A question about springs

Thinking about how to reduce the abruptness of the catch when soloing leading, when there is no haul bag in the system as a counter weight: might a metal spring be or use, or some other form of shock absorber?

Sorry if this a stupid question, or if I'm being lazy not doing the physics myself. I guess it comes down to a realistic spring constant and max of 50cm of extension of the spring

PS. I already use a screamer in the system, and have a couple of the CT reusable ones. However they need to be replaced or reset by returning to the belay. Which is a right pain on hard stuff, where I might fall several times.

What about the Edelrid Absorber Sling?

youtube.com/watch?v=mN1XJtQ…

I'm not sure if it's out yet, though.

I've incoporated a Yates screamer into the anchor attachment when I'm concerned about falling and wanting to reduce the impact forces.

I haven't tested it with a fall yet to speak for sure how well it works though.

john l. wrote:What about the Edelrid Absorber Sling? youtube.com/watch?v=mN1XJtQ… I'm not sure if it's out yet, though.

Thanks, but one would need to get back down to the belay and replace it with a new one each time one fell.

What I'm after is something that gives about the same amount of give as lifting up the belayer does.

David, maybe if you told us more about your setup it would be easier to envision where this device would fit in.

It sounds like it would need to be attached to your harness somehow, as you've mentioned not wanting to return to the anchor. There's probably not a ton of room between your harness and soloing device, which is where I'm guessing the spring would be. With a spring in the system, you'd probably want some sort of limiting / load bearing line running through / around it?

What about a rigging a anchor brake (like a Kong Kisa) in between you and your solo device? That would allow you to reset it after a fall and tune the amount of absorbed energy based on number of holes used, rope length, etc.

Perhaps you could use many wraps with a long piece of surgical tubing (i.e., the stretchy rubber band used for various physical-therapy exercises) through two locking biners. If it is too stretchy, then you just add another wrap or two. Then back it up a long, slack loop (or two) of 1" tubular webbing.

Such a system could be fairly light and reliable, and it ought to contract back after each fall without you having to go down and reset.

That Edelrid absorber is just a screamer. It's advertised for multi pitch climbing. Seems kind of stupid to me since you can't tailor the length.

Anyway to get back to your topic. Just blowing an idea out of my ass. It may be plausible to bundle a bunch of bungee cords like they use for jumping. Somehow make an eyelet at each end. You could experiment with different loads to max the bundle out, say at least 200kg up to say 600kg, maybe more I'm not sure. Ideally your want a limiter sheath to hold 2200kg but 1600 would be sufficient i think. This sheath would also protect the rubber bands from abrasion.

So let's say this bungee is 2 feet long static and 6 at full extension. Next tie your rope into the anchor as usual. Clip one ended of the bungee into the anchor. Grab 7 feet of rope slack and make another knot. Clip this knot into the other end of the bungee. This is your failsafe.

Disclosure: I've never seen or heard of anything like this and don't know how you'd make the end loop or what type of bungee to use. I think it would be doable with a lot of research, resources, trial and error.

Great minds Jon

David ...

Use the softest catching beal rope you can find ...

;)

I most certainly would not try to rig some contraption using springs, bungee cords or the sorts. This is not a new topic and soloists have been discussing this for years.

There are two main options. The first is to use the haul bag as a counterweight, which you said you dont have. The second is to use energy absorbing slings like a Screamer. You can place multiple ones in series to increase their effect. You can also use a via ferrata sling, which is just a larger version of a screamer. The Perzl Vertigo is a good option because it can be reused (although officially they are not supposed to be reused if you take a via ferrata fall on them).

gearx.com/petzl-zyper-verti…

A more advanced option would be to purchase only the energy absorbing plate that the lanyard runs through and attach that directly to the rope. The downside to that is it would take some serious testing to determine what threading sequence provides enough, but not too much, friction. Also, those devices are very rope diameter and rope wear dependent.

Mooring line snubber at any yacht chandlers. jimmygreen.co.uk/products/c…

Thanks everyone.

