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Tennis String Selection Guide

The appropriate string set-up in your tennis racquet for your game type and playing level is crucial for optimizing performance and maximizing your enjoyment of the game. Whether you use a conventional racquet or a BOLT, the right strings can make a huge difference in your tennis experience. Take time to find the ideal stringing that fits your game and it will be time well spent—on and off the court.

Begin your search for the best string set-up by honestly assessing your game style, playing level, frequency of play. Ask a coach for help in assessing your game, if you can. Are you a beginner, intermediate, or advanced tournament player? Do you prefer to play from the baseline or do you have an all-court game? Do you hit with a great deal of spin or do you hit more of a flat ball, with little spin? Other factors also affect ideal stringing. How often do you play? Are you a string breaker? Some players play only with polyester string because they break strings so often. Do you have any physical issues, particularly with your elbows or wrists? What are the specs on the frame you use? Head size of the frame warrants consideration regarding string selection and stringing tension as well.

The next challenge is sorting through the classes of strings—and four are available today: Natural gut, multifilament, synthetic gut, and monofilament (polyester/co-polyester).

Natural gut (power and comfort)—Natural fiber strand from the sinuous membrane of cow intestines, extracted in the form of a strand, or string. It's the most elastic string. Power and comfort come from elasticity; the strings give on ball impact and launch the ball back hard. Natural gut may be used with polyester strings to create hybrid stringing, but durability is an issue. Control can be enhanced by stringing at higher tensions. Some natural gut strings include: Babolat Touch VS Gut, Klip NG, Wilson NG.

  • Benefits: power, comfort, feel, good tension maintenance, as long as the strings hold up; appropriate for all levels of play

  • Drawbacks: poor environmental stability; expensive and low durability, which limits appeal for recreational players

Multifilament (power and comfort)—Intended to imitate the performance of natural gut, but for a much lower price and with greater environmental stability. Multifilament strings are made from hundreds of nylon micro-fibers wound together into a single strand. Like natural gut, they're elastic. Unlike natural gut, synthetic fibers make the string more environmentally stable and more durable. Increased durability over natural gut makes multifilaments a good option for polyester hybrid stringing (see below). Control can be enhanced by stringing at higher tensions. Some multifilament strings include: Wilson NXT, Technifibre NRG2, Technifibre X-1, Babolat Xcel, Kirschbaum MT.

  • Benefits: power, comfort, feel, greater durability than natural gut, more stable than natural gut, less expensive than natural gut; appropriate for all levels of play; good tension maintenance

  • Drawbacks: though more durable and more environmentally stable than natural gut, durability and environmental stability is lower than synthetic gut

Synthetic gut (balance of power, comfort, and control)—Typically made of nylon fibers wrapped around a solid core, synthetic gut strings are intended to mimic the playability of natural gut and multifilament strings, at a far lower price and with greater durability and environmental stability than either of the other two. Depending on tension (how tightly the strings are strung), synthetic gut can provide an equal balance of power, comfort, and control. Synthetic gut also is a solid low-budget option for polyester hybrids. A few examples of synthetic gut strings include: Prince SG, Head SG, Babolat SG, Gosen Micro.

  • Benefits: versatility, low price, good durability, environmentally stable; appropriate for any playing level, but recommended for beginners

  • Drawbacks: none stand out, though generally lack the feel and forgiveness of softer strings

Polyester Monofilament (control; enhances spin)—The stiffest string type of all four. Polyester monofilament in its simplest form is fabricated from a single strand of molten plastic. This string should be used with caution in a conventional racquet. It is not a power string. Polyester monofilament is intended primarily for advanced players who can achieve higher-than-average racquet-head speeds to impart maximum spin on the ball. Polyester monofilament string comprises two types: polyester and co-polyester. Co-polyester is the second generation of polyester string formulated for a softer and more forgiving response over first-generation polyester. Co-polyester is still very stiff relative to natural gut and multifilaments, but more comfortable than pure polyester. Polyester or co-polyester strings can be strung at lower tensions to help increase power. Polyester monofilament strings include: Luxilon ALU Power, Babolat RPM, Soinco Tour-Bite, Kirschbaum PLE, Head Lynx Tour.

  • Benefits: a spin string; intended for advanced players with fast racquet -head speeds; appropriate for intermediates only if they can achieve an above-average racquet-head speed; often used in combination with softer string to enhance power, comfort, and feel

  • Drawbacks: not for beginners; not recommended for intermediate players who cannot achieve a higher-than-average racquet-head speed; low comfort level; poor tension maintenance; more frequent re-stringing required

Variables in Strings and Stringing — Achieving Performance Goals


Power in a tennis string comes from its elasticity. Elasticity can result from the material of the string itself, as is the case with natural gut, the most elastic and powerful string. Power also can result from lowering the tension of the stringing. In a stiff string, power should be increased by lowering the tension of the stringing. Power can also be increased with the use of thinner gauge string. Thin strings of the same material in a thicker gauge, are more elastic.

