Let's Talk About Flex
Ski flex, much like waxing, may be as simple or as complicated as you want to make it. While ski flex is a very important thing for a racer to consider it is also important not to get so caught up in it that you lose focus on the most important component of speed. Which is the motor. In this case that is YOU! The Nordic hierarchy of speed goes - from most to least important - like this: 1. The strength (power + endurance) of the skier. 2. The flex of the ski in relation to the snow conditions combined with skier input. 3. The base structure of the ski. 4. The wax applied to the ski.
So,obviously, flex matters. How much it matters is highly dependant upon the skier. The brand new high school ski team member certainly does not have the same demands or needs of a skier competing on the World Cup.
Black and White. Either It Fits or It Doesn't.
A young skier who may just be getting his or her introduction to the sport certainly does not need to know about all of the potentially confusing details of ski flex. They just need a ski that fits properly for their ability so that they can go out and ski, have fun, and learn to love the sport. At Skihut we tend to fit less experienced skiers in softer classic skis and slightly stiffer (but not high cambered) skate skis. Why? Because here in northern Minnesota (and specifically Duluth) we tend to have hard, almost icy skate lanes. And we have a lot of hills. A new skier benefits in classic technique from a softer ski to get better, easier kick. Especially on the climbs (nothing is more frustrating to a new classic skier than constantly slipping). In skating they will benefit from the inherent stability of a stiffer ski when skiing our often very hard skate lanes. Stiffer skate skis have more widely separated pressure zones which result in a wider "wheelbase". A wider wheelbase is inherently more stable and easier to control when the conditions are hard. This stability allows the novice skater to ski under control and simply enjoy themselves.
In an area where they receive a lot of fresh snow, groom often, and generally have softer skate lanes a new skier would benefit from a softer skate ski. Softer skis tend to float across softer conditions where a stiffer ski would tend to plow into the snow. Because the skier actually sinks into soft snow - stability is not a problem. The snow itself will stabilize the ski.
Things Start To Get Cloudy.
For the skier with experience who may not yet possess advanced technique we tend to look for a "universal" flex. That being a classic ski with a long wax pocket that requires the skier to apply a bit of pressure to flatten that pocket for kick. With a skate ski we want ski characteristics that will remain stable on hard snow yet be soft enough in the tip and tail to climb easily and glide over and across soft snow. Most ski manufacturers now make skis more suited to fill this need. Basically a firm mid-camber with a softer tip and tail will work well universally. This skier may also want hard and soft snow - or warm and cold - skis - or klister skis - that's cool. We can do that.
Incomprehensibly Variable Shades of Gray.
For the skier who is highly competitive and who is looking for every possible advantage over the competition we need to stress: SKIER KNOW THY SKIS! This skier needs to pay attention to how his or her skis perform in differing snow conditions. They may need to supplement their "quiver" of skis so that they have good skis for any condition they may encounter. This is where things can get ridiculously complicated if one allows it to happen.
Conditions which influence ski speed include, but are not limited to: The moisture in the snow. The hardness or softness of the snow. The structure of the ski base. The flex of the ski in relation to snow conditions and skier input. All of these factors combine to dictate the gliding speed of any set of skis.
Now consider all of the possible combinations involved. Snow conditions could include: hard and dry, hard and wet, soft and dry, and soft and wet. Next you could consider the speed vs. stability factor. Generally speaking a stable ski is slow and a fast ski is unstable. A ski that feels fast on dry snow will most likely feel slow on wet snow. Why? Because the same long glide zones that make it fast on dry snow (weight dispersed - decreasing friction) will make it slow on wet snow (surface contact increased allowing for greater adhesion). A ski that feels stable on hard snow will still be stable on soft snow - BUT - it will also be painfully slow. The widely separated, high-pressure contacts points that make it stable on hard snow will make it plow into soft snow decreasing glide speed.
On dry (low humidity or cold) snow you want long glides zones. Long glide zones distribute the skiers weight so that there is less pressure downward on the ski over a given area. This pressure distribution helps the ski to glide faster on dry snow by decreasing friction against the snow. On wet snow those long pressure zones are the ski's enemy. Instead of increasing glide speed they increase the wet snow's ability to cling to the ski (think suction or adhesion) thereby slowing it down dramatically.
Let's look at each snow condition and discuss what type of ski flex (in reference to skating) would best suit them in terms of speed.
