String Breakage

Posted 21^st April 2025

Broken strings are a frustrating but unavoidable part of playing racket sports. Susceptibility to string breakage, however, much depends on the player’s style of play as well as the properties of the string they use – some recreational players are able to play with the same set of strings for several years, while prolific string breakers can barely get through a match without breaking a string.

This article aims to explain how and why strings break, and what you can do to help prevent premature breakages.

Causes of String Breakage

There are a number of causes of string breakage, which are summarised below:

Overstretching (Tensile Failure)

The most common string breakage is a sudden failure, where the string is stretched beyond its elastic limit – much like pulling an elastic band until it snaps. Often termed a ‘shear’ break, this generally occurs when the ball / shuttle contacts the string bed off-centre, near the top or side of the frame.

Shear break from contact near the top of the frame

The centre of the string bed is the most resilient area, as the load on impact with the ball / shuttle is distributed onto all of the main and cross strings. Hitting outside the centre puts stress on a less resilient section of the string bed, as a far higher proportion of the load is shared by fewer strings. When the ball impacts on the strings near the frame, the strings also stretch asymmetrically – the percentage of string elongation on the frame side of the impact is much greater than a typical impact near the centre of the string bed. This dramatically increases the tension in that short section of string and if this tension exceeds the string’s tensile strength limit (i.e., if the force is too great), the string will fail. In other words, there is simply not enough string to stretch between the ball / shuttle and the edge of the racket.

Shear breakages can happen on any mis-hit shot. In tennis, this usually occurs at the top of the frame on one of the central four main strings when the ball is hit with a high degree of force, most commonly on a serve or overhead smash, but can also occur on the side of the frame as a result of a poorly hit ground stroke. In squash, shear breakages are often caused by trying to hit the ball hard and flat off the side walls.

Abrasion (Wear)

Another common cause of string breakage is string-to-string abrasion. This form of breakage occurs in the centre of the string bed and happens gradually as a result of friction generated between the main strings and cross strings when the string bed contacts the ball or shuttle. Hitting with a lot of topspin or slice causes more string movement, accelerating wear on the main strings as they ‘saw’ back and forth on the crosses. Over time, the abrasion cuts deep into the string and the string becomes thinner and weaker until it eventually breaks.

Abrasion causes fraying of multifilament strings until they eventually break

With polyester strings, the visible result of this abrasion wear is notching of the strings whereas multifilament strings fray as the abrasion cuts through individual fibres.

Abrasion wear can be accelerated by the loose granules of some court surfaces that get picked up by the ball and get into the strings, as they act as an abrasive in the sawing process.

Damaged Grommets

Grommets protect the strings from being cut into by the frame. If a grommet is missing, the frame may cut the string, and a broken or split grommet may also present a sharp edge that can cut into the string and cause it to break prematurely – particularly on an off-centre hit near the grommet in question.

Damaged bumper guards can also cause premature breakages. If the string passes over the jagged shards of a broken bumper guard, this can cut into the string in the same way that the frame or a broken grommet can.

Temperature

Temperature-related breakages can occur during the winter months. Cold conditions cause the string to contract, increasing its tension and reducing its elasticity. Nylon, the primary material for many synthetic strings, also becomes brittle at low temperature. If a racket has been stored in a cold car boot and is immediately put into use, there is a chance the string may unexpectedly snap.

Clipping Court Surfaces

Some squash rackets don't have very deep grooves in the grommet strip for the strings to sit within, leaving the string exposed. If the racket clips the wall or floor, the string can easily be damaged, particularly at the 2 and 10 o’clock positions on the racket head where contact is generally made.

A heavily used bumper guard, worn down to a point where it no longer protects the string, also exposes the string to this kind of damage. Eye Rackets squash rackets, which don’t use conventional grommet strips or bumper guards, are particularly prone to this form of string breakage as the strings sit proud of the ‘eyelets’ and the shallow channel in the frame itself.

