What is DIN in ski bindings?

When skiers prepare for a day on the snow, it’s common for them to pay attention to their ski boots, ski helmets and even the weather conditions or types of snow they’re going to encounter. However, one of the most important and often least understood (or underestimated) elements are the ski bindings, and in particular the DIN value, which determines when the bindings should release the boot in the event of a fall. Not only is this setting crucial in terms of safety, it also has a direct influence on performance during the activity.

If you’ve ever used iconic bindings like the Marker MRR, Salomon 555, Look Nevada or Tyrolia 490, you’ll have experienced the DIN system built into these classic models. This standard is a constant reference in the ski industry, adopted in the 1970s following extensive biomechanical studies carried out by the Deutsches Institut für Normung (DIN). Thanks to German state-funded research involving fracture analysis in collaboration with hospitals, the DIN system was designed to protect skiers from serious injury. Although the name DIN has stuck, modern standards are now set by the ISO (International Organisation for Standardisation), based on this initial work, but applied worldwide.

In the US, some brands also use ASTM (American Society for Testing and Materials) specifications, a protocol separate from the ISO standard. Whereas the ISO standard tests bindings by applying pure torque to the boot, the ASTM protocol fixes the boot and applies force directly to the ski. These differences in method are based on distinct testing philosophies, with the Americans believing that their protocol better reproduces real conditions in the field.

In ski making, the design, geometry and construction process aims to maximise control and performance, as described in our article on ski making. However, all this advanced technology would be useless without properly tuned bindings, as they are the element that connects your movements to the terrain. Correctly adjusting the DIN of your bindings is an essential skill that every skier must master to ensure the safety and efficiency of their equipment.

In this article, we explain everything you need to know about the DIN of ski bindings, from how to calculate it to how to adjust it to suit your personal characteristics. In any case, the most important part of this article is to focus on the precise adjustment of bindings. Ready to go? Set the DIN and let’s go!

What is the DIN in ski bindings?

DIN is a trigger value for ski bindings, often mistakenly referred to as the ‘DIN standard’. In reality, this name refers to the safety standards initially developed in Germany by the Deutsches Institut für Normung (DIN). This standard, which aimed to protect skiers from injury, was adopted internationally and is now part of the ISO (International Organisation for Standardisation) standard. However, the term DIN is still commonly used in everyday language.

Origin of the DIN standard

In the 1970s and 1980s, the German DIN institute, supported by the state, conducted intensive biomechanical research to determine the trigger values that would protect skiers from fractures, mainly of the tibia and, to a lesser extent, the knee. These studies were based on in-depth analyses carried out in collaboration with hospitals and morgues, and led to the establishment of the first safety release standards for ski bindings. DIN’s work served as the basis for today’s safety standards, which have been adopted and adapted by ISO.

Today, although DIN initiated these standards, it is the ISO standards based on its German research that have become the worldwide standard. In the United States, however, some manufacturers also use the ASTM (American Society for Testing and Materials) standard, due to differences in testing methods and safety philosophy.

Differences between ISO and ASTM standards

The ISO and ASTM standards both define release protocols for ski bindings, but their approaches differ:

• ISO: The ISO test fixes the ski and applies pure torque to the boot, simulating a release by the force exerted at the foot.
• ASTM: This protocol fixes the boot in place and applies a force directly to the ski, a method that the Americans believe is closer to real conditions in the field.

These test differences reflect slightly different approaches to safety, and manufacturers must comply with both methods in order to meet the requirements of international markets.

How do I know which DIN to use for my bindings?

Setting the release value (or ‘DIN’) is a delicate balance that requires careful attention. If the value is set too low, fasteners can release prematurely, causing avoidable falls. On the other hand, setting it too high increases the risk of serious injury, as the bindings may not release at the right time in the event of a fall, exposing the skier to risks to the tibia and knee joints. Understanding and fine-tuning the DIN is therefore essential for all skiers, from beginners to experts.

Today, the ski industry has standardised the DIN at international level through the ISO norm, guaranteeing a reliable and uniform adjustment system, regardless of where the bindings are purchased or used. The release values are calculated from a number of factors: weight, height, ski level, and also boot length, which acts like a lever arm and plays a crucial role in adjustment. The longer the boot, the more the effort required to release the binding needs to be adjusted to ensure optimum release in a fall.

Tables of release values are available from ski shops and are essential tools for binding fitters. The ISOSKI application, developed by the Union Sport et Cycle, facilitates these adjustments by allowing skiers to calculate their release values and check the compatibility between their boots and bindings. This application provides a practical means of adjusting equipment, while encouraging users to consult a professional to check the precision of the adjustment.

