Category Archives: Testing Devices
Celebrity Visitors!
The World Headquarters of Racquet Quest, LLC was happy to welcome Randy St. Pierre and Henry Hamels for a visit!
Randy is a member of the Dunlop Stringing Team and is from the UK and Henry is the principal of String MD in Florida! Randy has been stringing racquets for quite a while and is always a source of good information…and he bought lunch!
Randy & Henry
Randy lives in a beautiful part of England so we are all invited to his house when the weather is better…is that right Randy?
Randy remembers stringing for a young player named Emma at a tournament in Nottingham when young Emma was in the 300’s world wide! Look at her now! Was it Randy or something else? I wonder!
Anyway it was great fun having these guys here and they are welcome anytime as are all of you reading this!
And the winner is…Head FXP 17
Head FXP is a string that seems to be largely overlooked and I am surprised after seeing the results of the installation and testing!
| String Name | Category | Gauge | Ultimate Tensile Strength/Lbs | Knot Strength/Lbs | Country of Origin |
|---|---|---|---|---|---|
| Head FXP | Multifilament - Nylon | 17 | 165.9 | 93.4 | Japan |
Both the tensile strength and knot strength are exceptional and the graph shows that this string is very “elastic” which is a good thing for tennis racquet string but sometimes just not considered.
Head FXP 17
The area under the solid red lines is considered a stress-strain curve and indicates the “elasticity” of string by how close the lines fit from 0 to 50 three (3) times. A perfectly elastic material would be one line even though it went through three (3) cycles. What you see here is quite good and one of the reasons it is the winner!
String Evaluation Program
Racquet Quest, LLC has for years been doing the extensive evaluation of racquets and string for the benefit of our client’s customization requirements.
Now we are making this evaluation “program” available to anyone that wants to dig deeper into the workings of the string in the racquet!
This is serious stuff and requires significant resources but it is worth it!
Please contact us of you would like to take advantage of our evaluation program!
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!
Racquet Quest, LLC
