Full Ski Analysis - $19

Classic Skis
Classic Ski Flex Sheet
The wax pocket is fully analyzed and marked. The skis are first loaded with half the skier’s body-weight positioned 8cm behind the balance point. At this setting the wax pocket is marked at 0.10mm, 0.15mm, 0.20mm and 0.30mm. The average coat of hard wax is about 0.05mm and these marks actually correspond pretty closely with appropriate positioning of 2, 3, 4 and 6 layers of wax. Skis which are appropriate for klister are also marked with a klister zone and a klister cushion zone (an area where it’s safe to build thickness on days when a cushion is necessary).

The ski is then moved so that the load is positioned 15 cm behind the balance point and the skier’s full body-weight is applied. This simulates a neutral-position glide phase with full body weight. At this setting the wax pocket is checked to ensure that it remains open in front of the foot. To ensure good speed it is important that there is not a lot of pressure put on the wax in a neutral full-weight position. Some skis which are particularly well suited for soft snow may stay open significantly forward of the half-weight marks and it is possible that another mark may be made in front of the half-weight kick-zone indicating the ability to lengthen the kick zone in soft conditions.

The load is then repositioned at about 8cm behind the balance point - roughly under the ball of the foot. With the skier’s full weight applied the ski is checked to ensure that the wax-pocket is flattened out. Many skis have a small residual camber at full-weight in a forward position. This zone is marked as an area where it can be a good idea to cushion the wax job with a slightly softer underlayer to ensure good kick.

Finally, some analysis is performed on the closing-weight of the ski. It is standard throughout the industry to consider a ski “closed” when there is still 0.1mm of residual camber. This is a standard that was developed to accomodate a thin layer of wax. I measure camber height with a very sensitive dial-indicator which is mounted in the flex bench itself. This system is more sensitive than most and I find that I get much more consistent reading if I measure to 0.2mm. Using this standard I am almost always within one or two KG of the ski manufacturer’s numbers. However, measuring the closing weight doesn’t take into consideration the “hardness” of the ski at that point. For instance, if a ski closes to 0.2mm on my machine at 35kg it may take an additional 3kg to close to 0.1, or alternatively it may take an additional 18kg to close that little extra bit. The difference is extremely important when you consider that the load required to “finish” closing the ski is basically the load required to put pressure through the wax pocket. A ski which closes to 0.2 at 80% body weight but finishes with only an additional 5KG will kick much more easily than a ski which closes at 60% but requires an additional 20kg to finish.

This process provides far more information than most flex tests because it provides an analysis of the reaction of the ski to different loading positions. Classic skis are generally designed to close with the weight in a forward position while they remain open with the weight in a neutral position. Unless measurements are taken with this in mind the resulting information is not very useful. The skis are flexed individually and there is always a difference between the two skis in a pair. Sometimes the difference is dramatic. This can be disconcerting, but I have found that if the skier can adjust to the need to wax the skis slightly differently they will be very satisfied with the result.

Skate Skis
Skate Ski Flex Sheet
Because most skate skis never actually “close”, I usually don’t mark them with a closing flex. In part this is because my flex tester can’t put enough pressure on many skis to close them down to 0.2mm residual camber. In addition to half-weight camber height, skate skis are also marked with a full-weight camber height. These numbers, in combination, can tell a great deal about the “action” of a ski. In general, the greater the difference between the half and full weight camber, the more lively the ski will feel.

I also mark the “bridge” length in front of the foot at half and full weight. The length of the bridge is analogous to the “wheelbase” of the ski. A broader wheelbase will give a more stable stance. The distance between the half-weight and full-weight bridge length will tell a lot about how quickly the ski builds stiffness in its response to an increasing load. Some skis build stiffness very quickly (the marks are close together) while others build stiffness more slowly (marks are far apart). I also mark the point at which significant pressure builds in the forebody moving back from the tip. The zone between the tip mark and the bridge-length mark indicates the forward running-surface of the ski at half and full weight, respectively. Any shift or change in this zone between half weight and full weight tells us a great deal about the way the ski deals with active loading. For instance, a ski where the pressure zone stays short and moves back toward the foot would be considered a “hot” ski because the pressure in the zone will continue to increase as the load increases. A ski where the pressure zone lengthens back toward the foot is considered a “cool” ski because the ski distributes weight over more and more surface area as additional load is applied.

Hot skis tend to have an early release to kinetic friction from static friction, and a really nice high-end break-point where they might leave other skis behind at high speed. Cool skis tend to feel more “slippery” at low speed because their broader distribution of the load yields lower static friction. Hot skis with a high camber-height differential will generally demand a fairly aggressive skiing style but will give a lot back to a skier who skis aggressively. Cool skis will favor a smoother lower-energy skier. For a given skier, a hotter ski will tend to be better in harder conditions and a cooler skis will tend to be better in softer conditions.