Looking at the Numbers and What They Mean

May 4

Posted by

The following table will shed some light on the numbers we use and hopefully shed some light on what they can mean in terms of your racquet.

By using these numbers you can describe what you think needs to be different to enhance your performance!
ManufacturerYonexWhat it Means
Racquet ModelYonex VCore Pro 97 HDRacquet being reviewed.
Reference Tension55 lbs - 24.9 kgStringing machine tension setting. Not, necessarily, the string bed stiffness.
String
Ashaway MonoGut ZX ProString brand name and gauge (Pro being 17Gauge)
Machine UsedTrue Tension ProfessionalStringing machine used.
Static
ASPS, RDC56The stiffness of all the strings as a unit. Normally between 30 and 65.
ASPS, FlexFour64.5The stiffness of the string bed as tested on this device.
Racquet Flex, RDC57 - After stringing50 is low (flexible) and 70 is high (very stiff). Clash 100 is 52 on this device. As is a Head Speed model.
Racquet Flex, FlexFour5035 is low (flexible) 70 is high (very stiff). Clash 100 is 26 on this device.
Racquet - In Plane Stiffness353.8 lbs/InchThis is how stiff the racquet head is across the middle. 300 is soft and 500 is very stiff. This affects the string bed stiffness.
Weight, Grams336285 is light and 360 is heavy.
315 is minimum target weight for performance.
Weight, Ounces11.85

The racquet weight in ounces, typically used in US.
Balance, mm322This is the center of gravity from the butt cap. If you put the racquet on a round rod this would be how much is hanging toward the butt cap.
Balance, Inch12.68This is the CG in ounces for US. Points head heavy or head light is part of this.
Length, Cm68.5This is the total length of the racquet and is the typical standard adult length.
Length, Inch26.968This is length in inches for the US.
Head Width, Inches9.57The inside width of the hitting area.
Head Length, Inches 12.54The inside length of the hitting area.
Head Area, cm2625.8The advertised hitting area in centimeters squared.
Head Area, Sq. Inch97.0The advertised hitting area in inches squared.
Number of Main Strings18The main strings are the vertical strings when looking at a standing racquet. Typically the longest strings.
Number of Cross Strings20The cross strings are the horizontal strings when looking at a standing
racquet. Typically shorter.
Ratio Cross/Mains.687The natural ratio of the string pattern (calculated).
Main String Grid7.25The total distance between right and left main string.
Cross String Grid10.18
The total distance between the first cross string and the last cross string.
Density (% of head filled with string).783
Average Cross String Space.509The higher this number the more the string will move. This number is used to help select the best string setup.
Average Main String Space.403The higher this number the more the string will move. This number is used to help select the best string setup.
Dynamic
Properties of a moving racquet.
Dynamic Tension, Kp, ERT37This is the stiffness of a string bed in kilograms per centimeter based on a frequency.
Dynamic Tension, Lbs/in206.94This is the above converted to pounds per inch.
First Moment, Nm.831This is how heavy the racquet feels in the hand. The higher the number the heavier the racquet will feel.
Polar Moment340This is the resistance to rotating about the center of the racquet on, say a mimes-hit. The higher the better.
Torsional Stability16This is the derived stability number. The higher the better within reason. Anything below 14 would need some help.
Swing Weight, Kg/cm2324This is the "inertia" of the racquet and probably the most important number in the review! The higher the number the more momentum through the ball but less manueverability.
Swing Weight, Ounces11.43
Swing Weight Calculated348.4This number will be larger than the previous swing weight because it is calculated from the very end of the racquet as if there is no one holding it. A very important number.
Power, RDC42Calculated by the RDC. High is 100
Control, RDC59Calculated by the RDC. High is 100
Manueverability, RDC71Calculated by the RDC. High is 100
Power, Calculated 1740.5This number is calculated based on a bunch racquet properties, Including length.
Head Points6.46 (negative = head heavy)This number is how positive or negative the balance is. A "point" is ⅛ of an inch so this racquet is a little over ¾ of an inch head light.
Head Weight, %47.0%Calculated based on weight distribution and length.
Center of Percussion21.0This is the spot on the string bed that returns a "solid" hit.
Dwell Time, ms8.50This is how long the ball and string are in contact with no swing. A big swing will reduce this number by about half.
Efective Stiffness - lbs28.2This number is calculated from the string bed stiffness and the racquet stiffness. Anything under 30 will be "soft" feeling and over 35 will be "harsh".
K, Lb/In179.5This is how many pounds it takes to deflect the string bed one (1) inch.
Recoil Weight160.8This number is the racquets resistance to rotating backward. The higher the number the better for volleys.
Twist Weight230.8This is the racquets resistance to twisting in your hand. The higher the better.
End Weight 139.8This weight is used to calculate the precise balance of the racquet.
Tip Weight 196.2This weight is used to calculate the precise balance of the racquet.
9 O'Clock100.4
This is the weight of that position on the racquet head and is used for precise customization.
3 O'Clock99.6This is the weight of that position on the racquet head and is used for precise customization.
Butt Cap135.6This is the weight of that position on the racquet and is used for precise customization.

Posted on May 4, 2021, in Good News!. Bookmark the permalink. Leave a comment.

Let us have your thoughts on this!