Cap construction vs. Sidewall

[BlueB]

This is an offspring of "cap/titanal Tomahawk" tread...

We might have even discussed this in the past, few years back.

Cap construction, if done properly, should be superior to sidewall construction. ANY 3d structure is stronger then a similar 2d structure. Fibres changing direction and plane, at the cap, or at the top sheet features (Virus, F2, Oxygen, etc.) add tremendous strength and torsional stiffness and reduce the thickness of the core required.

Let us leave snowboard industry for a while and talk skis, as the ski industry has been around for much longer, and went hi-tech long before snowboards. Also, they fioured out the mass production means and pump greater volumes out (less brands - bigger volumes in ski world).

There are 2 reasons that you do not see too much of cap construction in race department skis:

1) Metal technology doesnt land itselt all that great to cap.

2) Sidewall, or Sandwich as it is also called, is way easier to experiment with, to fine tune and produce low volume or custom runs.

Other than race and metal skis, almost all production skis are capped. Good example - Atomic's Metron revolutionised the ski world. When it apeared on the market there was nothing that performed at the same level. It has cap which becomes power channel. Ok, there are few other little tricks inside, but that's another story.

Back to snowboards.

Oxygens use to have very strong club of followers. They were prized for good edge hold and dampness. When you put them next to a sandwich board, you'll notice how thin they are. Cap takes function of the core. I recently got an old KR72 and it didn't feel much worse then stock Prior. Not bad at all for a 10 year older board. However I have to ride it more to really tel...

Downside of cap is that is prone to delam, as the forces multiply at the small lip where edge bottom lam and top lam meet. Extreme example is the Volant. Everyone says that these suckers have great edge hold and ride great until they explode. Reason is again small contact surface at the edge worsened by bad adhesion properties of metal used for the cap (see comment 1 in ski part of discussion). Before somone started blasting me - I do not say that Volant is better then any of the modern sandwich metal boards. I'm just saying it was a very special board, lightyears ahead of it's time.

Now, few experiments for non believers:

Take a sheet of paper, hold it by shorter edge and lift. It bends, right?

Now make 1/2in folds along longer edges, hold by short edge, lift. Ta-daaa!

So, the question is why we do not see more fiber boards with cap construction by our favorite builders? My guess would be: harder to custom make, overall harder to make if trying to produce good performing low volume run product, more potential for delam problems.

Also, as the cap allows for core to be thinner, it actually increasses the chances of flex being wrong, as the margin for the error becomes smaller proportional to the percentage of thickness reduction.

So you had a smartass industrial designer's view on the topic. It would be really nice to hear from builders and few other engeneering types around here, too.

[Fastskiguy]

I always thought that the sandwich ski is a better performer than the cap, that's why the race skis are mostly sandwich. I thought the cap was cheaper in big quantities so that's why you see lower performance stuff with the cap. Solomon had the first cap race ski but not now.....aren't they (race skis) still mostly the old sidewall construction? I've just gotta think that if caps were really better, you'd see'em underfoot at international events, regardless of price. Still, I'm interested to hear what others say too.

[pebu]

I don't have much experience in race skis or boards except for my rossi xvas (which is cap) and some friends volkl race tigers, which I don't know if they're cap or not, but I know both 4 stars and all stars are cap construction.

If anybody is looking to further their knowledge about board construction, check out Graf Snowboards. He builds snowboards and shows everybody how to do it. There is a forum dedicated to board building as well.

[Jack M]

....is short for "Metric Ton". As in, what those skis weigh. I'd never want anything that heavy on my feet.

Edit: oh yeah, forgot to say, sandwich is better.

[Bordy]

Sound like some one has bought the cap propaganda from probably a cap constuction company, I am guessing Garage. I really don't have the time to discuse the differances, and beleave I have done so on this forum in the past.

Cap construction Is a great way to omit sidewalls and allow the core to extend edge to edge. Its also much less expensive to produce and build and works great for recreational riding skiing. The fact that many other issues arise while using cap construction is proven by all of the tinkering done to improve the cap. Ie Power ridges, power rods, internal rods and tubes Duel tech etc...

Side wall construction is far superior. As dictated by the fact almost all skiis and snowboards at the WC levels are sandwiched. Side wall provide a dampner for the edge and all vibration transfer. It also allows a much stronger bond. And is much more expensive to create even in one of skiis and boards.

Tomahawk is a great example. With out metal their board where capped as soon as they where forced to use metal to stay competative they had to go to sandwich.

