 Poster: A snowHead
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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I was just thinking of buying something to hang my skis this way but read an article that said don't store them this way. Can't remember why or the impact.
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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You need to Login to know who's really who.
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Interesting, but no discussion of "Long term impact ".
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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My understanding is that skiing will cause the most damage to your skis.
Don’t think storing them vertically will cause that much damage and if it does you’ll have a reason to buy new skis  .
The only storage advice I follow is to keep them as cool as possible and away from direct sunlight.
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You'll need to Register first of course.
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Given that virtually every ski shop around will store then vertically, don’t think that’s an issue. Not sure what damage could be done from hanging ten from the tips either, not when the bracket grips on the side wall rather than the edge.
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| Spoon wrote: |
| My understanding is that skiing will cause the most damage to your skis. |
Think that makes a lot of sense as the pressures applied when skiing are much more than a few kgs. The same can be said when people question impact on hanging a bike by its wheel - forces when riding are much greater.
I am going to purchase the rack and will revert here when installed.
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Whilst on my last trip the hotel used the same type of rack. As I like to prep/wax/zardoz my bases the night before, to keep the bases apart do that they could 'dry' I'd hang each ski by hooking the front/toe binding on the rails.
obviously it means that you use double the space, but worked well for us.
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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I worked in polymer research for 15 years, the issue is that if the ski is kept bent for a long time, it will "creep" and be permanently deformed, in the case of a composite structure like a ski, it would have to be significanly bent for a really long time to have any effect, I very much doubt that the ski hangers shown will have any effect at all even after many years.
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As Tangowaggon rightly points out, "creep" can occur - and this is during prolonged exposure to relatively low stresses. Another term is "stress relaxation" - the atoms/molecules within the structure rearrange so that the stresses within the object disappear over time. This is quite different from short-term high stresses experienced whilst skiing. Even while skiing the stresses will be well within the elastic limit - i.e. the ski will return to its original shape after the stress is removed, rather than remaining permanently bent. Any stresses in storage are obviously low in magnitude, but they persist for a long period. Bend a pane of glass for a century and it will be permanently bent by the end.
I have no idea what the impact on skis of this type of storage may be. It may be an urban myth, but you're certainly not supposed to keep a pair of skis tied tightly together in storage as if they are they are supposed to lose their camber. My suspicion (though I haven't worked in polymer research for many years and certainly didn't spend 15 years there) is that in a composite structure like a ski, the impact of creep could be quite high.
In a wooden ski, made of either a single plank of wood or what is effectively plywood, then I suggest that the risk of damage arising from improper storage is very high. In a modern laminated ski, my suspicion is that the layers of glue will be where the damage occurs, if it does indeed occur.
The only question is how much stress the proposed method of hanging places on the ski.
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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Finally a topic on here I know. My day job is composite materials R&D. I have a PhD in composites but my knowledge of ski construction is basic so bare with me.
I assume we're talking about wood or high tec foam core or similar, fibre reinforced thermoset composite elements (carbon, basalt, glass, kevlar etc) some form of metal edges all held together laminated with thermoset adhesive.
If that is basically what a ski is there is no way at all that hanging under its own weight will cause any significant creep. Stress relexation can occur but only when a structure is strained - their own weight will be negligable here. Thermosets are much more dimensionaly stable compared to 'plastics' plus the metalic edges are bonded in too.
You could leave them hanging there for decades without effect from the mounting. Don't worry about it.
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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| ellfleet wrote: |
Finally a topic on here I know. My day job is composite materials R&D. I have a PhD in composites but my knowledge of ski construction is basic so bare with me.
I assume we're talking about wood or high tec foam core or similar, fibre reinforced thermoset composite elements (carbon, basalt, glass, kevlar etc) some form of metal edges all held together laminated with thermoset adhesive.
If that is basically what a ski is there is no way at all that hanging under its own weight will cause any significant creep. Stress relexation can occur but only when a structure is strained - their own weight will be negligable here. Thermosets are much more dimensionaly stable compared to 'plastics' plus the metalic edges are bonded in too.
