Category Archives: True Tension
The “Questron” has Arrived!
If you have been following Racquet Quest online and with the podcast, you know we are very fond of data! In keeping with that “fondness,” we have received our newest testing device, which I have named “Questron.”
During the last week, we have spent time getting Questron set up to do the kinds of testing we think is important for the tennis player, the racquet technician, and anyone else that cares about numbers!
It will be about another week before posting any data because we are “tweaking” some connection points, cycle settings, and refining the data’s graphing.
We have over 400 strings to test; however, we will eliminate many of those strings not relevant to today’s tennis player.
Even in the “testing” phase, we are discovering interesting facts about strings that will help us put together the best setup for you!
This is the “base” Questron. Future versions of this device will incorporate the “Power Potential,” “In-Plane Stiffness,” and “Dynamic Stiffness” testing that is currently done on other equipment.
Head Graphene 360+ Speed PWR
I suppose you have a pretty good idea what PWR means, right? Well, you would be correct! The Head Graphene 360+ Speed PWR is just that at a calculated power value of 2297.5! Compare that to the calculated power value for the Head Graphene 360+ Speed Lite of 1838.3! Twenty percent (20%) more powerful than the Lite!
This is what a 115 square inch head size can do for a racquet! The strings are quite a bit longer and more widely spaced which contributes to power, and comfort.
This head size is normally referred to as a “game improvement” racquet and relegated to those players that were not too athletic and/or didn’t want to exert too much energy on each stroke. In other words slow and short swings.
I am not sure that is the case with this racquet! Sure it has a big head and a thick beam but it sure does feel good when picked up (first moment)!
If we were going to recommend this racquet I would suggest some weight added to the rear end. The head does not need any additional weight.
Head Graphene 360+ Speed PWR
As I am working on this post I realize how much trouble it is to switch between racquet reviews for comparison so I am including a link to the Head Graphene 360+ Speed Series Comparison.
| Manufacturer | Head |
|---|---|
| Racquet Model | Head Graphene 360+ Speed PWR |
| Reference Tension | 56 lbs - 25.4 kg |
| String | Victrex PEEK fiber Experimental 7718 |
| Machine Used | True Tension Professional |
| ASPS, RDC | 48 |
| ASPS, FlexFour | 59 |
| Racquet Flex, RDC | 64 - After stringing |
| Racquet Flex, FlexFour | 59 |
| Weight, Grams | 276 |
| Weight, Ounces | 9.74 |
| Balance, mm | 352 |
| Balance, Inch | 13.86 |
| Length, Cm | 69.4 |
| Length, Inch | 27.32 |
| Head Width | 10.50 |
| Head Length | 13.81 |
| Head Area, cm2 | 734.8 |
| Head Area, Sq. Inch | 113.9 |
| Beam Width, mm, Shaft, Center, Tip | 26, 26, 28 |
| In Plane Stiffness, Pounds/In | 550.5 Lbs/In. |
| In Plane Stiffness, Kg/cm | 249.7 Kg/cm |
| Number of Main Strings | 16 |
| Number of Cross Strings | 19 |
| Ratio Cross/Mains | .640 |
| Main String Grid | 8.56 |
| Cross String Grid | 11.15 |
| Density (% of head filled with string) | .759 |
| Average Cross String Space | .532 |
| Average Main String Space | .535 |
| Dynamic Tension, Kp, ERT | 33 |
| Dynamic Tension, Lbs/in | 184.57 |
| First Moment, Nm | .764 |
| Polar Moment | 324 |
| Torsional Stability | 18 |
| Swing Weight, Kg/cm2 | 306 |
| Swing Weight, Ounces | 10.79 |
| Swing Weight Calculated | 342.0 |
| Power, RDC | 49 |
| Control, RDC | 52 |
| Manueverability, RDC | 83 |
| Power, Calculated | 2297.5 |
| Head Points | -1.57 (negative = head heavy) |
| Head Weight, % | 50.7% |
| Center of Percussion | 21.3 |
| Dwell Time, ms, No Swing | 9.18 |
| Efective Stiffness - lbs | 27.4 |
| K, Lb/In (SBS) RDC | 153.85 |
| Recoil Weight | 132.95 |
| Twist Weight | 225.40 |
| End Weight | 92.6 |
| Tip Weight | 184.4 |
| 9 O'Clock | 91.1 |
| 3 O'Clock | 90.6 |
| Butt Cap | 94.2 |
Head Graphene 360+ Speed Lite
As you probably guessed, this is the lightest of the Speed Series, 100 square inch head size, at a weight of 281 grams (9.91 ounces)!
There are several positive features in this racquet and one is the reasonable flex (stiffness) of 63 RDC, plus the uniform string pattern that provides a consistent hitting experience needed by developing players. This pattern should contribute to extended string life as well.
Head Graphene 360+ Speed Lite
As with all light racquets, this one can be customized as the need or desire arises, and I think that will happen more quickly than most other racquets.
This is just too light, in my opinion, for players wanting to improve all aspects of their game. Remember, weight is your friend! However, if you prefer a light racquet for any reason this is a top choice!
