Tactics for Safe Simul-Climbing
Using modern equipment to protect simultaneous movement
Simul-climbing is a paradigm shift in climbing efficiency. Standard multipitching requires each climber to wait statically for over 50% of the time! Simul-climbing greatly cuts these time losses down as both climbers move simultaneously for a large portion of the climb. When done safely, faster climbing means more climbing and more fun! It becomes reasonable to climb fully protected 500’+ simul-pitches with constant movement. The below information is my compiling of past articles and posts to present a digestible take on modern simul-climbing, where both the leader and follower are protected at all times.
Simul-climbing has been avoided in general practice due to the extreme consequence of a falling follower pulling off a runout leader and causing a long, harsh fall. With modern Progress Capturing Pulley’s (PCP), this danger can be mitigated by adding multiples of these devices to your rack to create “inline belays”. Another danger simul-climbing presents is the necessity for the leader to create runouts while saving gear to continue beyond a rope length. This can also be negated with the light weight nature of modern equipment, allowing many cams and draws to be reasonably carried. The last major consideration is the extra slack due to climbers moving at different paces. A firm agreement between climbers about the maximum allowable slack in the system is critical, and can be met by using a GriGri to modulate slack on the move.
This system is for advanced climbers only. You are accepting the risks of using devices AGAINST manufacturer instruction! One should have a solid foundation of multipitch efficiency, route finding, rope management, and self rescue skills before considering.
Simul-climbing begins with a standard lead belay until 35m-40m of rope is out. Around this point, the leader shoulder place a PCP attached to a anchor/bolt/solid cam and let the follower know it is in place. The follower then puts on their climbing shoes, ties a backup overhand ~20 feet below the GriGri, and clips this backup knot with a locker to their belay loop below the GriGri. The rest of the rope trails below with no knots. The follower begins climbing, effectively creating a “moving belay” with the GriGri still on their harness. The follower uses the GriGri to pull in slack one handed if on easier terrain, and then can stop at any stances along the pitch to belay slack back out. The aim is consistent pacing and distance between the climbers.
The leader continues on for as long as they have ample gear, placing PCPs every 30-35m to keep one between the climbers at all times. As their simul-pitch concludes, the leader builds an anchor and gives a standard top belay. The basic principle is simple, but please consider the nuances discussed below to ensure a margin of safety!
The leader has the relatively easy side of things - they lead in a normal manner, but just don't stop at the belay anchors! They primarily deal with extra gear weight due to the long simul-pitches.
Leader is in charge of placing PCP at consistent spacing. Leader should try to place PCPs at intervals slightly less than the space between the climbers, but at the best stances where gear is appropriate.
Leader places PCP onto a solid bolt, anchor, or excellent piece of gear with a dedicated locking carabiner. Do not extend the PCP away from the anchor point! This extension can allow enough play such that the leader may be pulled off if the follower falls. Petzl PCPs are rated to 15kN in “pulley mode”, so they may be adequate to hold a lead fall, but can be backed up with a draw at the same protection point.
Leader decides simul-pitch length on-the-fly based on available gear. If done well, any simul-pitch length beyond 1.5 times the rope length is a reasonable gain in efficiency. With practice saving gear, back cleaning, and modulating runouts (or bringing a huge ultralight rack!) simul-pitches can be upwards of 1000’.
At end of simul-pitch, leader anchors in and puts the follower onto a standard belay. Communicate to follower if possible so that they know the tension is now a belay, not the leader being short roped. Alternatively, leader may fix the line and follower could use previously cleaned PCPs to follow TR solo style.
The leader racked up with PCPs on dedicated lockers, with many cams and draws (racking in "stacks" helps with gear loop space).
PCP placed at anchor bolt. Draw is optional to back up PCP - when loaded cleanly, most PCPs are rated to hold around 15kN in "Pulley Mode", though a leader fall onto the device risks low load failure if the sideplates bind on the biner gate and crossload.
The follower has the more difficult job of matching the leader's pace and ensuring PCPs are in place where needed. Following on top rope with dangling devices and constant slack can take some getting used to.
Follower climbs with GriGri dangling down on belay loop in standard belay orientation with a 10-15ft cache loop on the brake side of the GriGri, and then an inline knot lockered to their belay loop below the GriGri. The rest of the rope trails below (or can be coiled/backpacked for snag-prone terrain).
Follower is in charge of setting distance between climbers this is primarily set by when they first begin simuling for the pitch, but can be changed on the fly by stopping and belaying in/out rope, and even changing the backup knot location. Around 40m between climbers seems to be a good balance of minimal rope drag and reasonable PCP spacing, working especially well on modern routes with 35m rap anchor spacing.