You could leave them hanging there for decades without effect from the mounting. Don't worry about it. |
God, don’t we just hate it when some newbie smart back bottom who actually knows what he’s talking about comes along and starts writing posts that are based on knowledge and understanding. If you carry on like that you’ll get yourself banned pretty fast and, let me make it quite clear to you, you would have absolutely no place at all in the Brexit thread.
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@ellfleet, thanks for the qualified response makes a lot of sense.
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You know it makes sense.
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 Don't worry, I've no intention of entering that thread and if it makes you feel any better my skiing is terrible.
To put some numbers to it:
- a 180 cm ski assumed to be made purely out of fibreglass (25 GPa stiffness, in reality it would be much stiffer than this)
- weight 2.7 kg
- dimensions assumed to be 85 mm wide and 6 mm thick (fairly conservative I guess as the thickness would be higher under foot and width would be higher at the ends)
Under its own weight it would only strain to 0.0002% which corresponds to a change in length of 0.0036 mm. This amount of force is below the level where we would even bother trying to quantify creep.
In fact if an 80 kg person dangled off the end for a few months you would expect at worst a 0.1 mm change in length if they waited long enough for stress relaxation.
To put these figures into context, if you take the same material from room temperature of ~20 degC and cool it to -10 degC I'd expect it to decrease in length by nearly a mm (if it were purely fibreglass).
I'd be curious to know if anyone ever tried this.
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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I really don't think you're doing the correct calculations here, ellfleet. What you've done is to say that because a chipboard bookshelf will only grow by .0002% if placed in tension, you can put books on it as you like and it will not bend. As we all know, that is not true!
I think you need to consider the construction of a ski first - and I know you say you know nothing of it but it is important. https://www.wagnerskis.com/journal/ski-camber-vs-rocker-skiers-guide/
We're worried about the impact on the camber in the ski (a ski is banana shaped) on account of its own weight, not whether a straight ski is going to get longer on account of hanging. It's a three-point bending test, but on its side, with the force provided by the ski's own weight. The beam's depth is small, the L is long, the Young's modulus is low - skis are designed to be springy. Therefore deflection is not inconsequential, hence my expectation of relaxation occurring in the adhesive layers - just like that chipboard shelf.
The internet tells us that the 'approved' way to store skis is flat on their sides on a shelf, so that no stresses are placed on the precious banana curve.
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Poster: A snowHead
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| James the Last wrote: |
| The internet tells us that the 'approved' way to store skis is flat on their sides on a shelf, so that no stresses are placed on the precious banana curve. |
And yet every ski and rental shop I’ve ever seen will store skis vertically. Are they mad?!! Don’t they know that the internet thinks they’re wrong? 
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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| James the Last wrote: |
I really don't think you're doing the correct calculations here, ellfleet. What you've done is to say that because a chipboard bookshelf will only grow by .0002% if placed in tension, you can put books on it as you like and it will not bend. As we all know, that is not true!
I think you need to consider the construction of a ski first - and I know you say you know nothing of it but it is important. https://www.wagnerskis.com/journal/ski-camber-vs-rocker-skiers-guide/
We're worried about the impact on the camber in the ski (a ski is banana shaped) on account of its own weight, not whether a straight ski is going to get longer on account of hanging. It's a three-point bending test, but on its side, with the force provided by the ski's own weight. The beam's depth is small, the L is long, the Young's modulus is low - skis are designed to be springy. Therefore deflection is not inconsequential, hence my expectation of relaxation occurring in the adhesive layers - just like that chipboard shelf.
The internet tells us that the 'approved' way to store skis is flat on their sides on a shelf, so that no stresses are placed on the precious banana curve. |
I'd say you're right - the calculations I wrote are fairly pointless in this context. My post is really more applicable to the "full rocker" profile shown in the link you posted.
Where there is a camber there will certainly be some deflection so ignore the 2nd post.
One could easily measure the deflection:
Stick a ski on its side, use a straight edge, measure the gap. Compare the gap with putting them flat on the floor bases down and hanging vertically.
I'd still be tempted to say that for thermosets materials with long fibre elements creep is not going to be of concern but I'm not sure if I can easily find figures to justify the statement - I'm not going to start modeling it.
I'm intuition suggests that any changes are going to be dwarfed by anything caused by standing on them and hurtling down a mountain for a few hours a day.
