Restring Tennis Racket Near Me? Trust The Answer

By: Tim Hahn, Owner of Aspen Hill Pro Shop

As a general rule, you should re-string as many times per year as you play per week. If you play twice a week, you should restring your racquet twice a year. All strings will gradually stretch and lose tension or go dead, even if you rarely play. When this happens, start swinging harder, gripping the racquet tighter to get the same results with the ball.

Swinging harder and gripping tighter makes control more difficult, fatigue sets in early and can even contribute to tennis elbow. fresh strings will help your racquet play the way it was intended. If you have questions about racquets or re-stringing please visit the Aspen Hill Pro Shop. Tim will be happy to help you. Tim is a member of USRSA, a Master Racket

Technicians, the Yonex National Stringing Team, and the USPTR.

My strings are fine for a few more months – I paid good money for them, they last, so what’s the problem?

The problem is that failing to change strings often enough can be detrimental to a player’s game and health. “Most people underestimate the effect a leftover string has on their game and their body,” says Dennis Fabian, Global Business Manager of HEAD’s Accessories Division.

Most serious tennis players will switch to a new set of racquets about every year. Top pros will change their racquets more often because they don’t want to leave anything to chance. However, some club players have been using the same frames for decades, relying on the maxim “if it ain’t broke, don’t fix it.” So is there a good reason to change your clubs frequently, or do you? Club players with their trusty old Dunlops have the right idea?

For a club player, a racquet frame can last a decade or more, but in the hands of a full-time player with powerful shots, it can wear out after a few months. Some players and their stringers are much rougher on frames than others, and their racquets degrade faster. Once racquets wear out, they feel different and need to be replaced.

Storing two to four racquets should prevent crises, but once they become too cracked or scratched you’ll need to change them anyway.

How long do tennis rackets last?

Racquets are typically made of fiber and resin. Frames are stressed by the forces exerted during play, especially when physically strong players are hitting big serves or aggressive groundstrokes. Eventually the fiber and resin will begin to break down and the racquet will lose some of its stiffness. As this happens very gradually, players may not notice the change.

Nonetheless, reducing stiffness affects the power and spin that can be generated from a frame and limits control. An expensive machine known as a “Racket Diagnostic Center” (RDC) can check for deterioration by measuring frame stiffness. Without this, you’ll likely have to rely on general guidelines to determine how long your clubs will last.

For a large racquet that practices regularly and plays tournaments, racquets last about 1 year and tend to lose stiffness after that. A club player who doesn’t hit the ball particularly hard and takes care of his clubs can easily last 10 years or maybe longer.

Variables affecting racket life expectancy

The lifespan of your racquet is influenced by several factors. How often you play will clearly be one of them and how hard you hit the ball. Some others may be less obvious. Racquet frames must be stored properly: they could be damaged by excessive heat or cold.

The stringing process is also critical. The string is usually of fairly high tension and needs to be removed carefully, and the clamps that hold the racquet in place during stringing should not be too tight. If the stringer is careless or its clamps have seen better days, damage can result. Each time the racquet is re-strung there is a risk of damage, so frequent re-stringing can also shorten the life of the frame.

Of course, a racquet can also be damaged during play, whether from scratches on a hard court or intentionally hitting the ground in anger. Pros can afford to throw their racquets around, but for amateurs it can become an expensive habit: once a frame breaks, it’s useless.

How many tennis rackets should you have?

If you’re a club player, two racquets should be enough. If you break a string or even a frame, you’ll get by with a spare line in your bag. Just make sure you only use one of the racquets until its string breaks so your spare doesn’t get used. Carrying two worn-string racquets puts you at risk of breaking both during a game and running out of one.

As a tournament player you should have enough racquets to last a two week tournament trip without having to resort to a potentially expensive and iffy local stringing service, so four or five should be adequate. Full-time pros might take ten or more and re-string them in batches for each event.

Signs that it may be the right time for a new racquet

If you don’t have an RDC, you probably won’t notice the gradual degradation of your racquet frame. Still, other things may indicate that they need to be replaced. As you play hard courts, the outer portion of the frame will gradually wear out as it gets scraped across the court every time you retrieve a low ball.

This is easy to spot and if the wear is significant then it is likely that your racquet’s weight, balance and stiffness have changed and it is more likely to break. Even worse is the dreaded crack. If you discover a crack in your frame, it will no longer function as it used to and you will need to replace it immediately.

Should you switch clubs even if they’re still good?

As you are young and getting bigger and stronger you may need to switch to a heavier racquet even if the one you have is in good condition. Serious adult players need to change racquets regularly to avoid the effect of gradual loss of frame stiffness, even if the racquets still look good. For club players, your racket should last for several years: if it suits you, there is little point in going through the hassle of changing it frequently.

Final Thoughts

Take care of your racquets, find a good stringer and you’ll put them to good use. Beware of gradual deterioration, but you won’t benefit from changing your racquet just to get the latest style.

Tests were conducted to measure changes in string properties and performance due to repeated use. Parameters measured included string tension, stiffness, peak force, energy return, dwell time, deflection, vibration frequency, and coefficient of friction between strings. Measurements were taken using test equipment to simulate shots and strung racquets measuring spin, speed and rebound angle. The results showed that the so-called string death is mainly due to the consequences of a decrease in lateral stiffness and an increase in static and sliding friction between the main and cross strings. Together these explain most of the player’s perceptions and complaints about strings going “dead”. (Note: Part 2 of this article is here: How Strings Go Dead – Part 2

Given these hypotheses, we set out to find out what happens to a string such that the “backlash” phenomenon can include seemingly contradictory statements that the string has too much power, is stiffer, and injures the player’s arm.

A side effect of the lateral movement of the main string is that it softens the feel of the string bed. If the net moves less easily or not at all, the impact shock will feel greater. Another good candidate for string death.

The other defining feature of the poly is its spin potential. The added spin of polyester comes from the lateral movement and snapback of the main strings. Decreasing the efficiency of this glide and snapback would reduce spin and would certainly count as “dead motion”. The string bed works in two planes, perpendicular and parallel to the racket head. Most players are more familiar with the vertical performance and describe their stringbed perceptions in terms of this conceptual vocabulary. But with the advent of widespread use of polyester, events on the stringbed have become more obviously three-dimensional, and our descriptions and research will evolve to reflect that fact.

