A ropewalker system with mechanical advantage

I am thinking about a rope ascension system for someone with limited strength, possibly hauling a pack.  A sit-stand system allows lifting the load using both legs, but it is inefficient due to sitback especially without a dedicated caving harness.  A ropewalker is highly efficient but it requires lifting the full load with one leg.  I sketched the foundation of a system that I think could serve. The idea is to give 2:1 mechanical advantage in an alternating step to provide an easier lift without the inefficiency of transferring weight on and off of a harness—a ropewalker in granny-gear, essentially.  It would not be as efficient as a full ropewalker with a chest box but it would also require less gear.

I would realize this by linking the left and right footloops through a pulley on the upper ascender.  Load would be on both feet at once but with one leg held straight that half of the load would be supported skeletally, wasting little energy.  At the bottom of the step weight is transferred to the lower ascender by a second cord sized to keep the ascenders from colliding, then the opposite foot is raised along with the upper ascender by hand.  The lower ascender would be lifted along with the climber by a leash over the shoulder.  This would not permit the fluid stride of a ropewalker where one foot is lifted at the same time the other is lowered as the user would need to hold the stationary leg in place until the step is complete, but I think it could still be pretty good within the niche.

Before I try this I wonder if it has already been done and there is experience I can draw from, or if there are any obvious reasons it cannot work.  Both ascenders would be attached to the climber with safety lanyards.  I have not tried to work out change-overs, rebelays, etc. This is just a starting point.  Is this worth pursuing?

Red arrows indicate movement of the ascender on the rope.

As a geometrically challenged person myself, all I know is, you gotta put it together and report back the results!

The blue line sure looks like a 2:1 but normally the advantage is gained by pulling the load up in the other direction! To lift the right foot, for example, isn't the green line to the left foot going to take all your body weight? Then you inevitably need to sit on a separate leash to the upper ascender to move the bottom one up?

jt newgard wrote:

As a geometrically challenged person myself, all I know is, you gotta put it together and report back the results!

I will. I may be trying to pull myself up by the bootstraps, and you're welcome to laugh at me.

The blue line sure looks like a 2:1 but normally the advantage is gained by pulling the load up in the other direction! 

Think of it like pulling yourself up to a quickdraw by pulling on the back strand of rope; it's 2:1 even in the other direction.

To lift the right foot, for example, isn't the green line to the left foot going to take all your body weight?

That's the intention.

Then you inevitably need to sit on a separate leash to the upper ascender to move the bottom one up?

When the right foot is pushed down force should transfer through the pulley and pull the left foot up, along with the rest of the climber, unweighting the lower ascender and allowing it to be lifted by a lanyard.

Cave exploring systems may be better than what climbers have developed for rope ascending for a person with limited strength as they use often use a full body harness.

Very clear answers! I'm seeing it now. Thanks

You gotta try it for sure! ;)

Doug Haller wrote:

Cave exploring systems may be better than what climbers have developed for rope ascending for a person with limited strength as they use often use a full body harness.

I am familiar with caving systems through chapter 7 of Vertical, as well as Derek Bristol's introduction to vertical caving. For my own needs I selected a "frogwalker" which adds a foot ascender to the basic sit-stand system to allow ropewalking, using the arms to stay close to the rope instead of a chest box. None that I have seen or tried yet quite hit the sweet spot I'm hoping to find.

A super deluxe ropewalker system incorporates a chest harness with a roller in it. Attached to that is a small pully with bungie cord attached to the two ascenders, bringing them up without the use of your hands. You can simply lean back and climb stairs. You do need a third, running ascender like a Gibbs above your top ascender to rest comfortably. This third one is attached to your waist. Otherwise, resting is facilitated by slumping onto the chest roller that jams into the top of your ascender.

Is this intended for free-hanging or on a wall that's slightly less than vertical? In the latter case, you're asking the lower foot to move upward while the upper foot moves downward, relative to the wall. Toes are going to drag and catch on wall features.

Tim Stich wrote:

A super deluxe ropewalker system incorporates a chest harness with a roller in it.

That's the "chest box" I mentioned earlier.

 Attached to that is a small pully with bungie cord attached to the two ascenders, bringing them up without the use of your hands. You can simply lean back and climb stairs.

And that's why my 2:1 idea can never be as efficient as a full ropewalker: one will still need to use the arms for balance.  However a true ropewalker is a lot of gear to manage, the chest harness is restrictive, and it requires some strength when hauling.  I built one with a DIY chest roller following Clinton Elmore's guide and decided it wasn't necessary for a 100 foot ascent; the frog-walker is more than enough.  On a 300 foot rope I imagine I would need a chest roller, but I'm not doing anything like that yet.

 You do need a third, running ascender like a Gibbs above your top ascender to rest comfortably. This third one is attached to your waist. Otherwise, resting is facilitated by slumping onto the chest roller that jams into the top of your ascender.

