Technical Tennis: Racquets, Strings, Balls, Courts, Spin, And Bounce - Brossura

Cross, Rod; Lindsey, Crawford

Brossura

ISBN 10: 0972275932 ISBN 13: 9780972275934

Casa editrice: Racquet Tech Pub, 2005

Riassunto

What are the single most important variables in racquet performance? What racquet and string features combine to provide the most control, comfort, and feel? How can a player create maximum spin? This informative primer answers these and other elusive equipment and performance-related questions that perennially plague hackers and experts alike. A simplified, layperson's companion to the authors' previous work, The Physics and Technology of Tennis, this conveniently sized guide to selecting racquets and strings includes bite-sized explanations of the possible expectations of equipment choices.

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Informazioni sull?autore

Rod Cross is the coauthor of The Physics and Technology of Tennis and has written extensively for the United States Racquet Stringers Association's (USRSA) Racquet Sports Industry and Racquet Tech magazines. He is a former associate professor in physics at the University of Sydney–Australia. Crawford Lindsey is the coauthor of The Physics and Technology of Tennis and the author of The Book of Squash. He is the editor in chief of Racquet Sports Industry magazine and at Racquet Tech Publishing. He lives in San Diego, California.

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Technical Tennis

Racquets, Strings, Balls, Courts, Spin, and Bounce

By Rod Cross, Crawford Lindsey

USRSA

Copyright © 2005 Rod Cross and Crawford Lindsey
All rights reserved.

ISBN: 978-0-9722759-3-4

Contents

FOREWORD, 
PREFACE, 
1 RACQUETS, 
INTRODUCTION, 
RACQUET PROPERTIES, 
CUSTOMIZING A RACQUET, 
2 STRINGS, 
STRINGS AND THE MODERN GAME, 
STRINGBED STIFFNESS, 
TENSION AND PERFORMANCE, 
DWELL TIME AND PERFORMANCE, 
3 BALLS & BOUNCE, 
BALL BASICS, 
BALL BOUNCE OFF THE COURT, 
BALL BOUNCE OFF THE STRINGS, 
4 SPIN & TRAJECTORY, 
SPIN BASICS, 
SPIN AND THE SERVE, 
TRAJECTORY, 
Further Reading, 

CHAPTER 1

Racquets

All racquet performance technologies boil down to two things — altering the stiffness of the frame and stringbed and the amount and distribution of weight. These, in turn, determine the power, control, and feel of a racquet.

INTRODUCTION

Hitting a tennis ball is an epic battle between player, racquet, and ball. The player ultimately wants to be able to swing the racquet as fast as possible and to change its direction in a split second, but he does not want the ball to be able to do the same thing to the racquet. He doesn't want the ball pushing the racquet backwards, twisting it in his hand, or bending it out of shape and direction. But making it more difficult for the ball to move the racquet also makes it more difficult for the player to do so. For the player to achieve the most maneuverability, the racquet has to be light, but to prevent the ball from knocking the racquet all over the place, it has to be heavy. And if the ball is pushing the racquet around, power is lost. So, the player also wants the racquet to be heavy to get the most power. But if it is too heavy, he can't swing as fast, and he loses power. What a problem!

Choosing a Racquet — the Basics

Given these problems, how does one choose a racquet? First we will start with some general common-sense principles and then get more specific. The hardest part of buying a racquet is to find one that you like best. The problem is not that there are not enough to choose from. The problem is that there are too many (Figure 1.1). You could spend six months trying every racquet on the market, each at a few different string tensions, and you might still have trouble finding the right racquet and string combination. In any case, by the time you tried number 100, you would have forgotten what the tenth one felt like.

Choosing a racquet is a process of elimination. You might find that you don't like heavy racquets or you don't like light ones. That eliminates about half of all racquets. You might also find that you prefer a large head to a small one or that you like stiff frames rather than flexible frames. That way you can eliminate about 90 percent of all racquets quite quickly. The best way of choosing a racquet is to spend about half an hour on a court hitting with as many different racquets you can find — the more the better, but at least ten. You will be able to reject half of them almost immediately because they won't feel right. By the end of the session you might find one or two that are pretty good. Come back a few days later and try the best ones again. Then decide. Either buy the best one or try another ten.