Control (Spin)

Control in a tennis string comes from its stiffness. A stiff string causes the ball to deform on impact, enhancing the string's ability to make the ball rotate. More rotation on the ball creates more friction with the air, causing the ball to lose energy and slow down, which translates to control of the ball flight. The inability of a stiff string to bend limits its power by reducing its launch capacity. Control in an elastic string can be increased by raising the tension of the stringing. Control can also be increased with the use of thicker gauge string. Thick strings of the same material in a thinner gauge, are less elastic.


Softer strings, those that are more elastic, tend to have better feel because the dwell time of the ball on the strings increases with greater elasticity. The ability of the string-bed to hold the ball, i.e., longer dwell time, can greatly enhance touch shots such as the drop shot and drop volley. The use of thin gauge strings is another way to enhance feel in racquet performance. Less material in the string makes for less material between the hand and the ball, leading to a more tactile feel at contact.

Pocket Player v Spin Player

Pocket describes the depression that happens to the string-bed upon ball impact. A player who hits a relatively flat ball with minimal spin can benefit from a large pocket on the string-bed. A large pocket indicates a large sweet spot, which results in increased dwell time for good control and better feel. A large pocket is most easily achieved with a soft string. The softer and more elastic a string is, the more it will deflect to create a pocket on ball impact, leading to greater dwell time of the ball on the strings. A pocket player hits the ball relatively flat with minimal spin and has average to below average racquet-head speed. Even professionals hitting a flat ball have a relatively slow racquet-head speed.

A player who hits with a lot of spin does not rely upon a big pocket in the way that a flat-hitting player does. In order to hit with spin, a player delivers more of a glancing blow to the ball, less square than a flat hit. Maximum spin occurs as a result of the string-bed brushing past the ball at high speed. Spin is optimized using stiff strings when the ball itself, not the strings, gets compressed at impact.

Arm, Elbow and Wrist Issues: Conventional Racquet

The rise of super-stiff polyester monofilament strings requires players using a conventional racquet to pay close attention to their stringing in order to avoid injury. Monofilament strings are harder on the body than any other string, particularly the elbow and wrist, and in a conventional racquet, where there is no buffer to reduce the harshness, the impact pop of ball contact on the stiff hard strings translates directly into the frame. Players with arm issues, poor technique, and/or minimal muscle development, should be using a soft string like natural gut, multifilament, or soft synthetic gut. Thinner strings and lower tensions should be considered for severe conditions. For those players who insist on using polyester in spite of injury issues, the tension should be lowered, or a hybrid stringing should be considered (see below).

At the upper levels of competitive tennis, most players will have no choice but to use polyester in order to be competitive. Polyester makes the ball bend, dip, dive and jump in a way that no other string can, and if one player has it and one doesn't, the player using polyester strings has a distinct advantage. In order to improve comfort, reduce the potential for injury, and to increase power and dwell time in a polyester set-up, many professional level players today are stringing their conventional racquets in the low 40s (lbs) or even in the 30s (lbs), far lower than a typical tension for a mid-range synthetic gut string which is about 55 lbs (24.95 kg). Professionals choosing to play with such extreme low tension is a good indication of just how stiff polyester monofilament is.

Arm, Elbow and Wrist Issues: BOLT Racquet

The Zipstrip of a BOLT racquet significantly reduces the potential for arm, elbow, and wrist injuries in a way that no conventional racquet can. The Zipstrip provides a spring-like buffer between the strings and the frame to eliminate the impact shock and vibration resulting from ball contact, before it translates to the frame. A Zipstrip's spring quality makes synthetic gut strings more elastic and feel like multifilament strings and makes multifilament strings more elastic and feel like natural gut; a Zipstrip makes natural gut even more elastic than it is. The Zipstrip even adds elasticity to steel and kevlar strings. In the case of polyester monofilament, Zipstrips mitigate most of the detrimental effects of its stiffness, while injecting flexibility and power too.

Players with arm, elbow or wrist issues just beginning to use a BOLT can relax the conventional racquet recommendations for minimizing injuries from ball impact. For those players with severe arm issues, it would be smart to avoid stiff strings even in a BOLT.

