An introductory bit of theory on why racket strings break

It is the moment many racket sports player fear… the breaking point of your racket’s string. Everybody who plays racket sports knows it’s part of the game, though it’s frequency varies from sport to sport. But then it also greatly can vary from player to player and that makes this question quite interesting. Why do some players have the fortune to play for longer period of times with one set of strings, while others seem to break them right out of the gate? Of course and as always, there are a lot of variables in the mix. To better understand this process and to check what we can do to prevent or minimise string breakage, we first need to find out why rackets strings do break in the first place.

Notching causes most racket strings to break

Notching causes most rackets strings to break. This is a result of the string pattern or weaves and the forces that are applied to it while swinging away (in an upward motion) to create spin. The vertical strings are often the first to snap after rubbing against the cross strings as a player puts spin on the ball. This rubbing causes a notch or a dent on the string, which eventually snaps. Players that play with a lot of topspin are more likely to break their strings more often because generating topspin causes more grip on the ball of the main strings, and thus movement in the strings and therefore more wear and tear. The same process applies to players who play with a minimal amount of spin, but playing with a lot of spin just fast forwards this process.

Mishits

While the main strings on a racket slide along the crosses during ball contact, the strings also stretch and deflect which create a trampoline-like effect on the ball. This deflection is most prominent in the rackets “sweet spot” since that is the area with greatest distance from the frame where the strings are longer and more flexible.

The closer the ball makes contact with the stringbed near the frame, the less the strings are able to stretch, absorb energy from the ball and deflect the ball. This is because the strings must enter the frame of the racquet through a grommet and make a 180-degree hairpin turn back through an adjacent grommet, which causes more resistance in that spot and less flexibility. This could cause an overload (or overstretch) that leads to the breaking of a string.

Mishits that occur toward the head of the racquet will more often break strings since the racket will tend not to twist (and thus, absorb less energy) like a mishit toward the left and right edges of the stringbed. If you, by mistake, hit your ball or shuttle in the top location or bottom location of the stringbed, the lack of cross strings will cause the main strings to bend back (and stretch) more than usual.

By doing that, the main strings are under more stress and that can make them break more easily. As with notching, the more powerful the shot, the higher the chance that breakage will happen. So, if you play a smash, the chances of breaking the string due to overstretching are higher than if you perform a drop shot.

Damaged or missing grommets

The grommets are a plastic element that is placed inside each hole where the string goes through. The grommets basically ensure that the string does not touch the frame directly. Since the frame tends to end up with sharp corners, the grommets ensure a smooth transition and an easier life for the string.

Over time, grommets will stretch and often tear, exposing the string to the sharp edges of the frame, usually where the paint of the frame is also diminishing. Grommets most likely to exhibit damage are in the 10, 2, 4, and 8 o’clock positions of the hoop where main strings make a 90-degree turn or are knotted, sometime through a shared hole with a cross string.

Excessive bumper guard wear at the 10 and 2 o’clock positions can expose string to the court surface. Stringers usually have tubing in stock to cut temporary tubings in order to finish the stringing process.

Weather

Extreme heat, cold, and humidity can severely weaken strings, especially when left in a hot vehicle for a long time. In addition, damp conditions like rain or a sweat soaked shirt in your tennis bag can have catastrophic effects on natural gut. Also, playing in rainy conditions with natural gut is a no go… the individual strains of the gut wil start to uncoil and create the perfect spot to break the string.

Stringing mistakes

Dirty clamps, mishandled string, and improper stringing techniques at home or in the shop can result in string breakage on the court. Broken strings are part of tennis, and all strings, no matter the type or cost, will eventually break if not replaced on a regular basis. String breakage is hard on the racket due to the sudden redistribution of force and tension, so anything you can do to avoid breaking strings will result in a happier, healthier racquet.

Fabrication faults

While rare, sometimes string is damaged during the manufacturing or packaging process. If not closely inspected before installation, damaged string can prematurely break. Also, string that is being kept in stock but exposed to air, high temperatures and humidity over a longer period of time can prematurely break.

Some recommendations to minimise string breakage

1. Inspect your string as much as possible. Slight notching and some fraying in strings are okay.  Deep notching and excessive fraying are indicators that your strings are nearing end of life. In fact, it is recommended to get a new restring when the tension has decreased by 20 percent. So invest in a tension meter or a recommended app on your smartphone to test this regularly.
2. Restring your racquet on a regular basis. We’ve created a specific post on this topic. All things being equal, and on the lower end of the spectrum, we recommend changing your strings at least at the beginning of the new season.
3. Avoid mishits.  Yes, they happen, but learning and improving on your technique will help minimise off center shots.
4. Ensure your string setup is suited for your playing style. Players who frequently break multifilament string should consider switching to poly strings.  If you’re avoiding poly due to arm or comfort issues, consider a hybrid setup with poly in the mains and multifilament or natural gut in the crosses or string at a lower tension.
5. Keep your racquets cool and dry. Some modern racquet bags come with insulated racquet storage, which is a worthwhile investment. Store your racquets and wet clothes in separate compartments in your bag.
6. While you’re inspecting your strings, inspect your grommets and bumper guard too.  Not all stringers are meticulous about inspecting racquets prior to restringing them. It usually depends on the service level they provide whether they take care of this for you or not. Let your stringer know if you spot torn grommets or areas of your bumper guard so worn down that the string is exposed to the playing surface. Individual grommets can be repaired or replaced, sometimes with nylon tubing to protect the string. When more than 6-7 grommets are excessively damaged, your stringer might recommend replacing the entire grommet and bumper guard set.
7. For home stringers, closely inspect your string and clamps prior to use.  You should get into the habit of physically and visually inspecting your string. Clean the jaws of your clamps with isopropyl alcohol and an old toothbrush to get rid of residual string coating and grit. Don’t make the (easy) mistake of adjusting your clamps to tight if your clamps are a bit greasy. This could damage the strings too much leading to premature breakage.

Your experience

What about your experiences? What can you tell us about breaking, and especially about saving racket strings! Please let us know in the comments. We, and other racket sports enthusiasts will be grateful for sharing your thoughts with us.