What's a Sewn Runner? Aka Sling




What's a Sewn Runner? Aka Sling

What’s a Sewn Runner?

A sewn runner, aka a "sewn sling" or "sewn webbing," is an essential piece of climbing equipment made from a length of webbing, sewn together to form a continuous loop. Runners are commonly used in climbing and mountaineering for anchoring, extending protection placements, and creating equalized anchors.

Here’s a closer look:

Construction: sewn runners are made from webbing, which can be nylon or Dyneema (aka Spectra or UHMWPE). The webbing is typically stitched together using high-strength thread to form a durable and secure loop. The stitching is done in a bar-tack* pattern, which provides strength and durability.

Types of Webbing

Nylon: known for its durability and flexibility, makes it a popular choice for climbers. It’s slightly elastic and the bit of stretch in it helps to absorb some of the forces during a fall. Nylon is also heavier and bulkier compared to Dyneema.

Dyneema (Spectra, UHMWPE): is lightweight and incredibly strong for its weight, making it ideal if you want to reduce the weight of your gear. Dyneema has very little stretch, so it transmits forces more directly. It can also be less resistant to abrasion and UV degradation compared to nylon.


Anchors: sewn runners are used to build climbing anchors by threading them through natural features or around artificial anchors, creating a secure point to attach the climbing rope.

Extending Protection: they’re often used to extend the placement of protection, such as cams or nuts, to reduce rope drag and prevent gear from being dislodged.

Equalization: climbers use sewn runners to equalize multiple anchor points, distributing the load more evenly.

Slings: they can also be used as personal slings for securing a climber to an anchor or belay station.

Sizes:common sizes include 60 cm (24 inches), 120 cm (48 inches), and 240 cm (96 inches). The choice of length depends on the specific application and your personal preference.

Safety & Maintenance:

Inspect Regularly: for signs of wear, abrasion, and damage. Any runner showing significant wear should be retired.

Avoid Chemical Exposure: both nylon and Dyneema can be weakened by exposure to certain chemicals, so keep them away from harmful substances.

Proper Use: it's crucial to use sewn runners as intended and to understand their limitations in various climbing situations.

Sewn runners are important to have in your climbing gear kit. Learn the different ways to use them and remember that maintenance ensures they’ll remain reliable and safe for climbing.

For even more information on climbing gear and safety practices, visit Climbing Magazine.

*A bar-tack pattern is a series of closely spaced stitches used to reinforce areas of a fabric or material. They’re strategically placed at points of high stress and potential tearing. Zigzag stitches are placed very close together to ensure there are no weak spots. In climbing gear, the integrity of bar-tacks is critical for safety. A well-executed bar-tack ensures that the sewn runner or other gear can handle the extreme forces generated during falls or heavy use. 

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