What are Climbing Ropes Made of?

What makes up a rock climbing rope? Different types of rock climbing ropes displayed on the ground. Two blue ropes, one black rope, one white rope, and a yellow rope are organized on the ground

What exactly is climbing rope made of? Climbing ropes are the most critical component in a climber’s safety system. Modern climbing ropes are made of nylon and polyamidematerials that are both incredibly strong and durable. These nylon ropes have been a huge technological innovation for the sport.

I know whenever I buy a dynamic climbing rope, I usually find a color and pattern we like and buy it. We can’t leave this crucial choice up to looks!

In this post, we’ll be analyzing the parts of dynamic climbing ropes. We’ll make sense of the terms you see online when shopping and help you make an informative decision the next time you’re shopping for a rope!

At Outdoor Rack Builder we have hundreds of climbing ropes in our database. Find your favorite rope and build your climbing rope for your next adventure!

After reading this, you’ll know exactly what makes up a rock climbing rope!

Table of Contents

What is a kernmantel climbing rope?

Modern climbing ropes are also known as akernmantel rope. There are two parts, the kern (or the core) andthe mantel (the sheath):

The dynamic rope is also known as a kernmantel. Kern is the outer sheath and mantel is the inner core.

Core (Kern)
The core of the rope provides the tensile strength for the rope. The core provides our ropes with the ability to safely catch and hold a fall. The manufacturer will take tightly braided nylon strands that are twisted together. This double helix-like design gives our rope strength.

Sheath (mantel)
The sheath or mantel is made of nylon and provides abrasion resistance against the textured rocks we’re always climbing on. The rope will rub against and over rock at one point during its life span. And the sheath protects its core. When we look at a rope and see the color and pattern stitching, we are looking at the sheath.

Climbing ropes are made to be durable and the kernmantel design helps accomplish that. The kern and the mantle come together to form dynamic ropes!

What types of rock climbing ropes are there?

There are four different types of ropes:static, twin, half, and single.

Two static climbing ropes on the ground.  One rope is black and the other is a white rope with a red pattern.

Static Rope

A static rope refers to the amount the rope will stretch. We’ve already talked a lot about dynamic ropes, which are ropes that are built to stretch to reduce the force on our bodies.

But is there ever a case when you would want a rope with no stretch? We want the rope to stretch on a dynamic fall to absorb impact. But what if we wanted to keep the rope in the same place like in a top rope anchor?

At Great Falls Park near Washington, DC, all of the top-rope anchors are usually natural rope anchors. This crag is unique because when you approach the cliff, you are already at the top!

There are plenty of trees and boulders for us to use to build our anchors. The Park Service forbids new bolts from being added so we make do with natural anchors. When setting up a top-rope anchor, you want the master point to be in the same spot. The anchor would not be effective if the rope stretch made the anchor sink six inches every time it was weighted.

So we use a static rope when you do not want rope stretch! I love using about 110 feet of static line for building top-rope anchors. But static lines are also useful for rescues, hauling loads, and our top-rope anchors.

Icon used for Twin Ropes
Twin Rope Icon

Twin Ropes

A twin rope is a dual rope system. Both ropes must be clipped into every piece of protection (never separate the twins!) Twin ropes are thinner and are lighter, and can be tied together for long rappels.

One downside of twin ropes is that you need a tube-style device for belaying. Since the climber is tied into two ropes, your belay device must be able to handle two ropes at once.

Icon used for Half Ropes
Half Rope Icon

Half Ropes

A half rope is similar to a twin rope, but the rope can be clipped into alternating pieces of protection. Half ropes work best for wandering routes. By clipping the ropes into alternating pieces of protection, we can eliminate rope drag. Tie half ropes together for long rappels.

Just like twin ropes, the downside is that you must use the tube-style belay device. I personally prefer to belay and be belayed with assisted braking device for some extra peace of mind.

Icon used for Single Ropes
Single Rope Icon

Single Rope

Three climbing ropes on the ground. Two blue ropes are on the side and a 70m yellow rope is in the middle.

The most common rope seen is the single rope. A single rope is one rope. This system only requires one rope. A downside of the single rope system is that a second rope must be trailed to make a long rappel doable.

How to quickly find the middle of a climbing rope?


A blue rope showing the middle marker for a bi-pattern rope. At the middle of the climbing rope, the pattern changes to a new pattern.

On a rope with a bi-pattern design, the two halves of the rope will have a different design. The rope has a consistent color scheme throughout, but the patterns will be altered. When the halfway point is reached during manufacturing, the manufacturer alters the sewing machine bobbins to create a new design.

