How to Choose a Belay Device

By Jon Wilson


Choosing the right belay device for you to belay with should be more than picking the nicest colour, or the cheapest in the shop. Similar-looking belay devices, which will all work, can have quite different properties when belaying a climber, even with the same rope. Here is some guidance from Jon Wilson, climbing wall manager at Calshot Activities Centre and member of the BMC Training and Youth Committee.

How do belay devices work?

Putting aside the assisted braking devices such as the Petzl GriGri, ‘manual’ belay devices work on a combination of friction and, to a lesser extent, a jamming effect between the device and the karabiner. Symmetrical devices can be used either way up with no change in their friction properties. Asymmetrical devices are designed to give higher friction or enhanced jamming action when used one way up but often can be used the opposite way up giving lower friction/jamming. This can be useful in some circumstances but potentially dangerous if the belayer does not notice they have threaded it ‘upside down’.

‘Slick’ or ‘Grabbing’?

Belay devices are often referred to as 'slick' or 'grabbing' devices. This refers to how easy it is for the rope to be taken in and out of the device. Many climbers like slick devices as it is easy to take in the rope on top ropes and feed it out when lead belaying. However, their properties also mean that it is harder to hold a big lead fall or lower the climber down in control. Grabbing devices may need an extra bit of care when taking the rope in or feeding it out but will probably make it easier to hold that fall. Most asymmetrical devices try and overcome this (with varying success) by making it slicker to feed the rope in and out whilst still making it easy to hold the falls and lower larger climbers. These asymmetrical devices do however often rely on the rope running through the correct section of the device when in the ‘locked’ position.

Common symmetrical belay devices
Common symmetrical belay devices L-R: 'slick' Black Diamond ATC, mid-friction DMM Bug and traditional 'grabby' Stich plate

Asymmetrical belay devices
Asymmetrical belay devices L-R: the Metolius BRD, which increases the jamming properties of the device as the karabiner is pulled into the slot, and the Black Diamond ATC XP, which produces more friction when the rope runs through the 'teeth'

4 things to think about when choosing a belay device

Size of climber/belayer: Smaller belayers belaying larger climbers may want a higher friction device to help hold falls and control lowers. However, watch for the belayer being pulled off the ground when holding a fall. A ground anchor may be useful in some circumstances. Conversely when belaying small climbers; especially small children, high friction devices mean it is harder to lower them down as there is too much friction in the system.

Grip strength of the belayer: This may vary between belayers; slicker devices will generally need a higher grip strength to be able to hold falls and lower in control.

Experience of the belayer: It is probably best that inexperienced belayers use higher friction devices as this will generally make it easier for them to hold falls and control lowers. However, some very grabby devices can make it very difficult for the belayer to take the rope in at all.

Rope diameter and condition: All belay devices are designed to be used with a range of rope diameters. For some devices this can be quite limited, check if you are unsure. Thin ropes will need higher friction than thicker ones. Remember, especially on climbing walls, ropes tend to get slightly thicker and stiffer over time.

Smaller belayers need to think about device choice carefully to make it easier for them to hold larger climbers

Assisted braking belay devices

These devices mechanically pinch the rope, allowing very little slippage when holding a fall. They are not hands-free devices, however! They help when holding falls and resting climbers but extra care is needed when lowering. Once the ‘brake’ handle is pulled there is often less friction than with many slick manual devices and you only have one free hand to control the speed of the lower.


Choosing the right belay device can be vital in keeping your climber safe. What may be best for them to belay you may not be best for you to belay them. Finally, remember most belaying accidents are due to lack of attention of the belayer not the incorrect device.

Further Information

Download the BMC Belaying and Abseiling leaflet at 


Jon Wilson is also a member of the BMC Training and Youth Committee


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