Category Archives: Tension
Prince Vortex 300
The new Prince Vortex design is a new offering of an older string pattern with 14 main strings and 21 cross strings in a variable taper beam…whew! You can see by the throat design that the main strings are longer that a conventional throat design. The longer the main strings the more energy they can return…sort of, and in some cases!
Vortex 300
The beam starts at the grip with a strong 25mm then tapers into a 23mm at the throat and then back to 25mm at the tip. Do not let the beam dimensions fool you! The RDC flex of 59 after stringing is quite acceptable for most every player style.
We have been taking coefficient of friction (COF) data for years but have not included it this review format, until now. The 14×21 string pattern is unique enough that it is worth including. You will see the numbers on the review specs so we won’t go into them now, however the numbers are interesting.
The 14 main strings contribute to a very “open” area right about where most extreme “spin” shots are hit according to our data of string failure positions.
The frame geometry is sort of “Aero” like. The shaft is trapezoidal that transitions into a “reverse” trapezoid around the head. It makes the racquet look stiffer than it is!
Take a look at the specs then pick up a demo to see what the numbers mean to you!
| Manufacturer | Prince |
|---|---|
| Racquet Model | Prince Vortex 300 |
| Reference Tension | 56 lbs - 25.4kg |
| String | Victrex 7718 |
| Machine Used | True Tension Professional |
| ASPS, RDC | 45 |
| ASPS, FlexFour | 58.5 |
| Racquet Flex, RDC | 59 - After stringing |
| Racquet Flex, FlexFour | 40.0 |
| Racquet - In Plane Stiffness | 526.3 lbs/Inch |
| Weight, Grams | 322 |
| Weight, Ounces | 11.36 |
| Balance, mm | 320 |
| Balance, Inch | 12.60 |
| Length, Cm | 68.6 |
| Length, Inch | 27.008 |
| Head Width | 9.94 |
| Head Length | 12.94 |
| Head Area, cm2 | 652 |
| Head Area, Sq. Inch | 101.1 |
| Number of Main Strings | 14 |
| Number of Cross Strings | 21 |
| Ratio Cross/Mains | .512 |
| Main String Grid | 7.30 |
| Cross String Grid | 9.50 |
| Density (% of head filled with string) | .686 |
| Average Cross String Space | .452 |
| Average Main String Space | .521 |
| Dynamic Tension, Kp, ERT | 32 |
| Dynamic Tension, Lbs/in | 176.98 |
| First Moment, Nm | .790 |
| Polar Moment | 336 |
| Torsional Stability | 17 |
| Swing Weight, Kg/cm2 | 319 |
| Swing Weight, Ounces | 11.25 |
| Swing Weight Calculated | 329.7 |
| Power, RDC | 47 |
| Control, RDC | 52 |
| Manueverability, RDC | 74 |
| Power, Calculated | 1921.1 |
| Head Points | 7.24 |
| Head Weight, % | 46.6 |
| Center of Percussion | 21.7 |
| Dwell Time, ms | 9.48 |
| Efective Stiffness - lbs | 30.2 |
| K, Lb/In | 144.23 |
| Recoil Weight | 165.41 |
| Twist Weight | 237.56 |
| End Weight | 134.5 |
| Tip Weight | 189.0 |
| 9 O'Clock | 96.2 |
| 3 O'Clock | 96.1 |
| Butt Cap | 131.4 |
| Coefficient of Friction: M | .400 |
| Coefficient of Friction: X | .262 |
Head Speed Pro Black
As you probably know by now Novak Djokovic plays with a version of the Head Speed but in black, not black and white! So it was only a matter of time until the all-black Speed Pro became available.
Until now we only had the black and white Speed Pro demo but now we have the black one!
