Atomic ski boot clipping into a ski binding

What’s Your DIN Number?

Written by Jans Ambassador, Jackson Hogen, of Realskiers.com.

Every skier, whether they know it or not, has a DIN number.  It’s the torque value that their bindings are set to, and it’s been called a DIN setting since the German Institute for Standardization—or Deutsches Institut für Normung—became the first national standards organization to adopt the norm that specifies uniform binding release/retention settings that we still follow today.

Here’s a little known fact about DIN settings: the expression is a misnomer, as they should be referred to as ISO settings. The International Standards Organization supersedes a national organization such as the DIN, so as soon as ISO ratified the same specifications, its rank should have nudged DIN out of the picture.

But the DIN tag has stubbornly held its ground. Even after every binding manufacturer extant labeled their release-setting table as the ISO chart, North American shops and skiers continued to reference the resultant number as a DIN setting, as though ISO had DQ’d by arriving too late to the party.

So what is a DIN number, and how is it derived?  A skier’s DIN number is determined by his/her weight, height, skier type, age, and boot sole length.  Of these factors, weight is the most important, as it has the highest correlation with the breakage resistance of the tibia. Height is used as a check on weight—skiers who are heavier may have their bindings set according to their height instead of their weight.

Our bones become more vulnerable as we age, so we lower a skier’s binding setting by a full DIN number for each decade they are over 50.  The skier’s boot sole acts as a lever on the toe and heel piece, so its length determines the torque derived by multiplying this length by the binding’s force setting.  Because a DIN number is essentially a torque setting, it’s directly affected by leverage: shorter boot soles require higher release/retention settings while longer boot soles need a lower force setting on the binding to arrive at the same torque.

Up to this point, our DIN number calculation is based on hard data: weight, height, age, and boot sole length aren’t fuzzy figures. But there’s one factor left to consider, and it’s wide open to interpretation. It’s your skier type, which isn’t quite the same thing as your ability. Skier type is more about speed, risk-taking, and aggression than it is about skill.  Skiers who go fast and take chances have a higher need for retention than skiers of a similar build who poke along at a leisurely pace.

All first-timers fall into Skier Type I, as well as any skier who is slow and cautious. Skier Type III lives at the other end of the skills spectrum and not only prefers to ski fast, but is willing to take on the associated risk. Skier Type II is anyone who doesn’t fit the descriptions of Types I or III, or anyone uncertain of their classification. Raising or lowering the skier’s DIN number according to his/her skier type is the last step in the process.

There’s one other wrinkle in the ISO/DIN release setting protocol, and it’s a loophole you could drive a truck through. The standard acknowledges the existence of a fourth, off-the-charts Skier Type III+, who for any number of reasons doesn’t want to use his or her standard setting. The Type III+ skier usually wants a higher than recommended setting, but the need for speed isn’t the only reason someone might request a non-standard setting. For example, skiers with prior injuries may feel better if one binding is set lower than the other.

The logic for writing a standard that recognizes the validity of using non-standard settings for special cases is rooted in the realization that ultimately the skier has the right to determine his/her own release/retention settings.  However, the American legal system doesn’t grant this same license to ski shops, which are enjoined to follow the letter of the standard. At the end of the day, skiers can do whatever they want (however ill-advised) but ski shop personnel cannot.

It’s important to reiterate a point alluded to above, that a binding’s release function is meant to protect the major weight-bearing bone in the lower leg, the tibia. While a binding may respond to loads that might injure soft tissue or ligaments, it isn’t able to react to all injury-producing forces. In other words, even a properly working, correctly adjusted binding can’t protect skiers’ knees—or any other part of them other than the tibia itself—from injury.

If properly adjusted, the modern Alpine binding is a marvel of engineering that has contributed to a steep decline in lower leg injuries.  But its brilliance can be neutralized by using a touring sole in a binding intended solely for use with standard Alpine boot soles.  Binding design is currently transitioning to accept boots with either touring, Alpine, or Grip Walk soles, but there are hundreds of thousands of bindings still in use that don’t have this multi-norm compatibility. To learn more about binding-to-boot compatibility, check out our recent blog post on it.

And if you have any doubt about the compatibility of a new boot with an older binding, swing by a Jans location and we will gladly inspect your setup. And while you’re at it, talk with an Expert about your correct DIN setting, and having your bindings adjusted to match it.

Learn more about the author, Jackson Hogan, of Realskiers.com.

Featured image provided by Atomic.

%d bloggers like this: