Ski technology guide

A Guide To Ski Technology

The two main trends in skis for the 2010 season are the use of Rocker and variations of it in many ranges of skis, and the development of skis that make it easier for skiers to explore turns of different shape and size.

Many of the technologies are not necessarily new in themselves, but the way ski designers combine various rockers and cambers, and manipulate side cut and tip shapes gives us products that allow many more skiers to ski different terrain, conditions and environments with confidence and in control.

Side Cut

When viewed from above, Side Cut refers to the shape of the ski. Today’s modern skis have much more Side Cut than earlier models, and this bowtie shape helps the ski turn. In general terms, the more pronounced the side-cut the easier the ski will turn.

Side Cut is often described in terms of the size of an imaginary circle that the edge of the ski defines (See below)

Sidecut Radius

Why is this important to me?

Skis with more Side Cut will be easier to turn and more playful – whereas skis with less of a Side Cut will tend to allow you to travel straighter and faster. Looking at the measurements given for a Side Cut, and the difference between the numbers will give an indication of how dramatic the Side Cut of the ski is. Side Cut numbers are given in mm and from tip-to-tail 115/70/98.

Waist Width

The waist width is the measurement of the ski at its most narrow point, which in many cases will be where the bindings are to be mounted and is predominately under the foot.

Narrow widths will signify skis that will be much quicker edge to edge in turns, such as Slalom skis, where as wider skis in the waist will be more stable and have better floating characteristics.

Why is this important to me?

When choosing a ski consider what skiing you like to do and where on the mountain it is. A wider width ski underfoot will allow for greater floatation in powder and mixed conditions, but may be a bit tougher to get completely on edge when on hard pack or groomed runs.

Radius

Taking the imaginary circle based on the Side Cut curvature; the Radius is the distance from the middle of the circle to the edge. Side Cut Radius is a useful way to compare skis and gives and indication of how pronounced the shape of the ski is. This is a static measurement.

Radius

Why is this important to me?

Looking at radius can help you gauge what the ski was designed for and therefore help you decide if that type of ski is right for the skiing you want to do. Recreational ski radius lengths would be in the range of 15-19m

Turn Radius

The Turn Radius is a variable factor which is affected by how much edge is applied, how fast the skier is going, snow conditions and the amount the ski bends under these factors.

Why is this important to me?

Where the actual radius is a static measurement, it would be an over simplification to assume that turn radius and radius are the same when they are not, due to the above factors. Which in addition, make the calculation of a turn radius very difficult. Understanding there is a difference is important because some documents imply that these two terms are the same. However, in most cases when you see the phrase Turn Radius in documents this will tend to be referring to the static radius measurement.

Radial Side Cut

Traditionally the Side Cut of a ski is designed to have a consistent arc throughout the length of the ski making the characteristics very predictable. Radial Side Cut designs are more suited to On-Piste skis than All Mountain or Big Mountain equipment and are the basis of how the majority of skis are designed. A true radial arc Side Cut ski with equal measurements tip and tail is seen mainly on symmetrical skis used in the pipe or park.

Why is this important to me?

There is a shift with manufacturers to explore different Side Cut shapes, and knowing that the majority of skis still tend to have a radial arc Side Cut will make choosing the right ski easier.

Progressive Side Cut (Technical)

Technically, all skis have a progressive Side Cut and elements there of to some degree as the Side Cut progressively increases as you move up the length of the ski from the tail to the tip. More Side Cut in the tip and underfoot makes for quick turn initiation and hard snow performance while allowing easy release in variable conditions.

A progressive Side Cut is usually described as two numbers such as 14/16 meaning the side cut ranges from 14m in the tip to 16m in the tail. Ski designers have experimented with varying the physical Side Cut shape and flow of the tip-to-tail edge, and this shape is one way to make the increasingly popular wide skis perform better.

