longitudinal & torsional stiffness of SL skis?

[Noodler]

Be interested if SoothSki.com measure any degradation in torsional stiffness of well loved skis that have reportedly lost their edge hold.

I think @AlexisLD has commented on this and that they have not yet measured any decrease in stiffness in their testing. However, it seems to me that there absolutely should be a loss of stiffness over time of any well used ski because I think most of us "core" skiers have experienced this happening in our ski quivers.

 

[AlexisLD]

I think @AlexisLD has commented on this and that they have not yet measured any decrease in stiffness in their testing. However, it seems to me that there absolutely should be a loss of stiffness over time of any well used ski because I think most of us "core" skiers have experienced this happening in our ski quivers.

@Noodler Correct, we haven't measured any change in bending or torsional stiffnesses, beyond the 5% accuracy of our machine. We measured SL and GS skis throughout the racing season of a U18 racer. This include a lot of ski sharpening and lost edge (steel is stiff). Not very many datapoint though. Maybe not enough ski days either, although the racer told us he could feel a difference between both pairs (after many days of skiing them). It would be interesting to do more measurements...

The general theory of composite is that they don't loose much stiffness over time because very little damage is happening to fibres over time. What breaks down is the resin holding everything together. This can increase the damping, specially during large deformations (everything is pre-stress in a ski because it is molded at elevated temperature, so you need to stretch quite a bit to open cracks in the resin).

I do believe something is changing in old ski, but I just could not tell you what!

That being said, I would also be very curious to take two identical pairs, blind test both of them to see if skiers can feel a difference, then ski one pair for a number of days, before finally blind testing both of them again. Placebo effect, along with the desire to buy more skis, can be very strong!

 

[geepers]

That being said, I would also be very curious to take two identical pairs, blind test both of them to see if skiers can feel a difference, then ski one pair for a number of days, before finally blind testing both of them again. Placebo effect, along with the desire to buy more skis, can be very strong!

Look forward to hearing the results of that.

Question is - will you get ski manufacturer support for that type of test?

 

[AlexisLD]

Look forward to hearing the results of that.

Question is - will you get ski manufacturer support for that type of test?

I think most people, manufacturers and skiers, think that skis last long enough... buying news skis after 100 days of use is not that big of a pain point for most people. Very few people shop for durability right now.

It is an interesting experiment, but it would be long and challenging to perform, as it is hard to get skis in and out the lab over long period of time, and there would be few actionable outcomes. What will you do about it if you find that something change in a ski after 100 days of use? There is also a risk that you are not measuring the right things, and that the full experiment would thus worthless...

It would be interesting, but it is not high on my priority list unfortunately.

That being said, if someone is willing to buy two pairs of skis and ship them to me at regular interval, I will happily measure them! That is the easy part!

 

[cantunamunch]

I think most people, manufacturers and skiers, think that skis last long enough... buying news skis after 100 days of use is not that big of a pain point for most people. Very few people shop for durability right now.

It is an interesting experiment, but it would be long and challenging to perform, as it is hard to get skis in and out the lab over long period of time, and there would be few actionable outcomes. What will you do about it if you find that something change in a ski after 100 days of use? There is also a risk that you are not measuring the right things, and that the full experiment would thus worthless...

Would the observation that some users find skis to be dead after 40-50 days of use change your mind?

One actionable outcome would be to reform preferences - like for round rib shaped reinforcement in the center section of the ski - at initial purchase.

 

[AlexisLD]

Would the observation that some users find skis to be dead after 40-50 days of use change your mind?

One actionable outcome would be to reform preferences - like for round rib shaped reinforcement in the center section of the ski - at initial purchase.

I am not sure. For most people, 50 days represents 5 years of skiing. They will want new skis after that much time regardless of their performance.

Most people don't really flex their skis much either (few moguls or high edge angle), so it might even be longer than that for them.

And most people also don't really feel much of the vibration response of a ski (they feel mostly how much a ski will generate vibrations, not how well it will damp them). If structural damping is what makes a ski become dead, then very few people will be able to feel that...

What do you do now after 50 days on one pair? Buy new skis? Would you pay twice the price that you are currently paying for a ski that can last twice as long? What are the benefits of having a ski that last that long? Don't you want the latest new tech?

Doing such testing to inform customers would also be expensive. It would takes hours/days to flex the ski on a machine and then the skis would be dead. When we measure the ski stiffnesses, it takes 2 min/ski and we can put the ski back in the rack afterward. It can be very cheap. Measuring durability/wear would be a completely different game (and there are many other way that a ski can be durable... doing rails, slap test, etc).