This review will include the white and black version of the Speed and we will include a comparison to the Wilson Blade Pro!
| Manufacturer | Head |
|---|---|
| Racquet Model | Head Graphene 360 + Speed Pro Black |
| Reference Tension | 54 lbs - 24.5 kg |
| String | Head Reflex MLT |
| Machine Used | True Tension Professional |
| ASPS, RDC | 56 |
| ASPS, FlexFour | 66.5 |
| Racquet Flex, RDC | 57 - After stringing |
| Racquet Flex, FlexFour | 50.5 |
| Racquet - In Plane Stiffness | 325.2 lbs/Inch |
| Weight, Grams | 334 |
| Weight, Ounces | 11.78 |
| Balance, mm | 325 |
| Balance, Inch | 12.80 |
| Length, Cm | 68.6 |
| Length, Inch | 27.008 |
| Head Width | 9.618 |
| Head Length | 13.10 |
| Head Area, cm2 | 636.1 |
| Head Area, Sq. Inch | 98.6 |
| Number of Main Strings | 18 |
| Number of Cross Strings | 20 |
| Ratio Cross/Mains | .662 |
| Main String Grid | 7.565 |
| Cross String Grid | 10.30 |
| Density (% of head filled with string) | .7735 |
| Average Cross String Space | .513 |
| Average Main String Space | .413 |
| Dynamic Tension, Kp, ERT | 35 |
| Dynamic Tension, Lbs/in | 195.7 |
| First Moment, Nm | .836 |
| Polar Moment | 341 |
| Torsional Stability | 15 |
| Swing Weight, Kg/cm2 | 326 |
| Swing Weight, Ounces | 11.50 |
| Swing Weight Calculated | 352.8 |
| Power, RDC | 42 |
| Control, RDC | 59 |
| Manueverability, RDC | 69 |
| Power, Calculated | 1832.1 |
| Head Points | 5.51 |
| Head Weight, % | 47.0% |
| Center of Percussion | 21.016 |
| Dwell Time, ms | 8.502 |
| Efective Stiffness - lbs | 28.25 |
| K, Lb/In | 179.49 |
| Recoil Weight | 159.3 |
| Twist Weight | 231.4 |
| End Weight | 134.5 |
| Tip Weight | 198.0 |
| 9 O'Clock | 99.0 |
| 3 O'Clock | 99.6 |
| Butt Cap | 134.0 |
And now for the white and black version:
| Manufacturer | Head |
|---|---|
| Racquet Model | Head Graphene 360+ Speed Pro |
| Reference Tension | 56 lbs - 25.4 kg |
| String | Victrex PEEK fiber Experimental 7718 |
| Machine Used | True Tension Professional |
| ASPS, RDC | 55 |
| ASPS, FlexFour | 66.5 |
| Racquet Flex, RDC | 60 - After stringing |
| Racquet Flex, FlexFour | 43 |
| Weight, Grams | 327 |
| Weight, Ounces | 11.53 |
| Balance, mm | 323 |
| Balance, Inch | 12.72 |
| Length, Cm | 68.5 |
| Length, Inch | 26.97 |
| Head Width | 9.69 |
| Head Length | 13.06 |
| Head Area, cm2 | 641.2 |
| Head Area, Sq. Inch | 99.4 |
| Beam Width, mm, Shaft, Center, Tip | 23, 23, 23 |
| In Plane Stiffness, Pounds/In | 335.2 Lbs/In. |
| In Plane Stiffness, Kg/cm | 152.0 Kg/cm |
| Number of Main Strings | 18 |
| Number of Cross Strings | 20 |
| Ratio Cross/Mains | .668 |
| Main String Grid | 7.62 |
| Cross String Grid | 10.37 |
| Density (% of head filled with string) | .768 |
| Average Cross String Space | .513 |
| Average Main String Space | .414 |
| Dynamic Tension, Kp, ERT | 37 |
| Dynamic Tension, Lbs/in | 206.94 |
| First Moment, Nm | .812 |
| Polar Moment | 336 |
| Torsional Stability | 16 |
| Swing Weight, Kg/cm2 | 320 |
| Swing Weight, Ounces | 11.29 |
| Swing Weight Calculated | 341.2 |
| Power, RDC | 45 |
| Control, RDC | 57 |
| Manueverability, RDC | 73 |
| Power, Calculated | 1908.2 |
| Head Points | 6.14 (negative = head heavy |
| Head Weight, % | 47.2% |
| Center of Percussion | 21.2 |
| Dwell Time, ms, No Swing | 8.58 |
| Efective Stiffness - lbs | 28.7 |
| K, Lb/In (SBS) RDC | 176.28 |
| Recoil Weight | 159.71 |
| Twist Weight | 229.85 |
| End Weight | 133.4 |
| Tip Weight | 192.8 |
| 9 O'Clock | 97.1 |
| 3 O'Clock | 97.5 |
| Butt Cap | 131.0 |
And now for the Wilson Blade Pro:
| Manufacturer | Wilson |
|---|---|