While particularly prevalent in squash rackets, this type of string breakage can also occur in tennis rackets as a result of the player going for a low ball on a hard court surface and scraping the racket on the court.

Defective String

Manufacturing defects are uncommon, but can be responsible for premature string breakage. Signs of a defective string include discoloration, unravelling, dents / notches or roughness.

Stringer Error

It’s possible for string to become damaged during the stringing process. ‘Nicking’ the string on a tool or sharp edge can weaken it, and pulling the cross strings too fast can burn (notch) the main strings and shorten the string life. Having your racket strung by a qualified professional stringer will ensure that the string is handled with the upmost care and the life of your strings is maximised.

How to Avoid Premature Breakage

It is understandably a frustrating situation for the player when strings break prematurely. It can also be one of the worst things a professional stringer experiences in day-to-day work, should they get the blame.

There are a few things that are important to understand before demanding a refund from your stringer after a premature breakage. The majority of premature breakages occur close to the frame and are the result of either a mis-hit shot or a grommet issue. If the string broke in the centre of the string bed, there is the chance it could be a string fault; however, a defective string is likely to break the first time it is used so if the strings are used for a couple of weeks or more without breakage, then it is unlikely to be defective. Persistent shear breaks are more often than not a sign of bad technique than a sign of poor-quality strings or bodged work by the stringer.

Premature breakages are very common with squash rackets and soft multifilament strings. An all-too-familiar scenario is where a recreational player buys a racket that has been factory-strung with a low quality, thick string designed for durability rather than playability. The player uses the racket for several months until, eventually, the strings break. The player then asks their stringer for a fresh restring with a high-performance multifilament string such as Tecnifibre 305, which while highly playable is not particularly durable. The string then breaks immediately in the first game and the player goes back to the stringer, disappointed in the short life of their expensive new strings and potentially having jumped to the conclusion that the stringer did something wrong.

The issue here is not stringer error, but a player / string mismatch, and is best resolved by the player opting for a more durable string.

Here are some other ways to reduce the risk of premature breakage:

Make adjustments to your game – many breakages are caused simply by the player hitting the ball much harder than they need to.
Use a thicker gauge string – thicker strings withstand notching longer and are less likely to break on an off-centre hit.
Lower the tension – while lower tension may allow more string movement and increase abrasion wear, it provides more resilience against extreme force.
Use a denser string pattern – open string patterns, which can enhance power and spin, have a larger spacing between strings and have more string plane deformation, which stretches the string further and makes it more likely to break.
Consider an alternative string – strings with braided jackets (such as those produced by Ashaway) are typically more durable than strings with twisted jackets, as the over-under-over design locks all the fibres in place and protects the core of the string for longer.
Avoid cheap strings – players often try to save money by buying their own string, but this can have drawbacks. Particularly when buying pre-owned sets or reels or string, it is impossible to verify how old the string is or how it was stored – if it has been kept for many years in direct sunlight or in a room with poor humidity control, it could belong in the bin. If you’re intent on buying your own strings, only buy them from reputable sources.
Regularly check the grommets and bumper guard – if you notice a damaged grommet, ask your stringer to repair it the next time you have your racket restrung, along with any worn bumper guards. Replacing the whole grommet strip can be a little costly, but even a temporary repair on a single grommet will serve to protect the string.
Store your racket appropriately – try not to leave the racket in a car boot or unheated garage, and protect the racket from the cold during transportation by carrying it in an insulated racket bag. If the racket does get cold, give it several minutes to warm up before using it.
Protect exposed strings – use head protection tape if the strings are open to being clipped on the wall.

Unfortunately, there is nothing a stringer can do to completely prevent breakages from off-centre hits. However, choosing the right string and caring for your racket can significantly reduce the risk of breakage and improve the lifespan of your strings, meaning less time and money spent getting it restrung – and less stress for your stringer!

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