We start by asking what makes a poly a poly in terms of performance. Most players agree that its distinctive feature is that it’s dead – it’s stiff, deforming the ball more and losing more energy as a result. The player can therefore swing each ball without hitting it over the fence and feels like they have more control. So getting even deadlier in terms of power delivery is probably not what the player feels when they say the strings are dead. Instead, the opposite is true – the strings lose their deadness and get stronger, or at least the ball keeps moving and the player feels like they’ve lost control and the string has taken over.

At impact, the only information the player has is the shock and vibration at the grip. The player feels that. He then interprets and describes the sensation of that feeling. Additional information also contributes to the interpretation – the sound, where did the ball land, what was the trajectory like and did I win the point, the game, the match? These considerations point to two directions in which to look for an answer—which changes to a string will change (a) the strike signal to the player and (b) the string’s performance on the court. In other words, what happens to a string to change the forces felt and/or the speed, spin and angle of rebound from the racquet?

It is often tempting to dismiss many such descriptions as imaginary, as they sometimes contradict scientific research. But tennis players are a finely tuned bunch, and when they say something has changed in stringbed or racquet performance, they’re usually right, even if their descriptions of what’s happening end up being missed or wrong. After all, how can two completely opposite descriptions of a dead string be correct? Well, as this research will show, it appears they can.

These are strange and contradictory descriptions of the dead strings. Some players experience too much string action and others experience a complete loss of string action. And these opposing opinions can be on the same string. Players can agree on how a string feels when it’s freshly strung, but disagree on how it feels after a match or two. Presumably, string properties change the same way with repeated hits for all players with a similar playing style, whether experienced in the same way or not.

Tennis players often complain that a tennis string, especially a polyester string, “goes dead”. It is generally described as occurring after 2-20 hours of gameplay. This phenomenon has different and often conflicting descriptions. Some of the descriptions are these:

THE EXPERIMENTS

The following tests were performed on nylon and polyester strings:

Repeatedly striking a single string with a pendulum hammer to measure changes in tension, stiffness, peak force, stroke excursion, and duration.

Repeated hits on a strung racquet by dropping a 20-pound kettlebell from a height of approximately 10 inches and then measuring the speed, spin and angle of high-speed ball rebound.

Hitting a strung racquet with a “stack driver” hammer to measure the peak force of the string bed and the duration of hitting after repeated hits.

Measurements of racquet vibration frequency after shots.

Coefficient of static friction between strings after repeated sliding under pressure.

Coefficient of sliding friction between strings after repeated sliding under pressure.

RESULTS

1A pendulum hammer tests

Several nylon and polyester strings were selected to obtain a range of scores for each string property. More polyester strings were tested as it is far more common to hear that polyester strings are dead compared to other materials. Consequently, the nylon strings were used as the baseline. The strings are shown in Table 1:

Table 1

Tested strings with Pendulum Hammer Brand String material Reference Tension (lb) Number of strokes Babolat RPM Team 16 Polyester 62 800 Dunlop Black Widow 16 Polyester 62 800 Gamma TNT Touch 16 Nylon 62 800 Gamma TNT2 16 Nylon 62 4000 Cherry Pro Line X 16 Polyester 62 800 L-Tec Premium 3S 17 (1.25) Polyester 62 800 Luxilon 4G 16L Polyester 62 7000 Luxilon Big Banger 16 Polyester 62 4000 MSV Focus Hex 17L (1.18) Polyester 62 5500 Polyfibre TCS 1.30 Polyester 62 2000 Prince Syn Gut Original 16 Nylon 62 4000 Prince Tour 16 Polyester 62 3000 Solinco Tour Bite 16 Polyester 62 9000 Tecnifibre NRG2 16 Nylon 62 2000 Tourna Big Hitter Black 7 17 Polyester 62 3000 Wilson NXT 16 Nylon 62 3500 Table 1 – Strings tested with pendulum hammer.

The strings were tensioned to 62 pounds. As shown in Figure 1, a pendulum hammer, weighted to produce a peak force equivalent to that encountered during a 120–140 mph impact on a single string, was lifted and released in multiples of 100, 500, or 1000 repetitions. After each set, another hit was performed to measure tension, peak force, longitudinal and lateral stiffness, hit duration, and string deflection. Not all strings have been tested equally. Some were affected only 800 times, others up to 9,000 times.

Figure 1 – Structure of the pendulum test. The load cell and photocell are connected to an oscilloscope where changes in voltage, string deflection and time are displayed. This information is used to calculate longitudinal and lateral stiffness, peak force and energy return.

LOSS OF VOLTAGE. The most talked about phenomenon of string performance is that all strings lose tension the second they are placed in the racquet – up to 15 pounds in a minute. Polyester sheds more than nylon, which sheds more than gut. Strings stabilize quickly after the first few minutes. But they lose a lot of tension in the first few hits, up to 20 pounds in 20 hits on the test machine. But here, too, they are stabilizing somewhat. But even after losing 20-35 pounds before a game, stiffer polyester strings can create a stiffer stringbed than softer nylon strings, which only lose a few pounds. None of this temporary loss of tension is that important. The most important thing is how the string feels when you start playing and, if you like that feel, how long the string keeps that feel.

What is important is how the string changes after it has been played in. We were interested in what happens to the string after 100 test hits. At this point, most strings have reached their stabilized rate of degradation. Figure 2 shows how the tension decreases as the number of hits increases.

Figure 2 – Absolute change in tension after the first 100 beats. The reference tension for all strings was 62 pounds. Each string had a different tension after the 100 beat break-in period.

Figure 2 clearly shows the different initial tensions after being cocked to 62 pounds and then hit 100 times. The range of tension difference is about 30 pounds for 100 hits and about 40 pounds for the projected 10,000 hits. This is an exceptional difference from strings that all started at the same tension. But does it matter?

Maybe it’s not the absolute change in voltage that matters, but the rate of change? The different rates of voltage drop are not fully apparent from Figure 2 – the curves all look almost parallel to each other. Figure 3 corrects this and shows the percentage change in tension of each string relative to its own tension at 100 beats. Each string starts at 100%, although the absolute value at which they start can be radically different due to all the preliminary tension losses described above in Figure 2.

Figure 3 – Percent tension change after stringing and break-in.

While Figure 2 highlights the absolute stresses but not the degree of stress change, Figure 3 shows the degree of change relative to the initial stress at 100 beats. The strings are in the same order in both diagrams, but Figure 3 shows a greater separation between the strings in their relative tension loss – perhaps 2-3 separate clusters.

