Ski Materials and Construction

[ReturnToMonkey]

I am finding a ton of really bad misinformation regarding the properties of various materials when it comes to ski construction. From the skibuilder forum to Folsom Skis's website and more, I see claims about materials that are literally the opposite of what's truth. How much actual materials engineering goes into most ski design and how much is purely driven by economics and trial-and-error? I know a lot of companies talk about experimenting with shapes and layups, sending a few prototypes with their employees and riders to the mountains to get feedback. But to me, "poppy" "stable" "torsionally rigid" and "durable" mean pretty much nothing as everyone has a different qualitative scale.

I am interested in hard, empirically determined numbers. I want to see the coefficient of friction of Durasurf 4001 compared to Isosport 4400 in laboratory testing before being sent to the variable mountain. Why does every company put carbon fiber stringers on TOP of their cores instead of the bottom, where it would show its strengths far better? (I know some do both). How much would the elastic modulus and shear strength change by using 100% recycled fiberglass mat for a binding retention layer? Why ABS sidewalls when PET is easier to work with and ABS is only better at high temps... obviously not the operating environment of skis? I've heard basalt fibers may be an eco-friendly alternative to carbon fiber, but how is the compressive and transverse strength? How do different sidecuts affect the flexibility of different regions on the ski?

It doesn't seem like many ski companies release any numbers that answer these kinds of questions. Yes, their methods and designs probably must retain some secrecy for competitive reasons, but do many companies even KNOW the answer to these questions? I think the wide variety of performance and durability when it comes to skis answers that. Some do care about quantitative data. Some only consider one number, the price tag. What are some things that ski companies definitely test before sending their skis into the wild for real-world testing? Why do some companies clearly not care about creating a truly engineered product?

 

[ASSholebomber22]

I'm willing to bet most freestyle-esque skis and companies don't have the data you're looking for and instead go after formulas that work well enough, especially the smaller ones. This sounds like stuff for the race community and I'm sure when there's big medals on the line there are absolutely engineers hashing all of this out. Hopefully some industry guys can provide some insight into the analysis or lack thereof when engineering a ski. One thing also is that the market likely doesn't require such data as plenty (maybe most?) of skis are bought based purely on subjective means anyways. As always tho, I'm just blowin smoke and I've been wrong before, curious about this stuff as well.

 

[migidimigi]

I think Blister Labs is aiming to provide this type of almost scientific testing and real life, objective comparisons between brands.

 

[lil.Boye]

i don't care too much about analytics. i think a solid review is far better than seeing the fiber structure of the fiberglass.

 

[ReturnToMonkey]

i don't care too much about analytics. i think a solid review is far better than seeing the fiber structure of the fiberglass.

And neither do the people who buy a car, yet the car manufacturer knows all the important properties of every design decision in the vehicle. In my opinion, it's a testament to how good the design is, but they don't have to relay that information to the customers. Sorta comparing apples to oranges but I hope it gets my point across

 

[IsaacNW82]

From my understanding it is a mix. On the race ski side of things, there is much more science and data. On freeski and freeride side, I see very little. I think the majority is trial and error, but that doesn't mean there aren't plenty of STEM background professionals in the industry (for example ON3P's founder is a biology major, I think).

Ski websites are more about marketing than anything, so don't expect much there. Forums are mostly hearsay and you have to sift through the piles of crap. For specific material properties, a lot of the manufacturers have some info publicly available online (for example Durasurf 4001 has a basic brochure with some measured mechanical properties).

My honest opinion, as someone who works 40 hours a week as an Engineer, is that it is not a very high-tech or data driven industry in general, save maybe some of the race side of things. Too small of an industry, too complicated to model anything that correlates well on snow, zero incentives to share data with competitors.

P.S. Basalt is closer to S-glass in mechanical properties than carbon

 

[ReturnToMonkey]

P.S. Basalt is closer to S-glass in mechanical properties than carbon

Thanks for that great answer. I literally never had heard of basalt stringers until reading about Niche Snowboards a little before posting this thread. Seems interesting how does it compare in durability? I would think it would be quite brittle.

 

[IsaacNW82]

Thanks for that great answer. I literally never had heard of basalt stringers until reading about Niche Snowboards a little before posting this thread. Seems interesting how does it compare in durability? I would think it would be quite brittle.

I honestly don't know. It has better fatigue strength, and an elongation at break between carbon and glass. So my shot in the dark is it would keep its pop longer than a glass ski. No idea how it handles impacts, how it is to wet down, or how damp it is when you make a composite structure.

If you want to go on a deep dive here's a great paper on the fatigue strength of glass, carbon and basalt laminates (I just read the abstract tbh):

https://pegoretti.dii.unitn.it/resources/Untitled-Folder/Papers/109-Dorigato-Fatigue-resistance-of-basalt-fibres-reinforced-laminates_JCompMat-2012.pdf

Damping and fatigue strength of composite materials are complex and generally not well understood; there a few studies of vibrations/damping in skis, but I'm unaware of any fatigue life (or any other well-defined durability tests for that matter) studies specifically on skis.

Weirdly enough the only ski I remember using it extensively is an intermediate Rossignol ski, the experience 86 basalt.

 

[alude]

I am clearly biased, but I think the conversation should shift from material to the ski properties. It is just too easy for a marketing department to claim that a "new" material is revolutionary. Material are too often associated with some kind of black magic / buzzword, and often, as you said, opposite from what is known to be truth. Furthermore, it is not just the materials that is important, but how you use them. Measured properties are what they are. You can't cheat them and they give you a consistant picture of how the ski will behave.

