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Risks of Falls on Toothed Ascenders and Backup Devices Without an Energy Absorber

2026-09-28 18:08 #clamps

For fall protection, you must not use:

• Hand, chest, foot, and other ascenders as well as progress-capture pulleys certified as Type B rope adjustment devices under EN 12841, or sport rope clamps certified to EN 567 and UIAA 126;

• Toothed or ridged fall-arrest/backup devices classified as Type A rope adjustment devices under EN 12841 without an energy absorber.


And this isn’t just about device strength, manufacturers’ instructions, PPE standards, or work-at-height regulations.

Toothed devices can strip or tear the sheath of ropes — both static and dynamic — at loads of roughly 4–6 kN. In some cases, such as a factor-2 fall on a thin static rope, they can even cut through the rope completely.


A torn sheath may not sound catastrophic, but there’s more to it than damaged rope. You can drop another metre or two — possibly onto the ground or a ledge — subject your body to higher loads, trash your gear (the rope gets cut back, the clamp gets retired), compromise the rest of the job or climb, and set a pretty bad example for everyone watching.


As the practical tests and videos above show, generating enough force to tear a rope sheath is not actually that difficult. That said, quite a few factors affect how likely this is to happen. These include, for example:

• Fall factor and the amount of rope involved in the fall.
• User mass.
• Rope type, diameter, construction, and condition.
• Ascender/backup device design.
• Whether a lanyard connects the user to the ascender/backup device, and what type of lanyard it is.

*As for the Micro Traxion, SPOC, and other compact progress-capture pulleys used as fall-protection devices in simul-climbing or solo climbing — that deserves a separate discussion... 😉
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