String tension level and string condition.

The strings of a tennis racquet is a function of the string and the tension level. Like the choice of string, the initial tension level also has a strong influence on the character and playability of your racquet.

Tension is the application of force/pull to the strings by a machine to achieve the desired playability of the string bed. Most modern racquets are strung at 40–70 pounds (18–32 kilograms). The higher the tension, the more control and less trampoline effect the player will experience. A lower tension level provides more power, but also less control.

Based on the chosen string or string combination, each player has to find out for himself which tension level gives him the best feel for the shot.

Tournament players vary tension by 1–2 kg, depending on the type of court, temperature, height above sea level and the way the opponent is playing. However, this only makes sense if you re-string so often that the strings are always relatively fresh. Some professional players such as Roger Federer, Novak Djokovic and Rafael Nadal even switch to a freshly strung racquet in the same rhythm as they get new balls during a tournament.

A string is subject to natural aging regardless of whether it is used. From the time the string is installed, it will begin to lose tension, often more than 10% within the first 24 hours. After that, the drop of tension slows down significantly, but it continues, even if the racquet is not played at all. This is especially true when a racquet is exposed to major temperature fluctuations or direct sunlight.

With tension, the elasticity also decreases.

As the tension decreases, so does the elasticity – and with it the power, control and shock-damping performance of the strings. The US Racquet Stringers Association therefore recommends re-stringing a racquet as soon as the tension drop reaches approx. 25%.

With the stringster app you can keep an eye on the condition of your strings. For the most accurate results, take the first measurement right after stringing – before you play the racquet for the first time.

Monitor the loss of tension
and elasticity of your strings
over the course of time!

Get your free download: the stringster app checks the condition of your strings by their sound.

When does it make sense to string with pre-stretch?

Pre-stretching originated at a time when natural gut strings were not produced as perfectly as they are today. Due to the short pre-stretching with increased force, the natural fibers of the gut string were able to fit together more firmly and the desired tension was retained for longer. Even if natural gut strings are produced more stably today and are additionally plasticized, most stringers still recommend the use of pre-stretch for this type of string.

In the case of synthetic strings, however, the effect of pre-stretch is very controversial. We do not recommend this with monofilament strings. And for multifilament strings, too, our measurements have so far not been able to confirm that the ordered tension is retained longer thanks to pre-stretch.

The disadvantage, however, remains that the elasticity (“freshness”) of synthetic strings is reduced from the start by pre-stretching.

Tip: If you normally string with 10% pre-stretch, try alternatively to string without pre-stretch – but with 5% higher tension than usual.