If you can't find a club or shop that will let you try ten racquets, then be persistent. Get your club to organize a racquet hitting — like a wine tasting where you can taste as much as you like for free.

Mistakes When Buying a Racquet

There are several common mistakes that you can make when buying a racquet. The first one is to choose one because you liked the advertisement you saw in a tennis magazine or because some new high-tech feature appeals to you. By all means try it if you like the sound of it, but don't forget to compare it with a few others.

Another mistake is to buy the racquet that feels best in the tennis shop. Hitting the air with a racquet is not a good way to find out how the racquet behaves when you hit a tennis ball. There is no shock, no vibration, and no sense of feel or power when you swing at the air.

Don't buy a racquet because your favorite player uses it or because your friend uses it. Racquets don't do all the work. You have to match the racquet to your own strengths and playing style in order to find one that works best for you. Try the same brand as your favorite player or friend if it appeals to you, but try a few other brands as well.

Players often decide that they want a racquet that is both light and powerful, a perfectly natural choice. Here again, it is better to try hitting with a variety of racquets before buying one. You might find that a 250-gram racquet is indeed light but a 300-gram racquet also feels light and delivers a bit more power.

The last mistake is to buy the cheapest or the most expensive racquet because of its price. Maybe the best one for you is indeed the cheapest or the most expensive, but price alone is not a good way to choose a racquet. There are lots of good racquets in the medium price bracket. The most expensive racquets tend to be the new high-tech models that everyone wants to try because they are new. Sometimes they are indeed very good, but it is really up to you to be the best judge of that.

Three Types of Racquet

Racquets can be classified as being suitable for beginners, recreational players, and serious competition players. Different folks have different strokes and benefit from different types of racquet. Serious competitors and professionals generally use a moderately heavy and flexible frame with a relatively small head and narrow cross-section — about 20 millimeters (mm) in the direction perpendicular to the string plane. Recreational players tend to prefer lighter and stiffer racquets with larger heads that have relatively wide cross-sections, typically around 25 to 30 mm, classed as "widebody" racquets (Figure 1.2).

Professionals hit the ball in the middle of the strings about 9 times out of 10, whereas some recreational players miss the middle 9 times out of 10. A big head helps to minimize this problem by keeping the ball well away from the frame. A racquet with a large head has the additional advantage that it rotates less about its long axis when a ball is hit off-center. The advantage of that is that the shot will be more accurate because the tendency for the ball to fly up into the sky or into the bottom of the net is reduced (see "Twistweight" later in this chapter). The disadvantage for a top player is that it is harder to rotate a racquet with a big head about its long axis. Professionals swing and twist their racquets around much faster than recreational players. A racquet with a big head would slow them down.

There are many other differences between different racquets. For example, there are differences in the number and spacing of the strings, differences in the size and shape of the holes and grommets where the string passes through the frame, differences in the shape of the handle and the head, etc. Some racquets might have a bigger sweet zone than others or are more powerful than others or will give you better control. Each of these differences can be confusing to someone unfamiliar with the jargon or who is not completely familiar with the technical details of racquets.

Equipment selection can be confusing for reasons other than just the racquet features themselves. The player's psychology and belief system about racquets as well as the fit of the player and the racquet are also important.

Racquets and Player Psychology

What a player knows or does not know about the physics, technology, and biomechanics of racquets, strings, and swings influences his perception of what is happening during a shot, whether it is good or bad, what the reasons for it might be, and how to correct or improve on it. A player's knowledge (right or wrong, fact or opinion) that he brings onto the court is the only lens through which he can observe and analyze events. When assessing a racquet's performance, and without any knowledge of racquet mechanics, a player may simply have to rely on trial and error until the racquet performance and player expectations, assumptions, and perceptions all meld into the perfect blend, whereupon the player exclaims, "This racquet is incredible." Of course, what he or she really means to say is, "I have found the racquet that best compliments both my stroke biomechanics and style of play, as well as facilitates the execution of my tactics and strategies." We can determine a "best" racquet in the lab based on certain performance parameters, but that does not mean it is best for any particular player. It only tells you how that racquet is likely to be felt and perceived by a player with a particular stroke and style.