The follower may use a hand to feed slack in through GriGri while climbing easier terrain, and then can stop at stances to belay slack back out if needed to maintain a consistent distance to the leader. Using this "moving belay" method, topo indicated belays spots are arbitrary, so don't be afraid to stop at any stances to tether in and give a momentary active belay.
Follower is in charge of not removing the current PCP until leader tells them the next PCP is placed. They must ensure one PCP is between climbers AT ALL TIMES. Follower waits to hear leader give the "traxion on" command above before removing the current PCP. The follower can always stop at the current PCP and belay for a bit if the leader needs further distance before placing the next PCP.
Follower is not to let slack between GriGri and leader droop down past their feet! Slack is managed based on climbing pace and feeding in-and-out slack at the GriGri. Not allowing the rope above the GriGri to droop below the follower's feet equates to about ~6ft of extra slack maximum, allowing the leader to calibrate their protection placing to this known fall distance. This is a crucial agreement between climbers, as extra slack is a main risk of this system! The follower should attempt to pace with about half of the agreed upon maximum slack to allow the leader to clip up or bust quick moves.
The follower's setup - a small droop above the GriGri, a 10-15 foot cache loop, a back up knot to the belay loop, and a dangling tail with no knots.
The PCP is blindly being trusted. This may be the biggest unknown of the system, as a PCP binding on a locker gate and loading sideways may fail at a low load. Care should be taken to place the device with the PCP hanging on the large side of the carabiner with the gate away from expected direction of travel to help mitigate this risk. The smallest PCPs (Nanotraxion) do not fit over a locking gate sleeve and may be most trustworthy for this usage. The locking carabiner pairings should be chosen carefully with no tight bends which can bind the PCP plates. Always test each placed PCP to ensure the toothed cam is engaged!
Both the leader and follower are theoretically protected for safe falls. Climbers must be aware that falls may be slightly longer than usual for both of them due to the droop of slack at the follower’s end while giving a moving belay. Follower is always on a belay of sorts, either the PCP between the partner or the top belay at the end of a simul-pitch. Follower should be careful to not fall with significant slack when arriving at a PCP for risk of a coreshot, but a toothed PCP presents minimal risk to the rope unless the fall is immediately at the device.
Communication is crucial. Leader may ask for minimal slack, or a proper belay at any time. See Proposed Commands section below.
Downclimbing is dangerous for the leader. Since the follower cannot take in slack due to the PCPs inline, a downclimbing leader will create a large loop of slack in the system. For this reason, careful route finding is crucial! As a last resort, a GriGri could be used by the leader to take in slack as they downclimb.
Resupplying with a Pull Cord. A thin pull cord can be trailed behind the leader so that the leader can be resupplied with gear while apart from the follower. Both climbers need only to stop for a few minutes at a stance/ledge/anchor for the follower to tie all gear to the cord, and for the leader to pull it up and rerack. The climbers can then continue on, saving significant time over statically belaying in a follower, reracking together, and then statically belaying out the leader for the next pitch. This pull cord can also be combined with a ~40m lead rope for a lightweight method of rapping modern routes with <35m rap anchor spacing.
3-5+ PCPs + dedicated lockers (Petzl Microtraxions, Nanotraxions, or Edelrid Spocs; use a large enough locker that the PCP does not bind at the bends)
Lots of UL Draws and Alpine draws
Many Cams for linking pitches (small cams are lightest!)
Top belay device
Adjustable PAS/tether (useful for hanging momentarily at steep anchors to place PCPs)
Adjustable PAS/tether (important for anchoring into gear to give an impromptu active belay)
GriGri + Locker
Extra Locker (for backup knot below GriGri)
Skinny Lead Rope (8.9-9.2mm is nicest for the constant drag)
40m Pullcord (optional for resupplying on long simul-pitches. Can be as thin as paracord, or thicker if used to rap )
Traxion On: Leader tells follower they have placed a PCP.
Simuling: Follower tells leader they are transitioning from a static belay to a simul-climbing moving belay.
Active Belay Please: Leader requests a full belay. Follower should anchor into the next gear/bolt (ideally a stance) and give an active belay with the inline GriGri.
With you: Follower tells leader they have a stance or are anchored in and giving a proper belay. Note “belay is on” is confusing in this situation since the GriGri is already inline.
Simul On: Leader tells follower that an active belay is no longer needed
Belay is On: leader is anchor at end of the simul-pitch, follower is now on a standard top belay. This is not a crucial command, but lets the follower know tension upward is not them short roping the leader.
Line is Fixed: leader is anchor at end of the simul-pitch, but follower needs to switch to TR-solo style follow methods using PCPs cleaned during the pitch.