So you have decided to try your hand at rock climbing or tree climbing, and you want to ensure that you have the right rope for such an undertaking. Yet, after deciding, you soon find yourself confused about which climbing rope to select, given the myriads of ropes in the market today.
It may require you to spend hours of research and readings to figure out the right rope for your climbing needs. But you can skip this lengthy process if you read through this article, for we have already researched everything to facilitate the selecting process for you.
Your safety in tree or rock climbing is your responsibility. Hence, as a beginner, you need to choose the climbing rope with care, for it is an essential piece of equipment you would need in climbing. Moreover, you need to understand that each climbing cord has its specific breaking point, and thus, you need to select a rope that can handle the load that it needs to carry.
How to Determine the Strength of Climbing Rope: Key Factors to Consider
You will need to consider some critical factors when shopping for a climbing rope. These factors include dynamic and static weights, rope type (dynamic or static), diameter and length, rope features, knots, and safety ratings. Understanding these four factors will make the selection process for you easy and convenient:
Differentiate Between Static and Dynamic Weight
Several factors may affect the weight-load capacity of your rope. Thus, it will be useful to understand the difference between dynamic and static weights, for these factors have a bearing on a rope’s efficiency. When it comes to weight while climbing, the weight can be static or dynamic, or moving.
You may hang on the rope without moving, and that puts you in a static position with a static weight. A rope may have a maximum static weight, and you need to know this fixed weight to ensure your safety.
On the other hand, you need to know, likewise, the dynamic weight that a rope can handle. For example, if you lose grip on a rock and eventually fall, you carry a momentum that combines your weight and gravity force. Hence, you need to ensure that the rope you choose can handle the weight when you accidentally fall. In this regard, you need to consider both the static and the dynamic weight that a rope can hold.
Climbing Rope Types
As mentioned above, ropes come in varying weight capacities; moreover, some are dynamic and static ropes. The static ones do not stretch when under load; hence, they are fit for rock climbing. However, the dynamic ones feature better stretchability under different loads. This characteristic makes the dynamic rope ideal for rock climbing, but not for tree climbing.
Dynamic ropes come in three different types: single ropes, half ropes, and twin ropes. The single ones are perfect for sport climbing, traditional climbing, top climbing, and big-wall climbing. They come in varying diameters and lengths, which factor well in their overall weight capacity.
If you use a single rope, you need to choose a larger diameter rope, for it will bear all the load alone. You can also use single ropes for various climbing applications, and they are easy to handle than the twin ropes.
On the other hand, half ropes come with a thinner diameter than the single ones. When you use them, you distribute the load over two (thinner) ropes attached to various equipment. Thus, it is not easy to figure out each rope’s exact weight load because it gets distributed over two ropes. You can use this type to engage in traditional climbing and ice climbing and mountaineering.
Twin ropes, however, consist of two ropes. They differ from half ropes in how you use them. In the use of the twin ones, you attached both ropes to a location and equipment. This technique shifts the distribution of weight, with both ropes bearing a specific portion of the load.
Rope’s diameters vary from one rope to another. For example, single ropes range from 9.4mm to 11mm in diameter, with a 10.5mm average diameter. On the other hand, half rope’s diameters range between 8mm to 9mm, while twin rope’s diameters range from 7mm to 8mm. Static rope’s diameters mostly range between 9mm to 13mm.
It will be useful to remember that higher-diameter ropes have higher load capacities. Nevertheless, many climbers want thinner cords because they are more convenient to handle when tackling challenging routes.
Dynamic forces also include impact force. The greater the diameter of a rope, the better it can assuage impact forces. The Apollo rope, for example, can handle a 7.5kN impact force. Some factors also augment the impact force, like the load, which may further strain the rope’s fibers.
The length may also affect the impact force of a fall. Hence, the longer the rope, the better it can absorb the shock created by a fall. On the other hand, half ropes like the half rope Beal Gully which has 7.3mm thickness carries an impact force of 5.2kN while the twin type has 7.9kN. This fact implies that the kind of rope also has a bearing on the impact force.
When choosing a rope for climbing, you also need to consider its length. The range of dynamic climbing ropes is between 30m to 80m, while standard dynamic rope is 60m, which meets most climbing tasks.
It will be useful to remember that the longer the rope is, the more durable it will be. If you intend to go outdoor climbing, you need to choose a 60m rope or more. Remember that its length should be twice the length of the distance you would intend to tackle.
When climbing, you should be familiar with the necessary knots that you need to make. Different knots have different effects on the rope’s capacity. In general, knots can decrease the overall weight that the rope can support.