Unfortunately some properties that you listed like the coefficient of friction of the ski base are hard to measure in a simple definitive and representative way. The CoF will be influenced by the snow, the temperature, base preparation, etc. It is also hard to say to what extend the number collected will be important for most skiers. It quickly becomes a mess to make sense of the data collected and communicate that clearly to a customer. Same goes for vibration response.

That is why we started at SoothSki by measuring the most basic properties and see if/how people find that useful. Obviously, we are not measuring all the properties that could be important, but maybe we capture 80% of what people feel on snow with 20% of the efforts required to measure everything in details... maybe!

 

[IsaacNW82]

I am clearly biased, but I think the conversation should shift from material to the ski properties. It is just too easy for a marketing department to claim that a "new" material is revolutionary. Material are too often associated with some kind of black magic / buzzword, and often, as you said, opposite from what is known to be truth. Furthermore, it is not just the materials that is important, but how you use them. Measured properties are what they are. You can't cheat them and they give you a consistant picture of how the ski will behave.

Unfortunately some properties that you listed like the coefficient of friction of the ski base are hard to measure in a simple definitive and representative way. The CoF will be influenced by the snow, the temperature, base preparation, etc. It is also hard to say to what extend the number collected will be important for most skiers. It quickly becomes a mess to make sense of the data collected and communicate that clearly to a customer. Same goes for vibration response.

That is why we started at SoothSki by measuring the most basic properties and see if/how people find that useful. Obviously, we are not measuring all the properties that could be important, but maybe we capture 80% of what people feel on snow with 20% of the efforts required to measure everything in details... maybe!

just here to say I 100% cosign everything alude said here. After all, he did co-author one of the papers I have read on ski vibrations...

 

[alude]

Thanks for that great answer. I literally never had heard of basalt stringers until reading about Niche Snowboards a little before posting this thread. Seems interesting how does it compare in durability? I would think it would be quite brittle.

Oh, and to go back to that and eco-friendliness... I don't believe much in "stringers". They are a great way to add a tiny little bit of something into a ski so that the marketing department can talk about it. In some cases, there is so little material that it almost feel like homeopathy.

For eco-friendly products, we need simpler products right now designed with process that take less of the least impactful materials. We don't have to rely on new material that will maybe takeoff in 10-20 years, we can do it right now. Carbon fibre is 10x worst than fiberglass (and is not that useful for skis). It was however super trendy during the last 5-10 years and you had to put carbon stringers somewhere in your skis to talk about it. I am glad Rossignol is following the more "boring" route. Hopefully they go all in:https://www.rossignol.com/us/essential

Adding a stringer of basalt to a normal construction won't make it eco-friendly. Some companies have tried however to completely replace fiberglass with basalt:https://www.compositesworld.com/articles/basalt-fibers-alternative-to-glass

 

[ReturnToMonkey]

Oh, and to go back to that and eco-friendliness... I don't believe much in "stringers". They are a great way to add a tiny little bit of something into a ski so that the marketing department can talk about it. In some cases, there is so little material that it almost feel like homeopathy.

For eco-friendly products, we need simpler products right now designed with process that take less of the least impactful materials. We don't have to rely on new material that will maybe takeoff in 10-20 years, we can do it right now. Carbon fibre is 10x worst than fiberglass (and is not that useful for skis). It was however super trendy during the last 5-10 years and you had to put carbon stringers somewhere in your skis to talk about it. I am glad Rossignol is following the more "boring" route. Hopefully they go all in:https://www.rossignol.com/us/essential

Adding a stringer of basalt to a normal construction won't make it eco-friendly. Some companies have tried however to completely replace fiberglass with basalt:https://www.compositesworld.com/articles/basalt-fibers-alternative-to-glass

I agree 100% with all of that sentiment. Stringers play an important role in increasing rigidity in something large and thin, such as sheet metal panels. The main thing they add to a ski is to the price tag and marketing material like you said. CF is also horrible for the environment lol. I think if a company really wanted to, they could layup like one ply of 0/45/45 CF all the way across the top and bottom of a tapering bamboo core, where the thickness of the core controls the stiffness. Bamboo grows relatively quick and uses less energy than other woods. A more progressive company would replace the CF with recycled glass and bioresin. Checkerspot claim they have been developing polymers that are actually a bit stronger than their petroleum-based counterparts, which makes me hyped. I wish I knew more chemistry so I could help them take those developments further

 

[IsaacNW82]

I agree 100% with all of that sentiment. Stringers play an important role in increasing rigidity in something large and thin, such as sheet metal panels. The main thing they add to a ski is to the price tag and marketing material like you said. CF is also horrible for the environment lol. I think if a company really wanted to, they could layup like one ply of 0/45/45 CF all the way across the top and bottom of a tapering bamboo core, where the thickness of the core controls the stiffness. Bamboo grows relatively quick and uses less energy than other woods. A more progressive company would replace the CF with recycled glass and bioresin. Checkerspot claim they have been developing polymers that are actually a bit stronger than their petroleum-based counterparts, which makes me hyped. I wish I knew more chemistry so I could help them take those developments further

I would be careful with the phrase "biobased" tbh. Nothing against it, companies are right to use exceptional resins like Entropy's supersap resin, but even then it is only 29% biobased (meaning the rest is presumably petroleum based or otherwise not sustainable...). And then you have companies bragging about biobased cores and sidewalls, which is insane considering you can build both out of wood. Sure, better than ABS, and it may have legitimate mechanical advantages over wood, but the greenwashing is insane to me.