HOW TO CHOOSE A CLIMBING ROPE?

Choosing the right climbing rope for your type of climbing requires some knowledge about various features manufacturers guarantee, and balancing features VS prices. Climbing ropes have to meet the minimal standards set by the European Union (CE) and can apply to pass also the higher standards set by the International Climbing and Mountaineering Federation (UIAA). On this article we will have a
general view on the ropes that are currently on the market and understand all the tests they have to pass, learning what those signs on the label mean.

First of all, let’s look inside a rope! Climbing ropes are made of an internal kernel, composed of filaments woven in bobbins, and an external mantle, which is a protective sheath. While the mantle is vital to preserve the filaments from damage caused by abrasion, humidity and solar light, it is the kernel which does the thought job, holding
circa 70% of the tension.

Since 2010 Beal produces climbing ropes with their new design Unicore, which binds the sheath to the kernel (core), preventing slippage and dramatically reducing the possibility of falling when the sheath is cut under load.

UIAA guidelines for DRY ropes

The UIAA has released in 2014 the guidelines illustrating their new Water Repellent standard. In order to be labelled “Dry” by the UIAA, the amount of water a climbing rope can absorb should be less than 5% of its weight. “Dry” ropes must be treated with water-repellent products on both core and sheath. You can watch this video on how engineers at Mammut tests their ropes.

Under this new regulation, climbing ropes are now separated into 3 different categories:

  • No water-repelling treatment at all
  • Only Sheath treated
  • Core and Sheath treated

WHICH ROPE CAN I BUY?

This is just a list of the most famous ropes currently available. They are all single or triple-rated ropes. The price refers to the 70 meters model and can vary depending on where you buy and offers they may have.

Producer
Model
Treatment
Diameter (mm)
Weight (g/m)
Sheath (%)
Dyn Elongation (%)
Falls
Price €
Beal Stinger Unicore Dry 9.4 59 38 33 8 200
Beal Stinger Unicore Sheath 9.4 59 38 37 8 170
DMM Orbit Dry 9.6 61 38 ? 8 190
Edelrid Swift Pro Dry 8.9 52 34 33 5 202
Edelweiss Performance Sheath 9.2 57 ? 37 5 205
Edelweiss Performance Dry 9.2 57 ? 37 5 240
Gilmonte Next Sheath 9.6 60 35 34 7 150
Mammut Infinity Dry 9.5 59 40 30 8 220
Mammut Infinity Sheath 9.5 59 40 30 8 160
Mammut Infinity None 9.5 59 40 30 8 120
Maxim Pinnacle Dry 9.5 61 36 40 7 $295
Metolius Monster Dry 9.2 53 50 35 5 240
Millet Magma None 9.5 57 ? 35 6 155
Petzl Arial Sheath 9.5 58 40 32 7 180
Petzl Volta Sheath 9.2 55 42 33 6 205
Roca Kalymnos None 9.8 64 ? 30 6 96
Sterling Fusion Nano IX Dry 9.0 52 ? 33 6 280
Tendon Master Dry 9.1 56 ? 29 5 140

WHY ARE CLIMBING ROPES DYNAMIC?

What makes climbing ropes so special is their elasticity, and this is why they are called dynamic.

During a fall a climber is subjected to acceleration at first, and sudden deceleration at the end of the fall. The purpose of elongation is do absorb and dissipate the impact force produced at the end of a fall, avoiding the final recoil. Numerous researches proved that the max impact force a human being can tolerate is about 15 times one’s own body weight[1]. This means that a person weighting 80 kg can tolerate an impact force not higher than 12kN[2]. Ropes should thus be enough elastic to dissipate the impact force that passes 12kN.

 

 

WHAT DIAMETER SHOULD MY ROPE BE?

In the last 20 years, thanks to new materials and manufacturing techniques, the diameter and weight of climbing ropes have drastically diminished. The majority of climbing ropes on the market have a diameter smaller than 10mm. Thin ropes are appreciated for their ease of use, but they wear faster.

Diameter always comes in relationship with weight, and when buying a rope it is important to know both measures. When comparing two ropes of the same diameter for example, we should pay attention to their weight too. The label on a new rope should show both measures in grams per meter (g/m).

