Belay Devices: Are they well suited for Tree Climbers?

There has been a lot of discussion about using belay devices for tree climbing. Many belay devices are lightweight and perform well for their intended uses. Products like the Trango Cinch and Petzl Grigri have made the leap from being a rock climbing belay tool, using dynamic or more springy rope, to a tree climbing progress capture device used with static or less springy ropes typically used for tree climbing. A belay device can also be used by a tree climber in a number of ways, including as a lanyard adjuster. Some go so far as to claim a device like the Madrock Safeguard (a hybrid belay device) can work as a tree climbing saddle’s rope-bridge adjuster.

My intention is to help educate and draw more attention to the similarities and differences between rock and tree climbing gear. I touch on the topic of non-conforming uses of gear, outside of a manufacturer’s guidelines. I’m not an expert rock or tree climber and my views may be taken with a certain degree of skepticism. However, I do my own research and accept responsibility for my opinions and views.

Tree climbers are resourceful when it comes to making things do what they may not necessarily be intended for or designed to do. For that reason, I will try to clarify things for beginners to better understand the trade offs when using belay devices for tree climbing.

As a rock climber is being belayed, the ground person uses a belay device that connects to the belayer’s climbing harness. Rope passes through the belay device, enabling the belay person to feed and retrieve rope or simply manage slack.

When considering the purpose of the belay device, there are two primary functions being addressed. The device locks onto and engages the rope when shock loaded and it enables the belay person to feed rope out or in through the device. The principle is fairly simple.

When a climber falls, it shock loads the belay device, which then engages or locks onto the rope, enabling the belay person to absorb the shock load of the falling climber and then feed more rope through the device to safely lower a climber back down to the ground. The weight of the falling climber is transferred to and absorbed by the belay person and partially by the dynamic rope absorbing the shock load. A belay person also helps the climber by managing the slack of the rope, by feeding rope in or out through the belay device during the climb.

Tree climbers typically use static ropes, without the same degree of elasticity of dynamic ropes used by rock climbers. A vast assortment of belay devices are currently in use and one of the two that have made a cross-over is the Trango Cinch. It’s no longer in production, but it supported larger diameter ropes used by many tree climbers. The Trango Vergo is the Cinch’s replacement, but 10.7 mm is the largest diameter rope it uses, based on the manufacturer’s guidelines.

The Cinch and GriGri, according to the manufacturer, offers a range of use by allowing a range of rope size diameters to work within the device itself. The GriGri supports ropes sized 8.5 mm to 11mm, and the Cinch 9.4mm to 11mm. Since tree climbers are known for pushing the envelop and by experimenting beyond what a manufacturer recommends, they’ve found that certain devices may work on certain larger static climbing sized ropes with varied levels of efficiency, contrary to the product manufacturer’s instructions and/or guidelines. Some tree climbers are more cavalier and do this solely at their own risk without first contacting the manufacturer to determine whether this is an acceptable risk. One may argue that there’s perhaps a 0.5 mm degree of variance, given the fact that a rope changes between the time it’s brand new and becomes more fully broken in, but using this or any product outside of the product manufacturer’s guidelines, is not recommended.

In the context of being used as a progress capture tool for a climbing lanyard, a belay device may perform well, notwithstanding the fact that, by design, a rope can move or be feed through the device when it isn’t engaged or tension loaded by the pull of the rope. For tree climbers, whether this can cause the rope to creep or slip unintentionally is almost a certainty, because that’s what a belay device is designed to do. Nonetheless if a tree climber is mindful of the device’s characteristics and maintains a consistent load on the device when in use, it becomes an issue whereby the climber assumes further liability and decides to set their own levels of risk tolerance.

Taking this a step further, a tree climber can use certain belay devices to capture progress on ascent, and as a rappelling device on descent. Since belay devices are not necessarily designed for the purpose of tree climbing, performance varies when compared to other assisted braking descending devices using larger braking cams. Opinions do vary and with the exception of the GriGri, many major tree gear retailers sell a more robust and fuller featured variety of assisted braking descending devices, like the Petzl Rig or ID, including many with built-in lock-off and/or anti-panic functions.

Tree climbers have an assortment of options when it comes to rope grabs, auto-breaking-descenders, even multicenders, all of which can be used as lanyard adjusters. Multicenders like the Akimbo, Rope Runner, Unicender and Hitch Hiker are in fact ideal lanyard adjusters, but maybe not as lightweight, compact, inexpensive and practical for the majority of climbers. I’m on a personal quest for the perfect all around, lightweight, multicending lanyard adjuster designed specifically for static climbing ropes with 11 to 12.5 mm diameters.

The following video is several years old and new products and upgrades to these products are available, but the review discusses which types of devices are better suited and why belay devices are comparatively less effective when used in ways beyond their intended purpose.

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Andrew Joslin

Nice work John!