Category Archives: Technology
By The Numbers
Here we go with this numbers thing, again!
Our Racquet reviews are a bunch of numbers, but what do these numbers mean to you?
We have put together this table with a brief explanation of how each number can be used by you to understand how that property can be helpful.
If you see terms such as typical or normal, ignore them! With tennis players, there is no such thing as “typical and normal”!
If you need to be convinced, take a look at a previous post!
Please let us know if there is a number that needs more clarification or a number we are missing!
| Manufacturer | Yonex | What it Means |
|---|---|---|
| Racquet Model | Yonex VCore Pro 97 HD | Racquet being reviewed. |
| Reference Tension | 55 lbs - 24.9 kg | Stringing machine tension setting. Not, necessarily, the string bed stiffness. |
| String | Ashaway MonoGut ZX Pro | String brand name and gauge (Pro being 17Gauge) |
| Machine Used | True Tension Professional | Stringing machine used. |
| ASPS, RDC | 56 | The stiffness of all the strings as a unit. Normally between 30 and 65. |
| ASPS, FlexFour | 64.5 | The stiffness of the string bed as tested on this device. |
| Racquet Flex, RDC | 57 - After stringing | 50 is low (flexible) and 70 is high (very stiff). Clash 100 is 52 on this device. As is a Head Speed model. |
| Racquet Flex, FlexFour | 50 | 35 is low (flexible) 70 is high (very stiff). Clash 100 is 26 on this device. |
| Racquet - In Plane Stiffness | 353.8 lbs/Inch | This 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, Grams | 336 | 285 is light and 360 is heavy. 315 is minimum target weight for performance. |
| Weight, Ounces | 11.85 | The racquet weight in ounces, typically used in US. |
| Balance, mm | 322 | This 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, Inch | 12.68 | This is the CG in ounces for US. Points head heavy or head light is part of this. |
| Length, Cm | 68.5 | This is the total length of the racquet and is the typical standard adult length. |
| Length, Inch | 26.968 | This is length in inches for the US. |
| Head Width, Inches | 9.57 | The inside width of the hitting area. |
| Head Length, Inches | 12.54 | The inside length of the hitting area. |
| Head Area, cm2 | 625.8 | The advertised hitting area in centimeters squared. |
| Head Area, Sq. Inch | 97.0 | The advertised hitting area in inches squared. |
| Number of Main Strings | 18 | The main strings are the vertical strings when looking at a standing racquet. Typically the longest strings. |
| Number of Cross Strings | 20 | The cross strings are the horizontal strings when looking at a standing racquet. Typically shorter. |
| Ratio Cross/Mains | .687 | The natural ratio of the string pattern (calculated). |
| Main String Grid | 7.25 | The total distance between right and left main string. |
| Cross String Grid | 10.18 | The total distance between the first cross string and the last cross string. |
| Density (% of head filled with string) | .783 | |
| Average Cross String Space | .509 | The higher this number the more the string will move. This number is used to help select the best string setup. |
| Average Main String Space | .403 | The higher this number the more the string will move. This number is used to help select the best string setup. |
| Properties of a moving racquet. | ||
| Dynamic Tension, Kp, ERT | 37 | This is the stiffness of a string bed in kilograms per centimeter based on a frequency. |
| Dynamic Tension, Lbs/in | 206.94 | This is the above converted to pounds per inch. |
| First Moment, Nm | .831 | This is how heavy the racquet feels in the hand. The higher the number the heavier the racquet will feel. |
| Polar Moment | 340 | This is the resistance to rotating about the center of the racquet on, say a mimes-hit. The higher the better. |
| Torsional Stability | 16 | This is the derived stability number. The higher the better within reason. Anything below 14 would need some help. |
| Swing Weight, Kg/cm2 | 324 | This 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, Ounces | 11.43 | |
| Swing Weight Calculated | 348.4 | This 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, RDC | 42 | |
| Control, RDC | 59 | |
| Manueverability, RDC | 71 | |
| Power, Calculated | 1740.5 | This number is calculated based on racquet properties. |
| Head Points | 6.46 (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% | |
| Center of Percussion | 21.0 | This is the spot on the string bed that returns a solid hit. |
| Dwell Time, ms | 8.50 | This 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 - lbs | 28.2 | This 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/In | 179.5 | |
| Recoil Weight | 160.8 | This number is the racquets resistance to rotating backward. The higher the number the better for volleys. |
| Twist Weight | 230.8 | This is the racquets resistance to twisting in your hand. The higher the better. |
| End Weight | 139.8 | This weight is used to calculate the precise balance of the racquet. |
| Tip Weight | 196.2 | This weight is used to calculate the precise balance of the racquet. |
| 9 O'Clock | 100.4 | This is the weight of that position on the racquet head and is used for precise customization. |
| 3 O'Clock | 99.6 | This is the weight of that position on the racquet head and is used for precise customization. |
| Butt Cap | 135.6 | This is the weight of that position on the racquet and is used for precise customization. |
Head Graphene 360+ Prestige Mid
The Head Prestige Mid is, in my view, the quintessential Prestige! This Prestige is the tennis racquet you would buy even if you don’t play tennis! It would sit right next to your Porsche 550 that you don’t drive much, but both make you feel really good!