Watch out for misconceptions: while a thick rope is not necessarily safer or stronger than a thinner one, a thinner rope does not necessarily weight less than a thicker one.

When choosing what rope to buy, pay attention also to which belay device you and your climbing partners will be using. Some devices can only work with thick ropes, while other are designed for new and thinner ropes.The old GriGri for example does not accept ropes thinner than 10mm, while the MicroJul works best with 7mm ropes. Have a look at our page dedicated to Belay Devices to understand more on them.

WHAT IS THE DIFFERENCE BETWEEN SINGLE AND HALF ROPE?

Single ropes are used for leading and top-rope climbing. Single ropes are are the most resistant and long,  and thus can be used one at the time, to belay a climber or to rappel.  Single ropes come in length of 60, 70 or 80 meters. While in countries like England it is hard to find lengthy climbing routes, it is vital to have at 70 meters rope in Sardinia, as many problems are 35 meters high. Single ropes’ diameter varies from the old 11mm to the actual 8.6mm.[4]

Half ropes must be used in pairs. They are normally used for multi-pitches and trad climbing. Apart from double security, half ropes allow climbers to rappel faster, using the entire length of the ropes, descending 50 or 60 meters instead of 30. The diameter of half ropes is generally smaller than single ropes, and varies from 9mm to 7.3 mm[5].

Knowing that these ropes can only be used in pairs, we recommend buying them in pairs. This is to make sure you are always using a good pair of ropes and not recycling an old one in rough conditions.

A pair of half ropes should have the same length, to prevent falls when rappelling or other similar incidents. It helps to have ropes of the same diameter, and it is recommendable to have them in different colours.

It exist also another kind of rope, twin ropes, which is now disappearing from the market as replaced by single ropes. Although they are thicker than half ropes, they must be used in pairs and clipped together on each quickdraw.

 

STATIC RESISTANCE

To pass homologation by European Norms, climbing ropes should not break under a steadily pulling before reaching 18kN. A second test adds an eight-figure know. Knots can limit the resistance of a rope up to 50%. When pulled steadily with an eight-figure knot, a rope should hold up to 12kN.

 

DYNAMIC RESISTANCE

Each rope’s label must state the minimum number of falls it is guaranteed for. Single ropes must withstand at least 5 falls from 5 meters and fall factor 1. Single ropes are tested with a mass weight of 80kg, while half ropes are tested with a mass weight of 55kg. As stated before, the impact force at the first fall should be lower than 12kN for single ropes and 8kN for half ropes. Tests are repeated at 3 minutes intervals.

Although European (EN892) and UIAA Standards require only 5 falls, manufacturers usually guarantee at least 8 falls.

 

EXTENSION

Extension during the first fall

European Standards demand that at the end of a 5 meters fall with a mass weight of 80kg a rope should not extend 40% more than the initial length.

Extension under load

To check the extension under load an 80kg weight is attached to the end of a rope. When the rope is pulled up, it should not extend more than 8% of its initial length for single ropes or 10% for half ropes.

Although elongation is the main characteristic for climbing ropes, an excessive elongation makes it much harder to perform certain safety manoeuvres. It is thus necessary to create ropes which could absorb the impact force with the lesser elongation possible.

 These are the standards that allow a rope to be put on the market. Nonetheless there are many other aspects that are not regulated, such as manoeuvrability on rain of frost situations, the resistance of the kernel against a sharp hedge, the ease of movement inside belay devices of karabiners, the tendency to get knots etc.

 

KNOTABILITY

To test the behaviour and flexibility of a rope, manufacturers make an overhand knot under a 10kg load. The internal diameter of the knot should not be less than 1.1 times the diameter of the rope.

These are the standards that allow a rope to be put on the market. Nonetheless there are many other aspects that are not regulated, such as manoeuvrability on rain of frost situations, the resistance of the kernel against a sharp hedge, the ease of movement inside belay devices of karabiners, the tendency to get knots etc.

 

WHAT IS A CORDINO?

A Cordino is a thin rope, usually from 6 to 8 millimeters in diameter. They are made just like usual ropes, with internal kernel and outer sheath. Cordino were usually made of Nylon, but if used to create knots such as the Machard or the Prusik it is recommended to have them in Kevlar, which is resistant to extreme heath and eventual melting/burning.