Progressive Side Cut (Marketing)

From the marketing side of Progressive Side Cut there is a grey area between the technical definition and marketing language. Though progressive Side Cut technically isn’t new to the industry, and all skis have an element of it, what is new is how manufacturers are varying ski shape and Side Cut design to get variable turn characteristics in one ski. Some refer to these characteristics as a progressive Side Cut, others varied, dual or multi radius (See Explained: Progressive Side Cut /Varied Side Cut/ Multi Radius/ Dual Radius).

Explained: Progressive Side Cut /Varied Side Cut/ Multi Radius/ Dual Radius

Traditionally, the Side Cut shape of a ski describes a perfect arc, or part of a circle, which runs from the tip to the tail of the ski.

But as skis have gotten wider in the past few years, a traditional Side Cut and radial design have caused problems, especially in longer All Mountain skis. Using a Radial Side Cut design tip to tail on wide and long skis destined for All Mountain or powder use can cause hooking of the tip, over twisting of the ski and a very difficult release at the end of the turn.

The solution is to make the Side Cut less towards the tail thereby making the ski slightly narrower and also friendlier to ski on because the tail will release more easily – a bonus in crud or powder.

From a marketing perspective, when describing how a pair of skis can perform a multitude of turn sizes; Progressive Side Cut, Varied Side Cut, Multi Radius, Dual Radius all refer to this recent trend in ski design where manufactures are specifically sculpting ski shapes and using materials to make it easier for skiers to actively adjust the size and shape of their turns, including during the turn.

Expert skiers are able to vary their turn shape to increase or decrease its size while in different conditions, by adjusting edge angle and pressure to the tip or tail of the ski, but this skill takes time to acquire and practice. However, with modern manufacturing and designs, skis are now being produced that make for quick turn initiation and easy tail release allowing for skiers to achieve the same results as an expert skier in various conditions.

Different manufactures have approached this theme in a mixture of ways such as manipulating the shape of the ski tip to make it slightly wider but softer, which will let the tip engage smoother making the ski edge and carve in a more consistent arc. Others have included Rocker to raise the tip of the ski off the snow, which reduces the contact length on hard pack, producing a smaller turn, but still allowing the ski to float when off piste. Some designs are made with adaptive Cambers allowing more effective edge only when the ski is rolled beyond a certain angle, while others have combined all these elements into one ski.

With the many ways of obtaining results through material use and Side Cut design, it is important to remember that even though there are broad categories that skis fall into (Piste/All Mountain, Freeride, Big Mountain) these lines are now less defined. The versatility of many products and design characteristics mean that intermediate and advanced skiers now have better access to the ability to adjust turn shape on the go. No longer is your turn shape and terrain choice solely dictated to you by the equipment you’re skiing on.

Self Steering Effect

The Self Steering Effect occurs on all skis but is much more evident on skis with a large Side Cut. As the ski moves forward while on edge, the tip of the ski naturally engages the snow and begins to flex along the length of the ski and alter the direction of travel. The effect of this design feature on all skis can be increased or decreased depending on the speed and edge angle, and is the basis of how skiers are able to carve turns much higher in the fall-line and at greater speeds.

Why is this important to me?

All skiers use the Self Steering Effect to control their speed and direction whether the turns are skidded or carved. Choosing a ski with a more pronounced Side Cut will have a greater Self Steer effect and be more suited to pisted skiing where carving and speed control are more desirable. In deeper snow or varied conditions, the Self Steer effect is still present, but with the variables in the off piste snow, skiers are less worried about the carving ability of the ski.

Effective Edge/Contact Length

The Effective Edge can be described as the amount or length of edge that is in contact with the snow when tilted on its side. The amount of ski edge that is in the snow is one of the factors that will affect the size and type of turn.

Contact length is similar, but it refers to the length of base material that is in contact with the snow.

Why is this important to me?

Conceptualizing these two factors will help to further understand the implications of Rocker, Camber and modern ski design. (See below: Camber & Rocker). Imagine a ski sitting on the floor viewed from the side with an exaggerated Rocker shape tip and tail that looks like a semi-circle. With it balanced upright on the ground there is very little contact length of base material against the surface of the floor. If that same ski were in deep snow, then much more of the base would be in contact with the snow.
Though the above is exaggerated, this is the effect of Rocker, less contact length on the hard pack but more flotation when in deeper snow. With that same ski back on the floor, if it were tipped over on its side to 45 degrees there would be more edge in contact with the floor surface, increasing the effective edge and the turning ability of the ski.

