This is an excerpt from Nick Bollettieri's Tennis Handbook-2nd Edition by Nick J. Bollettieri.
Let’s start with the facts. The energy created in a tennis ball that meets a racket breaks down into the following components:
- 60 percent of the energy comes from the string bed (the strings in the racket).
- 30 percent of the energy comes from the ball (a rubber object in motion with its own energy).
- 10 percent of the energy comes from you and your racket frame (frame only, not the strings).
This proves the importance of proper stringing, correct tension, string type, quality of strings, and age (freshness or resilience) of strings. With this in mind, let’s start with the most important item in hitting a tennis ball, the strings.
The 10 Commandments of Strings
Whatever type or brand of string you use, the following 10 commandments of strings apply. Study each carefully. They will help explain the many differences in today’s string selections and how they can affect your game.
- Lower string tension generates more power (providing that excessive string movement doesn’t occur).
- Higher string tension generates more ball control (with less power, placement of the ball improves).
- A longer string, or string-plane area, produces more power.
- Lower string density (fewer strings in the string pattern) generates more power.
- Thinner strings generate more power.
- Strings with more elasticity generate more power and absorb more shock at impact.
- Softer strings, or strings with a softer coating, tend to vibrate less.
- Thinner strings produce more spin on the ball.
- Lower string density (fewer strings) generates more spin on the ball.
- The more elastic the string, the more tension is lost in the racket after a string job (prestretching will reduce this effect).
String Types and Construction
Not too long ago, players had just two choices in strings - natural-gut strings or nylon strings. Natural-gut strings have been used since tennis was invented. Most top professional players still use natural gut because of its amazing characteristics, which are found only in a natural fiber.
Today, many nylon strings are referred to as synthetic-gut strings. This name can be misleading. The most important point to remember is that all such strings are made from a nylon-based product. True, many synthetic-gut strings have special features that make them last longer than regular nylon strings, but in basic chemical analysis they are virtually the same product.
If the added features of a specific synthetic-gut string favor your game, feel confident in continuing to use that product. But remember, a freshly strung racket with the basic nylon string will greatly outperform an expensive synthetic-gut string that is old and has lost its resiliency.
The basic construction types in today’s nylon or synthetic-gut strings can be classified into the following groups. Each construction technique is for a specific purpose.
- Solid core (polyester strings)
- Solid core (single wrap)
- Solid core (multiwrap)
- Multicore (single wrap)
- Multicore (multiwrap)
- Aramid fiber and hybrids (Kevlar and other materials)
Of these construction types, solid core with a single wrap is by far the most widely manufactured string, making up more than 70 percent of all strings manufactured today. The main reason for the wide acceptance of this string is its overall performance at a price much lower than the price of natural gut.
To help you find the best string type for your individual game, take a look at table 14.1. Refer to later sections on construction and gauge to fine-tune these recommendations.
To define each type of string better, let’s look at a few of the more popular groups and their playing characteristics.
Solid-Core Synthetic Strings
Polyester strings fall into the solid-core category. Although they have been around for many years, polyester strings have recently found great popularity among players at all levels. Like all synthetic strings, they are available in different gauges (string thickness) and from a variety of manufacturers. The advantages and disadvantages are as follows:
- Greater control
- Claims of exceptional feel
- Resists notching
- Tension loss
- Less ball speed
- Increased shock and vibration
- Difficult to install (for stringer)
Note that polyester string is less resilient than other synthetics, so a claim of more control also means the player cannot hit the ball as hard.
Solid-Core (Single Wrap) Synthetic Strings
Solid-core synthetic strings with a single wrap make up 70 percent of today’s string market. These popular strings derive their durability from having a large solid core. An outer wrap of smaller filaments (or fibers) improves tension retention. The outer wrap assists in two ways by (1) helping to hold the tension on the string and (2) protecting the core from notching and other abrasions caused by impact with the ball.
Because of the string’s popularity, a wide choice of gauges is available. Manufacturers price their strings competitively. If this is the best-playing string type for you, shop around. You can probably find the same string from several companies, differing only in packaging and pricing. The advantages and disadvantages are as follows:
- Wide variety of gauges
- Excellent value
- Very durable (thicker gauges)
- Balance between power and control
- Too many choices
- Better strings overlooked
- Will go "dead" before breaking
- Shock and vibration to arm
Multifilament Synthetic Strings
Multifilament synthetic strings are coreless and have multiple synthetic fibers twisted together in a manner similar to natural gut. Fibers vary in thickness and number. The biggest advantage of this type of construction is playability. These strings are technically difficult to produce and carry the highest price tag among synthetic strings. They are the best-playing synthetic-gut strings and most closely resemble natural gut in all characteristics. The advantages and disadvantages are as follows:
- Exceptional feel
- Increased power
- Less shock and vibration to arm
- Excellent for wide-body frames
- Tension loss
- Premature breakage
- Susceptible to notching from topspin
Despite the countless number of synthetics on the market today, most players still judge natural gut the best, although many of the top professional players have moved to the polyester category or to a hybrid of polyester and natural gut. String manufacturers try vigorously to duplicate its exceptional feel and playability, but so far they have fallen short. Thus we often hear or read the statement "Plays most similar to natural gut."
Natural gut is made from high-grade beef intestine. Only the upper part of the intestine is used. The process is a delicate, hands-on procedure that requires up to three months from start to finish. Note that natural gut is a by-product of the beef industry. No cows are slaughtered just to make gut. The labor-intensive work needed to produce natural gut accounts for its high price compared with synthetic strings.
Natural gut is the best-playing string available; its power is unmatched. Natural gut will hold tension much better than any synthetic string, and it absorbs shock and vibration much better as well. The actual "dwell time" (time the ball is on the string bed) is longer with natural gut than it is with synthetics, so the player experiences a much greater feel. An old saying in the tennis world is this: "Once you have tried gut, you will never go back to a synthetic. You’re hooked!"
Over the years, people have questioned the durability of natural gut. These doubts have arisen because some stringers don’t know how to handle natural gut. Natural gut is extremely durable when handled correctly and remains playable longer than a normal synthetic string. Synthetic string will lose an average of 15 to 18 percent of initial tension in the first 24 hours after stringing. Natural gut will lose an average of only 5 to 8 percent. The synthetic string will become "dead" (lose its resiliency) after 15 to 20 hours of normal play, whereas natural gut will stay resilient for its entire life.
If you have had arm or shoulder problems, natural gut is the best remedy for you. It is made from hundreds of individual "ribbons" of the intestine, twisted together to form the string. Each ribbon acts independently as well as with others when a ball is struck. Each ribbon absorbs shock and vibration to deliver optimal power. Natural gut is considered a multifilament string and is available in many different gauges. All that you have learned about construction and gauge applies to natural gut. The following list further addresses its benefits and drawbacks. The advantages and disadvantages are as follows:
- Tension maintenance
- Best for arm and shoulder
- Longevity of playability
Learn more about Nick Bollettieri’s Tennis Handbook, 2nd Ed.