1. Hard and dry. Best flex - Relatively soft midflex with medium tip and tail flex. Creates long glide zones. Cold, dry structure. In relation to ski flex - hard and dry are conflicting snow conditions.
Here in Northern Minnesota this is a common condition. Our less frequent snowfalls usually mean longer periods between grooming resulting in a very hard-packed track surface. When combined with single digit to below zero degree Farenheit temps - our snow can be very....., well,... ice-like. Speed on this condition is no problem. You have a guarantee of speed. The problem is controlling your ski. The fastest flex for this condition is a soft ski. A soft ski will have longer glide zones which will increase the glide speed. BUT - at what cost to control and energy return? Remember - a soft ski is inherently less stable. An elite level skier will probably be fine with a soft ski (to a point - there is such a thing as a *too-soft-to-be-fast ski) because their technique, strength, and experience will carry them through - no worries. But the less polished skier needs to consider stability. The more one struggles trying to simply stay upright and on the trail the more fatigued one will become. So, even though they will be absolutely flying, they will eventually lose this struggle for control. They will become far too tired to keep their focus. They will lose technique and ultimately they will lose a lot of time. It is a deflating experience.
*"Too-soft-to-be-fast" -The midflex of the skate ski is too soft. The snow will absorb the skier's energy so that there will be no energy return or "pop" from the ski. This ski will also be horendously unstable on firm snow.
2. Hard and wet. Best flex - Relatively stiff mid flex with stiff tip and tail. Creates wide "wheelbase" with shorter glide zones to inhibit wet snow adhesion. Universal wet to wet structure. In relation to ski flex - hard and wet are complimentary snow conditions.
A rare condition. Think spring melting snow - ice klister conditions. A hard base with wet snow or standing water on top. Here we want less glide zone so our ski doesn't get stuck to the snow. Luckily the flex required to get these shorter glide zones lends itself to hard snow stability. Hard snow and wet snow have the same basic requirements. Too bad they rarely exist together.
Yes - it is possible for a skate ski to be too stiff for this condition. If a skate ski is too stiff there will not be enough force produced by the skier to keep the ski stable. The ski will tend to skitter out from under foot on hard snow and will plow like the dickens on soft snow.
3. Soft and dry. Best flex - relatively soft mid flex with soft tip and tail. Creating longer glide zones. Cold, dry structure. In relation to ski flex - soft and dry are complimentary snow conditions.
Here we need a ski that will float across and through soft snow. A soft gradually flexing tip is needed to keep the ski from plowing. This tip flex needs to transition smoothly into a relatively soft mid flex in order to avoid "hot spots" - or areas where the ski will plow into the snow (hot spots may be indicated by short dry [white] spots on the ski base, after skiing, that appear about 1/3 of the way up the tip or just behind the heel). The ski doesn't need stability here. It will sink into the snow - gaining stability from the snow itself.
4. Soft and wet. Universal mid flex with universal tip and tail. Creating a mid-length glide zone in an attempt to balance wet snow adhesion with soft snow float. Universal warm to warm, wet structure. In relation to ski flex - soft and wet are conflicting snow conditions.
This is the most perplexing snow condition. For wet snow we would prefer short glide zones. Short glide zones are found on stiff skis. But stiff skis tend to plow into soft snow. For soft snow we would prefer long glide zones. Long glide zones are found on soft skis. But soft skis get "suctioned" to wet snow. So the best you can do is split the difference and choose a universal flexing ski. Structure the heck out of them, and stay strong.
What Does It All Mean?
As you can see there is a lot to think about if you choose to think about it. If we were to throw in the strength of the skier (which does play a role in how a ski flexes) and the specific course profile (hills - soft tips for climbing?..stiff mid-flex for "pop"?...extra stability for descents?) or the fact that two sides of any large hill will have totally different snow conditions, we could really start to worry ourselves into an "over-analysis paralysis" coma. What about ski length?...It matters too. In some skis more than others. But that is opening a whole new can-o-worms!
Suffice it to say that ski flex matters. But don't freak out about it. Most racers may be successful with two good pair of skate skis - some with just one. Same thing with classic. If you are strictly a recreational skier - forget everything you just read - never come back to this website again - and get out there and just have fun skiing!
Are Your Skis Right For You?
If you have questions about your current ski's flex please feel free to e-mail me - Mick D. at firstname.lastname@example.org - we will be glad to help you out. Even if you have a few pair and you need to figure out which ones will excel in what conditions - no problem - shoot me an e-mail, call or stop in. We are here to help.