Category Archives: True Tension
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 |
2020 is Coming Into Focus!
2019 came and went in a blur! In a few days it will 2020 and with it will come some exciting new tennis stuff, for sure!
I am not so good at predicting things but I do it anyway! Here are a few predictions I will make for 2020:
- Tennis racquets will become more expensive, but only slightly.
- On-line sales of tennis racquets will increase. See this previous post.
- Customer satisfaction with on-line sales will decrease.
- Small specialty tennis shops will be the source of information, then #2, and then #3.
- Players will stick with a racquet longer, making customizations as needed.
- String and stringing will become a more important component of a racquet purchase. See below!
- Tennis related injuries will continue to be a problem for the sport going forward.
No Underage Polyester, Please!
Thank you for thinking about the “long term” for all tennis players!
There are no bad strings just bad applications!
The right equipment is crucial to the long term enjoyment, and winning, of tennis!
The local representatives I deal with are committed to our “well being” even though some may feel like they are facing “extinction”!
An excellent example of what we are talking about just walked in! Two (2) new racquets so poorly strung it is shocking!
The customer is having serious arm issues with an excellent racquet, with a terrible string setup! But the string setup is probably considered by many to be the ultimate combination, that is RPM Blast in the main and VS Touch in the cross! That combination is coming out in a few minutes! No more polyester!
The quality of the stringing is what is so wrong! Had you or I received this racquet, we would have returned it at once! Why? Because it exemplifies the attitude of so many stringers that is “who cares”!
Happy New Year!
Head Graphene 360+ Gravity Tour
Head is adding another racquet to the very popular Gravity Series! This racquet is the Gravity Tour and in a nutshell, is a lighter version of the Gravity Pro. Both are 18 x 20 string patterns and, the Gravity Tour is a 22mm beam as opposed to a 20mm beam for the Gravity Pro.
Head Graphene 360+ Gravity Tour
You would think the 22mm beam would be stiffer (power?) than the Gravity Pro, but in this case the extra weight of the Gravity Pro makes it a little more power forward. Our tests show the RDC stiffnesses to be the same (60), and the FlexFour shows the Gravity Tour slightly stiffer in the shaft, 51 as opposed to 46 for the Gravity Pro.
From a numbers standpoint this racquet (14 grams lighter) will fit a player wanting a little more maneuverable racquet but not as powerful as the Gravity Pro. ← Click on this link to see the review.
This review is of a “play ready” racquet. That is an over grip, and vibration damper. These accoutrements do contribute to weight and swing weight to a minor degree.
| Manufacturer | Head |
|---|---|
| Racquet Model | Head Graphene 360+ Gravity Tour |
| Reference Tension | 55 lbs - 24.9 kg |
| String | Pro Evaluation String 1.20mm |
| Machine Used | True Tension Professional |
| ASPS, RDC | 58 |
| ASPS, FlexFour | 70 |
| Racquet Flex, RDC | 59 - After stringing |
| Racquet Flex, FlexFour | 51 |
| Weight, Grams | 324 |
| Weight, Ounces | 11.43 |
| Balance, mm | 329 |
| Balance, Inch | 12.87 |
| Length, Cm | 68.6 |
| Length, Inch | 27.008 |
| Head Width | 9.92 |
| Head Length | 12.86 |
| Head Area, cm2 | 646.6 |
| Head Area, Sq. Inch | 100.2 |
| Beam Width, mm, Shaft, Center, Tip | 22, 22, 22 |
| In Plane Stiffness, Pounds/In | 319.1 Lbs/In. |
| In Plane Stiffness, Kg/cm | 144.7 Kg/cm |
| Number of Main Strings | 18 |
| Number of Cross Strings | 20 |
| Ratio Cross/Mains | .694 |
| Main String Grid | 7.87 |
| Cross String Grid | 9.80 |
| Density (% of head filled with string) | .763 |
| Average Cross String Space | .490 |
| Average Main String Space | .433 |
| Dynamic Tension, Kp, ERT | 38 |
| Dynamic Tension, Lbs/in | 212.54 |
| First Moment, Nm | .797 |
| Polar Moment | 329 |
| Torsional Stability | 15 |
| Swing Weight, Kg/cm2 | 314 |
| Swing Weight, Ounces | 11.08 |
| Swing Weight Calculated | 337.9 |
| Power, RDC | 40 |
| Control, RDC | 62 |
| Manueverability, RDC | 77 |
| Power, Calculated | 1856.8 |
| Head Points | 4.88 (negative = head heavy) |
| Head Weight, % | 47.7% |
| Center of Percussion | 21.2 |
| Dwell Time, ms, No Swing | 8.35 |
| Efective Stiffness - lbs | 29.2 |
| K, Lb/In (SBS) RDC | 185.9 |
| Recoil Weight | 153.46 |
| Twist Weight | 232.2 |
| End Weight | 125.9 |
| Tip Weight | 192.8 |
| 9 O'Clock | 98.4 |
| 3 O'Clock | 97.2 |
| Butt Cap | 122.0 |
Yonex VCore Pro 97 – 330
It should be no surprise that this model is the heaviest of the VCore Pro Series! However, I can’t stress enough the need to demo this racquet and feel what the weight will do for your game!
