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01-21-2014, 08:42 AM #1
Which kind of strings will benefit the most from PRESTRECTHING?
There are basically 3 types of strings; soft, medium and hard. Soft type typically stretch the most when being strung and hard type (ie Zymax67, BG80) strectch less.
Most people agree that pre-stretching will reduce tension loss so can the stringing gurus here enlighten me?
01-22-2014, 04:50 PM #2
I find the Zymax 67s to have very little stretch to them. I have tried Yonex BG65, Toalson BL8000, Toalson NP66, and Yonex NBG95. These string stretch way more than the Zymax 67s. I find that prestretching does wonders, especially in performance lasting longer.
I want to get a Wise 2086 tension head so it can prestretch the strings for me instead. Currently I hang a 10 pound weight on the string while having it tied to a post in the basement. I have a Prince Neos 1000 crank machine and this is a great way to prestretch.
01-22-2014, 08:36 PM #3
If you browse thru those few threads from @stringtechno , you'll find that slow strings (like BG65, VS850) require prestretch more than fast strings (BG80). Also if prestretch is not done, one can compensate by being a slow stringer, ie let the string rest longer under the pulled tension before clamping and going to the next string.
Last edited by visor; 01-22-2014 at 08:38 PM.
01-23-2014, 12:59 AM #4
If you look at the test figures the prestretching matter becomes easier.
When you prestretch a string you “pull ” the remaining elongation of the string out of the string at a higher tension than the stringing tension.
This means that the string becomes stiffer and that it will loose less tension in play.
The more remaining elongation a string has the more effect it has to prestretch.
I.o.w there is not much use in prestretching a stiff string.
01-23-2014, 04:00 AM #5
01-23-2014, 06:28 AM #6
A slow string needs more time to develop all the elongation when you tension the string, because there is more friction inside.
Most of the time a slow string is a string with more remaining elongation also.
But you can only notice that when you string a string.
01-23-2014, 02:42 PM #7
01-23-2014, 05:11 PM #8
Due to a weaker core, these strings have more than usual amount of string creep, ie they gradually get longer by themselves under tension, even without hitting!
Last edited by visor; 01-23-2014 at 05:14 PM.
01-24-2014, 07:03 AM #9
Fast and slow stringsHow do u notice that the string being strung still has a lot of elongation left? Is it more like a 'soft' string? Generally are they multifilaments?[IMG]file:///C:/DOCUME~1/FREDTI~1/LOCALS~1/Temp/msohtmlclip1/01/clip_image001.gif[/IMG]
If you use an electronic constant pull machine the strings ist still stretching as long as the tensioner keeps making “repulls”.
If you have a drop weight the lever keeps moving down as long as the string stretches.
These graphs show the difference between a fast string and a slow string.
The graph shows the tension in the string while pulling tension on a lock out machine.
So the tensioner does not compensate for the loss of tension and the tension drops until all the tension (at the lower tension) is developed.
As you can see the tension in the upper strings drops very quickly while the tension in the lower one drops gradually during a longer period.
The upper string is a fast string the lower a slow one.
01-24-2014, 11:48 PM #10
A little bit more information:
The figures under the graph show the elastic / total elongation of that string. And as you can see the slower string is also the stiffer one so it is not always so that a stiffer string is faster.
01-30-2014, 07:43 AM #11
Fair enough that pre-stretching has less influence on a stiff string. After all, you're putting less energy into it.
However, for a given relaxation, a stiff string will lose more tension.
Therefore, wouldn't there still be some benefit to pre-stretching a stiff string (even if it's less than a compliant one)?
01-30-2014, 08:36 AM #12
It is the elastic elongation that maintains the tension in the racquet. And in a good stiff string there is more elastic than remaining elongation.
So the higher the elastic index (elastic el / total el) the smaller the loss of tension tension.
We once called that index (see the table) the quality index but changed the name to elastic.
When you prestretch you remove the remaining elongation but if there is not much remaining elongation there is not much to remove either.