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Racquet
Glossary |
| Term |
Defined |
Balance
<index> |
The static measure of weight distribution of a strung tennis racquet.
Balanced is measured from the handle (butt) end in points, inches
and / or centimeters. Commonly referred to as “points”
head light or “points” head heavy. One point equates
to 1/8 of one inch. The balance point is measured from the center
point of the racquet. Static balance affects the racquet’s
swingweight (see swingweight). Balance also affects how heavy or
light the racquet “feels.” As a general guideline most
of the very-light game improvement racquets are head heavy which
is necessary to supply enough mass, which translates into power,
to the area of the frame where the is ball is contacted.
For
example, a racquet that measures 27.5 inches long with a static
balance of 14.75 inches. The racquet’s center or mid-point
is 13.75 inches. The racquet’s balance is 8 points head heavy
or one inch head heavy, measured from the racquet’s center
balance point.
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Beam/Cross-Section
<index>
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The width of the frame measured in millimeters (mm). Frames with wider
beams will be stiffer than thinner beamed frames, all things being
equal. Many frames have differing beams at various locations of the
frame, depending upon the manufacturer’s desired results. |
Dampening
<index>
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The ability to reduce frame shock and vibration before they reach
the player’s hand and / or elbow. This can be accomplished by
some sort of vibration suppression system, usually located in the
handle. Racquet weight is effective in decreasing frame shock and
vibration. Racquet stiffness is also effective in reducing frame shock
and vibration. |
First Moment
<index>
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How the racquet feels when you pick it up by the handle, it is also
known as “pick-up” weight. An approximation of the racquet’s
maneuverability that is based upon weight and balance. |
Grip Size
<index>
|
Measurement of the circumference of the grip. Standard grip sizes
ranges from 4 to 4.75 inches. A very good approximation for measuring
your grip size is to hold the handle with an Eastern forehand grip.
The conventional grip size would allow you to fit your index finger
between the palm and longest finger. An alternative method is to
measure from the tip of the ring finger to the bottom lateral crease
on the palm of the hand. Obviously personal preference plays a big
part in this decision. Also players using Semi-Western or Western
grips prefer smaller grips since it is easier to make the significant
grip change from forehand to backhand with a smaller grip. Keep
in mind that many of today’s racquet grips cannot be reduced
in size.
Our
recommendation: if you’re between grip sizes, choose
with the smaller grip size. It’s easier to build up a grip.
US
grip sizes |
European
grip sizes |
4
4 1/8
4 1/4
4 3/8
4 1/2
4 5/8
4 3/4
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0
L1
L2
L3
L4
L5
L6 |
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Head Size
<index>
|
This refers to the strung area of a racquet and is usually measured
in square inches or square centimeters. All things being equal,
a larger head size provides more power and a larger sweetspot. A
smaller head size provides less power and consequently more control.
Although no industry standard exists, listed is SRS’s unofficial
classification:
Midsize
(mid): |
Less
than 95 square inches |
Midplus
(MP): |
95
to 104 square inches |
Oversize
(OS): |
105
to 115 square inches |
Super
Oversize (SOS): |
116
or more square inches |
|
Twist Rate
<index>
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Technically, Polar Moment of Inertia. How stable a racquet is on off-center
hits, including its resistance to twisting. A racquet with a larger
polar moment will be more resistant to twisting on off-center hits.
Racquets with wider heads will have larger polar moments of inertia.
Oversize racquets usually have a larger polar moment and resist twisting
better than better than smaller head size racquets. Polar Moment of
Inertia can be increased by adding weight at 3 and 9 o’clock,
increasing grip size to as large as comfortable. Remember increasing
weight will change the racquet’s weight, balance, and swingweight. |
Frame Shock
<index>
|
The initial, high amplitude oscillation of the racquet during and
immediately after ball contact. Often confused with frame vibration,
frame shock is generally believed to contribute more to wrist, elbow,
and/or shoulder injuries than vibration. Off-center hits increase
the amount of shock transmitted to the hand and arm. Certain handle
systems and frame technologies are designed to absorb frame vibration,
Völkl’s Sensor Handle System, Pro Kennex’s Kinetic
System are two such systems. Adding weight, lowering string tension,
using thinner gauge strings and increasing grip size, to a point,
are effective in reducing or absorbing frame shock. String vibration
dampeners are ineffective in reducing or absorbing frame shock. |
Sweetspot
<index>
|
The area of the strung racquet that provides the greatest energy return
(power) and accuracy with the least amount of shock or vibration.
There are three sweetspots: the Center of Percussion, this offers
the least amount of initial shock to the hand when struck. Shock is
generally accepted as the most potentially harmful to the player’s
arm. The Node of Percussion or Node Point produces the least amount
of vibration when struck. Frame vibration is what players often feel
after ball contact. The third sweetspot is the Coefficient of Restitution
or the racquet’s power. It is the lowest of the three sweetspots.