But a string that starts at 50 pounds and loses 5 pounds loses 10% of that tension and a string that starts at 10 pounds and loses the same 5 pounds loses 50%. Can the same 5 pounds feel radically different to a player depending on their initial tension? The answer is that what you perceive as stringbed firmness depends on both the string property known as stiffness and tension. So the feeling of dropping 5 pounds depends on the stiffness of the string dropping the 5 pounds.

STIFFNESS. We are concerned with two types of dynamic (shock) stiffness – longitudinal (k) and perpendicular (k p ). We measure longitudinal stiffness as the force required to stretch a string of a given 1 inch (lb/in) length:

F = kx

where F is the longitudinal force along the string, x is the strain, and k is the longitudinal stiffness. In a string, the force is the increase in tension. Solving for longitudinal stiffness we get:

k = F/x

The more you stretch a string, the more force is required for each additional stretch, and the string supposedly becomes stiffer. But some strings require more force for each additional stretch than others. In other words, the more an impact stretches a given string, the higher the stress will be during the impact, and it will be higher with stiffer strings.

Perpendicular stiffness is measured as the force required to push a stretched string 1 inch sideways:

F p = k p y

where F p is the perpendicular force, y is the deflection and k p is the perpendicular stiffness. Solving for perpendicular stiffness we get

k p = F p /y

These stiffness formulas look very similar, but as we’ll see, they give very different numbers. (NOTE: See Appendix A for more explanation of longitudinal and lateral stiffness.)

So the question is whether a change in either type of stiffness will cause the string to die. Figure 4 shows the change in longitudinal stiffness with decreasing stress (i.e. with increasing impact).

Figure 4 – Change in longitudinal stiffness with decreasing stress (i.e. with increasing impacts).

It can be seen from Figure 4 that for all strings measured, the polyester strings are equally stiff or stiffer than the nylon strings at any longitudinal tension. This is important because nylon strings aren’t typically described as dead, so they serve as a kind of baseline. Remember, all of that tension is the result of originally pulling the tension to 62 pounds and then hitting it 100 times.

Figure 5 shows the change in lateral stiffness with decreasing stress.

Figure 5 – Change in lateral stiffness with decreasing stress (i.e. with increasing impacts).

Figure 5 shows a completely different picture compared to Figure 4. The polyester strings (all not in the “Nylon” box) have the same or less transverse stiffness than the nylon strings. It takes less force to move these strings sideways a given distance than nylons. This is very interesting. These strings are easier to deflect than the nylons, and when the tension is released they become even easier. This is despite being inherently stiffer longitudinally at all tensions. They are more difficult to stretch but less difficult to deflect than the nylons.

DEFLECTION AND DWELL. Does this show up in our deflection measurements? Does the deflection for each string increase as the tension decreases? Figure 6 shows that this is the case.

Figure 6 – Change in deflection with decreasing stress (i.e. with increasing impacts).

Figure 7 shows the same for dwell time vs. voltage.

Figure 7 – Change in dwell time with decreasing stress (i.e. with increasing strokes).

Figure 6 shows that although virtually all polyester strings have less tension than nylon strings, half deflect about the same amount as nylon and half deflect more. Figure 7 shows a similar phenomenon for dwell time: half of the polyesters have about the same dwell time and the other half have a longer dwell time than the nylons. What does that mean? A longer dwell time means that the ball stays on the strings a greater distance of the hitting arc, thereby launching with a higher and/or wider trajectory. And more stringbed deflection could further change the rebound angle depending on where on the stringbed you make contact. Together, greater deflection and dwell time can cause the ball to fly longer and wider, depending on the horizontal and vertical arc of the shot at impact. Then your controller may be dead.

Figure 8 shows a very dramatic relationship between lateral stiffness and residence time. As transverse stiffness decreases, residence time begins to increase more and more rapidly. Perhaps a player can feel this extra dwell time or notice the longer, wider, higher trajectories associated with it.

Figure 8 – Change in dwell time with decreasing transversal stiffness.

So we seem to have evidence that changing string characteristics can lead to flying balls, loss of control and too much power as many players have complained about. One facet of string dieback is that control falls off due to increased dwell time and the resulting change in launch angle. Polyester’s magic of taking power from punches and returning it to the player’s punch is dead. Its deadness is dead.

(NOTE: See Appendix B for “fingerprint” plots of all parameters of each string.)

If low tension and vertical stiffness are the necessary conditions for “going dead” syndrome, does that mean that strings that stay above an absolute threshold of tension and stiffness don’t or can’t go dead? That can’t be because many higher tension strings are also supposed to be dead. We have only identified one way of dying. There needs to be more to explain the scope of strings that are marked as such and why they do so. Next we will analyze the rebounds of a fully strung racquet to see if we can find changes in string parameters that result in changes in performance (i.e. speed, spin and rebound angle).

1B. Racquet and kettlebell test

A Wilson Pro Staff Six.One 100 was strung at 52 pounds with Dunlop Black Widow 16, Polyfibre TCS 16 and Solinco Tour Bite 16. A Wilson Steam was strung at 52 pounds and tested with Solinco Tour Bite 16. Each setup was subjected to hits with a 20-pound kettlebell dropped from about 10 inches. After each group of hits, scissors were used to move the strings back and forth to simulate lateral string movement wear that was not seen with the vertical kettlebell drops. Scissors were placed in five adjacent string squares and opened 50 times, moving each string 100 times in the striking area. The combination of the kettlebell drops and the scissor motion was designed to outperform the normal impact of a ball, thus accelerating any possible property changes. However, the string movement was not performed under perpendicular loading, as that would be the case in an impact and therefore may not have had the desired effect. Screens 1 and 2 show the techniques for hitting the racquet and moving the strings.

movie 1

Racket Stroke Technique > << >> [] Big Screen 1 — Kettlebell Drop.

movie 2

String Movement Technique > << >> [] Movie Screen 2 — Technique for simulating string movement and wear.

After each series of kettlebell drops and scissors, balls were shot at the hanging racquet to measure rebound speed, spin and angle. The goal was to observe any change in performance characteristics due to repeated impacts. Because the speed, spin, and angle of balls fired from a ball machine vary slightly from shot to shot, these input parameters have been normalized (method described in the Spin and Material article) to be the same for a given racquet . Each racquet has been normalized separately because we are interested in performance changes for a specific racquet, not between racquets. About 15 balls were fired and measured after each series of kettlebell drops. Table 2 shows the average results.

