Category Archives: Dwell Time
Why String Bed Stiffness (SBS) matters.
String bed stiffness is a critical performance metric and therefore deserves more attention than it gets in the discussion(s) of string characteristics.
In this video, which is a little “jumpy” at first, you will see the data we collect for every racquet we do. For this discussion, we concentrate on these data:
- Reference Tension
- RDC string bed stiffness
- Flex Four-string bed stiffness
- Racquet Quest SBS (String Sense) stiffness
- Effective stiffness
- Master Tensometer string bed stiffness (kg/cm^)
Head Squared
We have demo racquets of the new Head Squared racquet. The racquets will arrive soon, and those who have tried it agree it is quite a different racquet!
The racquet specifications make this a model that will suit players of many abilities, and is a stable and easy racquet to play with!
You can demo your Head Squared now at Racquet Quest for delivery about mid-April!
Head Squared
Because this racquet is so different, we have done a few “customizations”. This post will include two (2) of those customizations. After you take a look at this data, we can discuss what players thought of each.
| Manufacturer | Head |
|---|---|
| Racquet Model | Head Squared |
| Reference Tension | 54 |
| String | MonoGut ZX Pro PEEK |
| Machine Used | True Tension Pro |
| String Bed Stiffness - RDC | 47 |
| String Bed Stiffness -FlexFour | 55 |
| Strig Bed Stiffness - SBS | 46 |
| String Bed Stiffness - ERT | 32 |
| Racquet Flex, RDC | 59 |
| Racquet Flex, FlexFour | 46 |
| Racquet - In Plane Stiffness | 391.1 |
| Weight, Grams | 318 |
| Weight, Ounces | 11.22 |
| Balance, mm | 306 |
| Balance, Inch | 12.05 |
| Length, Cm | 68.7 |
| Length, Inch | 27.047 |
| Head Width | 9.94 |
| Head Length | 12.85 |
| Head Area, cm2 | 647.1 |
| Head Area, Sq. Inch | 100.3 |
| Beam Height @ Grip, mm | 22.5 |
| Beam Height @ Mid, mm | 25 |
| Beam Height @ Tip | 23 |
| Beam Width @ Grip, mm | 10.5 |
| Beam Width @ Throat, mm | 12.4 |
| Beam Width @ Mid, mm | 10.1 |
| Beam Width @ Tip, mm | 12 |
| Number of Main Strings | 16 |
| Number of Cross Strings | 18 |
| Ratio | .687 |
| Main String Grid Inch/mm | 7.63/193.8 |
| Cross String Grid Inch/mm | 10.40/264.2 |
| Density (% of head filled with string) | .791 |
| Average Cross String Space | .578 |
| Average Main String Space | .477 |
| Dynamic Tension, Kp, ERT | 32 |
| Dynamic Tension, Lbs/in | 178.9 |
| First Moment, Nm | .736 |
| Polar Moment | 303.0 |
| Torsional Stability | 13 |
| Swing Weight, Kg/cm2 | 290 |
| Swing Weight, Ounces | 10.23 |
| Swing Weight Calculated | 297.8 |
| Power, RDC | 41 |
| Control, RDC | 58 |
| Manueverability, RDC | 93 |
| Power, Calculated | 1733.3 |
| Head Points | 11.81 |
| Head Weight, % | 44.5% |
| Center of Percussion | 21.4 |
| Dwell Time, ms | 6.83 |
| Efective Stiffness - lbs | 26.2 |
| K, Lb/In | 150.6 |
| Recoil Weight | 157.1 |
| Twist Weight | 234.4 |
| End Weight | 142.2 |
| Tip Weight | 175.6 |
| 9 O'Clock | 85.4 |
| 3 O'Clock | 85.2 |
| Butt End | 148.1 |
| COF, Main | .323 |
| COF, Cross | .346 |
See what a subtle change in swing weight makes to the racquet.
