Rope sheath slippage is when the outer core and the inner sheath of a rope move or stretch separately from each other. Normally the two parts of a climbing rope work the best when they move together, as designed. But when certain sections of a rope are stressed (like the area where you tie a figure 8 knot every time you climb) and do more work than the rest of the rope, it can cause the sheath and core of the rope to separate and move differently.

Kernmantle Rope Construction
Climbing ropes are made of two separate components that each perform specific functions. The many fibers of the core provide the rope's strength and the woven sheath provides handling and protection. Both parts are equally important.

Traditional ‘kernmantle’ ropes are made of a bunch of tiny strands that are twisted together into ‘yarns’ which are then combined and twisted again to become the core or ‘kern’ of the rope. This core then has a ‘mantle’ or sheath woven around it which protects it from fray and abrasion, and makes it easier and smoother to feed through devices and around carabiners.

These two separate pieces, the core and the sheath, work together to provide the strength, stretch, and energy absorption properties of the rope. Because they’re made of different materials and are woven and twisted in different ways, they react differently to long term stress. This can mean that the core and sheath recover at different speeds, and over time this can add up to separation as they contract and rebound repeatedly over time.

Ultimately this slippage can mean that the sheath moves down the rope in one direction. When this happens enough, it can cause the core to stick out of one end of the rope, and the opposite end becomes a hollow floppy sheath with no core at all!

Identifying Sheath Slippage

Luckily it’s pretty easy to identify when your rope sheath is slipping. You’ll either experience a bulge in the rope where the core is bunched up (less common) or it’s easy to identify on the ends of the rope (most common). There are two directions the sheath can slip and you’ll notice it at the ends of the rope when the sheath

  • become too short. You’ll see this as the white core yarns sticking out of an end of the rope.
  • become too long. You’ll feel the sheath is flat and floppy and feels like a soft hollow straw.

The photo below demonstrates both these scenarios.

Rope Sheath Slippage 1
On top you'll see the sheath is too short, exposing the core. On bottom you'll see the sheath is too long, creating an area with no core.

Is Sheath Slip Bad?

Sheath slippage is not bad if you fix it (explained below), cut off that area of rope, or don’t rely on that area of the rope for strength.

How to Fix Sheath Slippage

The good news is that this doesn’t mean you have to toss your rope, and there is something we can do to get things back on track. Maxim ropes (made by the Teufelberger group) have put together a video for their method of returning rope back to its previous state.


Essentially you’ll need to lay the rope in a relaxed pile and pinch/pull the sheath back to where it belongs.

  • As a first step, you’re looking to stretch the sheath back over the exposed yarns.
  • Once you’ve successfully moved things back to where they belong (this can take a while and provide a REAL good workout, which you might want to wear gloves for), a second and most important step is to remelt and seal the two pieces back together.
  • Edelrid recommends using a heated rope cutter for this, but you can also use tape, a sharp knife, and a lighter.

If you’re not into shoving 60m of sheath a few inches down the length of a rope, another option is to cut a good distance from both ends and heat seal them. This essentially ensures that what’s left is rope with a proper sheath:core ratio, though it does shorten your rope a bit.

So how do we avoid it?

The main cause of sheath slippage is repeated use on the same section of rope. Usually this is in some form of pre-rigged top rope setup where people are continually tying into the same end of the rope over and over, and the rope is constantly being pulled and hung on in one direction.

Indoor climbing gyms are a bit of a perfect scenario for this, but you can also notice sheath slip after a long day of many people taking turns up a toprope outside. Storing your ropes by hanging them from a single end strand is another catalyst for causing slippage.

LotsofTopRopes 2
Prehung topropes are the most common time you'll find sheath slippage in ropes. This is because climbers tie into the same section of rope at very high usage rates, creating a disproportionate strain on that section of rope. Gym employees should look out for sheath slip and either cut, repair, or replace ropes as they see too much use.

As we mentioned earlier, rope sheaths and cores stretch and recover at different rates. If a rope is left to hang on the same section over and over after it has been weighted, it becomes more difficult for that stretch to relax across the entire length of the rope. Essentially, only the hanging end has the freedom to relax, while the weighted end gets pulled again and again, dragging the sheath along with it.

The best way to avoid this is to periodically pull the rope down and flake it into a loose pile to relax for a few hours. This happens naturally in outdoor climbing more often than in a gym, but swapping ends from time to time also helps the stretch of the rope even out.

Sheaths That Don’t Slip

Rope makers have been aware of this phenomenon for a while and there are several brands with models out there with various technologies to help avoid it. In 2012 Beal launched their Unicore line of ropes with the core and sheath chemically bonded together. Their goal was to make a rope that would still function safely even if the sheath were to be cut, but of course a helpful side effect of this is the impossibility of sheath slip. Some brands like PMI and Edelweiss use Beals patented technology on some of their models, while other brands like Edelrid and Fixe have created their own version of sheath to core bond.

Maxim has approached the problem a bit differently and instead have come up with a way to weave some of the sheath yarns into the core as the rope is woven. This Platinum® essentially bonds the two parts mechanically rather than with a glue and basically makes it impossible for the two parts to move or load separately. Currently this tech is only available in their static lines of rope.


Ultimately rope sheath slippage is a phenomenon when our climbing ropes get a lot of use in the same locations over and over, causing the sheath and core to move slightly in opposite directions. The good news is that when you notice it, you can correct it with a bit of elbow grease and a hot knife or lighter.

The best thing you can do for your ropes to keep them from developing this issue is to rest them between uses, never hang them from a single strand when storing them, and to swap ends from time to time to make sure the stretch and wear are evened out over the whole rope.

Sheath slip does’t have to mean the end of your rope’s life, but just like most gear in climbing, the more you do to keep your rope in good shape, the longer it will serve you with fewer problems.

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