Crux (climbing)

Wolfgang Gullich starting the crux move of Action Directe, one of the world's most difficult routes.

A crux in climbing, mountaineering and high mountain touring is the most difficult section of a route, or the place where the greatest danger exists. In sport climbing and bouldering, the most technically challenging point in the climb is also called the crux section. In describing a climbing route using a topo, cruces (or cruxes) are usually shown with a key symbol.

The grade of a climbing route is based on the technical difficulty of the crux (e.g. 8a (5.13b) in the sport climbing system, or V13 (8B) in the bouldering system), and for traditional climbing routes, an additional grade is used for the risk of personal injury to a climber of a fall at the crux (e.g. the British E-grade system). That means the rest of the route might be considerably easier, however, a route may comprise several cruces of equal difficulty, or simply be a route of a very consistent level of difficulty with no sections that stand out as harder than the rest.

In planning a route it is important to know how far it is before the crux is reached, because cruces (or cruxes), can only be overcome with sufficient reserves of strength. Sport climbers have come to use a kneebar to rest before, or immediately after, a crux; they can also continually practice a crux using top roping.