U could use a cap with metal but I think the forces of the metal while riding would probably break the weak edge bond of the top sheet.

The folded paper anolige is great I us it all the time to show how caps can fail. With your paper folded put a little nick in the edge and watch it bend.

If you had a sidewall instead of folded top sheet then the nick would not remove all the strength. Much like all Volant and Agression capped stainless products fail.

Of course there is some on out there who feels Caps are better, etc. And that awsome there should always be several construction methods and thoose who feel one is better then the other.

As alway i say look to what the WC riders and pros are on that is a very good indicator of what works and is "NEXT GEN"

[Randy T.]

Okay I'm not an Engineer, although I do play one at work and I'm not an expert here but I did learn a couple things while attempting to take a snowboarding class (that's a story for another thread I'll have to revive).

- So for the experiment with the paper, yes that concept does play out BUT I have to question whether the material used for the top sheet, forget about the metal boards, and let's just say were talking about a Donek that uses a fabric material for the top sheet. Does that fabric even when used in a 3d structure really add that much strength and torsional stiffness to the board with just the addition of a narrow width of area?

- Also we must take into consideration that non cap construction has an added element of an ABS sidewall, profiled to the thickness of the core, and this material is going to contribute to the boards stiffness.

- There is a lot involved in laying up the different layers of fiberglass and different uses of their weave that I think play the biggest role in creating the boards strength and torsional stiffness.

- One other thing is the mention of cap construction using a thinner core. Is that really true or just an observation from looking at boards? I have not heard that before.

Hopefully Sean or someone else that really knows what they are talking about will chime in.

That was just my 2 cents.

RT

[bobdea]

you don't even really need a pnuematic press for a cap OR sandwich depending on what you want to put in there........

according to a SOLOMON employee caps are great for three reasons 1, they feel a little different in that they are not as grabby (they don't hold a edge) this is really great for people who can't ski because the ski is not going to catch as much.

2, you cut out a entire step in lay up so it save a insane amount of money in time and parts.

3, when they do break the customer is going to be buying new gear because it's allot harder to make repairs to them.

Even Atomic, one of the biggest pushers of caps won't put one on their skis for speed events (SG and DH) both of those models are sidewalled, I know as I have waxed both models of skis.

even softbooters are figuring it out and everyone is moving away from the construction.

rossi dual tech and dual tech with VAS both of those refer to a cap on top of a sandwich and the VAS part is a foam core(yet another low end construction being hawked as high end) with wires in that rub on themselves that create friction that is supposed to be disapated as heat or something.

a burton rep told us that the only real advantage in their eyes were caps were light and that they were also cheap when cranking out the low end stuff.

[bobdea]

BTW, oxygen is now Atomic as far as softboot models go and not one of them is capped.

[LeeW]

Ive always liked sandwich. Cap are a b---h to repair if you got 'em dinged. Rossignol skis did switch to cap but switched back to sandwich. which im happy about.

[David Kirk]

I agree that cap construction has some merits but I believe that most of them are related to ease and cost of construction and not performance. If tooled up for it it's silly cheap to make them compared to the more complicated sidewall construction. There are also fewer components involved with sidewall. More SKU's means more money and time.

The folded paper scenario is an interesting one. I agree if you take a sheet of paper and fold it it will become stiffer and give the otherwise flimsy paper some structure. If the question were how do you use the least amount of material to make the stiffest structure then maybe a cap would be a good thing.

Unfortunately the folded paper analogy falls down in real life. When you take your folded piece of paper and try to bend it one of a few things will happen when you apply enough force.

1) it will kink........... anyone with a metal cap top sheet board will have had the opportunity to study this closely while walking down the hill holding a folded up board in their hands.

2) the "vertical" part of the folded paper (the sidewall) will rip. You will have exceeded the tensile strength of the top sheet material. Most of the time that top sheet material doesn't like being put in tension. The notable exception is with a metal topsheet. See #1 above.

3) or............. when stressing the folded sheet the paper will have the "urge" to go flat again. Most cap failures fall into this group. When stressing the top sheet it has the tendency to try to flatten out and this puts the bond of the sidewall part of the cap under a huge amount stress. This puts the bond of the curved-over sidewall into tension and that is not a happy place for an epoxy bond to be. Epoxy joints can deal with shear very well but if you try to peal them apart things don't go so well. If you've spent time in the back room at a shop and seen the types of failure that come into the shop you'll see too many pealed open cap "sidewalls".