Racquet Brand String Number Beats Speed ​​In (mph) Spin In (rpm) Angle In (degrees) ACOR Spin Out (rpm) Angle Out (degrees) Wilson Pro Staff 100 Dunlop Black Widow 16 1 50.3 334 26.1 .403 1455 34.1 Wilson Pro Staff Six .One 100 Dunlop Black Widow 16 800 50.3 334 26.1 .375 1505 36.3 Wilson Pro Staff Six. A 100 Dunlop Black Widow 16 2000 50.3 334 26.1 .374 1535 37.3 Wilson Pro Staff Six. Six per staff. A 100 Polyfibre TCS 16 500 52.4 445 25.9 .384 1618 36.2 Wilson Pro Staff Six. A 100 polyfibre TCS 16 1500 52.4 445 25.9 0.393 1603 36.0 Wilson Pro Staff Six.one 100 Polyfibre TCS 16 2500 52.9 0.393 1618 35.4 445 25.9 0 Wilson 100 Solinco Tour Bite 16 1 52.8 351 28.3 .417 1757 37.7 Wilson Pro Staff Six.One 100 Solinco Tour Bite 16 300 52.8 351 28.3 .423 1666 36.6 Wilson Pro Staff Six.One 100 Solinco Tour Bite 35 1.30 28.3 .424 1693 36.8 Wilson Pro Staff Six.One 100 Solinco Tour Bite 16 1800 52.8 351 28. 3 .419 1730 37.2 Wilson Pro Staff Six.One 100 Solinco Tour Bite 16 3000 52.8 351 28.3 .425 1697 37 .3 Wilson Pro Staff Six.One 100 Solinco Tour Bite 16 4000 52.8 351 28.3 .411 1700 37.2 Wilson Pro Staff Six.One 100 Solinco Tour Bite16 3000 37.2 16 5800 52.8 351 28.3 .405 1719 37.1 Wilson Pro Staff Six. One 100 -Turna -Big -Hitter Black 7 17 1 53.2 269 26.2 .376 1394 35.2 Wilson Pro Staff Six.one 100 Tourna Big Hitter Black 7 17 2300 53.2 269 26.2 .357 1452 36.5 Wilson Dampfer 105S Solinco Tour 3 16 1.8 Bite 0.357 25.4 .389 1554 33.8 Wilson Steam 105S Solinco Tour Bite 16 1000 50.8 361 25.4 .393 1559 33.5

Table 2 – Strings tested with kettlebell strikes.

Table 2 shows that performance in each category changed very little due to repeated abuse. At first glance, this seems to say that changes in string properties due to repeated use will not affect performance. Last but not least, we hypothesized that the increased dwell time due to the loss of tension would produce a higher and wider launch angle as the ball stays on the club for a longer swing arc. The data in Table 2 do not contradict this hypothesis. Increased dwell time does not affect the angle of rebound from a freestanding racquet. The racquet does not rotate sufficiently during impact, particularly during the peak power phase, to launch the ball at a different angle. But during a swinging impact, the face of the racquet can move through an angle large enough to alter the ball’s trajectory during impact. We were also unable to measure the dwell time with our high-speed rebound test. To do this, we ran the next test – the “Stack Driver” test.

1C Racket Pile Driver Test

To test if racquet dwell time has actually increased and to see if peak power changes, we ran a “stack driver” test. The racquet was placed horizontally on the table with supports under the toe and neck. The string bed was under a steel bar loaded with about 8 pounds including the bar and fitted with a force gauge connected to an oscilloscope. The shaft hammer should strike 4.5 inches from the inside tip of the racquet, near where the kettlebell and ball impacted. The stick was raised about 14 cm above the racquet and dropped, releasing about 5 joules of energy on impact. The peak force and dwell time of the ram head were measured. This test was done with only one string – Polyfibre TCS 16. Measurements were taken after each series of kettlebell drops described above. The results are shown in Table 3.

table 3

Peak power and dwell time of pile driver after kettlebell drops Club brand String number

Reaches Peak Force

(lb) residence time

(mph) Wilson Pro Staff Six.One 100 Polyfibre TCS 16 1 141 33.5 Wilson Pro Staff Six.One 100 Polyfibre TCS 16 500 135.5 35.72 Wilson Pro Staff 100 Polyfibre TCS 16 1000 136.5 35.75 Wilson Pro Staff Six.One 100 Polyfibre TCS 16 2000 136.5 38.85 Wilson Pro Staff Six.One 100 Polyfibre TCS 16 3000 136.5 37.91 Wilson Pro Staff Six.One 100 Polyfibre TCS 16 4000 138.1 36.73 kettlebell impact.

The results in Table 3 are somewhat confusing. For the first 2000 kettlebell hits, peak power decreased and dwell time increased. This is as you would expect as the tension decreases with the hits and is consistent with our single string tests above. However, at 4000 hits, peak force increased and dwell time decreased. More hits would be required and more strings would be tested to see if it was a reversal or an outlier.

1D Racquet vibration frequency test

As a final test with the fully strung racquet, we measured the vibration frequency of the Polyfibre TCS setup after each series of kettlebell hits. This test was performed to see if there were any changes in vibration that a player could feel when the tension was released, which could be interpreted as string death. As Table 4 shows, there was no change in vibration frequency due to changes in string properties. At least for this one racquet setup, that would argue against the change in vibration as the player’s perceived indication of a property change.

Table 4

Racket Vibration Frequency by Kettlebell Drops Racket Brand String Number

Hits vibration frequency

(Hz) Wilson Pro Staff 100 Polyfibre TCS 16 1 152 Wilson Pro Staff 100 Polyfibre TCS 16 500 151 Wilson Pro Staff 100 Polyfibre TCS 16 2000 152 Wilson Pro Staff 100 Polyfibre TCS 16 3000 154 Wilson Pro Staff 100 Polyfibre TCS 16 4000 152

1E. Coefficient of Friction Tests

One of the hallmarks of polyester strings is the sideways movement and snapback of the main strings. The snapback is the main contributor to the added spin and higher launch angle that polyester provides. The lateral movement will also soften the power parallel to the string bed. The main factor in determining range of motion is the string-to-string friction between the mains and crosses. If this friction is low, the strings will move, and if it is too high, they will not move. For a given impact force, the measure of how much friction there will be depends on the coefficient of friction (COF). This is a measure of all of the factors that cause strings to stick together and prevent motion—atomic attraction, atomic-level fit of adjacent topographies, and relative deformation. Friction between strings comes in two forms – static and sliding friction. Static friction resists initiation of movement between strings, and sliding friction resists and retards movement once initiated. Each has its own coefficient: the static coefficient and the sliding coefficient. The static coefficient is generally larger than the sliding coefficient. The friction formula is

F = µN

where F is the frictional force, μ is the coefficient of static or sliding friction, and N is the normal force perpendicular to the surface, pushing the two surfaces together.