As I am working on this post I realize how much trouble it is to switch between racquet reviews for comparison so here is a link to the Head Graphene 360+ Speed Series Comparison.
| Manufacturer | Head |
|---|---|
| Racquet Model | Head Graphene 360+ Speed Lite |
| Reference Tension | 56 lbs - 25.4 kg |
| String | Victrex PEEK fiber Experimental 7718 |
| Machine Used | True Tension Professional |
| ASPS, RDC | 56 |
| ASPS, FlexFour | 68.5 |
| Racquet Flex, RDC | 63 - After stringing |
| Racquet Flex, FlexFour | 43 |
| Weight, Grams | 281 |
| Weight, Ounces | 9.91 |
| Balance, mm | 345 |
| Balance, Inch | 13.58 |
| Length, Cm | 68.5 |
| Length, Inch | 26.97 |
| Head Width | 9.71 |
| Head Length | 13.06 |
| Head Area, cm2 | 640.8 |
| Head Area, Sq. Inch | 99.6 |
| Beam Width, mm, Shaft, Center, Tip | 25, 25, 25 |
| In Plane Stiffness, Pounds/In | 422.5 Lbs/In. |
| In Plane Stiffness, Kg/cm | 191.6 Kg/cm |
| Number of Main Strings | 16 |
| Number of Cross Strings | 19 |
| Ratio Cross/Mains | .626 |
| Main String Grid | 7.30 |
| Cross String Grid | 9.53 |
| Density (% of head filled with string) | .710 |
| Average Cross String Space | .503 |
| Average Main String Space | .463 |
| Dynamic Tension, Kp, ERT | 36 |
| Dynamic Tension, Lbs/in | 201.4 |
| First Moment, Nm | .758 |
| Polar Moment | 311 |
| Torsional Stability | 18 |
| Swing Weight, Kg/cm2 | 293 |
| Swing Weight, Ounces | 10.34 |
| Swing Weight Calculated | 334.5 |
| Power, RDC | 42 |
| Control, RDC | 61 |
| Manueverability, RDC | 91 |
| Power, Calculated | 1838.3 |
| Head Points | -0.79 (negative = head heavy) |
| Head Weight, % | 50.4% |
| Center of Percussion | 20.7 |
| Dwell Time, ms, No Swing | 8.50 |
| Efective Stiffness - lbs | 29.6 |
| K, Lb/In (SBS) RDC | 198.31 |
| Recoil Weight | 126.53 |
| Twist Weight | 198.31 |
| End Weight | 98.6 |
| Tip Weight | 182.3 |
| 9 O'Clock | 90.5 |
| 3 O'Clock | 91.2 |
| Butt Cap | 98.3 |
Head Graphene 360+ Speed MP Lite
The Head Graphene 360+ Speed MP Lite may be the perfect racquet for a player looking for a thin(er) beam, 100 square inch head size, slightly lighter than most MP racquets!
As you will see in the specifications this racquet is about 28 grams (1 ounce) lighter than the MP model, and, just a little more flexible, or better said, less stiff!
Forty-nine point nine percent (49.9%) of the total weight resides toward the head of this racquet, so if you think in terms of “points” it is 0.16 points head light.
Some customization will make this a racquet that you can stay with for a long time. As your skills advance, so can the racquet!
Head Graphene 360+ Speed MP Lite
As I am working on this post I realize how much trouble it is to switch between racquet reviews for comparison so I am including a link to the Head Graphene 360+ Speed Series Comparison.
| Manufacturer | Head |
|---|---|
| Racquet Model | Head Graphene 360+ Speed MP Lite |
| Reference Tension | 56 lbs - 25.4 kg |
| String | Victrex PEEK fiber Experimental 7718 |
| Machine Used | True Tension Professional |
| ASPS, RDC | 51 |
| ASPS, FlexFour | 62 |
| Racquet Flex, RDC | 60 - After stringing |
| Racquet Flex, FlexFour | 49 |
| Weight, Grams | 293 |
| Weight, Ounces | 10.34 |
| Balance, mm | 342 |
| Balance, Inch | 13.46 |
| Length, Cm | 68.5 |
| Length, Inch | 26.97 |
| Head Width | 9.68 |
| Head Length | 13.06 |
| Head Area, cm2 | 640.8 |
| Head Area, Sq. Inch | 99.3 |
| Beam Width, mm, Shaft, Center, Tip | 23, 23, 23 |
| In Plane Stiffness, Pounds/In | 307.3 Lbs/In. |
| In Plane Stiffness, Kg/cm | 139.4 Kg/cm |
| Number of Main Strings | 16 |
| Number of Cross Strings | 19 |
| Ratio Cross/Mains | .624 |
| Main String Grid | 7.30 |
| Cross String Grid | 10.62 |
| Density (% of head filled with string) | .780 |
| Average Cross String Space | .559 |
| Average Main String Space | .456 |
| Dynamic Tension, Kp, ERT | 35 |
| Dynamic Tension, Lbs/in | 195.76 |
| First Moment, Nm | .782 |
| Polar Moment | 323 |
| Torsional Stability | 15 |
| Swing Weight, Kg/cm2 | 308 |
| Swing Weight, Ounces | 10.86 |
| Swing Weight Calculated | 342.7 |
| Power, RDC | 46 |
| Control, RDC | 57 |
| Manueverability, RDC | 81 |
| Power, Calculated | 1835.6 |
| Head Points | 0.16 (negative = head heavy) |
| Head Weight, % | 49.9% |
| Center of Percussion | 21.0 |
| Dwell Time, ms, No Swing | 8.91 |
| Efective Stiffness - lbs | 27.6 |
| K, Lb/In (SBS) RDC | 163.46 |
| Recoil Weight | 138.67 |
| Twist Weight | 205.8 |
| End Weight | 105.8 |
| Tip Weight | 186.5 |
| 9 O'Clock | 95.1 |
| 3 O'Clock | 94.5 |
| Butt Cap | 103.0 |
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. |
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