The latest edition of the Prestige Mid is the Graphene 360+ Prestige Mid, and it carries on the iconic tradition of all previous models and looks better doing it, in my opinion.
In left image, you can see the overall color scheme of all of the new Prestige series, but you can’t see the detail of the “cap system” that is different than the other three (3) Prestige models.
The lower image shows the transition location. But why?
Mid Cap System Transition
I think it is just a matter of weight. The cap system on the Mid stops halfway down the head instead of all around as on other models.
This slight reduction in weight allows for more customization options and this is a very customizable racquet.
So, if you are interested in an “iconic” racquet to place next to your 550, this is the one!
What could be better than arriving at the courts in your 550 and pull out your Prestige Mid racquet!
Game, Set, Match!
| Manufacturer | Head |
|---|---|
| Racquet Model | Head Graphene 360+ Prestige Mid |
| Reference Tension | 55 lbs - 24.9 kg |
| String | Victrex PEEK fiber Experimental 7718 |
| Machine Used | True Tension Professional |
| ASPS, RDC | 57 |
| ASPS, FlexFour | 72.0 |
| Racquet Flex, RDC | 63 - After stringing |
| Racquet Flex, FlexFour | 36 |
| Weight, Grams | 344 |
| Weight, Ounces | 12.13 |
| Balance, mm | 317 |
| Balance, Inch | 12.48 |
| Length, Cm | 68.5 |
| Length, Inch | 26.97 |
| Head Width | 9.25 |
| Head Length | 12.67 |
| Head Area, cm2 | 593.4 |
| Head Area, Sq. Inch | 92.0 |
| Beam Width, mm, Shaft, Center, Tip | 20, 20, 20 |
| In Plane Stiffness, Pounds/In | 428.6 Lbs/In. |
| In Plane Stiffness, Kg/cm | 194.4 Kg/cm |
| Number of Main Strings | 16 |
| Number of Cross Strings | 19 |
| Ratio Cross/Mains | .615 |
| Main String Grid | 6.87 |
| Cross String Grid | 8.88 |
| Density (% of head filled with string) | .663 |
| Average Cross String Space | .467 |
| Average Main String Space | .429 |
| Dynamic Tension, Kp, ERT | 37 |
| Dynamic Tension, Lbs/in | 206.9 |
| First Moment, Nm | .834 |
| Polar Moment | 341 |
| Torsional Stability | 15 |
| Swing Weight, Kg/cm2 | 326 |
| Swing Weight, Ounces | 11.50 |
| Swing Weight Calculated | 345.7 |
| Power, RDC | 47 |
| Control, RDC | 53 |
| Manueverability, RDC | 69 |
| Power, Calculated | 1888.9 |
| Head Points | 8.03 (negative = head heavy) |
| Head Weight, % | 46.3% |
| Center of Percussion | 21.1 |
| Dwell Time, ms, No Swing | 8.43 |
| Efective Stiffness - lbs | 29.9 |
| K, Lb/In (SBS) RDC | 182.69 |
| Recoil Weight | 166.4 |
| Twist Weight | 221.8 |
| End Weight | 146.7 |
| Tip Weight | 197.3 |
| 9 O'Clock | 104.6 |
| 3 O'Clock | 102.8 |
| Butt Cap | 134.6 |
Head Graphene 360+ Prestige Tour
When we do the testing and “number taking” for our demo racquets, we try to think as the consumer may think and include comments that may help the consumer make the best decision.
