Sandwich construction
Here the ski is built up in layers (as the name suggests) The process is manual and you "build" the ski in a mold. First the sole and edges are added, then the cushioning and stiffness layers, then the core and finally additional cushioning/stiffness layers. The whole thing is glued with epoxy and held under pressure before being cut, sidewalled and decorated. It's a slow process and much of it is done manually. This is why the price of sandwich-constructed skis is often higher than cap and crossover-constructed skis. Sandwich skis are the most stable and versatile skis and the way the vast majority of top skis are produced, whether for racing, piste, all-mountain, freeride or twin tip.
Cap construction
is the "cheap" solution. The ski is built up in a "shell" which is the top side of the ski. The core and the various materials to determine the flex of the ski are placed in the shell. Everything is held in place by a foam compound before the edges and soles are added. On the cheapest skis there is only the shell and foam! The big advantage of this design is that it can be mass-produced, reducing costs and benefiting the consumer. The disadvantage is that it has been a challenge to design the cap shell to provide the same stability as a sandwich construction. This means that cap skis tend to bounce when pressured by speed or weight.
The advantage of cap construction is that the ski is lighter than sandwich construction.
Cross-over construction
Here, the best of both sandwich construction and cap construction are used. Typically you build the "innards" as a sandwich and then put it in a cap shell. Another model used is to have a sanwich construction with sidewalls as the foundation in the middle of the ski, while the tip and tail are built with a cap construction. The advantage of both is that you can get some of the stability properties of the sandwich skis and part of the production process can be automated. This gives engineers new opportunities to work with the properties of the ski and many top skis have something from both constructions.
Sidewalls
Are essentially the finish of a sandwich-constructed ski. Once the layers are built up, you need to "close off" the sides. This is done with different materials and at different angles. With the choice of materials, you can make the sidewall a parameter for the flex and stiffness of the ski, while with the angle you can optimize edge grip and torsional stiffness. Choosing strong materials can also increase durability. This is especially beneficial for twintip skis that need to withstand rough rides on snowpark rails and other obstacles.
Stiffness/flex
A ski's stiffness has a big impact on stability and edge grip. Stiffness is also related to torsional stiffness. The stiffer a ski is, the easier it is to make it torsionally stable. The stiffest skis are slalom race skis. To make the slalom ski as fast as possible from turn to turn and have as short a turning radius as possible, a lot of compromises are made on length. Since a short ski doesn't have as much edge grip as a long ski, you need to stiffen the skis to the maximum.
Stiffness is also very important for other types of skis. For example, a lot of work goes into making twintip skis soft at the ends (butter zones) but still stiff underfoot and on off-piste skis, a soft front end gives good lift in loose snow, while stiffness in the rest of the ski makes it bite in difficult snow and exposed terrain.
Soft front ends also make the ski livelier and easier to turn. Combined with a rocker, you can almost give them power steering... Learning to ski has never been easier!
Torsional stiffness
This is the stiffness that keeps the ski from twisting. Making skis torsionally stiff has been a challenge for many years. In fact, the benefits of carving skis were recognized as far back as the early 70s. The challenge was torsional stiffness. When the skis could twist, the wide tips and tails would just lay down and all edge grip would disappear. It wasn't until the advent of snowboarding in the late 80s that torsional stiffness was seriously addressed. The wide boards couldn't ride on hard surfaces without stiffening up. By the end of the 90s, they were able to stiffen the skis enough to put the first carving skis into production. While the first carving skis still lacked some torsional stability, the latest generations have become truly torsionally stiff while retaining some flex and bend in the longitudinal direction of the ski. This means that even the most beginner-friendly skis have gained good torsional stiffness. Furthermore, the development has also opened up for the production of wider, off-piste skis. It's interesting to think that without snowboards there wouldn't have been carving skis and wide off-piste skis.
Edge grip
Once you've been out on a steep, icy piste, you know how important edge grip is. Most people think it's all about sharpened or unsharpened edges. It is, but there are other things that are just as important. Firstly, it's about technique. The more you can edge your skis, the better you can grip and the harder you can press the edge into the ice, the better. In addition, the torsional stiffness and edge length also have an impact on grip. The more you can distribute the pressure, the better the grip. This means that a long edge makes better contact. At the same time, a long edge also provides more stability and better balance when riding on ice (and everywhere else). If the ski isn't torsionally stiff, it will twist and the ends will lose grip.
Damping
Skis are designed with the ability to spring, also known as tension, trampoline effect or pop. The springiness is important to make the skis rebound at the end of the turn, so you can economize on power. On the other hand, the ski needs to be damped again quickly after the release so that it doesn't wobble. There are many different ways to do this. On the one hand, there are softer gel-like layers between the crisp layers of the skis, which are also known from the heels of running shoes. Manufacturers are constantly working to optimize material selection and placement. In addition, different types of damping are added to the exterior design to make the skis responsive.
You can feel the tension in the ski by holding it under the tip and with the other hand pressing the center of the ski against the floor. Releasing it quickly relaxes it and bounces off the floor. If you grab it again quickly, it should settle down again.
Sidecut/talering
With the advent of carving skis, the focus suddenly shifted to the waistline of the skis. The more hourglass shape you can put into the ski, the shorter the turning radius you can create. Wide ends and a narrow waist make the shortest, but a short ski makes it even more extreme. On modern skis, you see some that not only have a regular waist ring, but some where the widest points are pulled away from the ends and towards the center of the ski. This is especially true on all-mountain and off-piste skis, this type of sidecut is called EARLY TAPER by some brands. The intention is to make them even easier to handle in loose and packed snow. On such skis, the radius becomes smaller because the waist becomes larger and they are therefore also a little easier to turn on the piste. With a lot of heel ring, torsional stiffness is slightly compromised. The wide ends simply twist more, resulting in a loss of edge grip. Slalom skis with a very narrow waist are therefore stiffer than other skis to prevent them from twisting too much.
Camber
In the old days, it was much easier. All skis had camber. The camber is a tension in the ski, which means that it only touches the ends when unloaded. It is used to create tension or trampoline effect or pop. It goes by many names. It works a bit like a flash arc. When you press down on the camber it creates tension and if you release it quickly, it "kicks" back. With good technique, by loading and unloading, you can get the ski to help with the camber. The camber also allows for a gradual build-up of edge pressure, which is a prerequisite for a smooth flow on the piste.
Rocker
A few years ago, rocker was touted as the new black in ski technology. There were many skeptics, but the fact is that the rocker has meant a lot to ski development. In simple terms, rocker means that the ski is bent. Often only the tip of the ski (tip rocker) has rocker, but on many all-mountain, freeride and twin tip skis there is also rocker in the tail (tail rocker). The most common is that the rest of the ski is a camber construction, but on the widest powder skis, which are designed to play in the deepest and lightest powder, there is sometimes a full rocker. This actually means that the entire ski is banana-shaped the "wrong" way.
On the big powder skis, the rocker provides a lot of flow in loose snow, but it also makes the ski more willing to turn and playful. When you put the banana shape on edge, it is already shaped to turn. If the skis are very long and wide, they would be almost impossible to turn.
Also on all-mountain and twintip skis, which often have a little width, it is a good help for turning, but above all, it also gives a good lift when skiing in rutted and powdery snow, for example in the afternoon when the sun has turned the surface into slush-ice. On twintip skis, the rocker offers another advantage. Namely, the edges don't have the same tendency to fish and suddenly make false cuts. This is important in both take-offs and landings, and it's also a big help when riding backwards.