I believe you need a third ascender for safety as well, unless you are using the Mitchell system where the chest box is a life support component.

Kevin Neville wrote:

Is this intended for free-hanging or on a wall that's slightly less than vertical? In the latter case, you're asking the lower foot to move upward while the upper foot moves downward, relative to the wall. Toes are going to drag and catch on wall features.

Good point!  I had hoped it would work for both.  With the setup sketched it would be possible to lift both feet at once, instantly converting to a poorly-proportioned frog system, but that would still have the problem of dragging the toes up the wall and unlike a regular frog one could not use the feet independently.  I suppose the system would need to be converted for anything much off vertical.  Perhaps a single-foot 2:1 by attaching the other end of the long foot cord back to the harness, or locking out the pulley in some way (a clove on the pulley carabiner might suffice) to give standard 1:1 with independent use of the feet?

As a caver who has had to do without before, I can attest to the truly game changing aspect of even a mediocre chest harness and roller. I personally prefer the single bungee rope walker, but I used everything from the frog system up to the double bungee before settling on the single. When properly tuned it looks and feels like riding a recumbent bike. This system also works well if/when things go less than vertical since all components are more or less independent of each other. 

The best resource available to really dig into these systems, and just about anything vertical, is On Rope One by Bruce Smith. abebooks.com/Rope-North-Ame…;gclid=CjwKCAjw9LSSBhBsEiwAKtf0n8laUgffWx_mEa1V5Up0Lt6hUZvzdQswYbsJ-YGUMithOLwTsIZJfRoC5MIQAvD_BwE

Bobby T wrote:

As a caver who has had to do without before, I can attest to the truly game changing aspect of even a mediocre chest harness and roller. I personally prefer the single bungee rope walker, but I used everything from the frog system up to the double bungee before settling on the single. When properly tuned it looks and feels like riding a recumbent bike. This system also works well if/when things go less than vertical since all components are more or less independent of each other. 

What style of chest harness and roller do you use?  How similar to or different from Clinton Elmore's 2012 system is yours?  https://www.youtube.com/watch?v=T8MqJnmU8H8

I tried a chest roller like his and I could see the benefit for long climbs where my arms and back would fatigue but I did not find it necessary on a short climb, preferring a frog walker like this, but without the custom equipment.  youtube.com/watch?v=8SpQ1AC…

Do you use the roller on all vertical climbs or only long ones?  For less-than-vertical sections do you fall back to a Texas system like Clinton Elmore, or something else?

I shall try to test the basic 2:1 concept without roller today.  Assuming it works at all if I find it too upper-body intensive I'll try to figure out if it's possible to add a chest roller.

Webfoot wrote:

What style of chest harness and roller do you use?  How similar to or different from Clinton Elmore's 2012 system is yours?  https://www.youtube.com/watch?v=T8MqJnmU8H8

I tried a chest roller like his and I could see the benefit for long climbs where my arms and back would fatigue but I did not find it necessary on a short climb, preferring a frog walker like this, but without the custom equipment.   youtube.com/watch?v=8SpQ1AC…

Do you use the roller on all vertical climbs or only long ones?  For less-than-vertical sections do you fall back to a Texas system like Clinton Elmore, or something else?

I shall try to test the basic 2:1 concept without roller today.  Assuming it works at all if I find it too upper-body intensive I'll try to figure out if it's possible to add a chest roller.

Clinton Elmore's system is essentially a single bungy rope walker, if a little "crude". Generally when I'm going onto short, or less than vertical, climbs I end up with the system in the second video minus the croll or a chest roller, I do like the mix between fog and walker that he did though.  

Put me on anything over 100 feet though, and I'm almost always going to want that roller or a full frog system. MP says my file sizes are too large, so I'm going to PM you with photos of my setup. 

Bobby T wrote:

Generally when I'm going onto short, or less than vertical, climbs I end up with the system in the second video minus the croll or a chest roller,

You have only a single life-support ascender on the rope at this point?

Looking forward to seeing your photos.

I didn't find time to test my idea yesterday, and I probably won't for a few days now.

Webfoot wrote:

You have only a single life-support ascender on the rope at this point?

Looking forward to seeing your photos.

I didn't find time to test my idea yesterday, and I probably won't for a few days now.

Not in most cases, because my knee ascender has a sling attaching it to my harness. At the same time, in caving situations, I've always felt that the whole "single point" argument can get a little over blown. For anybody using a rappel rack, which I prefer, any time you're on rappel you have only one single point of contact. All of that said, there are times when I clip in with just my handled ascender and my foot. YMMV

I briefly tried this today and it was a failure.  I could not sufficiently keep slack out of the lower ascender system to prevent downward movement as weight was transferred onto it.  It was not a large sag but with forward progress being one half the step height in 2:1 it was still too much to be efficient.

Perhaps with a caving harness on the lower ascender instead of a bungee and a lot of rope weight below the system it would stay tight enough, but if a chest harness is used I think a conventional ropewalker with roller will be better.