Category Archives: Tips
I started thinking about this as I made my way to a routine doctor’s appointment last week. Here is the scenario I formed while waiting:
The doctor has been seeing all sorts of patients already today and I suspect the first glance at each one elicited some sort of reaction, quielty probably, like this; “Good Greif, that guy is fat! Bad trousers, terrible shoes, nice shirt, whats with the hair, dude?” etc, etc.
So what do you think happens when a racquet shows up for a checkup?
“Good grief, that is an old racquet, who would ever buy one of those, this person is too good for that racquet,” etc, etc.
As humans we can communicate how we feel to the doctor but your racquet can not, so it has other ways to tell you if it is healthy or not. Here are a few signs of an unhealthy racquet:
- Grommet set, and specifically the protective head bumper is worn out. If this is not fixed quicky the racquet will die!
- Grommet set individual barrels are broken or missing. If this is not fixed the strings will die!
- Overgrip is disgustingly dirty requiring exam gloves to remove it! Doctors use exam gloves too and you know what that means!
- Under grip is essentially rendered to powder, requiring exam gloves to remove it.
What is not so obvious sometimes is that strings need to be replaced. Even before they break! What!
Yes, strings loose tension over time and in some case rather quickly! By knowing what the original string bed stiffness was we can determine how much “stiffness” has been lost. For most players a degradation of 20% is maximum.
Depending on the string material a loss of 8 to 9% overnight is not uncommon…so that leaves 11 to 12% for playing.
Take a look at our String Frequency Calculator to get a better idea of stringing frequency required to keep your racquet really working for you.
To keep you playing at your best you need to keep your racquet at it’s best!
In addition to individual model specifications we like to do a consolidated series comparison so we can glance at the differences between racquets. Following is that comparison. All the data is taken with strung racquets with a vibration damper but no overgrip.
So, what is important in this data? Well, to us, everything or we wouldn’t include it but we like to explain some of the not so obvious numbers.
End Weight: the weight of the butt end of the racquet when using two (2) electronic scales
Tip Weight: the weight of the top end of the racquet when usisng two (2) electronic scales
Why important: this accurately calculates static balance and allows easy maching of multiple racquets
Swing Weight: the higher the swing weight the higher the energy colliding with the ball.
Why important: this is the most meaningful number in terms of momentum into the ball.
InPlane Stiffness: this tell us how stiff the racquet is when a load is apllied to the 3 and 9 o’clock positions.
Why important: a higher number means the racquet is stiff in that direction affecting string bed stiffness.
Stability: this tell us how the racquet reacts to ball impact.
Why important: the higher the number the more power and control that can be contributed to the racquet.
Position 1, 2, and 3: three (3) electronic scales are used to weigh the racquet.
Why important: we can match the rotational inertia of each racquet.
Peak Load: this tells us the peak force of the ball impact on your body. Higher loads contribute to injury.
Why important: we can make adjustments to the string bed stiffness to keep the peak loads safe.
Everything else should be clear but if you have questions please “Ask John”
OK, here’s the deal. I have written about this several times and each time I decided that it was a waste of time, so it goes back into a file somewhere!
The time is now that we really need to understand more about stringing as a consumer and what we can do as racquet technicians to make the life of a player better, more fun, and safer.
This a quick story to set the premise of the rest.
Several weeks ago I received a freshly strung (24 hours) racquet to perhaps make a few modifications to the racquet. The racquet was strung by the player, a very good junior with a high ranking. The racquet was 18×20 with a full bed of polyester at 53 pounds. When I asked why the response was “I have always done it this way”. Fair enough!
The string bed stiffness (SBS) using the Beer’s ERT300 was 23, the SBS using the Babolat RDC was 29, and the SBS using the FlexFour was 50. If you are familiar with these data, you know the numbers are quite low.
The racquet had only one mis-weave and one crossover, but it was severely distorted, i.e., very wide.
For a quick comparison, a properly strung racquet would have numbers like 36, 58, and 67 respectively.
So, the “softness” of the string bed when improperly strung was something that may not transmit as much shock to the body as a racquet that was properly strung at the requested 53 pounds and has a higher SBS!
Therefore a poor stringing may save the life of polyester based string! It may not be good for performance or racquet integrity but it seems that very few players care!
So what do we do?
For years I have been advocating for the use of a finished SBS instead of a “reference tension”. Why? Because each stringer and stringing machine probably produce a different result.
If a player comes to us and requests an SBS of 37 (Beers ERT300 for example), we can adjust the stringing machine to produce that SBS number. Our machines may be set at 40 to achieve the requested 37, and another shop may have to set their machine to something different. The object is to arrive at the finished SBS, and it is up to the racquet technician to be able to do that! The result will be a better performing racquet that will last longer.
So, it has been a while since you had your racquet strung and you are standing on the court about to receive and you ask yourself; “I wonder when I should get my racquet strung”.
Now is probably not the best time to think of it but if you do simply take a look at the short video for a quick answer;
In dictionary terms it is:
“the amount of extension of an object under stress.”
In tennis terms, it means the same thing when talking about tennis racquet strings.
How much does a string stretch under the reference tension load or otherwise stretched (impact)? The proliferation of wrist, arm and shoulder injury has brought attention to the property of “stiffness.” The problem is that your stiffness may be different than my stiffness, so there needs to be an “index” associated with each string, in my opinion. I have that data on over 500 tennis strings, but that is just me.
The images show the results of high elongation (left) and low elongation (right) string upon breaking.
Several years ago a player asked me “where is the string that is missing?” Well, it is not missing. The ends you see should be connected!
If the string has little elongation when it breaks there is nothing “pulling” it apart like the high elongation string. So each time you hit the ball, the string either elongates a bunch or it doesn’t.
In the case of the high elongation string, on the left, it absorbs a good portion of the “shock” associated with a hard hit, whereas the low elongation string, on the right, lets your body do the absorbing to a great extent.
So, it is reasonable to use very low reference tensions for low elongation string (35 to 45 pounds; 16 to 20.5 Kg) and higher tensions (45 to 60 pounds; 20.5 to 27.2 Kg) for high elongation strings.
You may ask, “how do I know how stiff a string is?” If you see the word “polyester or co-polyester” it is likely that string wil be stiff compared to natural gut, most nylon based multi-filament construction, and PEEK (Zyex) material. In my opinion, there is no “bad” string just “bad” applications. If in doubt…ask!