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Gear Guy

Petzl Tibloc and Climbing Rope Sheath Damage

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I recently purchased a Petzl Tibloc. Soon after I bought it, I noticed the aggressive teeth. Will these damage the rope?

——Walker Nosworthy, via

The Tibloc is in some ways a dream device. It only weighs 39 grams, is small as a walnut, clamps on cords 8- to 11-mm, is just about impossible to get off the rope accidentally, and costs about $25. It is tailor made for use as a holding ascender for light-duty pack hauling and times when you might need an ascender, such as on a multi-pitch free route when a fall could suspend you in space. The Tibloc is also handy for climbing a rope out of a crevasse. It is far from  ideal nor is it intended for use as a full-time ascender. It is awkward to get on and off the rope, has no handle so is difficult to grip, and, if used incorrectly, can skin a rope faster than a hillbilly strips a polecat. For wall climbing and other uses where you’ll be jugging a lot of line, use regular ascenders and bring a Tibloc as a back-up.

As you noticed, the Tibloc has teeth like a mako shark and can be just as ferocious. It is also made of very thin steel. Problems arise when you either don’t fully disengage the teeth before sliding the device up (or down) the rope, or you improperly rig the device for hauling so the rope bends across a Tibloc edge (it’s easy to mess this up). The website shows the do’s and don’ts. Go there and bone up as if you’re taking the GRE. Then practice.

Any toothed ascender can snag and fuzz a rope, but the Tibloc more so than others because it relies on the wedging action of a carabiner clipped through its eye. When you pull down on the carabiner, the carabiner mashes the rope into the Tibloc’s teeth. To slide the Tibloc up or down, you must fully release the carabiner. If you don’t, the teeth can scrape along the rope. You can cause the most damage, however, when you down jug. In that situation you also have to make sure to hold the device well out and away from the rope, a tricky task, or the teeth will pick at the rope and pull out yarns.  Note that the Tibloc is rated to 4.2 kN (about 900 pounds) on a 10mm rope. Heavier loads, such as those you might develop in a rescue haul, could cause rope damage.

If you can’t stop worrying about all those teeth, say you just watched the flick Teeth and are feeling a little, err, withdrawn, consider a toothless ascender such as those by Gibbs, SMC, Rock Exotica and Petzl. These devices rely on camming action, rather than teeth, to clamp the rope. The disadvantage is they take two hands to get on and off the rope. Great for mountaineering and glacier travel where you put the things on the rope once and leave them, but too cumbersome to use for walls or rock-utility purposes.

This Gear Guy question appeared in Rock and Ice issue 174 (January 2009).

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