Sweetspot location is determined by several factors, including weight,
balance, length, head size, and string tension. |
Swingweight
<index>
|
A measure of how heavy a racquet feels when in motion (swung). Also
known as the Second Moment of Inertia, swingweight is dependent upon
a number of factors including racquet weight, length, balance, and
head size. As a general rule a racquet with a heavy or higher swingweight
value will be more powerful than a light swingweight racquet but will
be less maneuverable. Heavy swingweight racquets are generally lighter
in overall weight. This is accomplished by locating the majority of
weight (mass) in the upper hoop of the racquet. The Wilson Hammer
was the first to introduce this technology. The objective is to retain
maneuverability without sacrificing power by distributing the majority
of overall weight to the upper hoop, where the ball is contacted.
Swingweight can be increased by adding weight above the pivot point
or by increasing length. Swingweight cannot be reduced. It is better
to err on the light side and add weight, if needed. |
Frame Vibration
<index>
|
The low-frequency oscillation of the racquet after ball contact. Generally,
more flexible racquets produce greater low-level vibration than stiffer
frames. Frame vibration and string vibration are often confused. Frame
vibration has a shorter duration and cannot be reduced with the use
of rubberized string dampeners. Some handle and grommet systems are
effective in reducing frame vibration. After market methods for reducing
frame vibration include adding weight and stringing at mid to lower
tensions. |
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String
Glossary |
| Term |
Defined |
Actual Tension
<index> |
The tension in a strung racquet, which is always lower than the
machine indicated setting or reference tension. This is due to string
relaxation or creep. A racquet strung at a reference tension of
55 pounds will be less, depending on head size, string pattern type
of stringing machine and type of string.
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Elasticity
<index>
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A term often used to describe a string’s liveliness or stretchiness.
The ability of a string to return to its original position after contacting
the ball. String material, string construction, gauge, and tension
all influence elasticity. Over time, strings lose stretchiness and
tension, making them play “dead” which usually requires
more effort from the player. |
Gauge
<index>
|
The measurement of string thickness. Most tennis strings are 15 –
18 gauge with a few specialty strings being 19 or 20 gauge. There
are 3 measurements for string thickness, Standard US, European, and
actual string thickness measured in millimeters. In the standard US
measurement the higher the number the thinner the string. Thinner
strings offer greater feel power, and spin potential than a thicker
string of the same material and construction. Thicker strings are
usually more durable. There has been an attempt to standardize gauge
specifications; there has been no agreement among the manufacturers.
Don’t assume all 16 gauge strings are created equal. One company’s
16 gauge might measure 1.30 mm, while another will be 1.32 mm and
a third might be 1.28 mm, this represents a half a gauge difference.
Listed below is the gauge conversion.
US |
European |
Milimeters |
14
15
15L
16
16L
17
18
19
|
11
9.5
9
8.5
8
7.5
7
4
|
1.50
– 1.65
1.41 – 1.49
1.33 – 1.41
1.25 – 1.33
1.22 – 1.28
1.16 – 1.24
7 1.08 – 1.16
4 .90 – 1.06 |
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Hybrid Strings
<index>
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The combination of any two string types. A hybrid use one type for
the main strings and another for the cross strings. A hybrid is used
to increase playability or durability for a desired result. A common
hybrid is using an aramid fiber (the material that bulletproof vests
are made from) for the mains with a synthetic for the crosses. Designed
for chronic string breakers. A more playable hybrid is using polyester
for the mains and a synthetic for the crosses. Another hybrid is using
natural gut for the mains and a synthetic for the crosses. This hybrid
provides very good playability and feel of natural gut with the cost
savings of using a synthetic cross. Hybrids can be also anything from
simply using different gauges for the crosses and mains to the above
mentioned hybrids. Hybrids offer the player a whole new world of choices. |
Reference Tension
<index>
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The indicated tension or machine tension racquet is strung at. Reference
tensions are higher than actual tension. Reference Tensions can
vary from stringing machine to stringing machine depending upon
the type of machine.
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Resilience
<index>
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Resilience is the speed at which a string returns to its original
position after contacting the ball. More resilient strings are more
responsive or lively; provide greater ball speed and / or power.
Over time, strings lose their resilience, returning less energy
to the ball.
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Stringbed Deflection
<index>
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A value produced from either Babbolat’s Racquet Diagnostic Center
or Beers ERT 700. Both give values for stringbed stiffness. While
these values do not correspond directly to actual tension, they offer
criteria for evaluating string performance. From an initial value,
both units are able to track the tension lost and performance and
determine how much potential energy or life is remaining in the strings.
The Babolat RDC works with a plunger type device and the ERT 700 uses
resonance frequency. |
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