Various string lengths require varying tension.

Around a century ago, tennis racquets were first strung with gut strings, which are now made from cow intestines due to their elasticity.

The breaking force of a gut string ranges from 48 to 55 kp, depending on the string gauge. Its elongation at break is 24%. The main advantage of a gut string is its stability after processing in a racket. Previously, a good gut string had less relaxation (approximately 5%) than an artificial string, which could relax up to 25%. However, IPDS® by Xception offers the same relaxation behaviour with a selected range of refined strings on the Xception as was previously only known with gut strings.
The sole drawback of gut strings is their susceptibility to moisture. Natural gut strings are appropriate for rackets up to midsize. However, they are not recommended for oversize rackets, which can be strung up to 35 kp or more, depending on the string used.

Synthetic strings have become popular due to their larger striking surface in the frame, which reduces the advantages of gut strings. Additionally, synthetic strings are known for their durability and resistance to moisture.

There are two types of synthetic strings: monofilament and multifilament. Monofilament strings, also known as injection-moulded strings, are made of polyester. These strings have limited tensile strength, elongation, and lateral stability due to their molecular structure. When hit badly, individual or multiple strings may break simultaneously.

Multifilament strings are made up of combinations of fibres or microstrings of the same or different plastics. These are twisted and welded together or separately surrounded by a plastic sheath.

Another type of synthetic string is the foil string. Polyurethane foils are cut into strips, twisted, and glued together to form this string. To reduce frictional forces, these strings are often heavily greased or oiled.

The most important characteristic of a tennis racket string is its elasticity. Elasticity refers to the ability of a solid body to return to its original shape after being deformed by an external force. The elastic reaction should occur immediately after the force is removed. The better the elasticity of the string, the faster the ball will travel when it leaves the racket. If the lateral elasticity is low, the player will need to apply more force when hitting the ball.

If the forces acting on the body are increased beyond a certain point, the body will undergo plastic deformation, which is irreversible. This phenomenon is known as plasticity.

Plasticity refers to the ability of a material to be deformed by external forces and retain this deformation after the stress has ceased. It is important to note that a tennis string should never be pulled into the plastic range, which would occur if a natural gut string were strung to over 35 kp. Tennis strings are classified not only by their elasticity but also by their diameter.

When a string is pulled, it stretches by a multiple of its original length. Friction occurs due to the molecular structure of the string, as the stretched molecules strive to return to their original resting state. It takes some time for the string to assume a new, stretched equilibrium state, which remains stable after about 12 hours. During this time, the string loses approximately 10% of its weight. As described above, in order to significantly reduce this relaxation, the string must be treated with both pre-tension and main tension. Please refer to the chapter on overstretching for more information.

With IPDS® by XCEPTION, you can achieve 100% reproducible stringing results, ensuring the same reaction behaviour of the string every time.

Regarding string thickness, fewer longitudinal and cross strings allow for a thicker diameter and higher stringing weight. The chapter on string hardness will provide a detailed explanation of the interaction between string hardness and thickness.

The majority of strings have a diameter ranging from 1.27 mm to 1.35 mm.
However, strings used by clay court players may have a diameter of up to 1.40 mm, and those used by clean and straight-playing athletes can be as thin as 1.25 mm.

Strings of different diameters have varying weights.

The balance point of the racket changes as a result. A natural gut string with a 1.25 mm gauge weighs 2 grams less than the same string with a 1.30 mm gauge. This racquet has a reduced balance point of 1 mm. The difference may not be noticeable to an amateur player, but a professional player will notice a difference in the length of the ball hit.

If a racket needs to be restrung, you can assess which string needs to be replaced by following these steps:

1. Beurteilen, warum, wie und wo die Saite gerissen ist. Mögliche Gründe:

– Playing on one side of the string bed
Many players unconsciously have markings on their grip, which can lead to one-sided loading of the string bed. To prevent this, try to distribute your shots evenly across the string bed.
This results in only hitting your forehand stroke on one side of the string, halving the life of your string.

– String break in the eyelet area
After repeated stringing processes, the eyelet band may become pressed through by the many ball contacts, causing the string to exert excessive force on the eyelet band and leading to its material giving way. As a result, the string may break on the sharp edge of the graphite. To prevent this, it is recommended to replace the individual eyelet immediately or, even better, the entire eyelet band.

– Was the correct string used? What is the material thickness?
What is the connection between the material, frame, and string hardness? If a racket is strung too tightly, the string may break quickly or move into the plastic range.

2. After evaluating the previous string, follow these steps:

– Remove the old string
– Check the string band, the eyelets or the holes
– Clean the eyelets (ash, moisture)
– Select the string to be wound
– “All-round check” of the frame to be restringed
– (balance point, weight, etc.)
– Check the grip
– Choice of string and stringing machine