Camber

Camber refers to the arched shape of skis. When placed on a flat surface, the centre of the ski does not touch the surface. The purpose of Camber is to distribute pressure along the ski. In recent years ski designs with no Camber (flat) and reverse Camber (barrel stave shape) have come on the market.
Skis without Camber will have more pressure in a short area under the foot and as a result the ski will pivot easily and behave like a shorter ski. Skis for groomed snow and carving should have camber while some skis for powder, backcountry and the terrain park are better without camber.

Camber

Under the additional pressures of speed and edging the ski will bend into reverse Camber. The combination of reverse Camber, Side Cut shape, speed and edging, is how the bent ski will carve a turn.

Why is this important to me?

The manipulation of Camber is a trend in skis which is affecting how skis are designed and ultimately what the ski is used for. Having a rough idea as to where and what you will ski will help you choose the right ski for that condition.

Rocker

Rocker is the manufactured rise of the tip and tail gradually away from the surface. The advantage to this is, the ski will now float in deeper snow conditions, as opposed to plough, allowing for easier turns in tougher conditions off piste and the ability to attain higher speeds. Off-piste in this case means big mountain conditions that go beyond an overnight dusting of snow. Off piste can at times provide very frustrating and challenging conditions that potentially take the fun out of skiing. By addressing these problems with the inclusion of Rocker in the tip, ski designers have made Off Piste much more fun and accessible.

In addition, the upward rise of the tip allows for greater manoeuvrability of the ski on hard pack surfaces because there is less ski in contact (contact length) with the snow.

As Rocker is a relatively new advancement, there isn’t conformity across the industry as to how to measure it, but for the majority of skis it can be described and measured as a distance length off the floor. Eg 220mm is the length of the ski tip that is not in contact with the surface. K2 has a slightly different system where they also measure how high the ski rises so they report two numbers. As a broad rule it seems that more Rocker for more snow is best. Less Rocker and a bit of Side Cut adds some versatility if you know you’ll have to negotiate some groomers on the way back to the lifts.

Rocker

Why is this important to me?

Having a ski with Rocker on it will make exploring and skiing Off Piste easier and more enjoyable. For those in bounds, Rocker on the tip and tail lets you ski backwards and makes landings more forgiving when doing tricks.

Taking into consideration Rocker, Effective Edges and Contact Length, it becomes clear that you can have a ski with Rocker characteristics that will feel “Shorter” when skied on piste due to its reduced contact length. But as the ski is rolled further onto the edge in a turn the physical amount of edge in contact with the snow increases and will vary the turn shape. Some ski-makers contour the tip of the ski taking this effect into account, which specifically increases the effective edge only when the ski is tilted or edged beyond a certain point. (See – Explained: Progressive Side Cut /Varied Side Cut/ Multi Radius/ Dual Radius)

Binding Mounts

Where your binding is mounted will have a large impact on the characteristics of the ski and how it will perform.

It is important to note that this only relates to skis that have the option to have a variable binding mount – not all skis have variable mounting positions. System skis and most All Mountain skis will have a pre-determined area where the bindings should be mounted. Deviating from this pre-set mounting point on anything other than skis that have this option is not recommended or safe.

The key element to keep in mind is “Where are you going to ski?” and “What are you going to use them for?” Once you have determined this it will ultimately guide you as to where you need to mount your bindings. The majority of skis still have a single point where bindings should be mounted, but there are growing numbers of skis that have an area range where bindings can be placed.

Boot Centre / Mid Sole

When ski boots are manufactured there is a small mark or line on the sole of the boot which marks the centre of the boot based on the overall length of the sole.

Why is this important to me?

With the advent of more skis having the option to mount the binding in variable locations, knowing the reference point from where the boot and binding is lined up is a key piece of information.

