“Slingshot” top rope solo? Edited to clarify.

When climbing with my kid, who is too small to belay me, I set the top rope, and my kid climbs. When I want to climb, I reset the top rope (with bunny ears, or two bights) then I rope solo.

Tell me why I shouldn’t just forgo resetting the rope, and “slingshot” self-belay. One drawback that I am aware of it that I will have to pull a lot of slack through my devices. Tell me some other reasons I’m gonna die...

Edit: I usually don’t have to pull slack, with my usual set-up. I’m also climbing very mild routes, because of the kid, so pulling slack isn’t a big deal in my mind.

As for stretch, it seems to me that it would initially be just the same as a conventionally belayed TR setup, and decrease to effectively zero as I approached the anchors.

To clarify: I would conventionally TR belay my kid, then when it was my turn, tie in to one end of the rope, then attach my devices to the other side of the rope. So, tied to my harness, up to the anchors, back down to my devices.

Edited again, because I am “timed out” from posting, because I am a new user (but longtime lurker):

I could fix it at the bottom to a bolt or some gear. The whole big question, though, is how do I make it easier to swap back and forth from my kid climbing on conventional TR to me climbing solo TR?

extra stretch

There would actually be less stretch giving that you’d fall on two strands of rope vs one. 

Yes,  a ton of extra rope stretch, if you are using a dynamic rope, which I assume you are since you were TR'ing your kid.

I may have misunderstood, Is he climbing one rope and the other strand is anchored at the bottom, slingshot back down to him? Or is it anchored at the top, and he is climbing on both strands?

One is more stretch the other less.

But the title "Slingshot" makes me think it is anchored at the bottom

I do it occasionally out of expediency. It’s fine for short, easy routes. Just pretend you’re taking a hand off to place gear every few feet or so and pull the rope through.

I don’t recommend this technique for overhanging routes as the extra rope tends to pile up around your shoulders and head. That very well could kill you if you fell and your head got entangled.

Normal TR solo is faster and much more fun

Rope stretch will be nearly identical. In the slingshot belay setup there is let's say 20m of rope being used in the system if the climber is 10 meters from the anchors. Force of tension is equal throughout the entire rope in both situations, the climbers weight is distributed across two strands of the rope in the slingshot belay. The side he is tied into is entering the force of tension in the downward direction and the strand with the microtrax is exerting a force in the opposing direction which is taking some of the force of the climber in the opposing direction since the climber will be held at a single point on the rope. The climbers mass is distributed between both strands of rope so there is half the weight on each strand but twice the amount of rope in the system so the stretch will therefore be half. In a fixed rope situation the climbers entire mass is on half the rope length so the 10m section of rope will experience twice the amount of stretch as each 10m section in the slingshot belay. The only advantage I see in the slingshot belay is that you wouldn't need to go up to the anchor after your son climbs to fix the rope up top, however, personally I would rather do that than take in slack while climbing. The alternative method you could experiment with would be to fix the end of the rope your son was tied in on to something near the bottom of the route, if it's a sport route the first bolt would work fine, then climbing on the belay side of the rope on the TR setup. I believe this is a common technique for arborists when climbing up trees by fixing the rope on the trunk of the tree, however I have never heard of it being used in rock climbing situations so I wouldn't try this method without input from a more knowledgable source on the subject before trying it yourself. I think a backup would be advisable to a single bolt at the base of the route since it is a single point of failure and you would deck if the bolt fails. Rope stretch would be greater if you did decide to try this method.

Andrew Steavpack wrote: Rope stretch will be nearly identical. In the slingshot belay setup there is let's say 20m of rope being used in the system if the climber is 10 meters from the anchors. Force of tension is equal throughout the entire rope in both situations, the climbers weight is distributed across two strands of the rope in the slingshot belay. The side he is tied into is entering the force of tension in the downward direction and the strand with the microtrax is exerting a force in the opposing direction which is taking some of the force of the climber in the opposing direction since the climber will be held at a single point on the rope. The climbers mass is distributed between both strands of rope so there is half the weight on each strand but twice the amount of rope in the system so the stretch will therefore be half. In a fixed rope situation the climbers entire mass is on half the rope length so the 10m section of rope will experience twice the amount of stretch as each 10m section in the slingshot belay. The only advantage I see in the slingshot belay is that you wouldn't need to go up to the anchor after your son climbs to fix the rope up top, however, personally I would rather do that than take in slack while climbing. The alternative method you could experiment with would be to fix the end of the rope your son was tied in on to something near the bottom of the route, if it's a sport route the first bolt would work fine, then climbing on the belay side of the rope on the TR setup. I believe this is a common technique for arborists when climbing up trees by fixing the rope on the trunk of the tree, however I have never heard of it being used in rock climbing situations so I wouldn't try this method without input from a more knowledgable source on the subject before trying it yourself. I think a backup would be advisable to a single bolt at the base of the route since it is a single point of failure and you would deck if the bolt fails. Rope stretch would be greater if you did decide to try this method.

OP is not fixing the rope at the bottom.

Arborists do this all the time. Called double rope or split-tail technique using something like a blake's hitch, rope wrench, or hitchhiker and a hard knot at the end of the rope. You will still have to pull slack through most of the time. But if you can rig to the ground then go back to regular TR Solo.