We do not want to make these posts so dull that you go to sleep, but data is essential, so we are going to include it…so stay awake!
Data is particularly relevant to the Prestige Series from Head.
This review is for the Prestige Tour, and it points to the differences between Prestige racquets that may go unnoticed or misunderstood.
The Prestige Tour is a 99 (645 cm²)square inch racquet with an 18 x 19 string pattern. If you have read the post on the Prestige MP, you may wonder, what’s the difference?
You may notice that the Prestige Tour has one (1) fewer cross string. Not a big deal. You may see that the Prestige Tour has one (1) square inch larger head size. Also, not a big deal. What you may not notice is the Prestige Tour has an in-plane stiffness of 400, and the Prestige MP has an in-plane stiffness of 359. That is a big deal! Even with a bigger head and fewer strings, the Prestige Tour has a higher string bed stiffness than the Prestige MP. The higher the in-plane stiffness, the less the racquet will “bend” during impact.
The Prestige Tour is more stiff overall (62 v 58) than the Prestige MP, and the 21.5mm beam contributes to that stiffness.
So, take a look at the numbers for this racquet to see if you can find other exciting differences!
Manufacturer Head
Racquet Model Head Graphene 360+ Prestige Tour
Reference Tension 55 lbs - 24.9 kg
String
Victrex PEEK fiber Experimental 7718
Machine Used True Tension Professional
ASPS, RDC 55
ASPS, FlexFour 71
Racquet Flex, RDC 62 - After stringing
Racquet Flex, FlexFour 49
Weight, Grams 325
Weight, Ounces 11.46
Balance, mm 327
Balance, Inch 12.87
Length, Cm 68.6
Length, Inch 27.008
Head Width 9.56
Head Length 13.12
Head Area, cm2 635.3
Head Area, Sq. Inch 98.5
Beam Width, mm, Shaft, Center, Tip 21.5, 21.5, 21.5
In Plane Stiffness, Pounds/In 400.0 Lbs/In.
In Plane Stiffness, Kg/cm 181.4 Kg/cm
Number of Main Strings 18
Number of Cross Strings 19
Ratio Cross/Mains .690
Main String Grid 7.81
Cross String Grid 10.00
Density (% of head filled with string) .724
Average Cross String Space .526
Average Main String Space .396
Dynamic Tension, Kp, ERT 35
Dynamic Tension, Lbs/in 195.7
First Moment, Nm .819
Polar Moment 334
Torsional Stability 18
Swing Weight, Kg/cm2 316
Swing Weight, Ounces 11.15
Swing Weight Calculated 347.5
Power, RDC 46
Control, RDC 55
Manueverability, RDC 76
Power, Calculated 1929.2
Head Points 4.88 (negative = head heavy)
Head Weight, % 47.7%
Center of Percussion 20.8
Dwell Time, ms, No Swing 8.58
Efective Stiffness - lbs 29.1
K, Lb/In (SBS) RDC 176.3
Recoil Weight 150.9
Twist Weight 222.7
End Weight 131.7
Tip Weight 195.3
9 O'Clock 100.7
3 O'Clock 101.4
Butt Cap 124.0
Head Graphene 360+ Prestige MP
We are finally getting the time to work on these marvelous new racquets from Head! In this case, it is the Head Graphene 360+ Prestige MP.
The Prestige is a fascinating series for Head, but I think it is often overlooked when considering a new racquet purchase. I believe the “performance” category excludes a lot of players that could very well use this racquet if it is appropriately set up. Secondly, I think players have the mistaken feeling that the Prestige series is too stiff!
I believe you will see by the following specifications that neither are necessarily true!
The Prestige series is, in my opinion, the best looking new racquet in a long time. However, in a performance racquet, what does “looks” have to do with it? In my opinion, a lot!