Classic Mount / Traditional Mid sole Mounting Point

Flat deck skis (those without pre-drilled mounting plates) will normally have a marking on the top sheet of the ski denoting the position where the boot centre should be lined up to. This position, as the name suggests, is the traditional point where skis have been designed to have the bindings mounted and skied from.

Why is this important to me?

This is the starting point for all ski bindings to be mounted. When lined up with the mid sole point on the boot it represents where the majority of skis are mounted and where the ski was designed to be skied from.

Progressive/ Centre Mount

Some flat deck skis have an area range where the ski can be mounted forwards or back of the Classic Mount position. By moving the mounting position forward (towards the physical Centre of the ski) it will make the ski tip and tail more equal in length but change how you balance and how the ski behaves. Equalling the length of the tip and tail reduces inertia and the swing weight, which decreases the effort required to spin, but also allows for better performance when riding switch (backwards) and doing rails.

Below is a rough guide for skis that have a mounting point range, using the classic stance marker as the point to measure forward from:

0 to 2cm forward: All Mountain Riding – If you plan on skiing mostly outside the park, and want the ski to behave like a traditional ski, you should stay on the conservative side and mount closer to the traditional mid sole mark.

3 to 5 cm forward: 50% All Mountain, 50% Terrain Park – When mounting beyond 3 cm, you will lose a little of the traditional feel of length in front of the binding, but with more tail, you gain the control in the air and riding switch. Seth Morrison mounts his skis at 5 cm forward.

6 cm to 7.5 cm forward: Terrain Park or Switch Riding – If you bought the skis primarily for the terrain park, or are focused on riding switch in the backcountry, you may consider mounting your skis this far forward. While you may sacrifice forward directional float and stability, it’s made up for in switch riding and landing balance and performance. From 6 cm to 7.5 cm forward is where Pep, Benchetler and Mahre typically mount their skis.

It is important to note when considering moving your mounting point for a specific use that the above guide lines do not take into account wearing a pack. Wearing a pack of any sort will affect your fore/aft balance point.

Why is this important to me?

Varying from Classic Mount /Traditional mid sole mounting point to these optional positions greatly affects the ski, and the above guidelines are an indication of the effects of mounting bindings in these alternative points.

Ski Flex

The flex pattern is a result of the materials used to make the ski and the design of the ski. The target skier (beginner, intermediate, advanced, expert) will determine what type of flex pattern is required.
In general:

  1. A ski that is soft in the tip will initiate the turn easily and perform well in soft snow.
  2. A ski that is stiff in the tail may not finish the turn easily but is well-suited to technique that places a lot of pressure on the tails at turn completion.
  3. A ski that has equal flex from tip to tail works well for larger turns and generally has a bigger “sweet spot” or is easier to balance on.
  4. Heavier skiers and experts prefer stiff skis for groomed snow.
  5. Lighter skiers, softer snow and developing skills prefer softer skis.

Ski Flex

Why is this important to me?

What flex pattern is right for you? Take your skill level and look at the range of skis designed for that level. Then look at the type of conditions you typically ski. Usually a stronger flex pattern performs better on ice and hard pack snow. A softer flex pattern would be suitable for softer natural snow. If in doubt try to see if you can Demo the model you are interested in.

Torsional Stiffness

Torsional stiffness is a phrase used to describe how easy or difficult it is to twist a ski about the longitudinal axis. Think of wringing out a towel. In the modern age of wide and shapely skis, torsional stiffness has become as important as flex used to be. Modern skis turn by bending while on edge. Wide tips and tails grip the snow first and as pressure is applied the ski bends and tends to twist. Twisting causes the ski edge to straighten out and lose a bit of grip. Racers don’t want to lose grip, their skis must be stiff in torsion so the edge continues to bite and maintains its arc. Such skis are precise but all that performance requires a skilled pilot.

Torsional Stiffness
Torsion

Why is this important to me?

Recreational skiers welcome a bit of softness in torsion because that prevents the ski from hooking in, hanging on at the end and behaving aggressively. As performance goes up so does price and that is often due to construction methods and materials. It appears that better materials and more complex constructions are required to make skis that are resistant to twisting.

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