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Are your poly-based tennis strings shearing at the frame?

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We have a theory.  Before putting it out there, it needs to be understood this theory was only recently developed and it has not yet been tested.  We will ask our blog readers who are stringers to help us test this theory.

We constantly read reports and have callers asking us about poly-based strings breaking prematurely at the frame.  This type of break is known as a shear.  For years we have known that poly-based strings are more prone to shearing than synthetic guts, but at the same time they are much more resistant to friction wear.

While we believe that some of the earlier generation softer poly-based strings may be  more prone to this type of breakage, the cause of breakage may actually be related to the technique of the stringer or his/her equipment.

I have had customers swear they had a bad batch (reel) of string because they experienced a high number of shears.  When I had them send the reel to me for testing, I was not able to replicate the shearing issue.  There is only one reasonable conclusion that can be reached.  My stringing equipment and technique allow for me to successfully install these strings with a lower likelihood of shearing than some counterparts.

My current theory is that this may likely be explained by the pressure of the clamps on the string.  I am wondering if it is possible to weaken/bruise these strings by clamping too tightly near the frame?  Most stringers are taught to clamp off as close to the frame as possible.  Let’s assume the clamps are too tight and the string is weakened.  It now has a vulnerable point near the frame.  Once the ball hits near the weak spot, BOIINGG!!

Since I do not know how to explain how to set the ideal clamping pressure for  a poly-based string, I have another suggestion.  If you are a stringer or if you use a stringer who experiences multiple shears with poly-based strings I have a challenge for you.  Stringers, please clamp off a few inches away from the frame.  Be consistent, but do not clamp next to the frame.  If you take your racquet to a stringer, request for them to clamp off 1 – 2 inches away from the frame.  The theory is without the weakened spot right next to the frame, the string will survive more mis-hits near the frame.  Please feel free to give it a try and report your findings back here.  I look forward to the results!

5 thoughts on “Are your poly-based tennis strings shearing at the frame?

  1. Boris Becker on said:

    Seems like your spot on!

  2. rackettec on said:

    We had the problem of popping string 3 times on a specific prince frame at a professional tournament and were using the Baiardo stringing machine. Initially the thought was that the string combination with the racket was the issue, but we found out it most likely was an issue with the clamps and clamping so I think you are right on with the idea that keeping the clamps away from the frame might keep it from weakening. I still preach that getting close to the frame keeps your tension loss down, but I think I will re evaluate my thinking regarding the poly issue. Its usally safer to losen the grip on poly anyways because it grips to the clamps easier with out slippage compared to synthetics.

  3. ggtennis on said:

    Excellent point on clamps gripping poly-based strings with less pressure than synthetics. Thanks for visiting our blog!

  4. gugamania on said:

    Same stringer same machine, it always shears on my IG speed, never shears on iPrestige or the open pattern BLX95. Nothing wrong with the grommets, no shearing with multis. I’ve never figured it out.

  5. ge on said:

    I came across your forum looking for information about shearing. Specifically with Babolat frames, First time the frame is strung, never an issue. Subsequent string jobs in the same frame risk breaking at the grommet. I started replacing some of the grommets and using a small file or dremmel tool to round off the sharp edge of the frame at the hole which I was able to see coming through the grommet. I used a magnifying glass. It was like a little knife. With poly I could get the frame strung and out the door BUT if I was stringing the frame with gut I could not get through the job without it breaking if it was a re-string. Trying to tube to grommet is challenging due to the narrow holes slightly larger than 16 gauge.


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