Cordinos can be bought in climbing shops by the meter, usually one or two euros per meter, depending on diameter and material (Kevlar is more expensive).

Just a note on Kevlar: if exposed to sun-rays, in the long-term UV light crystallises the fabric. Never leave kevlar under the sun for long periods and always undo all knots.

WHAT IS A SLING?

Slings are loops of sewn threaded Nylon or Dyneema. They usually come in two diameter measures: 60cm and 120cm. It is also possible to find them in much bigger measures but less popular in climbing.

Slings are used for many different reasons, such anchoring a climber to the belay-point to equipping trad-routes (think of passing a sling around a branch or a rock to attach your quickdraw) or even creating custom quickdraws.

KILOGRAMS VS NEWTONS

The measurement we use to define our weight (kilograms or pounds) is in effect the unit of measure of mass. Mass is measured in Kilograms, and it never varies: a body of mass 80kg will be the same on planet Earth as well as on the Moon or out in space. Mass is mass!

Newtons measure the force pulling a body towards a heavier body. We are attracted towards the center planet Earth. An object of one kilogram is attracted to the center of the Earth with a force of 9.8 Newtons. If you will take that same object to the Moon its mass will be just the same, but its weight will be much less.

Newtons are often rounded to facilitate calculations, and thus 1 kg is said to correspond to 10 Newtons. 10 Newtons make a Deca-Newton (daN) and 1000 Newtons make a Kilo-Newton (kN).

CARE & MAINTENANCE

The Dynamic and Static Resistance of a rope (as stated on its label) apply only when in new and pristine conditions. Friction against rocks, karabiners and belay devices, as well as the inexorable deterioration caused by UV rays, dust, aluminium oxide and water reduce considerably its initial resistance.

Should we be saying that it is imperative not to step on a rope resting on sharp rocks, walk on it wearing crampons or spill battery acid on it? This should be common sense, so let’s move to matters for which we’d need knowledge instead of judgement.

Wet Ropes

A wet rope, even if new, loses up to 66% of its resistance. This means that if a new rope is guaranteed to withstand 8 falls, it will only withstand 2 or 3 falls if wet. For a rope to lose resistance it is not necessary to be completely drenched, even thin rain affects its performance. All ropes actually on the market are treated either with chemical agents (Superdry or GoldenDry) or heating techniques (Duraflex or Dry Cover) to prevent water and dirt affecting their resistance.

Funny enough, a frosted rope loses only 50% of its initial resistance.

If a rope undergoes abrasion or a heavy fall when wet, it is strongly recommended to stop using it. Ropes recover the 100% of their resistance once dried out. It is important to dry ropes away from direct sun light, as UV rays damage the external nylon fibres.

Dust

If a rope is exposed to dust and mud, microcrystals penetrate the sheath and affect the performance of the kernel. Even the friction against anchoring points, karabiners and belay devices frees particles of aluminium that deposit on the sheath.

If a rope is dirty and leaves your hands black when belaying, you can be sure microcrystals have deposited on and penetrated the sheath. Subsequent friction (against anchoring points and belay devices) can only press the microcrystals against the internal bobbins, causing damages to the nylon fibres.

Cleaning ropes

To keep a rope clean it is good practice to brush it after each use, by using special spiral-shaped brushes.

Washing ropes

All manufacturers claim it safe, and also necessary, to wash dirty ropes in lukewarm water with no strong or improper cleaning agents. Although we recommend washing a climbing rope by hand, it is safe to use washing machines. We advice placing the rope inside a cotton bag (such as a pillow case) and throw it in a washing machine avoiding soap, high temperatures (30 deg. Celsius is fine) and tumble-drying. Dry the rope on shady and ventilated areas, uncoiling and moving it every now and then to avoid mould.

We know by experience that after you wash a rope something will not be quite right with it. If a wash makes it lose its external dry treatment, the rope will be exposed to faster water and dust assimilation. But most importantly you will experience stronger friction on belay devices, making the rope very uncomfortable to use.

To avoid stronger friction and faster abrasion we advise to complement the washing using wet-protection agents, which you can easily buy from the same rope manufacturer. The most common products used are produced by Beal, Camp and Nikwax.

