i found an string test on a german-homepage, a comparison beetwen yonex bg80p and NBG95. He also have the equipment to test the "surface hardness" after the stringing job (i dont know weather "surface hardness" is the right name for it in english. I will name it tension now).
He strung both strings at the same racket with 30pounds and test the tension for one weak & 3times practising. The bg80p lost 19% tension, the NBG95 32% tension. Of Course the bg80p is a little bit better in it, but 20% is also insane. Its so unconsistly & i believe consistency is so important to improve your game.
Here are many opinions from people about strings, which helps me a lot, but i try to find other tests about string where someone explore the characteristic over time or rather the exact tension lost over time.
Can someone help me?
Firstly, there is the natural loss in tension due to stretch
Secondly, the loss of tension may be affected by how much the racquet is played with (which is a non reproducible variable) Or rather, it very difficult to reproduce the exact conditions unless you have a robot hitting the shuttles in a controlled and consistent fashion.
Thirdly, even if you were to do number 2, how can that extrapolate into the real world practical use? I.e. does it really help having that information in a practical way?
I can only speak for myself but I don't place too much emphsis on the numbers .
When I feel a string has lost elasticity for my own style of play, I rather then get a restring done.
I will also do some restrings a couple of weeks before tournaments.