Why measure skis?
In our last article “The Story Of Sooth Ski: NETFLIX of SKIS", we talked about why we started measuring skis. We envision a world where skiers would receive highly personalized ski ratings and shopping recommendations, based on the DNA of a ski and the skiers’ needs. For that, we need essentially two things:
- A unified method of measuring skis (yes, I’m thinking of a standard for all manufacturers).
- Clarity in how we describe skis (terminology, categories, feelings).
Rating a mechanical properties isn't has giving a Best-of award or trying to reach the highest level. Each skier needs to find the best level from them. This starts from measuring because it's fully objective and scalable. From measurements, we can relate to on-snow feelings and we can also categorize skis.
Ultimately, on-snow feels are personal and just like Netflix, we're making the bold statement that we can know which ski/movie you would like, once we have a bit of information on your preferences!
What Matters In An Alpine Ski?
The important aspects of alpine skis can be broken down into the following sub-elements:
- Shape (or geometry)
- Weight and inertia (related to center of masse and mount point)
- Bending and torsional stiffness
- Vibration and damping
- Durability and lifecycle (footprint)
Those elements compose the entire measurable aspects of an alpine ski. Let’s review each of those sub-elements.
Alpine Ski Shapes (Geometry)
The shape of a ski would include what we see from a top view and a side view:
- Complete length
- Shapes of tip and tail
- Rockers and camber
- Sidecut (tip / waist / tail width)
- Mounting point and setback
All those elements influence the feel of a ski on snow. We measure and publish 100% of this information on our Ski Comparator. You can easily overlay skis to compare their shapes.
Alpine Ski Weight
Nowadays, the weight of a ski is a vital information for any backcountry avid, but it has also become clear people enjoy lighter skis, for the simple ease of carrying them around. Some skiers prefer heavier and damper skis.
With the weight and the overall surface of the ski, the surface-to-weight ratio can be calculated. It is amazingly useful for backcountry skiers and free riders. I invite you to read our post on the Surface-to-Weight Ratio.
To obtain lighter skis, it’s commonly accepted that certain compromise need to be done. In time those compromises may vary as materials technology evolution bring new options. However, we currently observe that a weight reduction can have an impact on other properties, such as bending and torsional stiffness. This can explain why lighter skis can have a very different feeling on hard snow. Heavier skis feel more connected, or "grounded", while lighter skis may feel more shaky, especially on chunky and icy snow.
Bending And Torsional Stiffness
So far, most of the shape is visible and the weigh you can easily measure with any scale. But for bending stiffness and torsional stiffness… our technology is game changing.
Bending and torsional stiffness is knowing “what’s under the hood”. It’s really amazing and highly addictive to know that!
I agree that if you’re very experienced at reviewing and testing skis, you can probably compare bending stiffness of various skis by hand flexing them. However, hand flexing is not the most precise measurement and is not easy to communicate. It is also hard to perform hand flex test on sub-section of a ski, while our machine return measurements at every millimeter of a ski!
Torsional stiffness measurement is our flagship innovation. Most manufacturers that have purchased our measuring system have done it for three reasons: speed, accuracy, and torsional stiffness. Again, we provide a value every millimeter, which is better than getting the simple average of the overall ski!
What’s The Use Of Bending Stiffness In Alpine Skis?
If you ride a mountain bike, you know that most shocks can adjust from hard to soft. You adjust according to speed and type of terrain. Everyone has a “comfort zone” for speed and terrain type. This comfort zone is personal and varies from one person to another. It’s the same thing with bending stiffness on skis. Everyone has a bending stiffness comfort zone for speed and terrain, which affects what you may enjoy for bending stiffness. This is very personal and the best way to determine your ideal stiffness is by trying skis. With our data, you can now compare to something you like.
What’s The Use Of Torsional Stiffness In Alpine Skis?
We have a patented technology to measure stiffness and this is key to quickly and properly measure torsional stiffness. There are many reasons why torsional stiffness is useful, but let’s consider the following story. During the early development stages, our co-founder and inventor of our technology had conducted a study with blank skis (white top sheets that prevents the skiers from recognizing which ski you have). Each pair of skis had a different flex pattern with variations of bending and torsional stiffnesses. Skiers of any level were invited to test. The results were staggering. The variable that skiers were the most sensitive to was torsional stiffness. Surprisingly, no one is talking about it or measuring it!
Torsional stiffness is associated to edge grip and playfulness. Generally speaking, high values of torsional stiffness have better edge grip and require better technique to appreciate. Lower values of torsional stiffness require less technique, but also produce a more playful and forgiving feel.
Why Is Stiffness Distribution Very Important In Alpine Skis?
Beyond the average stiffness value, is what we call stiffness distribution. Essentially, it’s like one section every millimeter. This enables us to plot a chart of the entire profile. With this level of detail, we’re able to identify where binding inserts have been placed, where a change in the layers occurs, where any variation of the core are shaped. And of course, we have this for both bending and torsional stiffness!
When I analyze skis I’m always very sensitive to the shovel and tail areas. Those specific areas have a huge impact on the feeling of a ski and we see significant variations from one ski to another.
Vibration and damping
Vibration is an aspect we do have the ability to measure with unprecedented level of accuracy, but it is also longer and more difficult than measuring the shape and stiffness distributions. We measure this on demand. If vibration and damping is something you would like to explore, you can continue with a more scientific reading here. I also invite you to read the following publication (way simpler to read!) from one of Alexis' students about alpine ski damping technologies.
Anyone who has experience working in a shop knows these two facts:
- People judge a book by the cover
- Many skiers shop by the color and the other ones only pretend they don’t care.
There might be a few exceptions to these rules and I think they all work in Alexis’ lab… they all have either a masters, or Ph.D. They are wrapped in science to a point they genuinely don’t care!
The good news is once you find a short list of product that match your the specs that you are looking for, you can choose the product that match your style the best.
Durability and lifecycle footprint
This is probably the less marketed aspect of skis, but we should expect this to change in the next few years. Some smaller companies such as WNDR Alpine and Ferreol are targeting the skiers who actually walk the talk when it comes to environmental footprint. One day, which I believe is sooner than we think, we hope that there will be clear guidance that will enable comparisons between skis based on their life cycle footprint.
How do we fund our project?
As of now, we are putting all « profits » generated by the sales of the SSP test bench towards measuring skis. This is not really sustainable, but we think it is the right thing to do and that skiers deserve independently measured data. If you like our measurements, consider donating here so that we can continue doing it. Thank you for supporting us.
What Does Sooth Ski Share With The Ski Comparator Application?
We provide a mountain of new information based on our measurements. The comparator is freely available on the web. We fully cover the shape, the weight, and the surface weight ratio. We also share the bending and torsional stiffness, including the entire stiffness distributions. We try to include as many skis as possible, but if you are a manufacturer and find that your skis are not included please contact us so that we can correct the situation.
Don’t miss our next part of this article which covers how to use the information Sooth Ski publishes. Our graphs may look complicated at first site, but if you’re a ski reviewer or a ski nerd, or in charge of purchasing for a shop… this is unique information that will help you a lot!!!