Lowering Out - Consider using a designated cord
This tip is from big wall expert Mark Hudon. See some more tips and El Cap Route photos at his website.
Many aid routes have long bolt ladders, such as the first couple of pitches of Leaning Tower in Yosemite and Monkey Face (shown above) at Smith Rock Oregon.
If the bolts go pretty much straight up, cleaning them is easy. But if the bolts traverse, and/or the rock becomes overhanging, and/or (especially) if the leader decides to backclean, cleaning becomes more difficult. When you reach the offending bolt/protection you’ll know it, because of the sharp angle of the rope as it shoots off to one side.
As the second, you may curse your backcleaning leader with enthusiasm: You’ll be stuck at the bolt, unable to clean the quickdraw because of the rope tension pulling off to one side.
In this situation, the standard technique is to remove the top ascender/aider, reclip it above the piece, and weight that aider. In theory, this removes the tension from the rope below, letting you clean the gear. (It can be a LOT easier to do this if you have a Grigri, recommended gear for cleaning traverses.)
This works fine on moderate traverses, but not so well if it's more extreme. When the next clipped piece is 4+ feet to the right, because you’ll be left hanging in space, unable to reach the piece you were trying to get out. More importantly, your lower aider will likely have been sucked into the quickdraw in such a way that you will be unable to get it out without cutting the quickdraw . . . Plus, unclipping your ascenders and re-clipping them to tensioned rope heading off sideways can be a little tricky and introduces the possibility you didn’t re-clip them correctly, which could be a Big Problem.
For a shorter lower outs, or for cleaning a roof or a traverse, consider this: use a designated short lower out cord.
Note that on a lower out, you leave the gear behind. So, it works best through a fixed point. If you're going to lower it through your own gear, better not go too far or you won't be able to swing back to clean it! (Just about every big wall climber makes this mistake at least once . . .)
Using a designated lower out cord like this can be especially helpful when climbing with folks relatively new to aid climbing, who may not have the more advanced following / cleaning skills.
The cord I like is a simply 5 or 6 mm cord, about 15 feet / 5 meters. This works perfectly for cleaning the bolts on Monkey Face as shown in the top photo, as well as roofs and traverses.
(Mark suggested using a longer length, about 40 feet / 13 meters for lower outs on big walls that are under about 20 feet. Much longer than this, you're probably better off using the climbing rope in the traditional manner. Check the topo, and bring a cord of the appropriate length for the lower outs that you anticipate.
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. 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 maybe even a couple of horizontal hook moves, you should anticipate having to do a lower out.
Here’s a much better way to clean a traversing bolt ladder.
Once at the lower point (which is some sort of permanently fixed gear, like cord/webbing, bolt with hanger, piton, stopper. etc), here’s what you do:
Tie your lower out cord to your belay loop.
Clip a spare carabiner to your belay loop.
Attach a fifi hook to your harness. Yes, usually you only use a fifi for leading, but in some cases like this, it's pretty handy for cleaning as well. Just keep it on your harness all the time. (I prefer girth hitching it through the top tie in point.)
Note: in the photos, tethers, aid ladders and the often-handy Grigri are omitted for clarity.
If there’s a mess of old tattered webbing at the lower point, cut away the junk with your knife and leave only one good piece. If you don't, there's a chance your lower out cord is going to get stuck in the tat when you try to pull it. This is more likely to happen when you use the standard method with the rope, which involves passing ad pulling a bight through the lower out point, but still, do people behind you a favor and cut away the junk. If you want to be even more courteous for the next team, add a quick link or your least favorite carabiner.
Pass the free end of your lowering cord through the lower out point.
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.
Slowly lower yourself out with the munter hitch. You will hopefully now be hanging directly below the piece of gear the leader placed after they did the pendulum. Hopefully it was not more than about 7 feet away, because you can only lower yourself half the distance of the length of your cord. If you're not quite in the fall line, be prepared for a little swing. (Yes, this will be exciting!) Let go of the munter hitch, and pull your lower out cord through the lower out point and back to your harness.
Here's the basic set up, using an untied / open cordelette that's about 5 meters long. (It can be much longer, this short length was easier for the photo.) Tie the rope to your belay loop.
For clarity, the following two photos do not have the normal gear you’d need cleaning on a big wall, such as the lead rope, ascenders, aiders, daisychains, etc.
Pass the free end of the rope through the fixed protection, and tie a Munter hitch in the spare carabiner on your belay loop. Now you can hoist yourself with a 2:1 mechanical advantage toward the fixed piece of gear. The Munter holds your weight. Now you have slack in your climbing rope, which lets you unclip and clean whatever the leader clipped to the fixed piece.
After your gear is cleaned, release the Munter hitch, and lower out. You should end up hanging vertically under the next higher piece of gear. Untie the Munter, pull the cord through the fixed gear, and continue ascending and cleaning as normal.