Nevertheless, its strength can readily outweigh whatever knot you can make on it. Here are the results of the study made by Lyon Equipment Limited about the effects of knots on various rock-climbing ropes:
- Barrel Knots, which you can use for tying carabiner, can keep 67 to 77 percent of the rope’s strength.
- Double Figure-of-Eight Knots commonly used in rock climbing can retain 66 to 77 percent of the rope’s strength.
- Double Overhand Knots can retain 58 to 68 of the rope’s strength.
Estimated Weight Capacity
Since several factors affect the weight capacity of a rope, the actual rope strength may vary. Even if you check the figures given by Lyon Equipment Limited, their calculations may only approximate the real strength. Below is the approximate power of some types of ropes with a standard size of 10.55mm:
- Beal Ropes can withstand up to 24.5kN.
- Edelrid Ropes can support up to 28.9kN if it is new. If it has undergone light glazing, it can withstand up to 30kN. If it has nominal damage, it can handle up to 27kN.
- Marlow Ropes can handle up to 31kN if it has undergone light glazing.
Standard Testing for Ropes
Ropes are often classified based on the standard testing done on them. Manufacturers perform this routine testing via different fall conditions to figure out the impact force of ropes. The impact force approximates the energy that may act on the drop weight during a fall. The more elastic it is, the longer it would capture and dissipate the impact force or energy.
Moreover, the higher the fall, the more violent the fall would be. It also heightens the released energy that tags on the climbing rope. For example, single and twin ropes can take 12kN impact force. Hence, you can carry around 12,646 pounds of weight using these ropes. However, half ropes can only handle up to 8kN of impact force if you load them with a maximum weight of 1,764lbs or 800 kilograms.
UIAA Safety Ratings
The UIAA stands for Union Internationale des Associations d’Alpinisme. It is the climbing and mountaineering federation that sets the safety standards for all climbing ropes. The UIAA came into existence in August 1932 in France.
The UIAA Safety Label was made in 1960 and was approved internationally in 1965. It develops and makes sure that safety standards for various climbing equipment are maintained. Moreover, the Federation uses different independent labs for testing ropes, and all ropes used internationally should pass the UIAA tests.
When you buy a dynamic climbing rope, you will see, on its packaging, the list of tests it has undergone, based on the UIAA safety standards. This list includes the fall rating, dynamic elongation, static elongation, and impact force. It will help to consider these ratings when selecting a climbing rope.
It will also be useful to remember that the UIAA fall rating standard is a safety standard and that all ropes that comply with that standard are safe for use in climbing. Likewise, you should bear in mind that those with higher fall ratings would last longer than those with lower ratings.
As a caveat, it will help if you inspect your rope after every severe fall to see if there are damages to it. Besides, make sure to retire it when it exhibits impairments.
Static elongation or working elongation is the elasticity a dynamic rope has when loaded with an 80kg weight. It will be useful to note that static stretching of twin and single ropes must not exceed ten percent of their whole lengths, while the extension of half ones should not exceed twelve percent.
If you are engaged in top-rope climbing, climbing fixed ropes, or hauling gear, you should carefully consider the static elongation factor. The higher the static stretching, the less efficient the rope becomes because it takes more energy for the rope to stretch.
The dynamic elongation refers to the length the rope stretches during its first UIAA fall. If it has a higher elongation then, it has a more prolonged fall. In this case, the lower the dynamic stretching, the better it will be, for it will prevent the climber from falling further and hitting the ground or a ledge.
Nevertheless, less dynamic elongation implies that the belayer, climber, and gear will experience higher impact force. According to the UIAA standard, ropes should not stretch more than forty percent of their entire length.
As mentioned above, the impact force is the force measured in kilonewtons. And it is the total amount of force placed on the falling weight during the primary UIAA fall. The lower the impact force, the less energy it exerts on the falling climber, gear, or belayer.
Lower impact force allows for a soft landing when you fall, but it comes with more significant stretch, leading to less efficiency when engaging in top-roping.
Many factors can limit the impact force. Such factors include the belayer’s and climber’s bodies’ energy absorption, rope slippage relative to the belay device, harness deformation, and belayer displacement.
The climbing rope does not have a specific lifespan nor shelf life. Still, manufacturers would usually recommend that you retire your climbing rope after ten years, even if you have not used it or have appropriately stored it. As a caveat, you should always routinely check the ropes if they are in top-notch condition.
If you are a bit worried about the wear on your rope, try to get new ones for you to be on the safe side. You can always have peace of mind as you engage in climbing whenever you are sure that your rope is in top-notch condition.
When selecting a rope, you should also consider other features like what treatments it had or how it underwent dry treatment to prevent water absorption. Go for those, likewise, that have middle marks, as well as end marks.