Contrast this with a sidewall construction. The top and bottom sheets are perfectly happy when stressed as the stresses are in bending and shear. The sidewall material is put under a bending and shear load. There is little to no tendency for different components to be pulled apart form each other.

My .02 cents

Dave

[D.T.]

I have had durability issues with capped boards, but not with side walled boards.

[tex1230]

I like sandwiches:

[NateW]

The folded paper anolige is great I us it all the time to show how caps can fail. With your paper folded put a little nick in the edge and watch it bend.

If you had a sidewall instead of folded top sheet then the nick would not remove all the strength. Much like all Volant and Agression capped stainless products fail.

I'm pretty sure Aggression's failures were caused by glue that just didn't bond well. Before I blew up my Aggression metal capped board, I blew up two of their non-metal, non-capped boards. IIRC, I got 7 or 8 consecutive days out of 3 boards. (They sent me a fourth and I gave it away. Got tired of hearing, "wow, I've never heard of that happening before.")

That said, I do believe that sidewall construction is preferable.

The problem with the folded-paper analogy is that the topsheet is not what gives a board its strength.

[Gecko]

I've always equated Cap boards with foamcore boards....great for short term but not a long lasting product.

[John Bell]

I have to admit I was stumped for a while before I figured it out.

[Steve Prokopiw]

It seems like lighter riders like me do fine with cap boards and heavier riders exert too much pressure for the cap construction to be reliable.I have owned at least half a dozen cap boards and the only one that didn't last long was a Rossi Strato wide that was, in fact, foam core.The funny thing is that I liked how it rode so much I bought the second one after breaking the first broadsiding a tree with it.The second one lasted until I had simply worn it out,so I don't disagree with what I've read about durability except that I did get about 75 days out of it.Ironically,for all the metal hype that I freely admit I will eventually fall for,the main issue with metal seems to be durability and at least until recently,the necessity to use the boards on groomed runs to avoid breakage or perceived abuse.For now,I just plain like the performance of the cap boards I own currently .

[BlueB]

Why no cap at WC, again:

There are 2 reasons that you do not see too much of cap construction in race department skis:

1) Metal technology doesnt land itselt all that great to cap.

2) Sidewall, or Sandwich as it is also called, is way easier to experiment with, to fine tune and produce low volume or custom runs.

All of WC skis are metal, except Rossi SL (unless they changed it this year). And read it again,

Cap construction, IF DONE PROPERLY, should be superior to sidewall construction.

This implies caped metal somehow sticking properly together. As they can't figure it out, result is no metal cap, thus no caped WC sticks. Simple?

As for Earl of Sndwich, he really invented sandwich: He liked to play endless card games. To be able to eat something without stoping the game, he ordered his buttler to stick a piece of cheese in between two slices of bread.

While at sandwiches, here's another kitchen experiment. It's a single sheet of very poor quality paper.

[bobdea]

there is plenty of metal in capped skis, just not configured like it is in a kessler, coiler or prior or like it is in a actual race ski.

rental skis even have metal to mount the bindings.

your average atomic is mostly metal, metal tubes actually. but this like the cap you don't see in speed events because it's more of a gimic than anything else.

very few people feel a cap works better for anything, the ones that do are suspect because they usually work for manufacturers that tend to make mostly caps.

sometimes I think you take a posistion based on it purely being the exact opposite of everyone else's.

I know what you're trying to say but it just does not hold up in the real world, between the number of boards i've owned (40ish), broken (a bunch) the boards I've repaired (close to 100) and the boards I've ridden (probably 100 or so) I can truthfully say caps are much more prone to failure, usually don't ride as well and are more common on low end POS boards like the rosignol recycler or the burton bullet.

and FYI all the WC race rosignols are sidewalled, the next step down are dual tech as they have been for years which have a sidewall under the cap but still have a sidewall.

Dynastar does or at least used to do something fairly similar. here's pic

and a description of rossi constructions http://www.bumps.com.au/SKIS/Rossignol_05/SKESKRO.htm

[Fastskiguy]

While at sandwiches, here's another kitchen experiment. It's a single sheet of very poor quality paper.

Doesn't that show a stiff, non-flexing structure that...if flexed...will crumple?

[Jrobb]

Doesn't that show a stiff, non-flexing structure that...if flexed...will crumple?

yes but the material differences are blatantly obvious. Paper vs. Glass fiber( or carbon or Kevlar whatev.) The design however is the same. The matrix (hardened resin) IS the folds of the paper. Implemented differently, it is designed and expected to flex in some way or else it can be built to be extremely stiff...again depends on materials and layup (design).

