Petzl Knee Ascent System

The Petzl Knee Ascent system connects your foot ascender to your harness with a bungee that runs up past the knee. It keeps the ascender pulling upward so your stride stays smooth, which makes rope walking faster and less tiring.

How it works

A foot ascender on its own can lag behind your stride. The Knee Ascent system clips the ascender to your harness through an elastic cord at the knee, so it lifts with your leg on every step.

Paired with a foot ascender and a chest or hand ascender, it creates a rope-walking setup for long SRS ascents. See related gear in foot ascenders and foot loops.

Climbers who rope walk a lot, especially on tall trees, often say the knee system makes the foot ascender feel like part of their leg. It cuts down on the hitch in the stride that slows a climb.

Setup and inspection

Adjust the length so the bungee keeps light tension without pulling your leg out of line. Follow Petzl's setup steps exactly and test low.

It is an ascent aid only. Life-support gear must meet the applicable standard (ANSI Z133 and the manufacturer's instructions), be inspected before every use, and be used only by trained climbers. Inspect the bungee, webbing and connectors before every climb.

Bungee loses stretch over time, so watch for a slack feel or a cord that no longer pulls the ascender up. Replace worn parts according to Petzl's guidance and store the system out of sun and heat.