CopolyX
Hall of Fame
Collaborative Effort:
When it comes to poly strings, we all
need to make sure adult recreational players
and juniors know the facts.
By Bob Patterson:
I speak to many manufacturers,
coaches and racquet technicians,
and the consensus is that
recreational adult players and
junior players are using the
wrong type of string, tension—
or both.
Stiff polyester strings are prevalent in
the marketplace and dominate the pro
tours, but are they suited for the average
club or league player? Most in this
industry don’t think so.
First, the very benefit of poly strings
is their ability to bend and snap back
faster than other materials. This snap
back enhances spin on the ball. A pro
can swing out and get more spin on the
ball while generating a heavier shot.
You might think that would be the same
for your average junior or club player,
but it is most definitely not the case.
Most players can’t generate enough
racquet-head speed to bend stiff poly
strings in the first place. If the string
doesn’t bend, it can’t snap back, and
there is little or no spin enhancement.
Many recreational players who
switch to a poly never adjust their tension.
I’m always amazed to hear of a 3.5
adult or junior using a full poly set-up
at high tensions. This is a surefire way
for a player to hurt his or her arm.
Second, monofilament poly strings
lose their elasticity—or the ability to
snap back—much faster than nylon
or other string materials. Since poly
strings have a fairly dead feeling to
begin with, their decline is less noticeable
for recreational players, who tend
to not restring as often as they should,
which only makes the problem worse.
Not only is poly string wrong for
most recreational and junior players,
it can be harmful. The stiffer string
coupled with stiffer, lighter racquets
creates much more shock to the player
when the ball impacts the stringbed.
In recent years, we’ve seen arm and
wrist injuries sideline many top pros,
and these athletes train and take every
precaution to prevent injury. If we all
know it is a problem, how do we fix it?
It starts with education: inform players
about why they should alter their string
set-up. It is better for their health and
for their game.
Manufacturers need to step up, too.
It is easy to market a string their top
sponsored player is using, but companies
need to make rec players aware
that string may not be best for everyone.
Then they need to offer a softer,
better suited string.
The bottom line is that we all need to
address this issue. Injured players play
less, and may stop playing altogether.
And that’s not good for anyone. •
Bob Patterson:
Executive Director of
the U.S. Racquet Stringers Association.
Tennis Industry: Nov/Dec 2017
Tension Conventions
How does stringbed stiffness affect performance
on the court? Our expert breaks it
down, to help you better service your players.
By Bob Patterson
COURT C O N S TRUCT I O N
RAC Q U E T S T R I N G I N G
Does tension actually affect a
player’s performance?
To answer this, we first
must understand the definition
of “tension.”
In tennis, most people understand
that “tension” usually refers to the
tension applied when installing the
strings. We refer to this as the “reference
tension.”
Once all the strings are installed, the
resulting tension is usually referred
to as the “actual tension” or “dynamic
tension” of the strings, which is not
necessarily the same as the reference
tension. As a matter of fact, the tension
of each individual string will vary from
each other.
This is a result of many factors, such
as variance in string length, friction and
the string material itself, just to name a
TennisIndustry
few. Unless we are measuring individual
installed strings, when we refer to
dynamic or actual tension, we are
really referring to the stringbed tension,
which is actually a complex result
of the various tensions and other
factors that result with all the strings
installed in the frame.
Measuring Stringbed Tension
The stringbed tension or stiffness can
be measured in a variety of different
ways, but the two most common
methods are by deflecting the stringbed
with machines such as the Babolat
Racquet Diagnostic Center (RDC) or
an RA machine, or with harmonics,
like the Beers ERT devices. The RDC
applies a force to the center of the
stringbed and measures the deflection
that occurs. The Beers devices vibrate
the stringbed much like a guitar tuner,
and provide a reading of the resulting
tension of the stringbed.
While both methods are quite accurate,
what does it really mean? Before
we get into that, let’s discuss what
contributes to stringbed stiffness.
While there are many contributing
factors, we have identified seven as the
most influential:
1
Headsize/String Length: All
other things being equal, the
length of the string in the
racquet will be a determining factor for
stringbed stiffness. The longer the
string, the more easily it will deflect.
2
String Type: The material
the string is made of and the
manner in which it is
constructed also will affect stringbed
stiffness. The more the string stretches
(elongation), the softer the stringbed
will be.
3
String Gauge: The diameter of
the string definitely affects the
stringbed, but not in a uniform
or predictable manner. A thinner gauge
of a certain string will not always string
up tighter or looser than the same
string in a thicker gauge. Our research
indicates that other factors contribute,
so in some strings the thinner gauge
will end up tighter, while in others the
thicker gauge will end up tighter.
4
Pattern Density: Like headsize,
the density of the pattern
affects stringbed stiffness.
More strings in the pattern mean more
stiffness of the stringbed. This applies
not only to the number of mains and
crosses, but also to how the strings are
spaced. The closer the strings are to
each other, the stiffer the stringbed.
Think about it in terms of strings per
square inch: denser equals stiffer.