AFNOR’s role in European ski binding regulations

In Europe, AFNOR (Association Française de Normalisation) is the body that contributes to the development of technical standards for ski equipment, in collaboration with ISO. While the DIN standard was the first to define release values, AFNOR plays a complementary role in Europe, establishing safety standards adapted to the European market. It ensures that bindings meet safety and performance requirements, guaranteeing that release values are within precise tolerances to protect skiers.

AFNOR regulations, while not replacing the DIN standard, complement international standards by checking that bindings marketed in Europe comply with rigorous technical parameters, including weight, release height and applied force. This supervision helps fastener manufacturers to comply with ISO standards and the specific requirements of the European market.

Understanding DIN and the standards surrounding it is the first step to skiing safely. In the following section, we’ll explain the precise factors that influence the DIN calculation and how to determine the appropriate release value for each skier.

How is the DIN value calculated?

The DIN value is calculated according to several key factors that influence the release force of bindings. The weight of the skier is one of the main criteria: the heavier the skier, the greater the force required to release the boot to ensure a secure binding.

Height also plays an important role, as taller skiers exert more torque on their bindings due to the length of their legs, which acts like a lever arm. Boot length, another often overlooked factor, amplifies this leverage: a longer boot often requires an adjusted release value to balance the forces in torsion and forward fall. Skiers with small feet may require a tighter fit, while those with larger feet benefit from a looser fit for the same level of skill, weight and height.

Skill level is also important. Beginner skiers, who ski at slower speeds and have less control, need a lower DIN, allowing the bindings to release more easily in the event of a fall. Conversely, advanced skiers, who are confronted with more intense situations, need a higher DIN value to avoid accidental release.

Age is also a factor. With age, bones and joints become more fragile, and a slightly lower setting can offer extra protection by making it easier to release the bindings in the event of a fall.

Impact of type of skiing and snow conditions

Depending on the type of skiing you do, the DIN setting can vary. Those who ski more aggressively, such as freeride or freestyle, need higher DIN values to ensure that the bindings stay in place during sudden movements. Skiers who stay on piste, on the other hand, may opt for lower DIN values, depending on their skill level and snow conditions.

Finally, snow conditions play a role. In hard or icy snow, falls can be more abrupt, so it’s essential to adjust the DIN to avoid premature or late tripping.

Use of reference tables and the importance of adjustment by a professional

Tables of DIN values, available from ski shops, provide a basis of reference according to weight, height and skill level. However, it is advisable to have your bindings adjusted by a professional to ensure safety and performance, as inadequate adjustment can compromise both.

These tables include an approximate DIN release value and are often supplied when the bindings are purchased, with a detailed DIN table included in the box. It is therefore advisable to keep this documentation in order to adjust your fasteners correctly.

Here is the standard table for adjusting the DIN according to the skier’s profile:

Selection of the release value according to the skier’s mass as per ISO 11088:2023(F)

This table is only a basic guide, as it is essential to take into account your personal characteristics and the type of skiing you do. The wrong setting can affect both your safety and your performance on the snow. If in doubt, consult your local dealer for a personalised and precise setting of your bindings.

How do I set the DIN of my ski bindings?

Correctly setting the DIN value of your bindings is essential for a safe and effective skiing experience. Although many skiers prefer to leave this task to a professional, it’s important that you know the basic process to understand how your equipment works and be able to make the necessary adjustments.

To adjust the DIN of bindings, you need a basic tool that you’ll find at the entrance and exit of ski lifts: a flathead screwdriver or a Phillips screwdriver, depending on the model of binding. This is one of the things we recommend you take in your ski rucksack, but in a foldable format so that it doesn’t get stuck in the event of a fall. Back to our subject. Modern bindings have clearly marked numerical scales on the front and back of the binding, which makes adjustment easier. It’s important to set the value at both the toe and heel of the binding, as these two points are involved in releasing the ski in a fall.

It is essential to check the DIN regularly, especially if there has been a change in equipment, such as the use of new boots, or if the skier has undergone physical changes (such as significant weight gain or loss).

Calibration tools and professional verification

Some ski shops or specialist technicians have advanced calibration tools to check that bindings are released correctly, ensuring that the DIN value corresponds precisely to the release forces required. This type of periodic check is particularly recommended for advanced skiers, freeriders and those practising in extreme conditions, where precise release is crucial to safety.

In short, although setting the DIN may seem simple, it must be done with precision and adjusted to the skier’s specific characteristics. Neglecting proper adjustment or ignoring regular checks can increase the risk of injury and compromise your experience on the slopes.

Special thanks to Sébastien Rideau, LOOK Brand & Category Manager at Rossignol, for his proofreading and expertise.