Think of the steel frame of a truck. If it wer simply flat not too strong, but formed to the shape of a "[" you increase the strength. Take it further and enclose the "[" shape like [] and you get a fully boxed structure...even stronger. The flex is built into the material and the design has to account for that, but the material has to be able to deflect some otherwise you end up with too stiff that breaks when flexed.

In the offroad crowd some Toyota Tacoma owners would enclose their "[" shaped frames to "box them" If the entire frame was done and not accounted for how the vehicle flexed when offroading, the frame would not bend along the length of the reinforcement but at one point not reinforced and since it was concentrated there, ultimately break there.

With cap I think adhesion is the main factor. You have tension, compression, and shear at the bond area...good luck. As opposed to mainly shear and compression or shear and tension. (generalized more or less

J

[BlueB]

sometimes I think you take a posistion based on it purely being the exact opposite of everyone else's.

Shhhhh, don't tell anyone ;)

All great ideas and inventions came from stepping away and chellenging well established concepts... Even if nothing great would come out of this one, it still made for good discussion.

It would still be nice to hear from Bruce, Sean and company.

[bobdea]

you like to stir the pot a little

[Bobby Buggs]

bob, I see im not the only one who cant sleep

[www.oldsnowboards.com]

there is plenty of metal in capped skis, just not configured like it is in a kessler, coiler or prior or like it is in a actual race ski.

rental skis even have metal to mount the bindings.

your average atomic is mostly metal, metal tubes actually. but this like the cap you don't see in speed events because it's more of a gimic than anything else.

very few people feel a cap works better for anything, the ones that do are suspect because they usually work for manufacturers that tend to make mostly caps.

sometimes I think you take a posistion based on it purely being the exact opposite of everyone else's.

I know what you're trying to say but it just does not hold up in the real world, between the number of boards i've owned (40ish), broken (a bunch) the boards I've repaired (close to 100) and the boards I've ridden (probably 100 or so) I can truthfully say caps are much more prone to failure, usually don't ride as well and are more common on low end POS boards like the rosignol recycler or the burton bullet.

and FYI all the WC race rosignols are sidewalled, the next step down are dual tech as they have been for years which have a sidewall under the cap but still have a sidewall.

Dynastar does or at least used to do something fairly similar. here's pic

and a description of rossi constructions http://www.bumps.com.au/SKIS/Rossignol_05/SKESKRO.htm

Bob, vs what? Going along with the group because that is what they say?

Owned 40 boards? That is allot. Care to guess?

What I know, I ride allot of boards, I am not a paid representative of any cap manufacturer, even the opposite.

I know that one of my favorite all time boards was a cap. It performed as no other board I have ever ridden. Firm, snappy, incredible edge hold, etc. Could take incredible punishment and never lost camber. That is what I know.

Now I depend on the Duo-Board construction of the Tinkler's to provide a superior ride. They are not cap, Mike does not build cap construction boards. It still does not take away from the excellent cap boards I have ridden.

Fortunately I have not broken allot of boards , nor do I repair many, so this doesn't effect my decision to buy what works for me.

I think we get your point. Everyone says cap construction is poor, so it must be so. It is easy to harp about issue when everyone seems to aggree with you isn't it. It is wonderful we have these choices. Enjoy what ever board you chose. Ride on!!

Anyone else notice D-Sub is seemly happier and entertaining a kinder disposition these days and well Bob is taking on a more abrasive negative tone? Just an observation.

[Cyrus the virus]

I always thought that the sandwich ski is a better performer than the cap, that's why the race skis are mostly sandwich. I thought the cap was cheaper in big quantities so that's why you see lower performance stuff with the cap. Solomon had the first cap race ski but not now.....aren't they (race skis) still mostly the old sidewall construction? I've just gotta think that if caps were really better, you'd see'em underfoot at international events, regardless of price. Still, I'm interested to hear what others say too.

I think you are right all premium quality skis are done in sandwich construction! Cap is easier and cheaper to produce in higher amounts in cause of less pieces you need!

Its definately a fact that you can increase the torsional stiffness and make a thinner board, but the dynamic power who is influencing the board during riding will kill it easier and faster than a sandwich board.

Its much more difficult to adjust the flex on a cap board!

So why building a cap board its almost unrepairable if you damadge it. With high techfibers you can easily build boards in the same torsionally stiffness!