This racquet is the “true” 98 square inch (630 cm²) head size with an 18 x 20 string pattern and, of course, the excellent “cap system” that contributes to the performance of this racquet. You will see in the specifications that the swing weight is on the “light” side, allowing for customization to suit any player.
Head is now including a CPI, “Control Power Index,” and this racquet ranks as a CPI 200 compared to the Prestige Pro at CPI 300. The difference is a function of the tight string pattern and flex. The thin 20mm beam throughout contributes to the nice flex of RDC 58 after stringing.
A lower CPI indicates to us that the racquet will do no more than you ask of it! If you want the ball to go fast you swing harder! The racquet will not force to to “fear” your stroke!
If you are considering an 18 x 20 string pattern this racquet should be right at the top of the list.
Our COF numbers are quite good which indicate a positive contribution to “spin” considering the tight string pattern.
| Manufacturer | Head |
|---|---|
| Racquet Model | Head Graphene 360+ Prestige MP |
| Reference Tension | 55 lbs - 24.9 kg |
| String | Victrex PEEK fiber Experimental 7718 |
| Machine Used | True Tension Professional |
| ASPS, RDC | 58 |
| ASPS, FlexFour | 67 |
| Racquet Flex, RDC | 58 - After stringing |
| Racquet Flex, FlexFour | 39 |
| Weight, Grams | 337 |
| Weight, Ounces | 11.89 |
| Balance, mm | 313 |
| Balance, Inch | 12.32 |
| Length, Cm | 68.6 |
| Length, Inch | 27.008 |
| Head Width | 9.47 |
| Head Length | 13.05 |
| Head Area, cm2 | 625.9 |
| Head Area, Sq. Inch | 97 |
| Beam Width, mm, Shaft, Center, Tip | 20, 20, 20 |
| In Plane Stiffness, Pounds/In | 359 Lbs/In. |
| In Plane Stiffness, Kg/cm | 162 Kg/cm |
| Number of Main Strings | 18 |
| Number of Cross Strings | 20 |
| Ratio Cross/Mains | .653 |
| Main String Grid | 7.50 |
| Cross String Grid | 10.25 |
| Density (% of head filled with string) | .792 |
| Average Cross String Space | .513 |
| Average Main String Space | .417 |
| Dynamic Tension, Kp, ERT | 37 |
| Dynamic Tension, Lbs/in | 206.9 |
| First Moment, Nm | .803 |
| Polar Moment | 326 |
| Torsional Stability | 15 |
| Swing Weight, Kg/cm2 | 311 |
| Swing Weight, Ounces | 10.97 |
| Swing Weight Calculated | 330.2 |
| Power, RDC | 39 |
| Control, RDC | 62 |
| Manueverability, RDC | 79 |
| Power, Calculated | 1749.9 |
| Head Points | 9.29 (negative = head heavy) |
| Head Weight, % | 45.7% |
| Center of Percussion | 21.0 |
| Dwell Time, ms, No Swing | 8.35 |
| Efective Stiffness - lbs | 29.0 |
| K, Lb/In (SBS) RDC | 185.9 |
| Recoil Weight | 160.4 |
| Twist Weight | 226.8 |
| End Weight | 149.2 |
| Tip Weight | 189.9 |
| 9 O'Clock | 98.2 |
| 3 O'Clock | 98.8 |
| Butt Cap | 140.3 |
Head Prestige 360+
When you think of Head tennis racquets you likely think of the “Prestige” series, which for over thirty (30) years has been the “performance” racquet!
Because the Prestige series has been considered an all out players racquet the perception that it is stiff has been perpetuated over the years! This is not accurate, of course! The data above shows the unstrung numbers of each of the Prestige 360+ racquets. You will notice the flex is quite suitable for most players!
There is a Prestige for every player style and this new Prestige line has style that truly sets it apart. Sure there are other red racquets but the Prestige does red better than most other frames, in my opinion.
More data will be added as the demo racquets are strung and ready to go but in the meantime the above data will give you a really good idea of which Prestige 360+ will suit you. To arrive at an approximate strung weight just add 16 grams to the “overall weight”, and for swing weight add 30 grams to the “swing weight”.
Racquet Quest, LLC
