Cross country ski bindings can be a confusing topic to sort out. It has caused many frustrations for both new and experienced skiers alike, when one realizes that their new system may not work with their older gear, or worse yet, they bought the wrong boot for their binding system. Let’s get it straightened out here to help minimize any confusion and future problems.

1. Boots & Bindings MUST be compatible. Unfortunately, cross country ski bindings are not standardized. Boots and bindings from different systems will not work together. If you are upgrading gear, or purchasing used or new, it is critical that you purchase gear within the same system to assure compatibility and to avoid disappointment.
2. Which binding system do you have? There are two systems of bindings; SNS and NNN. They are not compatible with each other. Most newer boots and bindings will be labeled. If you can’t tell, measure across the boot bar or the binding attachment to determine your system. XC Binding Measurement System

1 1/8 inch or 27mm  SNS

1 1/4 inch or 30mm  NNN

1 5/8 inches or 40mm  NNN BC

SNS XAdv

70mm* Three Pin or Telemark

3. Differences between Skate, Classic and BC Bindings. Within each system (NNN & SNS) are 3 binding types that are designed for a specific skiing purpose: skate, classic and backcountry (or BC) bindings. Classic bindings are designed to balance torsional control at the toe, with sufficient heel lift to aid in hill climbing and diagonal stride. The amount of lift or flex in a binding is controlled either with a toe bumper or a 2nd axes connection in Pilot bindings (discussed under SNS). In some cases flex is measured with a flex number. The softer the flex (more lift), the smaller the flex number. Classic bindings allow for more heel lift than skate bindings, and they therefore have smaller flex numbers than skate bindings. Skate bindings are designed to maintain a powerful push through the entire skate motion, so torsional control and boot/ski positioning and angles are the priorities. As mentioned, skate bindings are stiffer with higher flex numbers than classic bindings.

4. NNN Bindings – What you should know? Most NNN bindings are manufactured by Rottefella and are licensed to ski manufacturers. Currently, Rossignol, Alpina, Madshus, and Fischer are using the NNN system. Of note: Fischer switched from SNS to NNN a few years back, so if you have some old Fischer boots use the measuring system above to determine which binding system you will need.
5. What is the difference between NNN and NIS? NNN Bindings include both traditional mount bindings (screw-in) and NIS bindings. This is important to note so you know that NNN boots are compatible with both types of bindings. NIS bindings refer to bindings which slip onto NIS (plastic) plates which are welded to certain skate, classic and touring skis. NIS integrated bindings offer better edge control, binding position adjustability and weight savings. Most midrange and high-end NNN skis are using NIS Plates.
6. SNS Bindings – What you should know? The companies using the SNS system are Salomon, Atomic and One Way. The SNS system has two types of bindings; single axis (Profil and Propulse), and double axis (Pilot). Pilot bindings have two connection points between the boot and binding, and Profil/Propulse have one.
7. What are the differences between these models? Pilot (2 axes) bindings are bumperless (no wearing out) skate and classic bindings. They offer more torsional, and tip and tail control, which can be helpful for skating as well as for new skiers learning any technique. Propulse is a new single-axis, classic binding with a bumper, released in 2010, that offers efficient kick, and more heel lift for hill climbing in an ultra lightweight package. Profil, pronounced Pro Feel, is the original Salomon binding (bumper) and it can used for both skating and classic, and either Pilot or Profil boots.
8. The Backcountry Binding Story. BC, or backcountry bindings, are used on touring and light touring skis. BC bindings are heavier than NNN and SNS Bindings, and the width of the boot/ski connection is wider, providing greater torsional control over a heavier ski. The wider binding can provide greater support in unbroken or ungroomed snow. BC boots are not compatible with any type of NNN or SNS Binding, and vice versa. Also, NNN BC and SNS XAdv BC boots and bindings are not compatible – they must match their system counterpart. They are used for ski touring in deeper, untracked snow in rolling to flat terrain. They are not designed for ascending and descending steep terrain.
9. 3 Pin and 70mm Bindings. 70mm Bindings and boots are measured across the front of the contact area of the binding or across the front of the boot. Rather than use an axel and clamp design like the others, 70mm bindings use either a matching three pin/hole design on the binding and boot with a clamp on an extended soul in front of the toe, or a toe retainer bar with a spring-loaded cable and heelbinding. These bindings are used for rugged touring, steeper terrain, and heavier skis, or for skiers who prefer a 3 Pin boot. The 70mm width of these bindings rub badly on 65mm groomed tracks/rails and even in skied-in tracks (not recommended), slowing the ski and the skier’s progress dramatically.