Of course not everyone will want a racquet of this weight but just trying it will give you some idea of what weight can do for you. Maybe not 330 (unstrung) but a little added weight nonetheless.
That makes the 310 (unstrung) version of this racquet a “standout”, and you can see the review here.
About this racquet, Yonex says “for intermediate to advanced players looking to play aggressively with control and feel”.
To achieve this combination Yonex has incorporated a “lock booster” grommet system that promotes string contact for effecient energy transfer”.
Namd™ graphite fibers are incorporated into the throat area allowing the racquet to flex even under the heaviest of hits!
To top it off Yonex has added a vibration damping mesh in the grip pallet area to filter out unwanted vibrations.
All said, this thin beam (20.0mm) racquet with a 16×19 string pattern is a players dream! So, don’t dream about it…demo it and decide for yourself!
| Manufacturer | Yonex |
|---|---|
| Racquet Model | Yonex VCore Pro 97 |
| Reference Tension | 55 lbs - 24.9 kg |
| String | Pro Evaluation String 1.20mm |
| Machine Used | True Tension Professional |
| ASPS, RDC | 53 |
| ASPS, FlexFour | 66 |
| Racquet Flex, RDC | 62 - After stringing |
| Racquet Flex, FlexFour | 48 |
| Racquet - In Plane Stiffness | 373.2 lbs/Inch |
| Weight, Grams | 344 |
| Weight, Ounces | 12.13 |
| Balance, mm | 321 |
| Balance, Inch | 12.64 |
| Length, Cm | 68.6 |
| Length, Inch | 27.008 |
| Head Width | 9.56 |
| Head Length | 12.62 |
| Head Area, cm2 | 611.3 |
| Head Area, Sq. Inch | 97 |
| Number of Main Strings | 16 |
| Number of Cross Strings | 19 |
| Ratio Cross/Mains | .638 |
| Main String Grid | 7.00 |
| Cross String Grid | 9.62 |
| Density (% of head filled with string) | .709 |
| Average Cross String Space | .505 |
| Average Main String Space | .438 |
| Dynamic Tension, Kp, ERT | 34 |
| Dynamic Tension, Lbs/in | 190.16 |
| First Moment, Nm | .847 |
| Polar Moment | 342 |
| Torsional Stability | 15 |
| Swing Weight, Kg/cm2 | 327 |
| Swing Weight, Ounces | 11.53 |
| Swing Weight Calculated | 354 |
| Power, RDC | 49 |
| Control, RDC | 51 |
| Manueverability, RDC | 69 |
| Power, Calculated | 1940.1 |
| Head Points | 6.93 (negative = head heavy) |
| Head Weight, % | 46.8% |
| Center of Percussion | 20.9 |
| Dwell Time, ms | 8.74 |
| Efective Stiffness - lbs | 28.6 |
| K, Lb/In | 169.87 |
| Recoil Weight | 161.48 |
| Twist Weight | 235.86 |
| End Weight | 144.4 |
| Tip Weight | 201.5 |
| 9 O'Clock | 102.6 |
| 3 O'Clock | 104.8 |
| Butt Cap | 138.0 |
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