Increasing either or both coefficients would decrease the amount and rate of sideways movement of the main string. This in turn would increase the perceived impact force, stiffen the string plane parallel to the string bed, decrease spin and decrease the angle of impact. In short, the racquet would feel harder, stiffer, less powerful and without spin production – i. H. the other side of the player-reported perception spectrum.

To determine whether or not the COFs changed with repeated use, we both measured using the TWU apparatus developed for this purpose (these are described in the articles “Static Friction and Rotation” and “Sliding Friction and Rotation”). The results are shown below in Figures 9-12. These graphs are more chaotic than the ones above that plot the other string parameters. One reason is that the friction devices were designed to measure friction “out of the box”, which does not require fitting strings into notched grooves when sliding up inclines. As a result, there is more spread in curve fits as strings sometimes “jumped the tracks”. The other part of the mess is that each string seems to respond differently to wear compared to others. It is these different amounts and rates of change that indicate not only the degree of string death, but also that some strings will die sooner or later than others. That’s exactly what players report.

Figure 9 shows the actual static COF versus repetitions and Figure 10 shows the COF as a percentage of the first repetition value. Figures 11 and 12 do the same for the sliding COF. The only difference in the plot is that the curve fits for the static COFs are polynomial fits and they are logarithmic for the moving COFs. These were chosen simply because they best represent the data to see the trends. In addition, the number of iterations for the rolling COF tests was typically lower due to the logistics of the testing process.

Figure 9 – Static COF vs. Reps.

Figure 10 – Percentage of initial static COF versus reps.

Figure 11 – Sliding COF vs. Reps.

Figure 12 – Percentage of starting sliding COF versus reps.

The data shows that both static and sliding COF tend to increase, although for some strings static COF first decreases before increasing. The data also shows that the COF of some strings increases faster than others. The question is, however, at what value of either COF do you start noticing a change in performance? Regardless of this level, it must be assumed that nylon COFs are generally greater than this threshold starting at installation. Wenn ja, dann wird eine Erhöhung des COF bei Nylon nicht so stark wahrgenommen, weil sich die Saiten von Anfang an so wenig bewegen. Die Polyester hingegen haben einen niedrigen Out-of-the-Package-COF, wodurch Längs- und Quersaiten gegeneinander gleiten können. Somit würde für Polyester eine Änderung des COF bemerkt werden, die diese Bewegung begrenzt.

Davon abgesehen enthüllen die Daten eine Anomalie, die ein interessantes Rätsel aufwirft. Einige Nylonsaiten gehören zu den niedrigsten statischen und gleitenden COFs (diese Saiten wurden mit zwei verschiedenen Saitensätzen getestet, um die Daten zu bestätigen). Dies widerspricht unserem Verständnis, dass sich Nylonsaiten nicht so effizient bewegen und zurückschnappen wie Polyestersaiten. Zwei Hypothesen stellen sich auf, warum dies so sein kann. Erstens hält Nylon die Spannung besser als Polyester, sodass Saiten in einem bespannten Schläger eine höhere konstante Kraft haben, die die Saitenkreuzungen zusammendrückt, was die Haftung und das Einkerben erhöht und als Ergebnis die Bewegung einschränkt. Zweitens fördern die zum Testen der Saiten verwendeten Friction Rigs nur Kerben in der simulierten Hauptsaite und nicht in der Quersaite. Das Kreuz wird stattdessen für die gesamte Strecke abgeflacht, über die die Hauptrutsche darüber gleitet. Das Testen so vieler Saiten ließ den Saitenkreuzungen keine Zeit, längere Zeit unter Druck zu bleiben und somit sowohl die Längs- als auch die Quersaite einzukerben. Da weichere Nylons dazu neigen, leichter einzukerben als Polyester, würde dies dazu neigen, die COF-Messung von Nylons mehr als von Polyestern zu beeinflussen. Kerbversuche müssen also noch durchgeführt werden.

HINWEIS: Siehe Anhang C für kombinierte Diagramme des statischen und gleitenden COF für jede Saite.

CONCLUSION

Die Daten liefern Beweise, um die Spekulationen vieler Spieler über die Ursachen und Wahrnehmungen des Absterbens von Polyestersaiten zu stützen. Die geringeren Spannungen und Quersteifigkeiten vieler Polyester führen zu längeren Verweilzeiten und größerer Durchbiegung. Dies hält den Ball für einen längeren Schlagbogen auf dem Schläger, was möglicherweise zu “Kraft”-Problemen führt, wenn der Ball tiefer, weiter und höher als gewünscht geht. Die Abnahme der Quersteifigkeit trägt auch zu dem Gefühl bei, dass die Saiten “matschig” werden oder sich wie ein Trampolin verhalten. Ein Kontrollverlust ist die Folge. Ferner kann somit der Hub selbst beeinflusst werden, um die Änderungen in der Saite zu kompensieren.

Auf der anderen Seite der Medaille verringern zunehmende statische und/oder gleitende Reibungskoeffizienten den Betrag und die Effizienz der seitlichen Hauptsaitenbewegung und des Zurückschnappens. Dies wiederum verringert den Spin, senkt den Startwinkel und versteift das Saitenbett parallel zu den Saiten. Dies wird als Kraft- und Spinverlust sowie als Zunahme von Steifheit, Härte und Schmerzen wahrgenommen, insbesondere wenn der Spieler zum Ausgleich noch schneller zu schwingen beginnt.

