences after knowing but they should realize that the actual tension they like is lower than they thought unless they're cutting string out after one hitting session. It's also that the way some people talk about feeling a pound or two difference between two newly strung racquets, yet they can't feel the typical characteristics of poly tension loss, is funny to me.
 
#4
I found the same, first big tension loss was after .5-1 hr of hitting and then it leveled off dropping maybe .5 to 1 pound per 1-2 hour session after the first 5-7 pound loss. From there you could play them another 20 hours and not lose much tension but I still found playability sucks after about 7 hours on poly so I cut it.
 
#5
All elastic systems that go through load cycles will change as the cycle count increases over time. When the response reaches the point the player notices the difference, it is time to get a fresher string bed.
 
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#7
Players are probably mistaking tension loss for loss of elasticity. Even if the strings don't lose tension after the first 2 hours, they lose elasticity, which to many would be playability. When they don't play as well, they are describing it as tension loss.
Yeah, and the reduced spin due to the reduced elasticity could lead to more depth on their shots, and since looser strings also offer more depth, they are just confusing the two.
 
#9
This elasticity thing seems overly technical.
Does it really matter which term gets used if both "loss in elasticity" or "loss in tension" result in more depth, more power, less spin, less playability?
 
#10
This elasticity thing seems overly technical.
Does it really matter which term gets used if both "loss in elasticity" or "loss in tension" result in more depth, more power, less spin, less playability?
Biggest problem in loss of elasticity is the loss of shock absorption that comes with it. That’s where the arm wrecking properties of poly come out. And where that “dead” feeling comes from.

All strings lose tension, even gut. Poly isn’t a whole lot different than nylon in that respect. It’s just that nylon retains resiliency and will absorb shock better.
 
#11
Players are probably mistaking tension loss for loss of elasticity. Even if the strings don't lose tension after the first 2 hours, they lose elasticity, which to many would be playability. When they don't play as well, they are describing it as tension loss.
Can you explain the difference because I don't get how they are NOT the same.

Elasticity is defined:
  • n. Physics The property of returning to an initial form or state following deformation.
  • n. Physics The degree to which this property is exhibited
So if the ball hits the strings it deforms them and basically stretches them. If elasticity is lost than the strings don't return to the original condition...IE they are now a bit longer. Which would result in tension loss. Its one reason why prestretching is supposed to help with tension maintenance...because you basically simulate the 1st few hours the OP is talking about.
 
#12
Biggest problem in loss of elasticity is the loss of shock absorption that comes with it. That’s where the arm wrecking properties of poly come out. And where that “dead” feeling comes from.

All strings lose tension, even gut. Poly isn’t a whole lot different than nylon in that respect. It’s just that nylon retains resiliency and will absorb shock better.
That sounds more like notching.
 
#13
In 2018 I strung my own racquets 25 times (all on an Eagnas Hawk 80). All racquets had full beds of poly except two which had natural gut in the mains and poly in the crosses.

In each case of a full poly stringbed the greatest drop in tension occurred after the first hit. Typically there was an 8% drop in tension from the tension off the machine (ex. Head Hawk Touch strung at 52.8lbs ends up as 48.6lbs after ~2hrs of hitting) with the most being a 13% drop and the least being a 3% drop. By the end of the second hit there was typically a 2% drop, and by the end of the third hit there was typically only a 1% drop. After ~6 hours of hitting tension loss was typically nonexistent or minimal at best. Tension was measured using RacquetTune which was deemed reliable here https://tt.tennis-warehouse.com/index.php?threads/racquettune-accurate-or-not.632950/.
I have observed similar with full poly.

I am interested to know which string had only a 3% drop after ~2 hours of hitting. Was that one of the gut/poly hybrids? If so, did both gut/poly hybrids behave that way?

Also, can you clarify your methodology? Is 52.8 lbs the machine reference tension or measured tension immediately after stringing? Was there any variation in the time between stringing and first hit? Asking because if you just leave the racket sitting at room temperature after stringing it will loose quite a bit of tension over several days. Did you take any measurements after e.g. 15 mins or 30 mins of play? I suspect that the 8% drop is mostly occurring within the first 15-30 mins or at least within the first hour of play.

My takeaway from this year long project is that anyone who says a poly's tension loss begins or is first noticeable after a week or two of hitting doesn't know what they're talking about. Playability may start to decline for certain polys after that amount of time but the string has settled into its final tension long before that point.
I noticed a correlation between loss of playability and loss of tension. Specifically, the onset of deadness seemed to occur when the tension loss bottomed out. In general, my strings seem to remain playable until the tension stops dropping. My interpretation is that tension stops dropping when there is no more elasticity, and it is predominantly the loss of elasticity that makes the strings feel dead and unplayable.
 
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#14
I found the same, first big tension loss was after .5-1 hr of hitting and then it leveled off dropping maybe .5 to 1 pound per 1-2 hour session after the first 5-7 pound loss. From there you could play them another 20 hours and not lose much tension but I still found playability sucks after about 7 hours on poly so I cut it.
I am cutting out string beds no matter what they are somewhere between 6-10hrs.
 

