Tennis Racquet Stiffness & Flex
Explanation, Video & Charts
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When purchasing or evaluating a new tennis racquet, one of the many specifications you’ll encounter is tennis racquet stiffness or flex.
At first, it may just appear to be another number in the list of specs provided by racquet retailers. However, it’s worth considering racquet stiffness and understanding how it impacts performance and comfort, especially if you deal with arm injuries like tennis elbow.
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Video Explanation of Racquet Stiffness
If you’re looking for a more concise explanation of tennis racquet stiffness, check out my video below – I still dive into all of the critical details, which this guide further supports.
For reference, here are timestamps to the different sections of the video if you’d like to jump to a specific section.
0:17 – What is Racquet Stiffness?
0:41 – How is Stiffness Measured?
1:18 – Example Racquets with High & Low Ratings
1:26 – Racquet Stiffness & Performance
1:56 – Racquet Stiffness & Comfort
2:11 – Stiffness Comparison Chart
2:33 – Demoing Tennis Racquets
2:57 – Additional Comfort Considerations
Here are links to the resources I reference in the video:
In the following sections, I go deep to explore the topic of stiffness and flex – I hope you enjoy it!
What is Tennis Racquet Stiffness?
Tennis racquet stiffness is a numeric value assigned to each racquet that measures how much a frame flexes during contact with a ball.
As a beginner, this measurement may seem arbitrary, but it can be a useful measurement that helps guide a player’s decision-making process during their search for a tennis racquet.
This metric becomes most useful as a point of comparison. For example, if you hit with two racquets, one that features a high stiffness rating of 72 and the other a rating of 60, you’ll begin to develop a sense for how these ratings impact the feel and performance of a racquet.
However, even if you’ve never had the opportunity to compare two separate racquets, you can still benefit from understanding the pros and cons of high and low ratings.
If you’re in the market for a new tennis racquet, I’d encourage you to use specs like stiffness as a guide to help narrow down a selection of racquets but to try a few before you make a decision.
Not only will you gain a better feel for how specs translate to playing tennis, but you’ll also be more likely to find a racquet you love.
How is Racquet Stiffness Measured?
As you might imagine, racquet stiffness is not easy to measure without the right equipment. As a result, companies have developed machinery to measure a variety of tennis racquet characteristics, including racquet stiffness.
Perhaps the most common machine for measuring racquet stiffness is the Babolat RDC (racquet diagnostic center), which measures racquet stiffness, weight, swingweight, and balance as well as stringbed deflection, to help players understand when it’s time to restring.
Racquet stiffness is measured by securing a racquet’s handle to the machine and applying pressure to the tip of the racquet head, which causes the frame to flex slightly. Through this process, the Babolat RDC or similar devices can calculate a racquet’s stiffness index or rating, otherwise referred to as a racquet analysis or RA.
The range or scale for stiffness for racquets will usually fall between 50 and 85, where the lower number indicates a more flexible racquet, and the higher number a stiffer racquet. However, the majority of modern racquets will usually fall somewhere between 60 and 75.
The Babolat RDC can take these measurements within a few minutes, and they are great for comparison purposes. However, these machines are not easy to come by, so the easiest way to get a wide variety of the specifications is to check your favorite online retailer, as they typically provide this measurement for comparison purposes.
For fun, you can get a sense of a racquet’s stiffness by placing it down on a flat surface and applying pressure to the racquet’s head. You might be surprised at how much it bends. Just be careful, if you press too hard, you can damage your racquet.
Are There Other Forms of Measurement?
Absolutely. It’s reasonable to assume most major racquet manufactures have mechanisms for measuring racquet stiffness.
For example, Wilson has a machine that measures what they refer to as the Stiffness Index (SI). However, the method is different than Baboat’s, so it’s natural the ratings or numbers used to represent a given racquet’s stiffness are different.
Since the measurement values are somewhat arbitrary, they’re only useful if you compare different ratings taken from the same machine. In this case, the Babolat RDC is the industry standard and used for the vast majority of measurements you’ll find online.
Racquet Stiffness and Performance
There are three primary areas where players will experience shifts in the performance of racquets with different stiffness ratings. The three most noteworthy include:
Let’s dive into each separately.
One of the most common misconceptions with tennis racquet stiffness is that a more flexible racquet – that is one that bends or flexes under pressure – will produce more power than a stiff racquet that doesn’t bend as easily.
The assumption is that as a frame flexes and rebounds during a swing, additional energy passes to the ball. In theory, this seems logical. However, a tennis ball will stay on the stringbed for a fraction of a second, which is less time than it takes for the racquet to recover.
As a result, the more flexible a frame, the more energy it absorbs, which results in a loss in power when hitting. Consequently, a stiff tennis racquet will flex significantly less during a swing and deflect more energy or power.
For this same reason, control racquets, also known as player’s racquets, tend to have more flexible frames, resulting in less power potential for the racquet but greater overall control.
As you can imagine, this statement is relative. A beginner will not necessarily find an increase in control and accuracy by switching to a more flexible frame.
Instead, control is primarily a function of a player’s skill and technique, which, combined with a flexible lower-powered racquet, allows them to dictate the placement of the ball more accurately.