 

[James]

What do you do now after 50 days on one pair? Buy new skis? Would you pay twice the price that you are currently paying for a ski that can last twice as long? What are the benefits of having a ski that last that long? Don't you want the latest new tech?

Not sure the point you’re making. The question was whether you’ve tested them or not. Not reinventing the ski industry. Not sure many who ski 10 days/yr are interested in ski data.

 

[S.H.]

Not sure many who ski 10 days/yr are interested in ski data.

Or are buying SL skis ...

 

[AlexisLD]

Not sure the point you’re making. The question was whether you’ve tested them or not. Not reinventing the ski industry. Not sure many who ski 10 days/yr are interested in ski data.

I was answering cantunamunch who asked if it made a difference to suppose that skis were going dead in 50 days instead of 100. The answer doesn't change much in my mind. It would be fun to know, but beside the knowledge we would gain, I am not sure it would make much of a difference either for skiers or manufacturers. It is a hard question to answer for many reasons, and would require ton of efforts/money to deploy so that it provides relevant information to skiers, with very little "value" in the answer (or some that I don't see yet). You might also get very similar numbers for most skis (or most skis that interest core skiers)...

As I said before, we measured the "wear" on a few skis. We didn't find any change in stiffnesses. Can I say that nothing change? No, nobody could say that with such experiment. One could always come up with one more thing that you could have measured, or different test conditions. I just know that continuing this experiment would be very difficult/long, and there is a good chance that we would not find anything again. I was asking you guys to provide reasons to tackle this so that I can change my mind about this!

 

[geepers]

I was answering cantunamunch who asked if it made a difference to suppose that skis were going dead in 50 days instead of 100. The answer doesn't change much in my mind. It would be fun to know, but beside the knowledge we would gain, I am not sure it would make much of a difference either for skiers or manufacturers. It is a hard question to answer for many reasons, and would require ton of efforts/money to deploy so that it provides relevant information to skiers, with very little "value" in the answer (or some that I don't see yet). You might also get very similar numbers for most skis (or most skis that interest core skiers)...

As I said before, we measured the "wear" on a few skis. We didn't find any change in stiffnesses. Can I say that nothing change? No, nobody could say that with such experiment. One could always come up with one more thing that you could have measured, or different test conditions. I just know that continuing this experiment would be very difficult/long, and there is a good chance that we would not find anything again. I was asking you guys to provide reasons to tackle this so that I can change my mind about this!

It would probably make a difference to me. Tend to ski one pair of skis nearly everywhere for a time. Only occasionally bother pulling a different pair for the day. (Mostly just forcing myself to cope.) In a good year I'll get 60-80 days and hoping for more. Fair bit of bump work, do my best to bend 'em of the groomers.

So if there was proof skis degrading after a certain usage then I'd opt for newies rather than extend into a second season. At least it would be easier to wave the credit card around.

 

[François Pugh]

It would make a difference for the one percenters. (or maybe even the 3% )

 

[AlexisLD]

So if there was proof skis degrading after a certain usage then I'd opt for newies rather than extend into a second season. At least it would be easier to wave the credit card around.

We initially built the Sooth stiffness measuring machine with that in mind. The idea was to have one in every ski shop and we would measure your skis after every tune. The technician could then tell you how much live was left in your skis.

Unfortunately, we couldn't find any stiffness change with use...

 

[Noodler]

We initially built the Sooth stiffness measuring machine with that in mind. The idea was to have one in every ski shop and we would measure your skis after every tune. The technician could then tell you how much live was left in your skis.

Unfortunately, we couldn't find any stiffness change with use...

That's interesting to learn of the initial intention. A test of the durability/longevity would require a "Consumer Reports"-like attention to the details to ensure that you control the variables. You can't just take skis that have been skied "in the wild" and make assumptions about how they've been skied. You would need to develop a method to realistically simulate ski use in a controlled setting. If you could do that, there would be some value for both the consumer and the manufacturers in being able to understand and market a higher perceived value for particular products. We do this all the time in our choice and consumption of products. Those products that are proven to be longer lasting and better able to handle the rigors of the task are those that can command higher initial sales prices and retain better value over their lifespan. Skis would be no different if we actually had the data (and it was trusted).

I often spend time looking at other skis on the chair and in sales listings for used equipment, specifically to see how well they have held up to the abuse. That's one of the reasons I ski a lot of Stockli; I have Stocklis that still look practically brand new after years of use. I value that as do others. It would be great to know how they're doing on the "inside" as well.

