Start by collecting information
As you can tel from the title, there are a few basic informations we need to collect for a ski fit. Primarily, we need to establish who you are. In this case, we're considering a women skier, who is advanced, measures 5'6", weights 130lbs and skis in the province of Quebec, so North American East Coast. The basic questions we need to answer would be the following:
Heigh and weigh are important, but size in also required, as some people are more muscular than others.
Your Skier Profile?
The Skier Profile is a bit subjective, so we try to bring in some objective information in there. The current ski and its specific appreciation is the best information we can obtain, especially if we have this ski in our database. We use it as a starting point for our comparison. Knowing the skier's appreciation of it enables us to target specific variations, such as more/less bending and torsional stiffnesses.
It is very common nowadays to own more than one pair of skis. But in this case, the customer wants to own a single pair of skis that does it all. This obviously calls for a large compromise, mostly on the ski width and weight (mass). We consider there are 5 large categories of skis. There are grey zones in each, which we differentiate with various subcategories.
The preferences are the topping on the pizza. Once you chose the size, the topping can still make all the difference between a ski you like and a ski you hate. This is where Sooth Ski Fitting is unique, because we know what's the performance of the material hiding under the top sheet of each ski. Bending and torsional stiffness can be extremely variable within a group of skis that have the exact same shape, often by more than 300%!
On-snow feelings depends on personal preferences. Some skiers may find that a ski has enough edge grip, while others don't. This is why it is good to have a ski as a starting point.
Finally, other preferences can also be taken into consideration, either as hard filters or optimal options within equivalent results.
Define The Baseline (performance reference)
A baseline is required in a proper ski fit as we all have our own interpretation of the feelings we have on skis. A simple example would be a comparison of one's personal high speed limit to the one of a World Cup athlete. The baseline would be very different. It is common to notice former ski racers still using FIS slalom skis after their racing carrer is over, because that level of stiffness remains their comfort zone, their reference.
In the case of the client described in this article, I unfortunately don't have the Rossignol Zenith 6 2008-2009 measures. It would be a lot easier if we had those measures. However, from reading some reviews (thanks to many dedicated ski testers and reviewers on the web), we can spot a ski we have in our database that is very likely to be equivalent and can be used as a baseline.
The Rossignol Zenith 6 was the all-around advanced ski of that time. It was described as a stable, fast and versatile ski. The current Rossignol Nova series would likely be the equivalent and we have measured those. We also have the Rossignol Famous series to compare. Using the free Sooth Comparison Ski Application I was able to select a few options that would compare to the Zenith 6. Applying filters to isolate Rossignol skis for women, between 150-158cm and 70-80mm wide, I obtained 12 measured skis (as of September 1st 2021).
Comparing the ones dedicated for advanced and experts (Nova 10 Ti, Famous 10 and Nova 8 Ca), I made interesting findings. The most important relative differences are on the torsional stiffness, which is responsible for the edge grip. The Nova 10 Ti was consistent from 2020 to 2021. On another hand, there were important differences between the Famous 10 2018 and 2019 (almost double the average torsional stiffness!). As for the Nova 8 Ca, it stands out as the softer in bending stiffness. Considering my client is advanced and skis faster than the average skiers, I'd opt to use the Nova 10 Ti 2020 as a baseline. Being in the middle of the pack, it's likely to be a close reference. The chart bellow is probably one of the most revolutionary ski rating illustration. In a glance, you have a good idea of the stiffer option in bending (affects the speed comfort zone) and in torsion (affects the edge grip).
reading the torsional vs bending stiffness charts
This chart requires very little time to understand and make sens of, but a few basic elements need to be explained:
- Never look at this as an absolute rating. You must look at the dots as relative to one another (one higher than another, one more left or right than another one...);
- The values are average. To get the entire story, you need to look at the profile of distribution. Essentially, in this chart you don't see the detail of a specific area, such as tip/tail for example. A ski behavior on the snow may vary considerably based on a specific area.
- Many skis considered similar may have differences of more than 20% on one of the scales. Consider that differences of less than 10% are very difficult to notice while skiing (Note: this statement was brought up by top ski designers who spent their life designing, crafting and testing countless prototypes). So do dig too far in the details, there are plenty of variations of more than 20% to search and compare!
The horizontal axis is for bending stiffness. Towards the left means the ski will be softer (bending). We tend to accept that softer skis have a lower speed comfort zone. But since we all have different comfort zones, ideally you spot skis you know and compare relative to those.
The vertical axis is for torsional stiffness. Towards the bottom means the ski will be softer (torsional). Torsional stiffness affects directly the playfulness and the edge grip. Lower torsional stiffness will be more playful and less edge grip.