5
Machine Type: There are two
basic types of stringing
machines: constant pull and
lock-out. A constant-pull machine,
which can be either drop weight or
electric, pulls the string to the desired
tension, and then continues to pull as
the string stretches to maintain that
tension until the string is clamped. A
lockout (or hand crank) machine has a
lever that pulls the string until it
reaches the desired tension, and then a
spring-loaded device locks the string,
allowing it to stretch and loosen
slightly. While both types of stringing
machines are accurate when properly
calibrated, the resulting applied
tension will be different between the
two types because of the methods of
their operations.
6
Stringer Technique: Even the
best racquet technicians in the
world do things differently.
The way a stringer weaves the string,
the time they take and other techniques
will vary, and even the slightest
variance can contribute to the resulting
stringbed stiffness.
7
Tension: Of course, the applied
“reference” tension will have a
direct effect on the stringbed.
www.tennisindustrymag.com
The higher the tension, the tighter the
stringbed, and vice versa.
On-Court Performance
Now that we know how the stringbed
is affected, how does it actually affect
performance on the court?
For decades, we always said, “String
looser for more power, and tighter for
more control.” Well, that was kind of
accurate, but not completely.
According to the book The Physics
of Tennis, stringbed stiffness really
has no effect on the speed of the ball
coming off the stringbed. Rather, what
is affected is the angle at which the ball
comes off—
so with a softer stringbed,
the ball leaves at a higher angle and
goes deeper in the court.
What we should be saying is, “String
looser for more depth on your shots
and tighter for less depth.” It doesn’t
have quite the same ring to it, but it is
more accurate.
So, what else does the stringbed
stiffness affect? A stiffer stringbed will
transmit more shock at impact with the
ball. Remember, the stringbed stiffness
is a combination of the seven factors
mentioned, so if you are using a really
stiff string, you may need to drop the
tension to compensate.
While spin on the ball is somewhat
affected by the stringbed, it isn’t
directly affected by the overall stiffness.
Research shows that spin is most
greatly affected by the speed of the
player’s swing and the angle of that
swing during ball contact. Factors such
as string snapback, gauge and pattern
density can all have an effect on spin
potential, but not the overall stiffness
of the stringbed.
So, when you consider tension
recommendations for your customers,
keep in mind all of the factors that
contribute to stringbed stiffness, rather
than just the reference tension. That
way, you’ll be able to help them choose
a tension that will suit their racquet
and their swing—and improve their
performance. •
Nov/Dec 2017 TennisIndustry 31
When it comes to poly strings, we all
need to make sure adult recreational players
and juniors know the facts.
By Bob Patterson:
I speak to many manufacturers,
coaches and racquet technicians,
and the consensus is that
recreational adult players and
junior players are using the
wrong type of string, tension—
or both.
Stiff polyester strings are prevalent in
the marketplace and dominate the pro
tours, but are they suited for the average
club or league player? Most in this
industry don’t think so.
First, the very benefit of poly strings
is their ability to bend and snap back
faster than other materials. This snap
back enhances spin on the ball. A pro
can swing out and get more spin on the
ball while generating a heavier shot.
You might think that would be the same
for your average junior or club player,
but it is most definitely not the case.
Most players can’t generate enough
racquet-head speed to bend stiff poly
strings in the first place. If the string
doesn’t bend, it can’t snap back, and
there is little or no spin enhancement.
Many recreational players who
switch to a poly never adjust their tension.
I’m always amazed to hear of a 3.5
adult or junior using a full poly set-up
at high tensions. This is a surefire way
for a player to hurt his or her arm.
Second, monofilament poly strings
lose their elasticity—or the ability to
snap back—much faster than nylon
or other string materials. Since poly
strings have a fairly dead feeling to
begin with, their decline is less noticeable
for recreational players, who tend
to not restring as often as they should,
which only makes the problem worse.
Not only is poly string wrong for
most recreational and junior players,
it can be harmful. The stiffer string
coupled with stiffer, lighter racquets
creates much more shock to the player
when the ball impacts the stringbed.
In recent years, we’ve seen arm and
wrist injuries sideline many top pros,
and these athletes train and take every
precaution to prevent injury. If we all
know it is a problem, how do we fix it?
It starts with education: inform players
about why they should alter their string
set-up. It is better for their health and
for their game.
Manufacturers need to step up, too.
It is easy to market a string their top
sponsored player is using, but companies
need to make rec players aware
that string may not be best for everyone.
Then they need to offer a softer,
better suited string.
The bottom line is that we all need to
address this issue. Injured players play
less, and may stop playing altogether.
And that’s not good for anyone. •
Bob Patterson:
Executive Director of
the U.S. Racquet Stringers Association.
Tennis Industry: Nov/Dec 2017
Tension Conventions
How does stringbed stiffness affect performance
on the court? Our expert breaks it
down, to help you better service your players.
By Bob Patterson
COURT C O N S TRUCT I O N
RAC Q U E T S T R I N G I N G
Does tension actually affect a
player’s performance?
