This video covers some of the ways in which to lower off from the fixed belays found at the top of sport climbs. Because these belays are generally installed by individual climbers, they can vary greatly in quality and construction. Some general principles apply:
1. When you reach the belay, secure yourself to it, independently of the rope. For example, using a quickdraw from your harness belay loop into one of the bolts. Some climbers use a sling which they larks foot onto their harness belay loop. The advantage is that it is more difficult to accidentally unclip or clip into the wrong part of the harness. If the belay bolts are not linked by a good strong chain, you might decide to clip into both for extra security.
2. Thread the rope through the belay. How you do this will depend on the type of belay. The video shows ways to do this without ever being completely detached from the rope. Make sure you have threaded your rope into the correct part/s of the belay. Sometimes you may have to leave your own karabiner or maillon behind because the belay is not complete or looks damaged/corroded.
Watch the video here:
This video was made with the assistance of: www.aqueousfilms.com
Diagrams showing some of the techniques used in the video can be found in Climbing Outside
Remember:
Always lower off from two independent bolts, thread both if they are not linked or the link is suspect.
Never lower off with the rope threaded through a hanger. The sharp edges may cut through your rope.
If the belay contains slings or rope, never thread your rope through these directly. Be prepared to leave a karabiner or maillon if you have to.
If there is a chain and ring linking the bolts, use the ring to lower off. This saves wear on the belay and on your rope.
Learn and practice these techniques in a safe environment, and if necessary seek qualified instruction.