What is the impact force of a rope?
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The impact force of a rope is the force transmitted by the rope to a mass in the standard test. The measurement is made at the falling mass, climber side. This impact force is not representative of actual forces encountered in a climbing fall. The dynamic test of the standard is an extreme test, as it simulates a factor 1.77 fall with a metal mass, with the rope attached to a fixed point.
In practice, numerous factors can limit these forces: energy absorption by the climber's and belayer's bodies, rope slippage in the belay device, belayer displacement, deformation of the harness...
| Rope type | Test mass | Max. impact force | Number of falls | |
|---|---|---|---|---|
| Single rope | 80 kg | 12 kN | 5 | |
| Twin rope (on 2 strands) | 80 kg | 12 kN | 12 | |
| Half rope (on 1 strand) | 55 kg | 8 kN | 5 | |
| Rope type | Test mass | Max. impact force | Number of falls | |
|---|---|---|---|---|
| Single rope | 80 kg | 12 kN | 5 | |
| Twin rope (on 2 strands) | 80 kg | 12 kN | 12 | |
| Half rope (on 1 strand) | 55 kg | 8 kN | 5 | |
Explanation of table
The single rope on a single strand must withstand 5 successive falls. The impact force in the first fall cannot exceed 12 kN.
