Choosing a Climbing Rope
Choosing a Climbing Rope
All ropes used for lead climbing are dynamic ropes. They are designed to stretch on impact to absorb the energy that's generated by a fall. MEC also stocks static ropes that have very little stretch. Static ropes are used only for hauling gear or in rescue and caving applications where there is no chance of a fall that will shockload the rope.
Modern climbing ropes are manufactured using a process of kernmantel construction. A nylon sheath (mantel) is tightly braided around the core (kern) of the rope. This outer sheath is the rope's "armour", designed to protect the load-bearing core.
Length
Sixty meter ropes have become the standard for most climbers. A longer, 70m rope allows you to extend pitches, but it will also weigh more and take up more room in your pack. You should always be aware of the length of your rope and the length of the pitch you're on, to ensure that you have enough rope to get up and to get back down safely.
Diameter
Climbing ropes are categorized into three types based on their diameter and intended use. You can identify the category of a rope by looking at the symbol marked on the tape at either end.
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Single
With a diameter anywhere from 9 to 11mm, these ropes are intended to be used individually for all around climbing and top-roping. Their relatively large diameter makes them more durable. They stand up to more abrasion and are able to withstand more test falls. The thicker ropes in this category (above 10mm) are good for high-abrasion situations (top-roping) and are the best choice for your first rope. The thinner diameter ropes (10mm and under) will suit alpine climbs, hard redpoints, and long pitches. They weigh less and are less bulky, but are rated to withstand fewer successive test falls. -
Half
Found in diameters from 8 to 9mm, half ropes (sometimes called double ropes) are always used in pairs. They are clipped into protection alternately, one line at a time, to keep the ropes running straight to limit rope drag over bulges, overhangs, and traverses, and to minimize impact force. Another advantage is the ability to descend with a full rope length rappel. Two ropes are also less likely to be cut by falling rock, ice, or sharp edges, and, when used properly, half ropes deliver significantly less impact force then a single rope. Purchase pairs in two distinct colours for efficient use and ease of organization. Although a pair of thin ropes weighs more than a single rope, the weight can be shared among partners, and in some situations (glacier travel) a single half rope can be used as an ultra-light option. -
Twin
Not common in North America, twin ropes are designed for alpine routes. The essential feature is that their thin diameter (7.5-8mm) makes them almost as light as a single line, but offers full rope length rappels and high safety margins. The twin rope system uses two identical ropes, but unlike half ropes they are both clipped into the same piece of protection. They require stellar management and organization to prevent twisting and tangling, and record much higher impact forces than single or half ropes.
Dry and Non-Dry Finishes
Dry ropes have been impregnated with a fluoropolymer-based solution to make them as water-resistant as possible. Absorbed water increases the weight of the climbing rope and reduces its strength considerably. Use of dry ropes is essential for alpine and ice climbers, or for glacier travel. Non-dry ropes will suffice in other conditions, although a dry treatment is also useful for reducing wear from abrasion.
Impact Force
Impact force measures a rope's elasticity and ability to absorb energy in a fall. The higher the impact force number, the more energy the climbing rope will transmit to the belay system and the protection. Low impact forces make for a soft catch and are a benefit with uncertain protection or falls on short lengths, but they usually mean the rope will have a greater stretch, which can be a nuisance when top roping.
Standard Tests
The International Union of Alpine Associates (UIAA) tests and certifies dynamic climbing ropes using standardized tests. CE certified ropes use virtually the same testing standards.
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Falls
Single ropes are tested by dropping an 80kg mass attached to a measured section of rope repeatedly until it snaps. The rating indicates the number of falls the rope withstood. Ropes that cannot withstand at least five falls are not approved. Half-ropes are tested with a 55kg mass. The fall rating indicates the number of falls withstood by a single rope strand. Twin ropes are tested with 80kg dropped on two strands. -
Elongation
Tests measure the dynamic elongation (stretch), of a climbing rope under a dynamic load. Currently, the maximum allowable stretch on the first drop of the test, using a single rope is 40% with an 80kg load. Information about the elastic property of a rope is important in its relation to impact forces. A rope with greater dynamic elongation will have lower impact forces. But, keep in mind that a climbing rope with lots of stretch can be difficult, if not potentially dangerous to use on a top-roped climb.