Wenn es nur so einfach wäre. Es scheint, wann immer ein kausaler Faktor wirkt, um eine Leistungsvariable zu erhöhen, gibt es einen anderen, der diese Variable verringert. In diesem Fall nehmen die Spannung und die senkrechte Steifheit mit den Wiederholungen ab, was das “Kraft” -Verhalten der Saiten erhöht, und die Wiederholungen erhöhen die Reibungskoeffizienten, wodurch sich die Saiten steifer und weniger kraftvoll anfühlen. Und dann, in einer anderen Wendung, sollte die Abnahme der Spannung auch die Reibung zwischen den Saiten verringern. Die Saiten gewinnen und verlieren also gleichzeitig an Kraftverhalten oder an Steifheits- und Weichheitseigenschaften. Es ist der Nettoeffekt, der die Wahrnehmung des Saitenspiels durch den Spieler bestimmt.

We offer two Ontario based retail locations. One is located in Toronto (1621 Bayview Ave.) and the other in Oakville (361 Cornwall Ave.). Click here for more details.

Badminton racquets become unusable when their strings are broken, damaged, or have no tension. A racquet can be damaged through normal wear and tear. Hand stringing a badminton racquet is safe and does not require any special machines or tools. To get a racquet ready to play again, all you need is a racquet frame, undamaged strings and patience!

Recreational badminton players can get back on the court without spending money on a new racquet or professional stringing services.

A: Yes, racquet frames will eventually “soften”. Over time, various stresses add up and eventually destroy the fibers and resin that make up your racquet, resulting in a frame that’s less stiff than it used to be. The change is very, very gradual and usually occurs slowly over many years, making it difficult to detect by just hitting the club. Some very observant players seem to be noticing it and have told me that they feel like their frame just doesn’t have the same feel or pop as it used to. The only way to objectively measure “softening” is to use a Racquet Diagnostic Center (RDC) to measure the stiffness of the frame. To accurately measure stiffness loss over time you would need to record a basic stiffness measurement when the frame is brand new and then continue measuring over time to track how much the stiffness has decreased. However, RDC machines are quite expensive, so unless you have access to one at your local pro shop, this probably isn’t a practical route.

To complicate matters further, the exact time frame the “softening” process takes varies based on a number of different contributing factors including – but not limited to – how hard the player hits the ball, how often the frame is used where the frame is stored, string tension, how often the frame is re-strung, and how careful the stringer is when stringing. There’s really no set deadline – it just depends. The good news is that there are several things you can do to prolong the effective life of your tennis racquets.

Choose an experienced, conscientious and careful stringer. Re-tensioning is actually one of the more stressful things a frame can go through, but that doesn’t mean you should avoid it! It is truly akin to the routine maintenance of a car, keeping your racquet performing as it should. A careless or inexperienced stringer can shorten the effective life of your racquet or possibly even cause immediate damage to the frame. An experienced stringer using a quality machine can minimize the stress on your frame during the stringing process and extend the life of your frame. Store your racquets in an air-conditioned area. Extreme temperatures and temperature changes are not good for your clubs. Don’t leave them in a sweltering car in the summer or in an unheated shed in the winter. Storage in a climate controlled area at room temperature will minimize damage from temperature extremes and temperature changes. Don’t hit your racquet, throw your racquet, bounce your racquet, or use your racquet to bang a ball out of a fence. While a few bumps and scrapes are inevitable during play, staying away from the above behaviors will save your racquet additional stress it doesn’t need.

I’m not sure if there is a “right” answer to this question, if it’s time for you to look at a new frame, and it’s hard for me to say for sure – it really just comes on it. Based on my experience I will say this: Ten years is quite a long time to use a frame, although I’ve seen people play very well with even older frames. If you play regularly (1-3 times a week) and have your racquet re-strung regularly (which you should), it may be time to try new frames.

How much has racquet technology evolved over the last 20-30 years? There are many answers to the question: are modern racquets better than old ones?

Tennis rackets have not changed massively in shape, size and material in the last 20 years. The move from wood to graphite was massive in the ’80s, but how much has changed since then? Are modern racquets better than old ones?

So what is modern and what is old? At a time when technology is evolving at the speed of light, ten years is a long time. 20 years is huge and 30 years is a whole different world. But clubs definitely don’t move as fast as electronics. Some might argue that not much has changed at all, and there are those who definitely prefer older racquets to modern ones.

Let’s start by looking at what has changed.

What has changed in clubs?

Along with minor material updates, larger head sizes and thicker bars are more common today. Let’s list it.

Head sizes have increased overall – most models today are 100 square inches.

Bar Thickness – The most popular racquets have thicker bars, ranging from 23-26mm.

Stiffness – Older racquets used to be very flexible (RA 50-60), now they are stiffer (65-75).

More Open String Patterns – There are more racquets today with open string beds like 16×19.

Lighter – Rackets are much lighter on average

These are the most common trends in racquets. Racquets have gotten bigger, lighter, stiffer, with more open string patterns and thicker bars. That doesn’t mean there aren’t more old-school racquets on the market. Medium sized racquets (90-93 square inches) are still available. There are racquets with very thin beams. And tight string patterns have made a small comeback with more 18×20 models being released in the last two years.

Why are we seeing these general trends?

Tennis has gotten faster. Players are fitter, move better and hit with more club head speed. Due to the changed swing mechanics (windshield wipers, more racket deceleration) they need lighter rackets (swing faster) that provide better topspin (open patterns and spin grommets). The faster pace requires the racquet to offer a little more power (higher stiffness). And because of the faster swing, they need more forgiveness (bigger head size, bigger sweet spot).

That all makes sense. And for a while, racquets like the Babolat Pure Drive really fueled this trend. Other brands followed suit with similar racquet models.

Then, in recent years, there has been a countertrend. Players suffered from wrist problems and tennis elbow due to the stiffer and lighter racquets (strung with stiff polyester strings at high tension). The Wilson Clash, HEAD Gravity and Prince Phantom came out trying to find a position between modern and old school racquets. That meant: a larger sweet spot, a semi-thick bar, a slightly more open pattern, but a more flexible frame for better shock absorption.

So why not use older clubs?

As you may know, many pros use older racquets that are painted to look like the latest model. Tennis players are definitely sensitive to change. For a professional player, the racquet needs to feel like an extension of his arm.

For this reason, many pros use the racquets they have always played with. But they’ve hit millions of tennis balls and can always hit the sweet spot.

Because of this, I think most recreational and club players should use more forgiving racquets. Most older racquets are heavy and/or have a small sweet spot. I really love the HEAD Pro Tour 630 (waiting to test the HEAD Pro Tour 2.0 reissue) but I know I won’t be playing my best tennis with it. Maybe once or twice, but not on average.