 

[cantunamunch]

That's interesting to learn of the initial intention. A test of the durability/longevity would require a "Consumer Reports"-like attention to the details to ensure that you control the variables. You can't just take skis that have been skied "in the wild" and make assumptions about how they've been skied. You would need to develop a method to realistically simulate ski use in a controlled setting. If you could do that, there would be some value for both the consumer and the manufacturers in being able to understand and market a higher perceived value for particular products.

Only if you want to create data for all consumers.

OTOH, It is perfectly acceptable to generate numbers for individual consumers off skis that have been skied "in the wild" so long as any overall statements are only applied to that individual consumer's concept of 'worn out' or 'still good'.

There is value for the individual consumer in that.

 

[Noodler]

Only if you want to create data for all consumers.

OTOH, It is perfectly acceptable to generate numbers for individual consumers off skis that have been skied "in the wild" so long as any overall statements are only applied to that individual consumer's concept of 'worn out' or 'still good'.

There is value for the individual consumer in that.

Apologies, but I'm not following what you're laying down here.

 

[cantunamunch]

Apologies, but I'm not following what you're laying down here.

Specific example:

A consumer feels their particular pair of skis are played out and won't hold an edge. Assume the use history of the skis is vague or unavailable. It doesn't matter. What does matter is that you have original Soothski test numbers for that model in factory new trim.

Having the difference between test values for that pair and a factory new pair is valuable information for that individual consumer. It doesn't apply to anyone else. They can then decide whether to throw money at base grinds, edge refinishing, chasing boot balance at the bootfitter or to just get something new.

It lets the individual consumer have a numeric basis for their individual sensations on a specific gear set. Golf has been able to market such a concept for decades. Why can't skiing, again?

 

[Noodler]

Specific example:

A consumer feels their particular pair of skis are played out and won't hold an edge. Assume the use history of the skis is vague or unavailable. It doesn't matter. What does matter is that you have original Soothski test numbers for that model in factory new trim.

Having the difference between test values for that pair and a factory new pair is valuable information for that individual consumer. It doesn't apply to anyone else. They can then decide whether to throw money at base grinds, edge refinishing, chasing boot balance at the bootfitter or to just get something new.

It lets the individual consumer have a numeric basis for their individual sensations on a specific gear set. Golf has been able to market such a concept for decades. Why can't skiing, again?

Ahh, I get your point now and agree. There is value in this service and it really goes back to SoothSki's original intention for the technology. Still, having a general sense for the longevity of the ski model's lifespan without needing to measure your own specific skis also has value and it is what we use for so many products in our daily lives. It's one of the things we consider when we buy cars, choose paint, select kitchen countertops, etc.

 

[James]

So are torsional stiffness measurements not precise enough to show a difference? There’s little doubt amongst long term skiers that skis lose their grip with advanced age of use.
Where would you measure it? I’d imagine measuring torsional stiffness in front of the binding piece is not easy.

 

[KingGrump]

Strange thing happened today. Took out an older pair of FIS SL today. Ski had about 50 days on them. Skis have nose picker tips. The skis had a fresh base grind and my usual hand tune. Normally, the skis are skied with the nose pickers pointing in. So there is a definite preference which edges are the inside edges.

Snow was very firm today. Skied the first run with nose pickers pointing in. There was definitely a lack of grip feel. Second run, the same lack of grip feeling persisted. Switch skis left to right (nose picker pointing out) on the third run. Felt an improvement with grip.
Half way through the day, switched back. That lack of grip feeling returned. Switched again. All is right with the world again. Finished the day with the nose picker pointing out.

Hmmm.

 

[Noodler]

Strange thing happened today. Took out an older pair of FIS SL today. Ski had about 50 days on them. Skis have nose picker tips. The skis had a fresh base grind and my usual hand tune. Normally, the skis are skied with the nose pickers pointing in. So there is a definite preference which edges are the inside edges.

Snow was very firm today. Skied the first run with nose pickers pointing in. There was definitely a lack of grip feel. Second run, the same lack of grip feeling persisted. Switch skis left to right (nose picker pointing out) on the third run. Felt an improvement with grip.
Half way through the day, switched back. That lack of grip feeling returned. Switched again. All is right with the world again. Finished the day with the nose picker pointing out.

Hmmm.

That is an interesting observation; especially since the skis are a clearly "marked" left and right and were probably skied that way predominantly (if not always). I trust your tuning ability, so I would discount any possibility of the tune being asymmetrical (especially on both skis). So I think all that leaves would be that the skis actually are physically worn out in a particular pattern and can be "revived" by utilizing parts of the skis' internals that were less "used up". That's what you're implying here, correct?