| Manufacturer | Head |
|---|---|
| Racquet Model | Head Squared |
| Reference Tension | 54 |
| String | Victrex 7718 PEEK |
| Machine Used | True Tension Pro |
| String Bed Stiffness - RDC | 47 |
| String Bed Stiffness -FlexFour | 55 |
| Strig Bed Stiffness - SBS | 46 |
| String Bed Stiffness - ERT | 32 |
| Racquet Flex, RDC | 59 |
| Racquet Flex, FlexFour | 46 |
| Racquet - In Plane Stiffness | 391.1 |
| Weight, Grams | 318 |
| Weight, Ounces | 11.22 |
| Balance, mm | 306 |
| Balance, Inch | 12.05 |
| Length, Cm | 68.7 |
| Length, Inch | 27.047 |
| Head Width | 9.94 |
| Head Length | 12.85 |
| Head Area, cm2 | 647.1 |
| Head Area, Sq. Inch | 100.3 |
| Beam Height @ Grip, mm | 22.5 |
| Beam Height @ Mid, mm | 25 |
| Beam Height @ Tip | 23 |
| Beam Width @ Grip, mm | 10.5 |
| Beam Width @ Throat, mm | 12.5 |
| Beam Width @ Mid, mm | 10.2 |
| Beam Width @ Tip, mm | 12.1 |
| Number of Main Strings | 16 |
| Number of Cross Strings | 18 |
| Ratio | .687 |
| Main String Grid Inch/mm | 7.63/193.8 |
| Cross String Grid Inch/mm | 10.40/264.2 |
| Density (% of head filled with string) | .791 |
| Average Cross String Space | .578 |
| Average Main String Space | .477 |
| Dynamic Tension, Kp, ERT | 32 |
| Dynamic Tension, Lbs/in | 178.9 |
| First Moment, Nm | .736 |
| Polar Moment | 303.0 |
| Torsional Stability | 13 |
| Swing Weight, Kg/cm2 | 290 |
| Swing Weight, Ounces | 10.23 |
| Swing Weight Calculated | 345,6 |
| Power, RDC | 41 |
| Control, RDC | 58 |
| Manueverability, RDC | 93 |
| Power, Calculated | 1733.3 |
| Head Points | 11.81 |
| Head Weight, % | 44.5% |
| Center of Percussion | 21.4 |
| Dwell Time, ms | 6.83 |
| Efective Stiffness - lbs | 26.2 |
| K, Lb/In | 150.6 |
| Recoil Weight | 157.1 |
| Twist Weight | 234.4 |
| End Weight | 142.2 |
| Tip Weight | 175.6 |
| 9 O'Clock | 85.4 |
| 3 O'Clock | 85.2 |
| Butt End | 148.1 |
| COF, Main | .323 |
| COF, Cross | .346 |
Where is my power?
Tennis players want power, control, spin, comfort, durability, and fun!
Well, so do we!
We collect data to contribute to your greater enjoyment of tennis, so we are including this video to address some questions about power!
Because we do not know how you are swinging the racquet, fast, slow, or in between, we must rely on data (numbers) to help us help you.
Cross String Tension…Yikes!
Cross-string tensions, or actually reference tensions, are the topic of this brief post.
First, every tennis racquet has a “natural” ratio, that is, if the reference tension (and machine setting ) is 50 for both the main string and cross string when the racquet is removed from the stringing machine, the tensions remaining will be in the area of around 50 for the mains and 37 for the cross.
The resultant tension is the natural ratio of that specific racquet.
The issue with changing cross-string tension either higher or lower than the main is that the racquet has changed shape. That is why we test for In-Plane stiffness for every racquet. The higher the In-Plane stiffness, the higher the cross-string tension will remain upon removal from the machine.
If the racquet has very low In-Plane stiffness, it has expanded in width with only the main string installed, so the cross strings need to pull the racquet back into a better (hopefully original) shape.
So, when deciding how much variation you want between the main and cross strings, please consider the racquet! In most cases, we suggest using the same string tension setting for both the main and the cross, since the cross string tension will naturally be lower.
Our True Tension Professional stringing equipment supports the racquet in such a way that we install the main string and cross string at the natural ratio, so the racquet does not change shape and the string bed is consistent.
If you are curious about In-Plane stiffness for a specific tennis racquet, please leave a comment below.
Racquet Quest, LLC
