node length

The node width is generally defined as the inside diameter of a node. The nodal range has a significance, especially for climbing ropes, as a measure of the knotability and, more generally, the flexibility or stiffness of a rope.

For test and comparison purposes, the knot range of the overrunning node is measured at a defined load in climbing ropes. The measurement is carried out for dynamic ropes according to European Standard EN 892 after a one-minute load of the knot or rope with 10 daN (approx. 10 kg) and subsequent relief to 1 daN. Given as multiples of the sea diameter, one obtains from the knot a factor, which is a measure of the relative stiffness of a climbing rope. In product information on climbing ropes, this factor is usually given as a "node width" (also "knotability" or "knotability factor"): the higher the value, the higher the stiffness and the worse the knotability; the lower the value, the higher the flexibility and the better the knotability. For dynamic climbing ropes the standard EN 892 requires a value of 1.1 or less, for standard climbing ropes the standard EN 1891 requires a value of 1.2 or smaller.

Ropes with a low node width in relation to the rope diameter are suitable for frequent knotting of nodes. Their flexibility makes it easier for the rope to pass through the safety and descender devices as well as intermediate safety devices when climbing. Static ropes are designed for a smaller working stretch and are therefore stiffer due to their construction. They are preferably used for ascending on the fixed rope in combination with climbing clamps and are combined for abseiling with semi-automatic safety devices or special abseiling devices.

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