The outcome of any shot depends on the racquet, the stroke, and what the player thinks the outcome is. An example is when players say that string material affects spin and that they get much more spin when they use stiff polyester string instead of a softer nylon. As we will see later in Chapter 4, lab tests have shown that string material, tension, or gauge do not have much, if any, effect on spin. When a player uses a stiffer string such as polyester, he loses power. He thus swings harder, and a faster swing creates more spin. The player then says that the string caused the additional spin, but, in fact, the player caused the spin by swinging faster to make up for the lost power. The player's explanation of cause and effect is incorrect, even if the outcome of more spin is true.

Another example is when players say they get more power from a stiff stringbed, even though it is well known that softer stringbeds produce more power. The possible explanation for such statements is threefold. First, stiffer stringbeds create more shock at impact, and this may be associated with "a hard hit" in the player's mind. Second, because there is actually less power potential in a stiff stringbed, maybe the player will then swing harder, consequently getting more ball speed in spite of the stringbed. And third, the sound of the impact on a stiff stringbed has a "ping" as opposed to a "thud" on a softer stringbed. The ping is more often associated with power. So, the interpretation of the shock and the ping plus unconsciously swinging harder all combine to give the perception, and sometimes the reality, of more ball velocity. But it is not the stiffer stringbed that is doing it, but rather the player's response to the stringbed.

Another example, which is actually the reverse of the one above, is when players say that their strings "go dead" after a period of time. It is true that all strings lose tension over time, but that actually results in more ball velocity, not less, because the stringbed is softer. As above, the player probably unconsciously slows his swing to keep the ball in and also associates the sound of the thud and less shock as indications of a weaker hit. These perceptions ripple effects throughout the player's strokes, shot selection, and tactics. Since he is swinging slower, he is also getting less spin. This, coupled with the fact that the ball stays on the strings longer with the soft stringbed and is thus launched at a higher angle, makes the ball take a higher, less aggressive trajectory, which also is interpreted as less "power." However, again, the lower ball velocity is a consequence of the player's reaction to perceptual cues, which, ironically were caused by more velocity due to the softer stringbed caused by the tension loss.

A classic example of how racquet performance is as much psychology as reality is demonstrated by a blind experiment that showed very few players, satellite tour players included, could discern as much as 20 pounds difference in string tension between otherwise identical racquets. Players were not allowed to touch the strings, string dampeners were used to dull the sound of impact, and players just hit four balls with racquet A and then racquet B. If they could tell that there was a difference, they couldn't tell which racquet was the higher or lower tension. Some might guess one way, some the other. In other words, the immediate feel of power and control in a racquet is not obvious. A player's opinion of a racquet is formed by his interpretation of what he feels, and that interpretation can hinge on the littlest of things that have nothing to do with the racquet's actual performance, such as the sound of the strings. In a sense, the sound tells him how he should feel about the racquet.

One last example is one that demonstrates how players can be fooled into thinking they have hit a ball faster, when they have not. Players sometimes get the feeling that the ball comes off the strings faster than usual or with less effort than usual. The effect is probably psychological rather than a genuine increase in racquet power for several reasons. In general, to hit the ball faster, you have to hit it harder by swinging the racquet faster. The result is usually felt as an increase in the force on the hand and arm. However, you can get an increase in that force just by hitting the ball at a different spot on the strings. Conversely you can get a decrease in the force, for the same ball speed, by hitting the ball in the middle of the strings. A decrease in the force on your arm, for the same ball speed off the strings, might give the appearance of more power, when in fact there is no change in power at all. The only way to know for sure is to measure (a) the speed of the racquet, (b) the impact point on the strings, (c) the speed of the incoming ball, and (d) the speed of the outgoing ball. No one has ever done that.

