Should poly-based strings be prestretched?

prestretchToday’s blog topic comes from a frequently asked question received via email and telephone from our customers.  We are often asked about prestretching poly-based strings.  While there are varying opinions on the topic, our position is resoundingly firm.  “Poly-based strings should NOT be prestretched.”

Because poly-based strings offer excellent durability from friction wear, the perception is that they are a macho product.

Impervious to beatings…
Strong like a bull…
Able to leap tall buildings in a single bound…
(You get the picture)

In reality, poly-based strings are more delicate and fragile than most strngers and players realize.  They need to be handled very carefully during the installation process…Especially many of today’s new poly-based strings that include chemicals and additives designed to make them softer. Poly-based strings should be treated as carefully, or moreso, than natural gut during the stringing process.  Failure to treat them properly can result in premature breakage and cause the string not to perform  to its potential.

For poly-based strings elasticity, (the ability to stretch out and return to original form), is supremely important.  Stringing at too high of a tension sucks much of the elasticity out of poly-based strings and prestretching has the same effect.

Proponents argue that tension loss can be reduced by prestretching.  They argue that the 13% – 20% initial tension loss can be reduced/better managed with a prestretch.  This may be true.  However, there is a HUGE FALSE ASSUMPTION lingering around the stringing universe that loss of tension = loss of playability.  In some cases, this can be true, but in most cases it is not.  I believe the perceived relationship between loss of tension and loss of playability is overblown and misunderstood.  In fact, Cross and Lindsey in The Physics and Technology of Tennis found that strings maintained their energy, resiliency and elasticity even after experiencing tension loss.  “We found that the energy loss was not zero, but close enough to zero to make no significant difference in the calculations.” (Chapter 30)

Tension loss can easily be measured with many of today’s tools.  It is perceived to be evil.  While there is no denying that it is a factor that can alter playability of a racquet, we would argue in the world of poly-based strings that tension loss is not as critical of a factor as loss of elasticity.  It is the ELASTICITY of poly-based strings that allow them to offer the desired performance.  PRESTRETCHING can damage/reduce this elasticity which is the main reason we do not advocate prestretching poly-based strings.

As our blog readers know, we could ramble onward ad nauseum.  Our goal was to keep this entry short while providing some context/support for our response.

“No, poly-based strings should not be prestretched.”

Please feel free to leave your thoughts and comments in the designated section below.

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2 Responses to Should poly-based strings be prestretched?

  1. tung says:

    i have been playing tennis for 8 yrs now. i have always used prince synthetic duraflex or pro blend, mainly because that is what the local shop suggests. recently, i have given poly-based strings a try. i am trying weisscannon scorpion and msv focus hex. i must say that these strings feel so different compared to the strings i used before. the scorpion and focus do feel soft and more elastic as the article mentions. my elbow doesnt hurt as much with these new strings, but i think im gonna need a long time to get use to the playability of these new strings

  2. Alberto Diaz says:

    I hve a question… I have a Lock Out machine that is properly calibrated… yet, every time I string with Polyester strings the final tension seems to be off (lower) by about 10lbs or so… I don’t know what I’m doing wrong. Does it have to do with pre-stretching the strings?.. Or maybe I should string Polys at a higher tension? how do I know how many lbs over should I go?

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