Belay devices explained

What every belay device has in common

Every belay device does the same fundamental thing: it adds friction to the rope so that one person can hold the weight of another. The rope bends sharply around the device, and when you pull the brake strand down and back, that bend pinches the rope hard enough to lock it off. No belay device holds a fall on its own. Your brake hand does. The device just multiplies what your hand can manage.

Hold that idea, because it is the thread running through all the types below. Whatever you are using, the brake hand never leaves the rope.

Tube-style devices

A tube is the simple, familiar one: a metal channel with one or two slots that the rope runs through, clipped to your harness with a screwgate. It is light, cheap, works with a wide range of rope diameters, and handles two ropes at once for double-rope trad and abseiling. Many people learn on one.

The trade-off is that a tube provides no extra help. If you let go of the brake strand, the rope runs free. That puts the whole job on your technique and attention, which is fine when your technique is good and your attention is on the climber, and unforgiving when it is not.

Some tubes have a guide mode, an extra attachment point that lets you belay one or two seconds directly off the anchor. In that mode the device pinches the rope automatically when a second weights it, which is handy for bringing people up multi-pitch routes.

Assisted-braking devices

Assisted-braking devices add a mechanism that helps lock the rope when it loads suddenly. They split roughly into two kinds.

• Mechanical (camming) devices have a moving part that rotates and pinches the rope when it pulls through quickly, similar in feel to a seatbelt. They are popular for sport climbing and busy gym sessions.
• Geometry-assisted (passive) devices have no moving parts but are shaped so that a hard pull pinches the rope against the carabiner. They tend to be lighter and work with two ropes.

The word that matters is "assisted", not "automatic". These devices reduce the consequences of a moment's lapse, but they can still let rope through if you are clumsy with the brake hand or if you hold the device wrong to feed slack. Treat the assist as a backup to good habits, never a replacement for them.

Choosing and using one

The honest answer is that the best device is the one you have been properly taught to use and use the same way every time.

• For mostly indoor and single-pitch sport, an assisted-braking device suits the repetitive catching of a busy session.
• For trad and multi-pitch with double ropes and abseils, a tube with guide mode is hard to beat for versatility.
• Many climbers carry both and pick by the day.

Two rules sit above the kit choice. Match the device to your rope diameter, because a device set up for a thick rope feels grabby on a skinny one and dangerously slick the other way round. And keep your brake hand on the rope at all times, with every device, no exceptions. The hardware buys you margin. The habit keeps your partner off the ground.