Polyester Hybrid Stringing

A phenomenon of modern racquet and string dynamics is the widespread use of hybrid stringing. In a hybrid string set-up, one type of string is used for the main (vertical) strings and another kind of string is used for the cross strings. The objective is to capture the qualities of spin generated by a stiff string, while adding power and comfort with a soft string. For players with arm issues that require the use of polyester in some form, a hybrid set-up can be a great solution. Hybrid stringing can make play comfortable enough to tolerate the polyester, while still generating enough spin to compete at a high level.

String Breakers

Today's big power game breeds chronic string breakers. In many cases, a chronic string breaker may have no choice but to use polyester string, polyester and co-polyester being the most durable strings available. A string breaker's dilemma occurs when the unbreakable polyester string is so stiff it becomes too much for the wrist, elbow, and arm to handle without discomfort or injury. For this situation, a good option is a polyester / co-polyester hybrid. Instead of a soft string, which would wear down quickly, to complement the polyester, a softer co-polyester, with greater durability, can be used to provide both comfort and power.

String Tension

String tension should correlate specifically with string type and player level. Higher tension for control, lower tension for power and comfort. In general, beginners should be using lower tensions due to slower swing speeds and advanced players should be using higher tensions due to faster swing speeds. Tension in a string installation is measured in pounds (lbs) or kilograms (kg) of force.

Tension ranges shown here are approximate and can vary according to head size, string pattern, and specific string characteristics. Relative tension ranges are noted for BOLT v conventional racquets.

  • In a conventional racquet of 100 square inches, a standard tension range for natural gut stringing is approximately 53 - 61 lbs (24 - 27.7 kg). In a BOLT, the optimal tension range for natural gut can be higher than in a conventional frame, at approximately 56 - 64 lbs (25.4 - 29 kg).

  • In the same conventional racquet with synthetic gut, a standard tension range is approximately 51 - 59 lbs (23.2 - 26.8 kg). In a BOLT with synthetic gut, the standard tension range is approximately 53 - 61 lbs (24 - 27.7 kg).

  • In a conventional racquet of 100 square inches, a standard tension range for polyester monofilament is approximately 42 - 50 lbs (19 - 22.7 kg). In a BOLT, a standard range for polyester monofilament is approximately 46 - 54 lbs (20.9 - 24.5 kg).

Racquet Frame and String Pattern

Two of the most consequential characteristics of the racquet frame with regard to stringing are head size and string pattern density. The strings in oversize and super-oversize frames are longer than the strings in a smaller head size. Due to their additional length, the strings in oversize head frames (105 - 115 square inches) and super-oversize (over 115 square inches), must be strung in a higher tension range over a 100-square-inch head frame to achieve the equivalent rebound qualities as in a smaller head size strung at a lower tension. This may affect the type of string used as well. For example, a string at a longer length in a large head size will certainly be more elastic than a shorter length of the same string in a smaller head frame. This may make the use of stiffer strings in a large head size more comfortable and powerful, and potentially may make it hard to maintain control with an elastic string in a large head size.

String pattern is another important consideration in determining string type and tension. A dense string pattern such as 18 x 20 (number of main strings and cross strings) tends to be stiffer than a less dense pattern such as 16 x 19. In general, a more dense and naturally stiffer string pattern may necessitate a soft string at a low tension so the string-bed doesn't become too stiff and unresponsive. On the other hand, a 16 x 19 pattern may benefit from a stiff string, or a soft string at higher tension, so that the string-bed doesn't get too lively and make the ball hard to control.

When to Re-string

The soft strings, natural gut, multifilament, and synthetic gut, retain good playability longer than the polyesters. For soft strings, a good rule of thumb is to re-string your racquet as many times a year as you play in a week. This isn't a hard-and-fast rule, it could be a different frequency depending on the circumstances, such as a player who tends to break strings more often. A sign that the strings need replacing is when they stretch out and become too elastic, and control of ball flight is lost.

Different rules apply for re-stringing polyester monofilaments. Polyesters generally need to be re-strung more frequently than soft string types. It's worth noting here that polyesters do not maintain tension very well, and players must be alert to when their strings go "dead". Polyesters do not break very often, even in the hands of the biggest hitters, so players must pay attention and re-string when the polyester loses its resiliency. When the polyester loses what little elasticity it has, it can become especially hard on the wrist and arm. A good rule of thumb for polyester type strings is to re-string as many times in six months as you play in a week, or twice as often as natural gut.

BOLT Stringing

The Zipstrips of the BOLT racquets soften the string-bed response significantly over a conventional racquet. A BOLT typically should be strung tighter, 1 - 4 lbs. (.45 - 1.8 kg), depending on the string, than the same stringing in a conventional racquet, in order to achieve an equivalent rebound quality. The inherent softness of the BOLT string-bed generally makes the use of stiffer strings a great fit. Visit the BOLT website for specific information.


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