To answer this, we first
must understand the definition
of “tension.”
In tennis, most people understand
that “tension” usually refers to the
tension applied when installing the
strings. We refer to this as the “reference
tension.”
Once all the strings are installed, the
resulting tension is usually referred
to as the “actual tension” or “dynamic
tension” of the strings, which is not
necessarily the same as the reference
tension. As a matter of fact, the tension
of each individual string will vary from
each other.
This is a result of many factors, such
as variance in string length, friction and
the string material itself, just to name a
TennisIndustry
few. Unless we are measuring individual
installed strings, when we refer to
dynamic or actual tension, we are
really referring to the stringbed tension,
which is actually a complex result
of the various tensions and other
factors that result with all the strings
installed in the frame.
Measuring Stringbed Tension
The stringbed tension or stiffness can
be measured in a variety of different
ways, but the two most common
methods are by deflecting the stringbed
with machines such as the Babolat
Racquet Diagnostic Center (RDC) or
an RA machine, or with harmonics,
like the Beers ERT devices. The RDC
applies a force to the center of the
stringbed and measures the deflection
that occurs. The Beers devices vibrate
the stringbed much like a guitar tuner,
and provide a reading of the resulting
tension of the stringbed.
While both methods are quite accurate,
what does it really mean? Before
we get into that, let’s discuss what
contributes to stringbed stiffness.
While there are many contributing
factors, we have identified seven as the
most influential:
1
Headsize/String Length: All
other things being equal, the
length of the string in the
racquet will be a determining factor for
stringbed stiffness. The longer the
string, the more easily it will deflect.
2
String Type: The material
the string is made of and the
manner in which it is
constructed also will affect stringbed
stiffness. The more the string stretches
(elongation), the softer the stringbed
will be.
3
String Gauge: The diameter of
the string definitely affects the
stringbed, but not in a uniform
or predictable manner. A thinner gauge
of a certain string will not always string
up tighter or looser than the same
string in a thicker gauge. Our research
indicates that other factors contribute,
so in some strings the thinner gauge
will end up tighter, while in others the
thicker gauge will end up tighter.
4
Pattern Density: Like headsize,
the density of the pattern
affects stringbed stiffness.
More strings in the pattern mean more
stiffness of the stringbed. This applies
not only to the number of mains and
crosses, but also to how the strings are
spaced. The closer the strings are to
each other, the stiffer the stringbed.
Think about it in terms of strings per
square inch: denser equals stiffer.
5
Machine Type: There are two
basic types of stringing
machines: constant pull and
lock-out. A constant-pull machine,
which can be either drop weight or
electric, pulls the string to the desired
tension, and then continues to pull as
the string stretches to maintain that
tension until the string is clamped. A
lockout (or hand crank) machine has a
lever that pulls the string until it
reaches the desired tension, and then a
spring-loaded device locks the string,
allowing it to stretch and loosen
slightly. While both types of stringing
machines are accurate when properly
calibrated, the resulting applied
tension will be different between the
two types because of the methods of
their operations.
6
Stringer Technique: Even the
best racquet technicians in the
world do things differently.
The way a stringer weaves the string,
the time they take and other techniques
will vary, and even the slightest
variance can contribute to the resulting
stringbed stiffness.
7
Tension: Of course, the applied
“reference” tension will have a
direct effect on the stringbed.
www.tennisindustrymag.com
The higher the tension, the tighter the
stringbed, and vice versa.
On-Court Performance
Now that we know how the stringbed
is affected, how does it actually affect
performance on the court?
For decades, we always said, “String
looser for more power, and tighter for
more control.” Well, that was kind of
accurate, but not completely.
According to the book The Physics
of Tennis, stringbed stiffness really
has no effect on the speed of the ball
coming off the stringbed. Rather, what
is affected is the angle at which the ball
comes off—
so with a softer stringbed,
the ball leaves at a higher angle and
goes deeper in the court.
What we should be saying is, “String
looser for more depth on your shots
and tighter for less depth.” It doesn’t
have quite the same ring to it, but it is
more accurate.
So, what else does the stringbed
stiffness affect? A stiffer stringbed will
transmit more shock at impact with the
ball. Remember, the stringbed stiffness
is a combination of the seven factors
mentioned, so if you are using a really
stiff string, you may need to drop the
tension to compensate.
While spin on the ball is somewhat
affected by the stringbed, it isn’t
directly affected by the overall stiffness.
Research shows that spin is most
greatly affected by the speed of the
player’s swing and the angle of that
swing during ball contact. Factors such
as string snapback, gauge and pattern
density can all have an effect on spin
potential, but not the overall stiffness
of the stringbed.
So, when you consider tension
recommendations for your customers,
keep in mind all of the factors that
contribute to stringbed stiffness, rather
than just the reference tension. That
way, you’ll be able to help them choose
a tension that will suit their racquet
and their swing—and improve their
performance. •
Nov/Dec 2017 TennisIndustry 31
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