Category Archives: Accuracy

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!

The graphs show the tensile strength and relative elongation of different material.

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!

Bolt 100 v2

Bolt tennis racquets have been around for a few years and we have reported on them in the past, however, the new V2 of the Bolt racquet lineup is very impressive!

If you are not at all familiar with the Bolt technology it is the “Zip Strip” that makes them unique.  The “Zip Strip” is a carbon fiber component that looks like a miniature tennis racquet cross-section that fits into the sides and top that actually do the “bending” during string and racquet impact!

This “bending” can mitigate harshness associated with very stiff strings or a very stiff racquet!

Arm problems are no match for the ZipStrips!

Before we look at the specifications you can visit the Bolt site for more information.

Bolt 98L, V2 
Racquet ModelBolt 100, v2
Reference Tension57 lbs - 25.9 k
String: Main/Cross
Head Reflex
Machine UsedTrue Tension Pro
ASPS, FlexFour64.5
Racquet Flex, RDC64 - After stringing
Racquet Flex, FlexFour46
Weight, Grams313
Weight, Ounces11.06
Balance, mm337
Balance, Inch13.27
Length, Cm68.5
Length, Inch26.98
Head Width9.589
Head Length13.13
Head Area, cm2665.1
Head Area, Sq. Inch103.1
Beam Width, mm, Shaft, Center, Tip24.5, 24.5, 23.8
In Plane Stiffness, Pounds/In454 Lbs/In.
In Plane Stiffness, Kg/cm178.7 Kg/cm
Number of Main Strings16
Number of Cross Strings19
Ratio Cross/Mains.642
Main String Grid7.37
Cross String Grid9.62
Density (% of head filled with string).688
Average Cross String Space.506
Average Main String Space.461
Dynamic Tension, Kp, ERT36
Dynamic Tension, Lbs/in201.35
First Moment, Nm.822
Polar Moment350
Torsional Stability19
Swing Weight, Kg/cm2331
Swing Weight, Ounces11.68
Swing Weight Calculated356.6
Power, RDC48
Control, RDC53
Manueverability, RDC66
Power, Calculated 2183.7
Head Points1.42 (negative = head heavy)
Head Weight, %49.3%
Center of Percussion21.4
Dwell Time, ms, No Swing8.50
Effective Stiffness - lbs29.9
K, Lb/In (SBS) RDC179.49
Recoil Weight157.0
Twist Weight234.11
End Weight118.7
Tip Weight196.1
Total Weight314.8
9 O'Clock103.0
3 O'Clock98.9
Butt Cap110.3
Total Weight312.2




Friction v Tension…what wins?

We all know what friction is.  It keeps our cars from sliding around, it keeps us from slipping and in general makes movement possible!

Friction also plays an important part in the string bed of your tennis racquet.  Friction between the strings and the ball create friction which in turn creates rotation.

What are, however, some of the downsides of friction in the string bed during, and after, the stringing process?

Friction v Tension

For more detailed information and a graph showing the forces involved go to our membership site,, but in the meantime this image will show the frictional forces at work!

This machine tension head will pull the string (blue) in the direction of the center of the racquet support structure instead of directly out the middle of the grommet.

It is obvious that this will create considerable friction and result in lower tension inside the grommet than outside the grommet.

Our equipment and technique eliminates this friction resulting in a uniform string bed.

Happy You Year!

Of course, we are all anxious for the new year to get here and erase 2020 from our memory!

We are designating 2021 as the You Year!  So, Happy You Year!

For the last few years Racquet Quest, LLC has put more emphasis on “custom racquets” and 2021 will see this emphasis extended to “you racquets”!

What exactly does “you racquets” mean?  It simply means that every racquet that leaves Racquet Quest, LLC is set up for your style of play and personal specifications.  Yes, even if the racquet is Off-the-Shelf and not a full custom!

This is the year of “you”! Happy You Year!

Many really good things are happening next year and we are glad you are going to be with us!




Consistency. What Does It Look Like?


Consistency is a component of almost every successful thing we do each day!

But, what does it look like? Well since this is a tennis centric post it will look like this:

What you are looking at is identical racquets, identical string, identical failure location!

If you find the very end of each string you will see how consistent this failure location is.

This string is a high elongation material so will notice that the ends of the broken strings are very far apart.

This is a good thing since it (elongation) contributes to comfort and power when hitting the ball.

This consistency may be why this player has a UTR of 13.3!

This failure location indicates the player is striking the ball with consistency!  That many explain the UTR of 13.3!

What else does this failure location show us?

  • Most impacts are not in the center of the racquet.
  • The string spacing in this area is a little more “open” which may “catch” the ball and contribute to rotation.
  • There are more strings for the ball to “roll” over before leaving the racquet which may contribute to rotation.

Consistency is important in everything we do.  Visualize it like the string bed of this racquet and try to hit the same spot each time you do something…anything!