Going Down?

From the very beginning of polyester based string(s) the manufacturers advised stringers to reduce tensions by 5 to 10 percent, and some still do.  You would be correct if you thought nobody did this back then! It was just too much to consider that kind of “softness”!

The 10% Solution

The 10% Solution

Today, however, tensions are going down and going down significantly!  I pulled up some data of a pro tournament I did in 1992 and found that then Polystar users were still requesting 60 to 65 as their preferred tension setting, even in Head Prestige Mid 18×20 racquets!  Now it is perfectly reasonable to use tensions settings as low as 40 pounds (18.14kg).

My recent experience is 44 to 54 pounds, depending on the racquet and what polyester based sting is being installed, is typical.  But why?

One reason is we have been brought up on “reference tension” instead of “string bed stiffness” which can be different numbers.  Another reason is that polyester based string was, and in some case still, not very stable.  This means tension loss is quick.  Of course polyester based string can be an arm, wrist, and shoulder irritant at high tensions.

Even at lower tensions some polyester based string exhibits a “stiffing up” as the ball impact force increases.  That is, the harder the ball is hit the stiffer the string becomes.  Here is the dichotomy…because polyester based string have low elongation, therefore, low power potential, the swing, and impact, must be harder to get the ball to go as far as you want, especially when freshly strung.

Lower tensions, (SBS), can help in the production of “spin” through compliance of the string to the ball.  String movement and “snap back” may contribute a little to “spin” but it is difficult to quantify.  To get the ball to spin the “slippage” of the ball on the string must be minimized, so reducing SBS is one way to achieve this.

The bottom line is that reference tension should be dependent on string, string pattern, player arm issues, and, of course, durability issues.  A 16 x 16 string pattern will be better at a higher reference tension than a 18 x 20 string pattern.  I have been working on a string that is much better at higher tensions!

So there!

Posted on February 28, 2015, in Learning, String, Technology. Bookmark the permalink. 4 Comments.

  1. John,
    If you were to graph the reference tension and String Bed Stiffness (SBS) with a commonly used polyester string (like RPM Blast 16g) starting at a higher tension going to a lower tension: what would the graph look like? It would seem based on what you describe that SBS would increase proportionately as the reference tension decreased. Is that correct?
    Roger

  2. Thanks, Roger, for the post. I will try to graph some data points but it is my experience that SBS decreases as the “Reference” tension decreases.

    I have plotted several racquets strung with polyester and they do exhibit a “stiffening” as the force increases.

  3. I understand the SBS will decrease along with the reference tension. I am thinking that as one reduces the reference tension the SBS will not reduce in an equal proportion. For example: RT 60 and SBS 59, RT 50 and SBS 52, RT 40 and SBS 48 etc….. I am making up the figures but does that make sense? Usually when I do have a lower tension racket to string (very few) I see the SBS being higher than the RT. I have strung a very good players (5.0 level) W Profile 2.7 with Prince Beast 16g at a RT 18lbs and a few in between. Not enough and all with different strings. I imagine that there is a sharp change than a plateau. It would just be interesting and helpful to know where those points are.

    • Roger, I have done a similar test a long time ago and I will try to find it and post it. I may re-do the tests using a different string so I don’t waste a lot of RPM Blast!

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