These examples can be multiplied many times over, but the point is that the player creates a perception of the facts in his mind and acts accordingly. A player can have all the facts wrong but still make all the correct stroke adaptations and be a great player. If you ask that player why he is great and how and why he hits the ball so fast and accurate, you will get a very confident answer, but one that might not be best to pass on to any other player as the how and why of the forehand (though you still may want to copy his forehand).

Racquet Features Combine with Strokes

The other complication when talking about racquet features is that they produce different results for different players. When we talk about increasing or decreasing power or control, we are talking about certain properties of the racquet. Put any racquet into a player's hand, however, and the result may be more or less power and control with respect to how and where the player is trying to hit the ball. The combination of any particular racquet with any particular kind of stroke may be complimentary or uncomplimentary to the desired result. In the same way, the "feel" and interpretation of that feel in the player's mind may cause him to change his stroke or tactics in ways equally favorable or unfavorable to the desired result. That is why so many players seem to hold such mutually exclusive and contrary opinions about the power and control of the same racquet (or string).

So, when we say that any specific racquet parameter or feature increases or decreases power or control, we are not saying that the end result for the player will be more power or control, but that independent of any player, the racquet demonstrates more power and control. The racquet is only an isolated entity in the lab, and lab results measure pure physics. A player swinging the racquet changes the conditions under which impact takes place. So, a new racquet will only perform relative to how it interacts with the strokes. The player doesn't change the physics, but the results of the physics might not match the player's intent.

No matter the control properties of a racquet, it has to be brought to the position, speed, and angle that the rebound off the racquet will be in the desired direction. A "true" rebound off a late racquet with "perfect control" does the player no good, and he has no control. A late hit off a "low control" racquet might be perfect though. The player's timing and stroke idiosyncrasies combined with the racquet's "control" will determine the direction and speed of the ball. So, making a world full of perfect control racquets could lead to less total control in the world of tennis, depending on how all these racquets interact with all the strokes.

One thing to keep in mind when choosing a racquet is that all performance variations (speed, spin, and direction of ball) due to equipment changes can be duplicated by changes in stroke. And likewise, small changes in strokes can be initiated by changes in equipment. As such, any change in equipment can either correct a deficiency in a stroke (relative to a racquet), or else require a change in stroke to accommodate the performance change initiated by the racquet. The ideal racquet for a player may be one that is "worse" or less "maximum" with regard to its lab-determined performance properties in order to "optimize" and "integrate" the racquet with the player's stroke.

Selecting a Racquet Is Art and Science

In light of the factors discussed so far, it is obvious that matching the correct racquet to the player will always be an art, but one that is more and more based in science. Similarly, there will never be one super racquet that fits all players. There will always be 200 models to choose from, and each will claim to have more of something or other than the competition. But "more" is not always more to a certain player. The player will choose the racquet that "feels" best, and he will then make up any number of performance reasons to justify his choice. Because the player has a vested interest in his racquet selection, some attention should be directed toward the care of the racquet.

Care of Racquets

Modern racquets are fairly rugged and don't need special care, unless you happen to be a good tennis player. The point here is that average tennis players tend to remain average regardless of what racquet they use, while good players need good racquets to compete at a serious level. At the elite and professional level, the care of a racquet is something that is so important that players often pay other people to look after them.

(Continues...)

Excerpted from Technical Tennis by Rod Cross, Crawford Lindsey. Copyright © 2005 Rod Cross and Crawford Lindsey. Excerpted by permission of USRSA.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

Dettagli dell'edizione

• Editore: Racquet Tech Pub
• Data di pubblicazione: 2005
• Lingua: Inglese
• ISBN 10: 0972275932
• ISBN 13: 9780972275934
• Rilegatura: Copertina flessibile
• Numero di pagine: 152
• Contatto del produttore: non disponibile
• Persona responsabile: non disponibile