How belay devices work
The belay devices primary job is to enable the belayer to arrest a fall by stopping the rope, and how the rope is stopped varies depending on which device is being used. Principally there are two actions that can be applied to the rope, "friction" and 'pinching'.
Friction- This is where the rope passes around tight bends through the device via the carabiner thus applying friction. This slows the rope from passing through, however this action is never instant and requires a level of skill and competence from the belayer.
Pinching - When the rope is passing through the device and around the carabiner, as above causing friction, it can also be pinched. The degree of how much the rope is pinched depends on the shape and depth of the device. Basically the flatter the device (such as the old Betabrake) the greater the pinching on the rope.
Camming devices are auto locking and are mechanical in operation, a GriGri for example. When the leader falls this applies sufficient force on the rope to turn the cam inside the unit, as it turns the rope is pinched between the cam and the wall of the device stopping the rope and the falling climber. This action happens very quickly.
The pinching action causes the device to 'Grab' the rope, the greater the pinching action, the quicker the falling climber is arrested
Types of belay device
Slick - These devices rely totally on friction to stop the rope and the belayer needs to hold the rope correctly in order to apply this friction. The main advantage of this device is that rope can be paid out quickly and efficiently when the leader requires it. But the belayer has to be attentive and experienced to arrest a fall. Example Black Diamond ATC
Intermediate - These devices use both a degree of friction and gabbing to stop the rope, and the balance between the two will vary depending on the design of the device. These devices also tend to have a toothed groove which helps to grip the rope and arrest the fall. Example ATC XP and the Petzl Verso
Grabbing - These devices are less popular and there are few on the market. Essentially they are a flat device that pinch the rope when it's loaded. Although the belayer can arrest a fall easily they can be awkward to pay out rope, especially if it's needed quickly.
Camming - These devices are mechanical and are probably one of the easiest to use, when used correctly. When the rope is loaded the spring loaded cam actually wedges the rope and jams it in the device. However paying rope out through these devices can be awkward and if held incorrectly may compromise how it works.
Styles of climbing - Appropriate belay devices.
For our full range please see our belay devices.
Indoor - Climbing walls have fixed running belays and top belays, ropes used are single and tend to be 10.5 mm plus in diameter as they get quite heavy use. An intermediate device is the best choice in this situation. Depending on the belayers experience and the diameter of the rope will effect the choice of device. Certainly for beginners a Grabbier device would be the choice such as the BD ATC XP. However more experienced belayer may want a slicker device such as the Variable controller, with the Verso from Petzl sitting pretty much in the middle.
Traditional Single pitch - For this type of climbing generally half ropes are used so the device must be capable of accepting two ropes. An Intermediate device would be the best recommendation . For a less experienced belayer a device which grabs the rope more would be preferable such as a BD ATC XP. For a more experienced belayer then a device that is slicker may be appropriate such as the Wild Country Variable Controller.
Traditional Multi Pitch - Though it is perfectly safe to use the devices that have been suggested for single pitch routes there is a second option. These are the 'Guide' type devices. These are attached directly in to the belay to bring up the second or even two people at the same time. In this mode the device becomes self locking with the use of an additional carabiner. The two most popular versions are the Petzl Reverso and the Black Diamond ATC Guide. Below is a short video about using the Reverso, a similar video can be seen on the ATC Guide page.
Sport - Single ropes of less than 10.5mm tend to be the norm for sport climbing. The belayer will require a device that can pay rope out quickly yet that can arrest frequent falls. The best option for this type of climbing would be either an intermediate device or a camming device. Intermediate devices such as the Variable Controller or the Petzl Verso are popular choices. In both cases if the belayer is experienced they could be used in reverse to provide a slicker operation, but the belayer needs to be attentive. Camming devices such as the Petzl GriGri or Edelrid Eddy are also popular for sport routes. Camming devices auto lock when loaded and are excellent when a leader is working a route. They also have the advantage of using less strength to hold the rope locked for extended periods of time
Ice/Alpine - Alpine climbing involves multi pitch climbing and like Traditional Multi Pitch one of the best options is to use a 'Guide' type device such as the Petzl Reverso. However often ropes in these situations can get iced up during climbing and become stiff to handle. In this situation a Slick device would be appropriate, as it's easier to pass the rope through whether taking in or paying out. A good example would be the BD ATC.
For our full range please see our belay devices.