This tip is from big wall expert Mark Hudon. See some more tips and El Cap Route photos at his website, hudonpanos.com
Many big wall routes require the leader to do a short pendulum over to a new crack system. When the second comes up to this pendulum point, they’ll need to do a technique called a lower out.
Traditionally, this is done with the climbing rope, but it’s moderately tricky to do. Depending on what technique you use, can involve untying and then re-tying into the climbing rope, which is always a little nerve-racking when you’re way off the deck. While for a long lower out you will to need to use your rope, for shorter ones you can try something different - use a designated short, skinny lower out cord.
The cord is a 25 foot length of 5 mm cord.
Use this for:
short lower outs (under about 10 feet)
cleaning awkward places. like roofs or traverses
cutting away old manky webbing that’s faster and does not require any monkeying around with your lead rope:
Keep the cord bundled up out of the way on your harness until you need it. If the second knows that the pitch they’ll be cleaning requires a lower out, they can tie a figure 8 on a bight with the cord through their belay loop before they leave the belay. (And you should be looking at the route topo and knowing that a move like this is coming up, right? If you see the leader doing a pendulum, or even a couple of horizontal hook moves, you should anticipate having to do a lower out.)
Once at the lower point, here’s what you do:
Clip a carabiner to your belay loop. (If it's not there already, tie your lowering cord to your belay loop.)
Pass the free end of your lowering cord through the lower out point, which could be webbing, a bolt, a piton, a stopper, or some other sort of permanently fixed gear.
Tie a munter hitch on the lowering cord, and clip it to the free carabiner on your belay loop.
Hoist on the free end to pull yourself close in to the lower out point, holding your weight on the munter hitch.
This takes the tension off the rope you’re ascending, which lets you unclip the lead rope and clean the carabiner the leader probably left there.
Lower yourself out with a munter hitch. You will hopefully now be hanging directly below the piece of gear the leader placed after they did the pendulum. If you're not quite in the fall line, be prepared for a little swing. Yes, this will be exciting. Pull on your lowering cord. It should pull easily through the lower out point and back to your harness.