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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| Quote: |
intuition suggests that any changes are going to be dwarfed by anything caused by standing on them and hurtling down a mountain for a few hours a day
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This.
It somewhat amazes me just how fragile people think skis are given their intended purpose...
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@James the Last, I think @ellfleet, is right. The skis are hanging vertically as is the load acting on them (self weight), therefore bending has almost nothing to do with it. Sure, if you elongate a curve it will flatten and there will be corresponding bending stresses but given the tiny strains involved, the flattening action will be negligible.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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The only mechanical effect that's apparent is from squeezing the ski tips together as they are pulled downward under their own weight If they move through the holding poles.
If you put your skis together and squeeze the tips, then you'll see the camber start to open wider.
There doesn't seem to be any size of forces there to permanently change the structure, as pointed out already, they're far more resilient to deforming than is normally considered.
I'd agree with @ellfleet, too, it's just such an insignificant force by comparison to the structure properties.
https://www.compositesworld.com/articles/composite-leaf-springs-saving-weight-in-production-suspension-systems
Similar structure geometry in this link with automotive components, and kept perpetually loaded during service life.
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one thing to consider is that if the ski edges are touching when stored they will most likely rust. make sure you separate or used straps...
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| ellfleet wrote: |
I'm intuition suggests that any changes are going to be dwarfed by anything caused by standing on them and hurtling down a mountain for a few hours a day. |
Probably... But then skis can apparently wear out in under a season (reportedly - I've just had a quick look through Snowheads which suggests that a pro can wear out a pair in 3-4 months) and if you're looking at keeping a pair in best condition for a decade then perhaps you do need to consider the storage conditions - the thing that kills skis (other than physical damage) is losing their springiness.
Nobody would question that boots should be kept done up when being stored - for the same reason.
@ski3 - those leaf springs are designed to be kept permanently loaded. Skis are designed to spend the vast majority of their lives - probably at least 330 days per year, plus 20 hours per day for the days they are being used - unloaded.
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| Quote: |
Nobody would question that boots should be kept done up when being stored - for the same reason.
@ski3 - those leaf springs are designed to be kept permanently loaded. Skis are designed to spend the vast majority of their lives - probably at least 330 days per year, plus 20 hours per day for the days they are being used - unloaded. |
Boots are themoplastic and most are thermoformable. Very liable to deform with time so the advice makes clear sense.
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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@James the Last, but wear out from what?
I reckon a season of daily use with fairly frequent servicing to keep them sharp will wear out the edges in a season.
Depends on the skis.
But it's not wear in terms of the ski losing its intrinsic properties...
@Cygnet, that's quite a nice concept. Don't think you need to spend any great money on "buttons" however... (these are €1.50 for 10)
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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| SnoodlesMcFlude wrote: |
| James the Last wrote: |
| The internet tells us that the 'approved' way to store skis is flat on their sides on a shelf, so that no stresses are placed on the precious banana curve. |
And yet every ski and rental shop I’ve ever seen will store skis vertically. Are they mad?!! Don’t they know that the internet thinks they’re wrong? |
Rental skis spend a significant proportion of their life during the season booked out to customers, who will store them in whatever storage their accommodation offers and damage them by skiing over rocks. Any damage due to incorrect storage will be less significant to them than to someone skiing one week a year who looks after their skis and wants them to last 10 years plus. Rental shops only have a limited amount of space (and would need to pay more for a larger unit), so they want to make best use of that space by using space-efficient storage. It also looks good for a rental shop if their skis are current models, so they get some benefit from renewing their stock rather than making it last as long as possible.
I'm not saying rental shops are wrong, just that their priorities may be different. Some of these points don't apply out of season, so if storing skis vertically was a problem then I'd expect rental shops to lay their skis down on the shop floor over the summer months.
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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@thelem, And the place that sells the ski initially? How many can you recall that don't store their skis vertically.
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@SnoodlesMcFlude, they would hope to have a given pair of skis in stock for a few months, not 10 years.
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You know it makes sense.
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| under a new name wrote: |
| @James the Last, but wear out from what? |
Going floppy, apparently. Goodness only knows if it's true... but I read it on Snowheads so it must be.
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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@James the Last, skis with erectile dysfunction?
Who knew!?
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FAQ
