This is a technique that when used right will speed up many alpine and multi pitch ascents. Why speed up your ascent? Personally I think speed is a key factor to moving safely in the mountains. If you climb slowly you are more likely to have unplanned bivvies, get stuck in storms or get caught out by rock fall or serac fall. Moving quickly over technical terrain is also good fun!
Starting with the basics: "simul climbing" is when two climbers move at the same time with a rope between them, placing and removing protection as they go.
Some basic rules for when not to simul climb
It is not always faster to simul climb moderate ice terrain. Especially if the climbing is straight up and the ice is brittle i.e the leader bombs the second climber with lots of ice. In this situation you will probably be faster pitching. The leader will move quicker, and the second will move faster. Overall on brittle ice where you are moving in a straight line fast pitching usually is safer and faster than simul climbing.
Climbing that is too hard. If you are not able to move at least three pitches worth of terrain in a single simul climbing block you are probably better off pitching.
Simul climbing tips
Simul climbing requires a change in mind set from the leader. Instead of focusing on where your lead cruxes are and placing lots of protection there, I often focus on where I can get the best gear and where I can place protection to coincide with the moment my second is arriving to the crux moves. I'm focusing more on protecting myself from the risk of the second pulling me off when they climb a crux section rather than stitching it up when I personally move through the crux sections of a pitch.
The best distance to have between the two climbers for simul climbing is usually 35 – 45 meters. This keeps rope drag down and usually allows you to have multiple protection points in case of a fall. When simul climbing an alpine snow/ice face you may wish to lengthen the rope to allow longer run-outs between protection, but when climbing complex wandering terrain for example a rocky ridge, it may be better to shorten the rope slightly.
Always try to maintain a minimum of 3 good protection points between the two climbers. Adjust for the terrain. Sometimes two bomber ice screws is enough. Other times 5 -8 cams might be appropriate amount to move safely together. You must bear in mind that if the leader places to much protection they will run out of rack and have to belay to soon eliminating the advantage of simul climbing. To avoid this usually the leader aims to run it out as much as possible on the first pitch before the second starts moving, then beginning to place more protection once both climbers are moving together.
Always have at least one Petzl Tibloc or Petzl Micro Traxion (or similar) between the two climbers at all times. Make sure you know how to place a tibloc on the rope so that a lead fall is onto the carabiner and not onto the Tibloc.
When using Micro Traxions, remember they are only rated to 250kg and are not strong enough to sustain a lead fall. Therefore you must place another piece of protection just after any Micro Traxion placements to protect the leader as well as the seconder. Each climber should have a Tibloc and Micro Traxion, so between a team of 2 you end up with two Micro Traxions and two Tiblocs. These are handy for self rescue, and by having four devices you will allow yourself to maximise any long simul climbing blocks.
When using a Tibloc with skinny ropes remember to have a fat carabiner rather than a small light weight carabiner. This will reduce the risk of slippage and sheath damage in the event of the second falling off.
On easy terrain where both climbers can move confidently a good simul climbing block can extend up to 300 – 500m.
Usually when planning to simul climb on a route you adjust the rack carried compared to the same route climbed in traditional pitching style. For example, climbing the Walker Spur on the North Face of the Grandes Jorasses would require a single rack and maybe 8-10 quick draws if you were planning to belay on every pitch. However when planning to simul climb some of the route I would add in more quick draws bumping that number up to 12 -14. I would also add in more rack. This allows for longer extended sections of climbing before a belay is necessary. Therefore we are trading off between extra pack weight and the ability to move quicker over longer section of the route.
Using a tag line
Using a tag line is a great trick for simul climbing hard routes. On harder pitches you end up placing more protection. However with a tag line your seconder can simply recycle gear up to the leader at any point so the leader doesn’t have to stop and belay just to re-rack. The seconder simply clips all the rack they have collected to the tag line and the leader pulls it up then keeps on moving. Often when simul climbing I will take two short ropes for this purpose. For example a 40m single rope for leading on and a 40m tag line for tagging gear to the leader.
You can create your own tag line with a single rope. Simply have the leader tie into the middle of the rope. The second ties into one end. The other end they can clip to their harness with a biner. Make sure as the leader you always clip your protection to the correct side of the rope. Then when you run out of rack you can tag up more from your second using the free hanging side of the rope.
When deciding if you want to have a tag line. Consider how you would back off the route if something goes wrong? Do you need to make long rappels on the descent? What will you do if your lead line gets cut? Thinking about these possibilities will help you decide on the type of rope and length to use as your tag line.
Tips for Using a Micro Traxion when seconding
A Micro Traxion is very handy when seconding. Simply clip this to your harness and onto the rope then if you find yourself moving faster than the leader at any point you simply keep climbing using the Micro Traxion to ensure there is no big loop of slack between yourself and the leader. Once you reach a good stance or a good piece of gear, take the Micro Traxion off, put the leader back on belay and give out the slack then start moving again. Ensure you put them on belay before taking the Micro traxion off to make sure you don’t risk them taking a big fall while the loop of slack is in the system.
You can also use your ATC in guide mode for the same purpose. However it doesn’t auto feed as you climb so its not quite as efficient as using the Micro Traxion.
Tips for Using a Micro Traxion when leading
A good trick if you want to belay a second through a short crux is simply place a Micro Traxion on a piece of protection before the second arrives to the crux section. Then pull the rope tight as they complete those moves. Once they have finished continue climbing. Remember this might mean you start climbing with a big loop of slack out. Make sure you place another protection piece to protect the Micro Traxion and yourself.
Communication is key when simul climbing. The calls traction on, traction off as you place and remove a micro traxion are essential. Your second needs to know if they can pull on the rope if needed to pass a crux move rather than risk a fall. I often carry two light weight radios to help with the communication when simul climbing.
Try to climb with your micro traxion or tibloc clipped in hard to the cam, bolt or piton, rather than a quick draw to extend it. Whenever possible I don’t place these on nuts or hexs due to the likely hood of them walking the gear out of the crack. Avoid long slings on your micro traxion as if the second falls off and you have a 120cm sling, which can be pulled upwards by the rope, you are likely to get pulled off as the leader. If the micro traxion is clipped hard into a pin or cam there will be less movement in the rope and less chance the leader could get pulled off. The down side is more rope drag and the possiblity of having your cam walk in the crack so you will need to balance this out with the risk of being pulled off.
Like any climbing technique, simul climbing requires a lot of practice, combined with all of the theory and knowledge explained here. If you want to move quickly and safely using this technique take the time to practice it with your regular climbing partners. I am constantly learning new tricks when I simul climb. Don't expect to get everything efficient and smooth on the first few climbs using this technique!