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TECH TALK

Fast Facts on Alpine Racing Gear from Winter 2010 issue

SKI GEOMETRY : Here’s some of base information on keywords like sidecut, radius and camber as well as technology you need to know before you head into the shop.

SKI CORES:
heart of the matter

by Ian March from Buyer's Guide 2010 issue

With skis, just as in love, we are often initially drawn to our mate by what’s on the
surface. But, as your parents should have told you, for true happiness, it’s what’s
inside that counts.


To avoid a broken heart, let’s go beneath the surface, right to the core. The personality and feel of a ski is the result of a combination of construction materials, construction methods and dimensions. If two or more manufacturers made skis with the exact same dimensions, they can still feel very different on snow, but for this discussion let’s take dimensions out of the equation. So what makes the difference? Likely the largest contributor to the ski’s feel is the core, mostly what it’s made of and also how it’s put together. The core influences such important factors as a ski’s weight, dampness (ability to absorb vibration), stability, responsiveness and energy. The following are some generalizations to keep in mind on ski cores, their construction and characteristics.


CORE MATERIALS
WOOD: Heavier, stable, damp, responsive, durable and solid-feeling with consistent flex.
INJECTED FOAM: Light, quick-feeling, less stable than other cores, but also less expensive to produce.
FOAM (milled or cut from a block): Light, energetic feel; generally less damp and less
stable than wood; more consistent flex than injected foam; and generally between injected foam and wood in terms of cost.
LAMINATE: Layers of materials bonded together using epoxy, heat and pressure. Various types of wood or foam can be laminated to create a ski’s core, e.g. using a centre of birch (for strength) with balsa bonded to it will produce a lightweight core that absorbs vibration well.


CONSTRUCTION
But wait! Again, just as in love, it’s not that simple. Let’s not forget construction. The
construction surrounding the core works with the core’s characteristics to ultimately finetune the feel and capability of the ski. There are three main construction techniques in today’s skis, each offering its own unique benefits and tradeoffs.

Volkl torsion box

Völkl’s inside look at a classic high-performance
construction: wood core, torsion box and titanium
laminate together offer great edge hold, responsiveness
and stability at speed.

 

 

TORSION BOX: Fibreglass layers wrapped around the core add torsional stiffness
to a ski, resulting in excellent edge hold, consistent flex and durability. Torsion-box
construction generally results in a more demanding ski to use. Stronger skiers take
note, a large number of race skis at the World Cup level, as well as many higher-end freeride skis, use torsion-box construction.


SANDWICH: Various laminates (metal, titanium, fibreglass) layer along the top
or bottom of the core to alter flex and dampness. For example, adding a layer of
metal can add weight (yes, this can be a good thing), stability and vibration absorption
(dampness).


 

In the Atomic skis that use a capped ski construction, the topsheet and sidewalls are all one piece: torsionally
stiff (for good edge hold) yet light in weight and forgiving.

 

 

 

CAPPED: In the case of capped or monocoque construction, the topsheet and sidewalls are formed as one piece, like a cap that surrounds the ski. The cap bears the load of the ski. While the cap adds to torsional stiffness, at the same time it allows the ski to be light in weight and softer overall (longitudinally), resulting in a more forgiving ski that still
has good edge hold—a very good thing for aspiring skiers who spend a lot of time on
eastern hardpack.

CHARACTERISTICS
So what does all of this mean? What about me and my search for the perfect mate? Easy there, Romeo, use your head here. Keep these core and construction characteristics in mind when thinking about what you’re looking for (in a ski!) and what “feel” you like:


• Do you like a light, quick ski? Are you less concerned about stability at speed? A foam core might generally keep the quick and nimble happy.
• Do you like to blast through everything, moguls and crud exploding beneath your feet? Maybe the solid feel and durability of wood is up your alley.
• Do you need or simply like a forgiving ski, but get nervous on hard snow and ice? Capped construction can offer both forgiveness and good edge hold.
• Do you aspire to race on the World Cup or at least beat your friends in the gates? The awesome edge hold of a torsion box, the dampening of a wood core and a metal layer just might be your ticket to the podium.


If you still have cold feet and are not sure, other questions you could ask
yourself are: What factors took a ski experience from the competent to the
sublime, and what in the ski helped make it so? Was it the ski’s solid feeling that
gave you confidence and enabled you to push yourself to new limits? The quick,
snappy, light feeling that made you dance through that mogul field? Or was it the
splashy graphics that look so…wait! If this is you, then please return to the
beginning and start reading again.


 

Some Rossignol skis use capped construction, in this case with a wood core and extra layers
of glass to up the stability,
power

 

 

 

 

 

One caveat: Remember that the characteristics we have been discussing
are generalizations. There is no substitute for actually trying a ski on snow. And when
you do get the opportunity to demo some skis, ask the rep what’s inside and then see
if you can feel the characteristics while ripping up the mountain. You’ll likely use
your demo time more effectively now that you’re an expert on core construction. And
don’t forget the old adage when searching for the perfect mate for the slopes: beauty
is in the eye of the beholder.






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©Ski Canada Magazine