I did this just the other day on a 5.veryeasy with my 2 4yo's. Was quicker than hiking around to take the anchor down.  Belayed myself up with a grigri, tied backup knots every now and then.  Lots of rope to pull thru though. Only for easy terrain in my opinion.

Double the fall force on the anchor? Probably not a concern, I've cleaned many routes this way with the kids.

Please note that OP's post contains 2 distinct scenarios:
(1) "tie in to one end of the rope, then attach my devices to the other side of the rope"
(2) "I could fix it at the bottom to a bolt or some gear"

We also have 2 potential references for comparison:
(a) TR solo
(b) normal TR belay

So the following 6 statements:
 "more stretch"
 "less stretch"
 "same stretch"
 "more force on the anchor"
 "less force on the anchor"
 "same force on the anchor"

...are all potentially correct depending on whether we're talking (1)vs(a), (1)vs(b), (2)vs(a), or (2)vs(b).

Serge Smirnov wrote: Please note that OP's post contains 2 distinct scenarios:
(1) "tie in to one end of the rope, then attach my devices to the other side of the rope"
(2) "I could fix it at the bottom to a bolt or some gear"

We also have 2 potential references for comparison:
(a) TR solo
(b) normal TR belay

So the following 6 statements:
 "more stretch"
 "less stretch"
 "same stretch"
 "more force on the anchor"
 "less force on the anchor"
 "same force on the anchor"

...are all potentially correct depending on whether we're talking (1)vs(a), (1)vs(b), (2)vs(a), or (2)vs(b).

or 7) "Yer gonna die"

I don't know what device you are using for toprope soloing, but I use a shunt with doubled rope (i.e. set up in top rope mode). I tie the bottom ends of the rope together above ground and weight with gear or a rucksack- this seems to work perfectly well and just takes a couple of seconds to take the knot out and be ready for toproping again.

Serge is correct, (1) would be a doubled moving rope system. (2) would be a single, fixed, non moving system.

Thanks for all your input, everyone who responded. No one has told me how I’m gonna die with this system, so I’ll give it a shot in the next few days.

I do this all the time, usually after changing my mind and deciding to do another lap on something I just rappelled from after a rope-solo lead.

Just anchor one end down first and climb on the other. But to reduce stretch you can:

If there are rings/links/small biners sufficient enough to jam an overhand on a bight, you can use that fact -- knot jammed against the links on the opposite side you're climbing on -- to effectively give you a single strand set-up. Of course you can also anchor the other end for extra safety should the knot slip. Just pull the anchor-end of the rope whem you're done.

You could even pre-set it this way to begin with and simply belay your partner as usual (the knot would be at you when they arrive at the anchor).

Either way I'm sure yer gonna die!

climbing coastie wrote: There would actually be less stretch giving that you’d fall on two strands of rope vs one. 

VERY wrong. That would only be the case if he were actually attached to both strands to limit them running through the anchor.

Otherwise, rope deflection will be delta = PL/(EA) where:

• P is his weight

• L is the length of the rope under his weight

• E is the stiffness of the rope

• A is the area of the rope cross-section 

If he is attached to one strand and it is fixed to the top, L will equal the length of the pitch since his weight is transferred directly to the anchor. If it is running through the top rope anchor and fixed at the bottom, L will equal twice the length of the pitch! So he will have twice the rope stretch.

Mark P Thomas wrote:

VERY wrong. That would only be the case if he were actually attached to both strands to limit them running through the anchor.

Otherwise, rope deflection will be delta = PL/(EA) where:

• P is his weight

• L is the length of the rope under his weight

• E is the stiffness of the rope

• A is the area of the rope cross-section 

If he is attached to one strand and it is fixed to the top, L will equal the length of the pitch since his weight is transferred directly to the anchor. If it is running through the top rope anchor and fixed at the bottom, L will equal twice the length of the pitch! So he will have twice the rope stretch.

But if he ties into one end, runs the rope to the top, and belays himself with the other end he will be on two strands and will result in less stretch. I believe even your math proves this to be correct, but I'm not 100% sure I'm doing it right.

I think we can leave this thread alone now, since OP screwed up and cratered 6 months ago.  (j/k)

I'll let it die after this comment mike. I want to provide some input in case someone hits this thread in a search so that it can stay dead.

I used this exact system before I decided I liked a fixed line better. I assume you're self belaying with a gri-gri as you climb. You will not die with the slingshot self belay but it is hopelessly inefficient. you need to pull twice as much slack through the system as with a fixed line, you may have to fight friction as you pull slack because now your rope is moving through the anchors and potentially dragging over the rock, and you introduce the opportunity for the end of the rope you tie into to interact with the gri-gri and potentially catch on the lowering handle making backup knots even more necessary. You also now have to faff about with two ropes in your way as you climb as opposed to one, and you introduce more wear (albeit minor) on your anchor and rope as they run across one another. I can't speak to rope stretch, as I have found no noticeable difference between a slingshot and fixed line self belay.

Conclusion: A fixed line is in every way superior. The slingshot self-belay its an inefficient system, but not entirely unsafe. You need to take more care with slack management and the interaction of your tie-in end belay device and there is no excuse for not using backup knots while using this system. That being said if top access is a pain, the climbing is easy, and you're aware of the inherent risks of the system you're using its a fine way to get some mileage in on a kid oriented day out climbing.