Det är inte helt lätt att ge ett absolut rätt svar på din fråga.
Samma funderingar beträffande utlösningskrafter etc återkommer ständigt.
På Ski Magazine´s forumsida kom detta upp i februari förra vintern.
Jag kände mig manad att ge lite information om detta eftersom jag själv deltagit i utvecklingsarbete, telemetrimätningar avseende krafter på fötter o ben under åkning etc under sjuttiotalet.
Jag hinner/orkar inte skriva om det till svenska:
"We take it from the very beginning.
During the period 1970-1975, the Swede’s and German’s tried to figure out the problem of broken legs in the ski-slopes.
The Swede’s tested forces of the skier’s feet, legs and skis during real skiing in various conditions. With help from orthopedic institute at Karolinska hospital in Stockholm the pioneer Einar Eriksson made big success together with the Germans.
In Germany they tested the durability of “fresh” human legs (bone) at real legs from traffic accidentally died people in different ages.
The result of this gave us that an slow force build up as in deep wet snow or slow speed are harder for the legs to withstand.
If you adapt a very short force (high speed in gates or on scattering icy slopes) to the legs, you can handle about 3-8 times the slow force.
Women’s legs are more vulnerable and get broken at bending forwards about 10-20mm with a force of 20-25kp. Men’s legs can take a force of about 30-40kp with the same bending.
The leg under the knee can be twisted with elastic deformation 10-12 degrees and the bone breaks at about 20-25 degree.
Of course this depends of the age and the physical design of the legs and therefore they found a relationship between the strength and the tibia. Tibia is the same as the widest area of your knee. For myself this is 94mm, an average dimension for a male.
A tibia of 70mm can handle a twisting force of 10kp with plastic deformation.
80mm –15kp, 90mm-18kp, 10mm-22kp.
To make it more complicated you have to figure out the age of the skier and of course the level of the skier.
All these testing gave us the plate bindings and the block binding (BOX) used by many freestylers in 1975-1980.
The DIN (Deutche Industri Normen) also gave regulations for the interface between the skiboot and the binding and the ski.
Because it was to difficult (timewasting) for the skishops to measure the tibia the DIN-settings was developed.
This means that you set the number to eight (8) if you have a weight of around 80kg.
The body mass about ten times the setting.
This is usually good enough for the most recreationally skiers in moderate speeds in moderate skilevel and in average physics.
For gate bangers and experts at high speed the settings must be increased about 1.5-3times the normal.
And naturally for old aunt Daisy decreased in the same way.
This was a shortform of the history of DIN.
The setting of DIN 8 for an 80kg skier is a little bit too high especially in slow soft rides on the snow and.
Take the DIN value and multiply with the factor 0.75 then you are more near the secure setting.
But, to make it more exactly measure your tibia and increase or decrease depending on your muscles, skiing technique, average speed, sole length of the skiboots, the skis and so on.
For example:
I am 46year, shoesize 10, 192cm, 86kg (naked), tibia approx 96mm and driving giant slalom skis (212, 207, 203 cm) in various slopes from soft snow up to nearly ice.
The Marker manufacture says about DIN 7 as basic setting for my weight and tibia.
This setting correspond to the legs bone elasticity zone.
Above this zone we have almost 2x the force before broken legs.
I drive between 9.0-15 depending if I compete or drive just for fun.
In several crashes, I have never broken any leg for over 30 years of skiing.
An easy selftest is to try release the bindings by the own muscles with bending the heel forward and rotate the toe out.
But of course, it’s also possible to drive really fast and hard with a minimum of DIN-setting if the skier really stands right on the ski and makes smooth and fine movements.
EXPERIMENTAL WITH THE DIN-SETTINGS MAY BE DANGEROUS IF YOU DO NOT REALLY KNOW HOW TO DO.
The mad Swede/ Arc Tracer"
den okuvlige minneskonstnären
fortfarande med gummistövlarna på
/Arc
