Hi again I dont know if im right on this, but I have the feeling that my zymax 67 string looses the tension too fast. So I wanted to hear if I could prestretch it to hold tension better, but I have read that its not good to prestretch Yonex bg 80 strings. Therefor I would like to have some advice Can I also Prestretch Zymax 70?
Zymax string keeps tension well. You don't need to Pre-stretch it. Same as BG80 and BG85. Only BG-65 could use some pre-stretch. But why pre-streth at all, just put 2 lb over what you want, it would get there in one week.
Zymax holds tension better than most if not all Yonex strings. Therefore, simply increase a bit tension when you string, you should be fine.
Panda's findings: not exactly. ZM62 holds tension without peer, excellent+ ZM70 is a distant second but still very good to excellent, relative to its peers ZM67 holds good to good+ but does lose tension like normal strings. Panda has found pre-stretching all strings by hand for about 2-3 minutes minimizes tension loss the best. Ideally tie one-end to a door handle or pole or wrap around smooth poll and just pre-stretch. Use about 15-20lbs. of tension and get the "slack" out. You can feel it because once you hold for about 30 seconds, release and re-pull, you can feel less slack. Don't over stretch. Pre-stretching by hand takes time and if you string multiple rackets in one day, can be tedious. So for Panda, he just uses a 10% pre-stretch on his ECP machine which doesn't work nearly as well. If you do not have a pre-stretch function, gotta do it by hand.
If you prestretch ANYTHING it will hold tension better, but the effect is certainly more pronounced for some strings than for others. As Dink said, Zymax 62 hardly gives anything on the prestretch and so tension just doesn't fall off - it had lost less than 1 lb over the ten sessions I used it (after the bedding-in period). On the (very) other hand, you can pre-stretch BG65Ti to the Moon and it will still turn into a trampoline within six hours. Zy67 is such and oddity - for yet another reason, it seems.
Hmm.. and the packaging on the Zy67 says the best sting in holding tension? Got conned but luckily its only S$7.80 a shot.
Badminton strings are very thin relative to tennis strings. Also in badminton the shuttlecock is very light when compared to a tennis ball. The combination of very thin strings and a light projectile to hit with will require strings that are very elastic, i.e. very low dynamic stiffness. You need the best elasticity to send the shuttlecock away, without having to dent the shuttle base, with ease. If you prestretch badminton strings the result is that the prestretched string will now have poorer elasticity or higher dynamic stiffness. I would not recommend any prestretching for badminton strings, in particular the very thin strings.
Herein lies the dilemma: If for... ...ultimate performance and/or durability: Panda would not stretch the string either. But the performance would only last a few days max. The string would quickly lose tension thereafter and play anywhere from 2 to 4...even 5lbs. lower in tension. If you're OK with this and/or are a professional player who needs the ultimate performance within a hours to days after the string job, and are OK with tension drop thereafter (while maximizing durability), this method is ideal. ...normal players: most people want to keep the string on the racket as long as possible without tension loss: if this is the case, then pre-stretch is required to remove the slack. But as stated before, do not pre-stretch too hard and best to do it manually for an extended period of time (hold gradually for a minutes). So, I guess it just depends on what you prefer.
I have been using ZM62 for quite a while now and I cannot allow this gross misrepresentation of its durability propagate. It can actually last 5 minutes, 7 tops...
Perhaps a good compromise is to string with a very small amount of prestretch of about 5 to 10% and also add in 1 or 2lbs more depending on the string. I don't believe that a 10% of prestretch on any string will reduce the elasticity so much that it feels unplayable. The worst case is if you're using a thick string such as BG65 which drops tension very quickly (1lb within the week of being strung/played and 2lbs after the second week from experience with 10% prestretch) and the crisp control feel will just disappear as the tension drops which by the end of the month you'll automatically reach for the scissors to cut out the string. By the way if the string will have a higher dynamic stiffness then wouldn't that feel as if it was strung at a higher tension? A lot of us don't get cheap stringing services and string packs which allows us to restring our racquets every month without costing a significant amount of money per racquet which could have been saved up for better purposes somewhere else. I guess there's a reason why the professional players have a string tension range, which is to counter the possibility of string tension drop depending on where they play at.
You can avoid prestretching by simply increasing your tension higher by say 2lbs than your normal tension. Wait for a few days for the tension to drop and you will find your preferred tension. A thin string, once stretched should stay stretched. If you prestretch a thin string like badminton strings, meaning stretching it and then loosening it to its relaxed state, the second time you stretch the string when pulling and tensioning it you will find the string's elasticity to be less good with the strings rebounding not as quick. If you have pulled and strung a racquet and decide half way on that you want to discontinue the stringing job. Using the same string the second time around, which is similar to prestretching, will result in poorer playability. Any thin string, once stretched, will have its molecular structure and orientation changed. Relaxing it and then stringing it again will result in a different molecular structure and orientation change.
I believe you're saying that the prestretching stretches the string's elasticity beyond its usual plastic region and thus making it deform and not be able to recover to its original state. On the other hand I shall test your suggestion of doing 2lbs more than the desired tension; meaning that my next string job should be BG65 with no prestretch at 32lbs since I'm playing at 30lbs with 10% prestretch which still drops in tension by 2lbs within 2 weeks of play. Hopefully it will stay at 30lbs for at least a few months after the drop and not loosen any further.
Nylon strings have two characteristics that may not be that great, one is loss of elasticity and loss of tension. Prestretching nylon strings will not be very different from the above. Both will lose elasticity and tension. Natural gut has superb elasticity, not so good tension-holding. Despite tension loss natural gut plays extremely well through out its service life. It is the elasticity that is the ultimate holy grail we are looking for. The new Zymax strings have much better elasticity than nylon strings although still not as good as natural gut. But Zymax strings seem to hold tension better than natural gut or nylon strings. I would suggest you avoid any prestretching or adding 2lbs more and then leaving for a week when using Zymax strings. The best playability of any string is when it gives the best elasticity. For nylon strings that means a service playability life of one week. For natural gut, it will play well until the string snaps.