PULLEY EFFECT

aka Parallelogram of Forces

Parallelogram of forces
When a climber falls, the belayer has to block the rope and counter the pulling force caused by the fall. The last quickdraw must thus withstand two equal forces: one on the climber and one on the belayer side. This doubling of forces is known as Pulley effect, or Parallelogram of forces.

Climbing ropes are dynamic and absorb part of the impact force, transmitting no more than 12kN to the climber. The rope pulling the last quickdraw at the end of a fall will probably exert a force of 12kN on the climber side, and 12kN on the belayer side too.

In reality many factors contribute to lower the force on the last quickdraw. The belayer side of the rope often pulls only with two/thirds of the force, reducing it to 8kN, and the angle of the rope also plays a crucial part. While 0 degrees angles double the force, 90 degrees angles increase the force of 1.5 times only and finally 120 degrees angles do not increase the force at all.

The reason why European Standards require all climbing equipment to withstand a force of about 22kN is due to the combination of the dissipation of the impact force by rope elongation and the doubling effect caused by the parallelogram of forces.

FALL FACTOR

Why is the fall factor important in climbing?

During a fall a climber gains great speed towards the ground, generating kinetic force that at the end of the fall is transmitted in part to the series of equipment used for the climb (harness, rope, quickdraws) and in part to the climber. The most dangerous part of a fall in an ideal situation, ignoring case-specific dangers such as rock ledges, is the final part: when the rope extends and the climber has to withstand the force caused by sudden deceleration. Studies carried out by the Air Force proved that the maximum impact force a person can withstand is about 15 times his or her weight. If falling head-down the maximum force a person can withstand is reduced to 4 times his or her weight. If a person weights 80kg, the maximum impact force he or she can withstand is 80 x 15 = 1200 kg.   (1200 kg correspond to more or less 1200 daN, or 1.2 kN)

How do you calculate the Fall Factor?

The Fall Factor is a relationship between the height of the fall, the length of the rope between the climber and the last anchoring point. It is expressed in decimal values, which in sport and alpine climbing go from a minimum of 0 to a maximum of 2. In certain cases, like in via ferrata, the value can be higher than 2, but in this article we will concentrate on the basic understanding of sport climbing fall factor. These are two typical situations:

Factor 2 Factor 0.5

First case: this case can happen when climbing on multi-pitches. The lead climber starts climbing the second pitch but after 2 meters he or she falls before being able to place the first quickdraw. The belayer blocks the rope and the climber falls a total of 4 meters (2+2). The falling factor will be calculated again by dividing the height of the fall by the length of available rope.FC=4/2= 2

Second case: a climber reaches 12 meters of height and falls. The last quickdraw is 3 meters below his or her harness. The belayer blocks the rope and becomes the last fixed point. The Climber will fall a total of 6 meters (3+3) with 12 meters of rope to absorb and dissipate the force. Fall Factor is measured dividing the meters of fall by the meters of available rope.    FF=6/12= 0.5

In the second case the falling factor could increase if, for example, the rope gets stuck on the last quickdraw or on a rock formation. In order to be certified by European Standards and by the UIAA, the impact force a climbing rope transmits to the climber must be lower than 1200 daN. Climbing ropes absorb the impact force by elongation, usually transmitting an impact force between 800 and 900 daN, depending on manufacturer and model. With use and wear a rope becomes less elastic, increasing thus the impact force transmitted at the end of a fall. When buying a new climbing rope it is important to check all the measures stated on the label. You can see below a table of values for three half-ropes by Beal. You can notice that the fifth column states the impact force values Beal guarantees, followed by guaranteed number of falls and elongations.

FOOT NOTES


[1] If falling head-up. In case of head-down falling the impact force is reduced to 5 times one’s own body weight.

[2] Max Force is measured in Newtons, multiplying body-weight times 15 (1Kg equals 9.8 Newton) F= 80*9.8*15= 11760 Newtons (rounded to 1200daN, or 12kN )

[3] CE and UIAA norms have established that the Kernel cannot move more than the 2% inside the Mantle.

[4] Edelrid Corbie – single rope – Diameter 8.6mm, Weight 51g per metre. (Updated May 2015).

[5] Beal, Gully – half rope – 7.3mm in diameter and weighs 36 grams per meter (updated may 2015)

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