Middle Marker

A yellow climbing rope showing a middle marker. The middle marker is dyed using a water-based dye that is UIAA compliant.

For ropes that do not have bi-pattern, some manufacturers will put a center mark at the middle of the rope. Sterling Rope uses a water-based dye that is UIAA compliant for marking the middle of the rope. The middle mark should last as long as the sheath.

Zoomed in middle marker on the climbing rope.

What is a rope diameter?

The diameter of the rope measures the rope’s thickness. Different climbing objectives warrant different diameters. Belay devices, such as the Petzl GriGri, can only operate with a certain range of rope diameter. Consult your user’s manual or manufacturer if you have questions.

When picking a rope, keep in mind that the rope’s weight will change based on the diameter you choose. A lighter rope will have a thinner diameter.

But there’s a trade-off. A larger diameter will last longer than a thinner diameter. Keep this in mind when you’re looking for a rope to be your workhorse vs. your redpoint rope.

Frequently Asked Questions

What is a dry treated rope?

Dry treated ropes prevent the rope’s nylon fibers from absorbing water. The rope’s sheath is bonded with water repellant particles. Dry treated ropes must pass a UIAA test to be certified as UIAA Dry.

A dry treated rope won’t absorb water, keeping it lighter (and unfrozen if cold enough). The dry treatment can be applied to the core, sheath, or both.

What is the impact force of a fall on a climbing rope?

Impact Force is the kiloNewton force that the climber experiences.

A lower number indicates less force on the falling climber, the belayer, and the gear. The higher the dynamic elongation, the lower the impact force.

Lower impact forces make for a soft landing on the rope when you fall, but with more rope stretch. Keep this in mind when choosing a rope specifically for top-roping. A rope with more stretch may be inefficient.

Manufacturers will give their opinion on what the best use of the rope is.

Some ropes excel at gym climbing, while other ropes are built for alpine climbs. Take a hint from the manufacturer when searching for your next alpine rope!

What is a rock climbing rope’s sheath mass?

The sheath mass is represented by a percentage. The sheath mass tells us how much of the diameter is represented by the sheath.

The Bluewater Lightning Pro has a sheath mass of 36%. That means 36% of the 9.7mm diameter is comprised of the sheath.

In this rope’s example, 3.49mm of the diameter from the sheath. And 6.21mm come from the core!

How many UIAA Falls does a climbing rope go through?

Each climbing rope has a different value. But the UIAA will test each rope at a fall factor of 1.77. They will literally force the rope to catch a fall that has the 1.77 fall factor.

Refer to this Petzl post for more information on how to calculate a fall factor. Always inspect the rope before use.

And don’t rely on counting the number of falls at this fall factor. If the rope is questionable, retire it.

How much does a climbing rope weigh?

The weight of your rope is going to depend on the rope length and the rope’s weight per meter. While you’re climbing, the weight of the rope is going to change the higher you get.

As a climber ascends, they will feel more weight due to more rope being out in the system. If the weight per meter is 5 grams and a climber climbs 10 meters, they will feel 50 grams of weight from the rope.

What is dynamic elongation?

Dynamic Elongation is the amount of rope stretch created during a dynamic fall. Rope stretch absorbs the force of a fall, protecting the climber from feeling a high force on their body. This is denoted by a percent.

If the dynamic elongation is 25% and the leader takes a 20 foot fall. The rope could stretch an additional five feet to absorb the impact of this fall

What is static elongation?

Static elongation is represented by a percent, and it shows the amount of rope stretch caused when a 80kg (176 pounds) weight is hanging off of it. Climbing scenarios where we see a static elongation would be top roping or while hauling.

What’s the difference between dynamic and static ropes?

Dynamic climbing ropes are designed to stretchwhen there is force while a static rope will not stretch. The dynamic rope stretches to absorb the impact force of a call. This means that less force is felt by the climber and absorbed by the rope stretch. Since a static rope does not stretch, it should be used when building top rope anchors. The static rope will keep your anchor in the same spot while climbing.

Rock Climbing Ropes Demystified

If you’re interested in learning more about how the rope is made, the Discovery Channel show How It’s Made had a segment showing the manufacturing process of the rope. The segment investigates the rope’s life from beginning to end.

Do you look for anything else when buying a new rope? Leave a comment below with what you’re looking for in a rope! And don’t forget to check out Outdoor Rack Builder next time you’re research gear!

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