As an example, the control-centric Wilson Blade 98 (16×19) v8 has a stiffness index or rating of 61, compared with the high-powered Head Titanium Ti.S6, which sits at 75.
Closely related to control, feel, or sometimes referred to as touch, is another characteristic that many players associate with racquets of varying stiffness.
Players will often describe racquets with higher-end stiffness ratings as having a crisp or lively feel, which goes along with their higher power and lightweight construction.
On the other hand, flexible frames are often described as having a plush or stable feel. In many cases, this quality results from the heavier weight that racquets with low stiffness ratings tend to feature.
Regardless, a player will typically feel more connected with the ball when hitting and is particularly useful for types of shots that require more finesse, such as volleys or drop shots.
It’s worth noting that the type of strings you’re using, which is ultimately the surface that comes in contact with the ball, also have a dramatic impact on a racquet’s feel.
Racquet Stiffness and Comfort
Beyond power and control, racquet stiffness also has an impact on comfort. As a general rule, a stiffer tennis racquet will tend to pass more shock and lingering vibration to the player’s hand and arm, resulting in discomfort with prolonged use.
On the other hand, more flexible racquets will deflect energy upon impact, sending less shock and vibration to a player’s arm. However, it’s important to note that these are generalities.
In other words, a stiffer racquet won’t automatically be less comfortable than a more flexible frame. Other factors, such as the racquet’s weight and balance combined with strings, will contribute to a tennis racquet’s overall comfort, so it’s important to take stiffness in the context of the overall racquet design and specs.
Going back to the example above, the Head Titanium Ti.S6 is 2.5 ounces lighter than the Wilson Blade 98 (16×19) v8. For most beginners or players who don’t have a tremendous amount of strength, this would be a significantly more comfortable racquet to play with, even though it has a stiffness rating that is 5 points higher.
This point brings us to an important note about tennis racquet stiffness and comfort – it’s somewhat subjective. More specifically, every player will find varying degrees of comfort with the same racquet.
What’s more, two different racquets with nearly identical stiffness ratings can feel very different for the same player, so your opinion will come into play as you begin to trial racquets.
Thoughts on Tennis Elbow
If you’re suffering from tennis elbow or any discomfort in your arm, then your racquet’s stiffness is a worthy consideration.
As covered in the previous section, the stiffer the frame, the more shock, and vibration a player will feel. However, you’ll also want to consider these factors:
- Weight: heavier racquets absorb more shock
- Materials and construction: some materials and construction methods are better at absorbing shock than others; such is the case with Donnay racquet’s that feature solid-core frames to help absorb shock and vibration
- Balance: shock will decrease as a racquet’s balance point goes higher, i.e., head-heavy racquets
- Grip size: grips that are too small can cause the racquet to twist or move in your hand and lead to discomfort
Keep all of these factors in mind if you’re dealing with an arm injury.
Strings and Tension Considerations
As it relates to comfort and frame stiffness, strings and their tension can also play a role.
First, different types of strings will offer varying degrees of comfort. On the softer side, natural gut and multifilament will typically provide the highest level of comfort while polyester strings or kevlar will be harsher.
Similarly, tension can increase or decrease comfort with higher tensions increasing the stiffness of the stringbed and lower tensions offering up slightly more comfort.
When combined, a racquet with high stiffness rating, using less comfortable strings like polyester at higher tensions, can be a recipe for disaster, which you can take into consideration.
Racquet Stiffness Comparison Chart
Here’s a simple chart to help provide context for what to expect from racquets with various stiffness ratings generally.
Keep in mind that stiffness is one of a combination of attributes that produce a racquet’s feel. As a result, you’ll find racquets within each range that offer more or less power, control, or comfort.
Moreover, one player may find that a racquet with a higher stiffness rating plenty comfortable, while another may find the same racquet harsh and uncomfortable to play with for an extended period.
Let’s take a look at a few different racquets that fall at the high and low extremes of frame stiffness.
Stiffest Tennis Racquets
Here’s a selection of the five racquets with some of the highest stiffness ratings.
|Dunlop CS 10.0||76|
|Head Titanium Ti.S6||75|
|Volkl V-Feel 9||74|
|Wilson XP1 Racquet||73|
|Tecnifibre TFlash 300 CES||72|
Most Flexible Tennis Racquets
On the other end of the spectrum, here are a few racquets that feature ultra-low stiffness ratings.
|Wilson Triad XP5 Racquet||46|
|Prince Phantom Pro 100||54|
|Wilson Clash 100L||54|
|Head MicroGEL Radical OS||56|
|ProKennex Heritage C98 Redondo MP||57|
Frame stiffness is one of many criteria that can help players make an educated decision selecting a racquet. However, nothing beats getting out there and testing a racquet for yourself.
Once you find a racquet that fits your needs, take the time to demo the racquet. With each racquet you play with, you’ll gain more perspective, which you can use as a reference for future comparison.
If you’re on the hunt for a new tennis racquet, be sure to check our list of the 20+ best tennis racquets for 2022.
Do you still have questions? Feel free to post a comment below – we’d be happy to help!
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