The horizontal axis is for bending stiffness. Towards the right means the ski will be stiffer (bending). We tend to accept that stiffer skis have a higher speed comfort zone. But since we all have different comfort zones, ideally you spot skis you know and compare relative to those.
The vertical axis is for torsional stiffness. Towards the top means the ski will be stiffer (torsional). Torsional stiffness affects directly the playfulness and the edge grip. Higher torsional stiffness will provide more edge grip and will feel less playful.
Establish The Hard Filters
Once we have our baseline, we can go back to what my client is looking for. A ski that will be used mostly on piste (80%), but will occasionally be used in glades or resort backcountry outings (20%). Here preferred terrains and conditions include powder and glades. Considering she skis about 20 days in a season, I assume certain less appealing conditions (crust, ice...) may be avoided.
I've determined my hard filters to be the following:
155mm to 160 cm (ideally 157-159)
Slightly longer will not make a difference in maneuverability, but will probably offer stiffer options for advanced skiers.
75mm to 85mm
Here's where most of the compromise happens. With this range, she will be able to complement this all-around option with a larger and lighter backcountry ski (95-105mm for east coast conditions) and an on piste oriented ski (under 72mm).
12m to 15m, as she's used to a slalom style so it would not be ideal to increase over 15m. Very short radius (10-11m) could also be interesting, but limiting the versatility.
Navigate The Options
I've used the SoothSki Compare Alpine Ski application to obtain the following results, when limiting to only 2020 and 2021 skis. The list is still long, with 25 options matching those hard filters!
From there, I can browse any specification I may want. For example, I can compare the sidecut and rocker lengths. This will tell me about the effective edge percentage, so the stability of the ski and also the adaptability to variable terrain. More rocker is better for variable terrain, but is also means less effective edge on piste.
Compare With The Baseline
Now you'll understand why the baseline was important to establish. The skier knows about the feelings associated to the baseline. The skier can also express an appreciation of that ski. Here are a few examples:
- One could say: "I love this ski, but I wish it could hold edge a little more". Easy to fix: choose a ski with an average torsional stiffness a little higher than the baseline!
- Another example could be: "I'd like to improve my abilities in bumps". In this case, you may want to reduce the average bending stiffness and also increase the rocker, so that the ski has less effective edge. It will make the ski easier to pivot in the narrow bumps.
- Finally, one could say: "My ski is great, but when there's snow, I'm unable to keep my balance". To help with this, you need to consider three essential components: 1) get a flatter camber and 2) add more rocker and 3) increase the setback to that the balance point is further back, which will make it easier to maintain the tip above the snow.
Once I've reviewed the options, I came down the 4 options which each have a slightly different touch, but would all be great for my client. As you know, the specification are very similar. If you were to pick up those skis in a shop, you'd have a hard time saying exactly how different they would feel on the snow. Yet they have distinctions that we cover in the formal recommendation step.
Provide The Formal Recommendation
I could geek out way more here and publish some bending and torsional stiffness distribution profiles! This is what you need to really get the cherry on the top. Among the 4 options, here are my final comments:
The Blizzard Black Pearl 82 has a bit more rocker compared to the other options and it has a nearly flat camber. Among the four options, it will be the more fun to take out in variable conditions, yet its high level of torsional stiffness will be great for edge hold. The radius is a bit larger with 14m, adding to the adaptability.
The Rossignol Experience 80 is similar to the Dynastar Intense 82, but stiffer. At higher speed, this will be more comfortable, but not easier in variable snow.
The Dynastar Intense 82 Pro offers the highest level of torsional stiffness, especially in the rear portion of the ski. I'm able to say this because I have access to the entire data on stiffness, which shows clearly this aspect. The tail end may even feel like it's too grippy for certain skiers, but since my client is advanced and used to slalom skis, I consider this acceptable. The Intense 82 Pro would feel like a larger slalom ski, full of energy.
Finally, I've added the Head Super Joy, because I believe this would be a ski my client would enjoy. It's more narrow with only 74 mm at the waist, so similar to here current ski, but has a small rocker and a good setback. Those aspects will make the ski enjoyable in varied conditions and terrain, while provide great on piste performance.
The graph below is what enabled me to determine most of what I've said.
This article is meant to show how we execute a ski fit. The process for the client is very simple and takes about 2 min. On our end, there's a fair amount of thinking and analysis so we ensure we cover all aspects, but over the years, we've developed tools to assist us. We measure skis because it enables us to compare anything out there, with the same kind of information. We've made almost all of our data accessible and FREE for everyone to enjoy. As of today, our Ski compare App remains a tool for knowledgeable skiers to use, but we're working on simplifying this. We still keep a few information behind the scene, such as bending and torsional stiffness distribution and vibration and damping analysis. Those require even more knowledge to understand properly.
Any comments are great comments, so drop a line and have a nice ski season.