Z-value (ski)
The Z-value , Din-value according to ISO standard 11088 , is the trigger value for ski bindings . It is displayed on the scales of the binding (toe and heel) and can deviate from the determined Z value due to the properties of the ski boots.
The safety release of the binding should take place when the torque acting on the shin bone exceeds a certain limit value. Force effects on ligaments or muscles are not taken into account. The Z value is a variable that increases monotonically with the specified torque limit value and has no physical unit of measurement .
There are two officially recognized methods for determining the Z-value.
- Tibial method: the width of the head ( Latin caput tibiae ) of the shin bone ( Latin tibia ) is measured and the value is determined based on the inclusion of the width of the tibial head, gender, age, driver type and the length of the shoe sole.
- Weight method: Table values are statistically determined from body height, body weight, age, gender, skiing style and ski boot sole length.
The statistical average of the Eurasian physique type serves as the basis for both methods. Age plays a role in bone density , as does gender - women have more delicate bones than men.
Ski service companies have had to have standardized binding testing and setting devices at their disposal since 2007. These determine the torque that acts on the shin bone and take into account not only the skier's biological data, but also the condition of the shoe. After setting the security binding, the specialist company is obliged to hand over a receipt to the customer. The name, date, location, setting parameters, trigger values and the actual set value must be noted on the binding scale.
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- Official script training course to become a sports fitter for ski bindings, 2007, VSSÖ (Association of Sports Equipment Manufacturers and Sports Equipment Suppliers in Austria)