I was getting my nano 7700 restrung today and I ask for 25 pound tension. Then the guy at the the counter says that I should have it at 24 and 26. I was really confused by this, and he continued to talk about yonex rackets having isometric headshapes and that has something to do with having two different tensions. Why is this? and is it really neccesary?
i dont know why. but its best to have it at 2 different tensions. eg 22 cross and 21 down or 21 down and 22 cross.
24 for main and 26 for cross. Yonex recommend about 10% tension difference between main and cross, with 2 pieces string method. This applies for most string machine configurations.