Equipment - Buying skis
Date first posted on eCommunity - 26
November 2006
I've had a request to give some advice about buying
skis, second-hand skis in particular. This is the time of year when people sell
off their old kit on ebay and through club websites. It's possible
to pick up some good stuff at low prices. But you need to know what
you are doing – the chances are that the sellers themselves do not
have a great deal of knowledge and they won't be able to give you
good advice.
In this posting I'll look mainly at the shape and size of skis. Next
week I'll take a look at the different boot/binding systems
available.
But first: a word on materials. Modern skis, XC or downhill, are
made from some form of plastic – glass fibre or carbon. Older skis
are made from wood. Unless you really know what you are getting
into, you should avoid buying wooden skis. They look nice (and they
are very effective over very cold and powdery snow). But they need
quite a lot of looking after – for example, you have to seal the
bases once or twice each season, using a special tar that you burn
in with a blow-torch.
WIDTH. Skis for mountain touring are commonly almost twice as wide
as those for track skiing. On untracked surfaces you need the width
to keep you from sinking into the snow. A typical ski for touring
along mountain valleys will be about 60mm wide at the shoulder,
while one for use on steep ground can be 10mm or even 20mm wider
still.
On prepared tracks, where the snow has been compressed by the track-cutting machine, a much narrower ski will be able to bear your
weight. The narrowest track skis are for racing, and these - whether
for classic or skating technique - are typically only 44mm wide at
the shoulder.
Some skis, like the "light touring" models often seen in
Scandinavia, are intended for a mix of track and off-track use and
are about 50mm at the shoulder.
SIDE-CUT. Side cut refers to the shape of a ski when viewed from
above. Some skis have almost no side-cut - they are almost the same
width at shoulder, waist and tail. Others have an hour-glass figure.
A ski with a lot of side-cut will tend to turn well when coming
downhill, which makes it a very suitable design for off-track skiing
on steep terrain. But it will not work well on flatter ground, for
example along valley bottoms, on which it will still tend to turn
rather than going in a straight line.
Track skis do not need good turning capability. The sportier sort of
track skis will be almost equally wide at their shoulder, waist and
tail: a typical measurement for a classic ski, in millimetres, is 44-42-44. A skating ski will generally have a very similar profile,
though some models are perfectly straight-sided and a few are
narrower at the shoulder than at either the tip or tail.
By contrast, a mountain touring ski for use in valleys might measure
60-53-57. And a model for steep mountain touring might measure 70-55-65.
CAMBER. Camber refers to the shape of a ski when viewed from the
side. When unweighted, the front and back thirds of the ski will be
almost flat to the snow but the middle third will rise up in an
arch. The arch is there to spread the skier's weight evenly along
the entire length of the ski. All modern skis are cambered. Downhill skis have a relatively soft
camber that allows them to flatten entirely to the snow under the
skier's weight; this helps them to turn when edged. But cross-country models need to have a stiffer camber in order to lift the
grip zone clear of the snow when the skier is gliding downhill. If
they were soft, their grip-zones would be flattened and the grip wax
would then catch on the snow and slow the skier down. In the process
the grip wax would soon be scraped off, and frequent re-application
would be necessary. Be aware that many skis now sold under a heading
such as "Nordic skis for steep mountain touring" actually have a
soft camber, like a downhill ski.
LENGTH. For decades the way to determine your correct ski length has
been to stand upright and reach your hand above your head: the tip
of the ski should come just above your wrist. This method of sizing
skis has applied to skis for classic technique. For skating skis the
rule of thumb has been: 15cm shorter than classical.
The hand-above-head method will work well if you are buying second-hand skis. However it may not work quite so well if you are buying
new kit, for many manufacturers are now using improved materials and
methods to produce "short-cut" skis, which can be about 20cm shorter
than traditional models. Short-cut designs are most commonly seen in
skis for light touring, but skating models are also produced.
Because short skis are much easier to handle than traditional
lengths, they are a good choice for beginners and occasional skiers.
A disadvantage is that they do not glide quite so well as longer
skis.
Partly because of new construction methods, and partly because of
increasing levels of overweight and obesity, more attention is now
paid to the skier's weight rather than height when determining the
appropriate ski length. Manufacturers produce charts for each of
their ski models. (For an example of charts relating to traditional
length skis, go to the website of the manufacturer, Fischer:
http://www.fischer-ski.com/en/. Select Products, then Nordic, then
Skis, then Racing, then Classic – and then click on Recommended
Lengths on the right-side navigation bar. If you want to look at
short-cut skis, then select Fischer's Nordic Cruising models.)
As you will see, the more specialised the ski, the more complicated
the chart. Top-end skis are offered with the choice
of "stiff", "medium" and "soft" flex in each length.
But no matter how complicated, sizing charts give only a guide.
Before buying a ski you should be sure to use the paper test, a
simple old method that has stood the test of time. You start by
placing the skis on an uncarpeted floor and then you stand on them.
When your weight is evenly balanced between them it should be
possible for a helper to slide a sheet of paper under the skis and
to move it from a point just behind your heels to a point about 30
centimetres in front of your toes. If you can not do this then the
camber is too soft for you and you should choose a stiffer pair of
skis, or a longer pair. Next, you shift all your weight on to one
ski. If the ski is right for you, you should have flattened the
camber out and trapped the piece of paper. If the paper can still be
moved, then the ski is too stiff for you. Be sure to try this part
of the test with both skis.
It can be seen that choosing skis is a fairly tricky business! You
need to know what kind of skiing you want to do. And you need to be
ready to ask the buyer a lot of questions.
NOTES
Much of the above is stolen from our new book. So now you don't need
to buy it and you can put the money towards your new skis. But if
you want to see more details of it anyway, then go to
www.xcuk.com/Pages/stride_and_glide.html.
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