Short-fixing is an experts-only technique that essentially separates a climbing team into two roped soloists via a knot at an anchor, allowing the climbers to move simultaneously. It’s most commonly used on one-day ascents of big walls, or to speed up the process during multi-day ascents.
Don’t confuse short-fixing with simul-climbing, when both climbers move together, without the rope fixed to an anchor in between. When simul-climbing, if one climber falls, the results can be catastrophic. When short-fixing, if one climber falls, the other climber is unaffected, as long as the belay anchor is bomber.
The technique: Let’s say the climbers have a 200-foot (60-meter) rope. The leader climbs 120 feet to the top of pitch one. She builds a multi-directional, bombproof anchor, and then pulls up the remaining 80 feet of rope. Once the rope is tight on her partner below, she ties it directly to the anchor. The rope is now “fixed,” and the follower can begin to climb, either using a solo toprope technique or climbing the rope with ascenders.
The leader now sets up to rope-solo the next pitch—an advanced technique you’ll need to have mastered in order to shortfix—using either a special belay device such as the Silent Partner (rockexotica.com), or a simple clove-hitch system. She can now climb away from the anchor, rope-solostyle, for up to 80 feet—the amount of rope she pulled up after reaching the anchor.
Almost always, the follower will reach the anchor before the leader runs out of rope. Once the follower hits the anchor, he clips in direct and puts the leader back on a standard belay. Repeat as needed.
This is an expert’s technique, which has many nuances. Racking and gear selection are important, because the leader will not have the gear she placed on the last pitch. Depending on the situation, you can climb with a bigger rack, bring a tag line to haul up gear (almost essential), or choose not to short-fix when you don’t have the right gear to start the next pitch. If you are hauling, that’s another bag of worms—the leader can’t haul while short-fixing, so the follower does the work (and progress will scream to a halt if the haul bag gets stuck).
Thoroughly understand and practice rope-soloing before you short-fix with a partner. The various strands of rope can be confusing, and it’s all too easy to set up a belay device wrong. Practice will keep things straight, neat, and safe.