Traffic

Hall of Fame
#15
I am cutting out string beds no matter what they are somewhere between 6-10hrs.
My son hits like a ball machine. Super consistent. Somewhere between 12-15hrs, he starts spraying the ball. He loses spin and power. Then tries to compensate. I know that isn't very scientific. But if you saw my son play, I think it is a very reliable observation.

We cut his strings at 12hrs no matter what. He has 3 racquets; one he plays with, one that's fresh and ready to go and one that's on the stringer table waiting to get re-strung. Rotate every 12hrs.

BTW, this also allows his strings to be "aged". A freshly strung racquet typically sits in his bag about 2 weeks before he pulls it out to play. So a lot of the initial tension loss is done by the time he plays.
 
#16
This elasticity thing seems overly technical.
Does it really matter which term gets used if both "loss in elasticity" or "loss in tension" result in more depth, more power, less spin, less playability?
I would say it does since they're two different aspects of a stringbed.
 
#17
This elasticity thing seems overly technical.
Does it really matter which term gets used if both "loss in elasticity" or "loss in tension" result in more depth, more power, less spin, less playability?
I would say it does since they're two different aspects of a stringbed.
I would say for the majority of people, no, it doesn't matter what you say. If you're really getting into the science behind strings and talking about how to make a better string and the science and engineering behind everything, then yes, it definitely matters. But when talking about how a string performs on court and just trying/comparing different strings, no, I'd say it shouldn't really matter as long as what's understood is; less control, less spin, less playability.
 
#18
Can you explain the difference because I don't get how they are NOT the same.

Elasticity is defined:
  • n. Physics The property of returning to an initial form or state following deformation.
  • n. Physics The degree to which this property is exhibited
So if the ball hits the strings it deforms them and basically stretches them. If elasticity is lost than the strings don't return to the original condition...IE they are now a bit longer. Which would result in tension loss. Its one reason why prestretching is supposed to help with tension maintenance...because you basically simulate the 1st few hours the OP is talking about.
The better term for what happens with poly is really loss of resilience which is the ability to absorb energy on deformation and regaining original form. Poly has low resilience which means it absorbs less energy and hence transmits more to the arm. Highly resilient strings like gut will still absorb more energy after losing tension and elasticity.
 
#19
I am interested to know which string had only a 3% drop after ~2 hours of hitting. Was that one of the gut/poly hybrids? If so, did both gut/poly hybrids behave that way?
Babolat RPM Blast 125 - off the machine at 49.1lbs and came to 47.4lbs.

Also, can you clarify your methodology? Is 52.8 lbs the machine reference tension or measured tension immediately after stringing? Was there any variation in the time between stringing and first hit? Asking because if you just leave the racket sitting at room temperature after stringing it will loose quite a bit of tension over several days. Did you take any measurements after e.g. 15 mins or 30 mins of play? I suspect that the 8% drop is mostly occurring within the first 15-30 mins or at least within the first hour of play.
I use RacquetTune to measure tension right off the machine and after each of the first three hitting sessions of a racquet. As mentioned above, 52.8lbs was the tension off the machine and 48.6lbs after the first hit. While I don't take note of time between stringing and the first hit, I typically string my racquet the night before the initial hitting session. You are correct, there was a time where I had to reschedule the first hit two days and out of curiosity I measured before the first hit and there was about a 3lb drop from the off the machine measurement. I do not measure mid hitting session.
 
#20
Babolat RPM Blast 125 - off the machine at 49.1lbs and came to 47.4lbs.
This is surprising and it contradicts my own observations. I have not observed that RPM Blast 1.30 loses significantly less tension compared with polys following the first hit.

Did you repeat the experiment to confirm that result?
 
#21
I would love to see what my PolyTour Fire 1.30 at 65# full bed lost after a 2 hour match. I know it was noticeable, but play time after that it didn't appear to be..

Sent from my LG Q7+ using Tapatalk
 
#22
This is surprising and it contradicts my own observations. I have not observed that RPM Blast 1.30 loses significantly less tension compared with polys following the first hit.

Did you repeat the experiment to confirm that result?
I have not since I was just trying out RPM for the second time. It came in a racquet I bought and I really liked it so I got a pack to see if it played the same with me stringing it. I was not disappointed. I can report on the final measured tension after I get home today.
 

norcal

Hall of Fame
#23
Well the great thing about racket tune is you don't have to claim things, just post it up.

Here's an example (Kircsh PLII 18/GOSM 17). I have found with this hybrid setup max tension loss is about 13-14% over time, hitting doesn't seem to be a big factor, time does.

 
#25
This is surprising and it contradicts my own observations. I have not observed that RPM Blast 1.30 loses significantly less tension compared with polys following the first hit.

Did you repeat the experiment to confirm that result?
Do you prestretch your string? I started to late last year, maybe that made the difference between our experiences.
 
#28
Do you prestretch your string? I started to late last year, maybe that made the difference between our experiences.
BTW, I prestretched for 16 string jobs and found that the average drop in tension after the first hitting session was 7% while for non-prestretched string jobs it was 9%. After the second hitting session there was a drop from the post-first hit tension of 2% and 3% respectively.
 
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