Does forgiven mean stiff?

no You don’t need to use stiff racquets and risk injuring your elbow and wrist. Today you can find racquets with a large sweet spot and a slightly more flexible feel. I don’t think there is no reason for players below NTRP level 5.0 to use head sizes less than 100 square inches (unless they really prefer the slightly faster feel of 95-98). In my last post on top 3 racquets for intermediate players, I listed HEAD Gravity MP, Wilson Clash 100 and Prince Phantom 100X 305 as three excellent options for the modern game without being stiff and lacking in feel.

The smaller the head size, the more weight you’ll need to create a decent sweet spot. And a 100 square inch racquet can provide good control despite the larger head size. Players under 5.5 rarely need the precision of a 95 square inch racquet. (Tennis is a matter of feeling and taste, so of course this is very personal.)

So forgiveness doesn’t have to be stiff. If you like stiff racquets, that’s fine too. But they are generally not recommended for players with arm problems.

summary

I love to play with classic racquets from time to time. And I’m using a 1997 racquet which is still forgiving and easy to play (read my Babolat Soft Drive review). But I don’t see myself returning to anything like a 95 square inch racket any time soon. I better play with a little more real estate.

Tennis technology has evolved slowly. Some materials come, go, and come back. Quality control may have deteriorated in most cases. So there are no definite answers to the question: are modern racquets better than old ones? Some are, some aren’t. There are racquets that are 20-30 years old that work well today. And there are modern racquets that play better than most old-school racquets. A good bat is a good bat. What you choose is up to you.

hp And if you don’t know what to get, check out the Tennisnerd Advice Service. DS.

Rule of Thumb – Well, you may have heard the rule of thumb that says you should restring your racquet as many times per year as you play per week. So if you play three times a week you should restring about three times a year. I think that’s probably a pretty good rule, and if you don’t want to think too much about re-stringing or aren’t even sure when you last re-stringed your racquet, you can follow this rule and it’s good. Instead, here are some other pointers to look for and watch out for in order to know when to restring a tennis racquet:

String Appearance – The easiest way to know when it’s time to tighten is to notice how your strings look. If your strings are fraying or looking ragged, the strings will start to loosen and you won’t get as much spin or power when you hit the ball. If your strings are looking scratchy, it’s definitely time to re-string them.

The Sound of Hitting the Ball – If you find that the sound of hitting the ball is not normal or familiar, it may be time to re-string the string. As your strings wear out, they won’t be as springy, and you may only notice this at first by a change in the tone of your hits.

The Feeling When You Hit the Ball – As your worn strings lose or have lost their elasticity, you may notice a dull or dead feeling when you hit the ball. The ball just doesn’t bounce off your racquet like you’re used to, especially on your groundstrokes. You may feel like you have to hit the ball harder just to get it to go the same distance as it used to.

Time Since Last Stringing – You may feel like you need to re-string just because it’s been so long since your racquet had new strings. This could be especially the case with a racquet you haven’t played with in a long time. And while the strings on this racquet look good, you’ll benefit so much from new bouncy strings that it might be worth the reasonable cost.

Well if you’ve decided, hey, it’s time to re-string but aren’t sure how to go about it, speak to Matt for more information

How often should you restring your tennis racket?

Ask any racquet stringer or tennis shop owner what is the number one question they get asked every day and many of them will answer you, “Do I need to re-string my racquet?” “When will I know it’s time to re-string?” ”

While this is a frequently asked question, it’s also something that not many players ever think about.

I know players at the clubs I’ve played at who have maintained the same action for years, and a new string is only ever considered when a string breaks.

However, strings wear out relatively quickly when played and consequently lose their elasticity and tensile strength.

Leaving them for too long can negatively affect your game. Let’s take a closer look at why and when you should change your tennis strings.

Why should you change your tennis strings?

Aside from snapping a string being the obvious reason to have your racquet re-strung, there are two other main reasons why it’s time to cut your strings and put in new ones.

loss of voltage

All tennis strings lose tension over time. They begin to lose tension as soon as they leave the stringing machine.

Depending on the string type, strings can lose about 10 percent of their tension in the first 24 hours after stringing, which continues as the racquet is played.

If you’re a player who relies on higher tension for control and find that your shot accuracy decreases over time, you may need to re-string to regain this element of your game.

String type Tension stability Natural gut very good Synthetic gut good Multifilament medium to good Polyester bad Kevlar very good

string performance

Not only do strings lose tension, they also eventually go dead. This causes them to lose their performance characteristics, which is most likely why you decided to string them in the first place.

This is especially true with polyester strings as they lose their snapback effect, which is a big part of how they help players generate topspin.

How do you know when it’s time to change strings?

visual indicators

Most advanced players will know that it’s time to restring purely by feel, but there are a few visual things to watch out for.

notches

When you touch the ball, your strings rub against each other and create friction, causing the strings to notch.

If you look closely, you can see grooves that form where the main and cross strings cross. This becomes more apparent in the top center of your racquet, which is hopefully the area where you make the most contact with the ball!

When you see that these notches are about to snap the string, or even getting pretty deep, it’s probably an excellent time to re-string the string.

Fray

Natural gut and multifilament strings are made up of many tiny fibers that are intertwined. When freshly strung they often have a coating to protect them, but once this wears out the fibers begin to fray.

This is a natural part of wear for this type of string, so some fraying is completely normal. Fraying can also be increased by humidity and wetness.

However, beyond a certain point, fraying reduces the strength of the string to the point where it breaks. So if you see fibers fraying at all angles and the string looks weak, re-stringing is probably the right choice.

Feel indicators

For players just starting out, you’re unlikely to notice subtle changes in feel on the stringbed. But as your technique develops and your feel improves, you will notice changes in the string’s play over time.

A loss of control

When the strings lose tension, the ball spends more time on the string bed, which can affect your control. A loss of tension can mean hitting long, making more unforced errors, or struggling to place the ball. If so, maybe it’s time you re-string.

Less top spin

When polyester strings lose tension, the string’s snapback decreases, which means you have to swing harder to generate the same amount of topspin as you would with a freshly strung racquet. Polyester strings also develop dead points, resulting in an erratic response.

If you find yourself hitting with less spin and needing to adjust your strings at every point, then it’s probably time to re-string.

So how often should you re-tension?

The reason for writing this post is because of the following question that we received via email. Below is my answer, modified to be a little more generic.