| Racquet Model | Wilson Blade Pro |
| Reference Tension | 54 lbs - 23.6 k2 |
| String | ALU Power Rough |
| Machine Used | Unknown |
| ASPS, RDC | 35 |
| ASPS, FlexFour | 53 |
| Racquet Flex, RDC | 62 - After stringing |
| Racquet Flex, FlexFour | 48 |
| Racquet - In Plane Stiffness | 387.1 lbs/Inch |
| Weight, Grams | 337 |
| Weight, Ounces | 11.89 |
| Balance, mm | 327 |
| Balance, Inch | 12.87 |
| Length, Cm | 68.6 |
| Length, Inch | 27.008 |
| Head Width | 9.6 |
| Head Length | 12.80 |
| Head Area, cm2 | 623.3 |
| Head Area, Sq. Inch | 96.6 |
| Number of Main Strings | 16 |
| Number of Cross Strings | 19 |
| Ratio Cross/Mains | .634 |
| Main String Grid | 7.37 |
| Cross String Grid | 10.40 |
| Density (% of head filled with string) | .7934 |
| Average Cross String Space | .547 |
| Average Main String Space | .461 |
| Dynamic Tension, Kp, ERT | 27 |
| Dynamic Tension, Lbs/in | 151.0 |
| First Moment, Nm | .850 |
| Polar Moment | 358 |
| Torsional Stability | 16 |
| Swing Weight, Kg/cm2 | 342 |
| Swing Weight, Ounces | 12.06 |
| Swing Weight Calculated | 360.35 |
| Power, RDC | 55 |
| Control, RDC | 42 |
| Manueverability, RDC | 59 |
| Power, Calculated | 2069.0 |
| Head Points | 5.04 |
| Head Weight, % | 47.07 |
| Center of Percussion | 21.535 |
| Dwell Time, ms | 10.755 |
| Efective Stiffness - lbs | 22.37 |
| K, Lb/In | 112.18 |
| Recoil Weight | 170.8 |
| Twist Weight | 234.0 |
| End Weight | 135.0 |
| Tip Weight | 202.9 |
| 9 O'Clock | 100.8 |
| 3 O'Clock | 103.7 |
| Butt Cap | 132.2 |
Dealing with Options, and What are the Options?
The little video you see above is just a reminder that we do not promote polyester based string for underage players! So, what is underage? Oh, under 100 would be a good number, I think!
OK, smart alec what are the options?
- No Polyester
PEEK/Zyex
Well, there are many, however, if the option is only relative to “no polyester” the best option is PEEK material. This material is usually referred to by the brand name Zyex which is the fiber division of Victrex of England and known by the Ashaway name as well. This material is normally found as a monofilament construction as is most polyester materials.
PEEK/Zyex offers exceptional durability and energy!
Multifilament
- Premium Playability
Natural gut still is the number one playing string available. We use Babolat and Luxilon natural gut but there are other options like Pacific, Klip, and others.
- Excellent Playability
Multifilament construction can act as a spring and return both performance, power, and comfort. Typically the more individual fibers the better. These fibers are usually bonded with a soft adhesive and show signs of “fraying” during use.
Strings in this category include Tecnifibre, Ashaway, Babolat, Head, Yonex, and Gosen and others. Expect to pay $42.00 + for these strings installed.
- Playability
These multifilament strings are typically constructed using fewer larger diameter fibers to enhance durability. The same “fraying” occurs with this grade of string as well however the larger diameter will last a bit longer usually.
Strings in the category include Tecnifibre, Babolat, Head, Yonex, IsoSpeed, Gamma, and others. Expect to pay between $35.00 and $40.00 for these strings installed.
Synthetic Gut
- Value
There are probably 10000 strings that fall under this umbrella! 9999 of these strings will be a nylon core with one or two overwraps bonded to the outer surface. This material and construction has been around for many, many years and has offered great service to millions of tennis players…and is still in major use today!
