As I understand it, twin ropes are normally reserved for Ice climbing, they are really designed to operate as a single rope (they share the load by being clipped together, and are really used just in case you chop one. (eek!). They are tested as if they are one rope, 80 Kg, factor 1.7 fall etc.
Doubles are tested individually, as they are used, but with a 55 Kg load. |