Hello, do you have a general recommendation for the frequency of re-stringing? I play doubles three or four times a week, mainly in my spare time, but also in doubles on the weekends in the summer. I wouldn’t consider myself an aggressive baseline player, but more of a touch player using sensible pace and placement over sheer power. I currently have a 53 lb Prince synthetic gut string in a Yonex DR 100, 6 months since last stringing. I really like this string, but I’m wondering if it’s a little loose and maybe I’m losing control. Any thoughts?

When it comes to racquet re-stringing, there is a general rule of thumb that most players are familiar with:

Over a year, you should restring your racquet as many times as you play in a week.

So if you play four times a week, re-string your racquet four times a year.

If you haven’t had a fresh string bed in six months, then I’d say it’s time to freshen things up.

Even if they look good, the loss of tension and elasticity over time will have reduced the string’s playability.

For most players, this concept of stringing as many times per year as you play per week is not a bad rule. Especially for recreational players who string with artificial gut and don’t hit a big ball.

However, the problem is that it is a fairly wide top that cannot be used for all types of players or all types of strings.

While the time you spend on the court is an important factor, other considerations determine the speed at which players restring their racquets.

This only applies to non-string breakers as they have no choice but to re-string once a string breaks, but factors include:

Frequency and duration of the game

play style

level of competition

budget

string choice

comfort

Aggressive ball racquets with full, heavy topspin hits will wear down strings much faster than flat-hitting doubles specialists with shortened swings and touch play.

For most players, a visual test is more appropriate than sticking to a newly covered calendar. My rule is based on both a visual look at the strings and how they play.

When they look good but you play poorly in a match? OK, it happens. Playing the next match and the one after that badly? It’s probably time for a re-string. Even if the strings were okay, you at least mentally reposition yourself 🙂

What about the polyester restring frequency?

Polyester strings are difficult to follow, and there isn’t really a calendar rule that needs to be followed. In general, while polyester strings are difficult to break for most club players, they die after 10-20 hours of play.

Not only that, they also break off unevenly, creating dead spots in the string bed, which can lead to erratic performance. However, because they don’t break, players often leave them in their frames for too long.

For this reason, it’s often recommended to swap out polys at least every few months to restore playability and reduce the risk of arm injuries as you have to swing harder to keep the same pace.

Final Thoughts

As with most things involving tennis racquets, ultimately restringing comes down to personal preference and how the individual player evaluates a racquet’s performance.

Many players love to play with a freshly strung racquet; others enjoy them more after a break-in period, and some even like strings when they’re dead dead.

I quite like a racquet soon after it’s freshly strung, so I usually restretch my racquets before a more meaningful game.

Or if I know I’m going to play a few times over the coming week, I’ll increase the tension so that when it comes to the second or third hit, the tension is about as high as it would be if fresh from the game would be stringing machine with my desired tension.

From there, it’s all about keeping track of your game throughout the life of the string job. Do I need to swing harder to generate pace and spin? Do the strings bite on the ball or do I have to readjust them after each point? Are shot placement and predictability starting to go awry?

If these questions come to mind after 2 or 3 batting sessions or matches, it’s usually time to re-string and that’s the rule I follow.

Depending on the strings and how often you play, this could take as little as a week or a few months.

While it’s not an exact science, I think it’s best to replace strings early rather than late. And your local club stringer or tennis shop too 😀

Find Your Ideal Tennis String Looking for a new string for your racquet? Use our easy-to-use tennis string finder tool. You can filter by string type, gauge, color, price, stiffness, and shape.

How often do you re-string your racquet? Let me know in the comments below

A tennis racket used by Switzerland’s Roger Federer against Rafael Nadal in the 2011 French Open final has been auctioned for a record price.

The red and white Wilson Six One Tour model fetched $55,000 (£42,000/€46,000) at Goldin Auctions’ online sale.

That’s the highest amount anyone has ever paid at auction for a racquet used by a male player.

The highest price to date was in 2007 when a collector paid $32,000 (£24,000/€27,000) for the wooden Slazenger racquet used by Britain’s Fred Perry in the 1934 Wimbledon final when he won the first of three consecutive singles titles.

The most a racquet fetched at auction was two years ago when a different Wilson model was used by American legend Billie Jean King when he was winning former world number one and ex-Wimbledon and US Open champion Bobby Riggs in an exhibition match defeated Houston in 1973, sold for $125,000 (£95,000 / €105,000)

The Donnay racquet used by Swede Björn Borg in his 1981 loss to John McEnroe at Wimbledon was sold by Christie’s in London 13 years ago for $18,500 (£14,000/€15.00).

Last December, Goldin Auctions sold Serena Williams’ broken racquet from her infamous 2018 US Open final loss to Japan’s Naomi Osaka for $20,910 (£15,900/€17,500).

The red and white Wilson Six One Tour model used by Roger Federer in his last loss to Rafael Nadal at the 2011 French Open broke the auction record for a men’s tennis racket ©Getty Images

Federer’s bat included a letter of authenticity from his agent and a Beckett authentication for the autograph.

Goldin Auctions described it as “an incredible piece of tennis history”.

At the final at the Stade Roland Garros in Paris, Federer attempted to become the first male player in the Open era and only the third man overall to achieve a double-career Grand Slam.

Nadal was the defending champion and the Spaniard successfully defended his crown, defeating his long-time rival 7-5 7-6 5-7 6-1 to claim the sixth French Open title of his career.

Federer also lost to Nadal in the French Open finals in 2007 and 2008 but won the title in 2009, beating Sweden’s Robin Söderling 6-1 7-6 6-4 in the final.

In total, Federer has won 20 Grand Slam singles titles – with Nadal, the most in history for a male player.

Re-stringing racquets London

We offer a professional racquet stringing service for tennis, badminton and squash racquets from our shop in Northwood Hills (North West London). We have hundreds of strings to choose from and our experienced staff can advise you on the most suitable strings for your playing style and recommend a tension if you are unsure.

Customers bringing their own string pay £25 for stringing.

Racquet Restring Prizes

Tennis Racket Restring

Tennis racquet string prices range from £25 to £65 depending on the type of string you choose.

Spring tensioner for badminton rackets

Plain Strings – £22

Premium Strings – £25

Squash Racket Restring

Plain Strings – £22

Premium Strings – £25

Racquets must be returned to us for re-stringing, which is usually done within 3 working days (excluding Saturday and Sunday). This may take longer at busy times but you will be notified when you return your club.

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