Strings in this category include at least one, and probably many more, set from every major brand! If you are really cost-conscious do not overlook this material. Expect to pay $27.00 to $35.00 for these strings installed.
And lastly, what is our gripe with polyester? Click on the link below to find out!
Click here to go to a comprehensive post that will explain our position.
As always, our position is “there are no bad strings just bad applications!”
What Can String Failure Tell Us?
Well, in the simplest terms, failure tells us it is time to have the request strung! However, there may be subtleties in string failure that can help us in our quest for tennis racquet performance.
Such as?
Is the failure shear related or tensile strength related? Was friction the major contributor to the failure? Where did the failure occur (on the racquet, not the court)? Was the failure during play or in the bag?
Shear-related failure is when the string breaks very near the racquet frame. This failure is called a mis-hit or shank! It is like cutting the string with a pair of scissors!
Shear Failure
Friction Failure
Friction failure is caused by just that, friction! Friction is caused by the string moving on each other. That rubbing creates friction and notches the string where it will fail.
If the racquet failed during play and it is not shear-related, the tensile strength of the string was exceeded. If a string has a tensile strength of 120 pounds and the tension is 60 pounds leaving 60 pounds to be used to hit the ball. Some big hitters can generate at least that much force on a solid forehand!
This graph shows the tensile strength of the string to be about 115 pounds. Given the movement of this string-on-string, the frictional notching can contribute to relatively early failure based on the hitters force.
This graph shows the tensile strength of the string to be about 155 pounds but it has to travel (stretches) further to reach that force.
So, you can see, with this information we can make better decisions when asked to suggest a string, or strings, for a client!
Which Comes First!
We all have heard the question “which comes first the chicken or the egg”? However, my question is “Which comes first the game or the string”?
I believe they happen simultaneously. But first a quick story.
In 2005 I was attending a Head product introduction on the island of Mallorca, Spain, Yes, that one!
The product introduction was exciting but what I am going to tell you about now was even more meaningful.
The Director of one of the top US Tennis Training organizations, at that time, was there and we were discussing teaching techniques and what he said after being in this part of Europe was “we need to start teaching our players how to hit this way!” Well, “this way” was the way of low-powered strings that were popular in Europe but not so much in the US, yet.
So, it began! The players could not hit harder, like the Europeans, unless they used the same string material as the Europeans and that was very stiff and mostly PET polyester.
So, the idea was the “egg” and the string was the “chicken”, sort of! I guess the feeling was that “if Americans are going to compete we must use the same equipment”.
Now, I believe the professional game can go on about its way but otherwise, we need to consider changing the game by returning to a combination of comfort and playability.
Our history shows us that the “high performance” life span of many polyester strings is about 2-3 hours, or less, maybe about 10-12 games. We don’t believe this is quite long enough for most players. But, how do you quantify “performance”? It may be different things for different players.
There are many components to performance but what if it was associated with UTR data? Racquet Quest can track UTR numbers and make some determinations based on that data. If a UTR is stable or increasing it is a good bet that the performance of the player and equipment is OK. However, if the UTR is slipping it is a good indication that something is not working as it should…but what?
We have found that, in some cases, it is injury or discomfort, that is causing the slippage! Stop it! The following data is for a 12 month period and acquired from the UTR website. Even small positive changes are tough! But negative changes seem to have an enormous impact more quickly than positive changes!
For example:
| Player | Racquet | String | UTR1 | UTR2 | Delta |
|---|---|---|---|---|---|
| A | Head Speed | PEEK | 12.84 | 12.86 | + .02 |
| B | Babolat Pure Aero | Polyester | 10.91 | 9.56 | -1.35 |
| C | Head Radical MPA | PEEK | 4.50 | 5.61 | +1.11 |
| D | Wilson Pro Staff 97 | PEEK | 5.0 | 7.03 | +2.03 |
| E | Babolat Pure Aero | PEEK | 3.8 | 5.64 | +1.84 |
| F | Wilson Blade 98 | Polyester | 10.0 | 9.41 | -.59 |
| G | Head Radical Pro | Natural Gut | 3.7 | 5.15 | +1.45 |
Racquet Quest, LLC
