Category Archives: Kinesiology
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.
Buy Direct?
As any business knows by now, there is a new way to do business regardless of what they are selling, and tennis racquets are no exception!
For several years players have been able to buy “special” racquets from some manufacturers. These racquets were typically unique graphics. The price of these racquets was, also, usually a bit more than “retail’ products.
Now, however, Wilson is making their “Pro” series racquets available through wilson.com, only. These racquets are what the cognoscenti refer to as “pro stock” racquets.
I think it is a good idea!
Why? Because so many players wanted “special” racquets and were paying exorbitant prices for racquets that may or may not be what they thought they were buying! We know because we see them!
Buying direct is one reason we have modified our model slightly by offering to a greater extent “custom” racquets. This way, you know what you are getting, exactly! I believe this will be the case with the Wilson Pro Series as well.
I believe it will not be far that more tennis racquet companies do the “direct” thing; however, “scale” is the issue and stringing and racquet setup. Some companies don’t have the resources for that, yet, so online sellers will still have some action, I think.
If you have a racquet technician you trust, purchase the racquet “direct” but have it set up locally. I think that is a winning combination!
Let us know what you think about buying directly from the racquet brand instead of online or locally.
Head Graphene 360+ Gravity MP/Tecnifibre RPX
Normally our racquet reviews are when a racquet is brand new; however, this is a case where the updated string, RPX, from Tecnifibre is an excellent opportunity to add another review to the site!
There are some excellent reasons to review the same racquet again with different string or tension settings.
- It allows us to evaluate new strings for comparison purposes.
- It will enable the player to demo the same Racquet with a different string.
- The string can affect the overall weight to a small degree but significantly impact swing weight.
For example, this racquet with Victrex 7718 PEEK string (15.9grams installed) has a swing weight of 318. With the new Tecnifibre RPX (18.0 grams installed), the swing weight is 325. That is not huge, but it is different.
Lead tape, commonly used to increase swing weight, weighs in at 2.8 grams for 12 inches! So, slightly over 2 grams of additional string weight in the strung area contribute to the difference between these strings.
Of course, this also means that swing weight can be reduced, somewhat, by using lighter string! We weigh all of the string we test for Power Potential, so we know which string can benefit either swing weight preference.
| Manufacturer | Head |
|---|---|
| Racquet Model | Head Graphene 360+ Gravity MP |
| Reference Tension | 55 lbs - 24.9 k |
| String | Tecnifibre RPX 16 |
| Machine Used | True Tension Professional |
| ASPS, RDC | 53 |
| ASPS, FlexFour | 62 |
| Racquet Flex, RDC | 59 - After stringing |
| Racquet Flex, FlexFour | 54 |
| Weight, Grams | 322 |
| Weight, Ounces | 11.36 |
| Balance, mm | 337 |
| Balance, Inch | 13.27 |
| Length, Cm | 68.6 |
| Length, Inch | 27.008 |
| Head Width | 9.92 |
| Head Length | 12.85 |
| Head Area, cm2 | 645 |
| Head Area, Sq. Inch | 100 |
| Beam Width, mm, Shaft, Center, Tip | 22, 22, 22 |
| In Plane Stiffness, Pounds/In | 381.0 |
| In Plane Stiffness, Kg/cm | 68.12 |
| Number of Main Strings | 16 |
| Number of Cross Strings | 20 |
| Ratio Cross/Mains | .617 |
| Main String Grid | 7.75 |
| Cross String Grid | 10.37 |
| Density (% of head filled with string) | .784 |
| Average Cross String Space | .480 |
| Average Main String Space | .520 |
| Dynamic Tension, Kp, ERT | 36 |
| Dynamic Tension, Lbs/in | 201.35 |
| First Moment, Nm | .843 |
| Polar Moment | 339 |
| Torsional Stability | 14 |
| Swing Weight, Kg/cm2 | 325 |
| Swing Weight, Ounces | 11.46 |
| Swing Weight Calculated | 365.7 |
| Power, RDC | 46 |
| Control, RDC | 56 |
| Manueverability, RDC | 70 |
| Power, Calculated | 1938.8 |
| Head Points | 1.89 (negative = head heavy) |
| Head Weight, % | 49.1% |
| Center of Percussion | 20.7 |
| Dwell Time, ms, No Swing | 8.74 |
| Effective Stiffness - lbs | 27.9 |
| K, Lb/In (SBS) RDC | 169.87 |
| Recoil Weight | 146.57 |
| Twist Weight | 236.38 |
| End Weight | 119.8 |
| Tip Weight | 202.2 |
| Total Weight Check | 322 |
| 9 O'Clock | 102.3 |
| 3 O'Clock | 101.4 |
| Butt Cap | 117.9 |
| Total Weight Check | 321.6 |
Know Your String!
Several years ago, when we were beginning to increase the use of Ashaway MonoGut ZX and ZX Pro, it was not unusual to get a call from a client saying, “my coach says I should not be using polyester!” We could not agree more, and you are not using polyester!
You are using PEEK polymer! This string material was, and still is, referred to as Zyex with polymer production capabilities of Victrex in England.
Given the appearance of MonoGut ZX, Babolat Origin, and a few other non-polyester monofilament strings, it is not easy to distinguish these from stiffer polyester material strings. So know your string!
Single strand (monofilament) strings will have a gleaming surface unless they have been through a “roughing” process. So will monofilament strings of different materials. It is hard to tell just by looking, and that is what can create some confusion on behalf of the coach and subsequently, the player. So know your string!
If your racquet technician does not put a label on the racquet that identifies the material (or string), then be sure to ask what material you are using. The material choices may be natural gut, Zyex (PEEK), Nylon, and Polyester. The string construction may be referred to as a monofilament, multi-filament, single wrap, etc. however, the material will probably be one of these four.
Know your string! If you are unsure, contact your racquet technician or “Ask John” on this site, and we will try to help.
Racquet Quest, LLC