Just to repeat, this is not about solving problems with high factor falls, or preserving the integrity of the belay. The issue is about getting through the crux. i.e. multiple falls. Getting back to the anchors to re-thread a reusable screamer isn't an option.

It comes down I think to putting a spring-like device on the belay. As the effect I've after is no more than the replacement of the weight of the belayer this seems more than possible.

Interesting device Jim.

F=ma, with m=60kg (weight of belayer) and a=g=10, gives F=600N. Can a piece of elastic something give this? I guess so.

From the video, it looks like the Edelrid Asborber sling has an elastic sling in addition to the screamer component. But it does look like the elastic sling lacks the tension to absorb a whole lot of force.

David Coley wrote:Thanks everyone. Just to repeat, this is not about solving problems with high factor falls, or preserving the integrity of the belay. The issue is about getting through the crux. i.e. multiple falls. Getting back to the anchors to re-thread a reusable screamer isn't an option. It comes down I think to putting a spring-like device on the belay. As the effect I've after is no more than the replacement of the weight of the belayer this seems more than possible. Interesting device Jim. F=ma, with m=60kg (weight of belayer) and a=g=10, gives F=600N. Can a piece of elastic something give this? I guess so.

The max force Forsheda give on their smallest one is 2kN which is probably to failure but I guess you need to get someone to actually measure the force to extend the snubber as the rope used and the number of turns makes a fair difference. Borrow one from a yachtie and bounce around on it maybe?

beal propaganda ....

Performance which greatly exceeds the Standard
requirements

In the dynamic tests conducted in the drop tower, generally known as the UIAA test, the Standards have two requirements:
- The ropes must withstand a minimum of 5 successive falls made at 5 minute intervals.
- The maximum impact force recorded on the first drop must be less than 12-kN for single ropes, and 8-kN for double ropes. Recorded impact forces are even more astonishing

Apart from Wall Master V, with very specific properties, all the single ropes have a maximum impact force of around 7-kN, and the double ropes around 5-kN.
But we go much further, because at the end of the series of successive test falls, our ropes still do not exceed the limit which is only required for the first fall! When you consider that rope loses some of its dynamic qualities with each fall, this is an incredible performance, guaranteed only by BEAL!

as you can see even in a "low friction" falls scenario a softer catching rope may well reduce the impact force at the runner ~2-3 KN or 20-30%

;)

I see absolutely no safety problem with tying in an industrial spring at the belay as long as you keep your rope tied into the belay and at the other side of the spring at the maximum stretch you desire. That would take a large amount of force off the anchor and provide a much more dynamic catch. It would also automatically reset itself and and industrial spring would not be damaged by multiple falls like a stretch band would. Even if the spring broke, which it wouldn't if you bought the correct one, the rope would still catch your fall like normal. There is no harm in trying it out in my opinion. It sounds like a great idea and I foresee no safety issues. Does anyone have any solid info on why that setup would not work?

David,

Do a Goggle search for "Gymnastics Ring Springs"

This device is used to connect the rings/cable to the support stand.
It allows the cable to stretch (i.e. through the spring's compression) when the gymnast passes through the bottom while swinging.

Gymnasts often surpass 6 G's during their swing, so I am sure it will take a small lead fall.

I would imagine you could install it at the bottom belay such that the rope is still totally in the system in the event of any spring malfunction. A picture is attached - perhaps, if this specific ring spring wouldn't work, it may give you an idea for something else.

I can definitely tell you that they certainly make a difference in the rings event (i.e. swinging with no spring vs. swinging with a spring).

Good luck.

Thanks Marty. Just so I can get an idea of scale, very roughly how long is the spring in the photo?
Thanks.

Hi Bearbreeder,
The last row of your table kinds of says it all. These are large forces. Even the lowest might be 5kN on the climber. And in the test (looking at the sketch) the belayer might be pulled upwards - with a solo the rope would be tied to the anchor. So, even though the FF would normally be lower on a fall from a crux (hopefully a runner near), the forces can be high.

This is what I experience when I fall on a silent partner. It can be brutal.

David,

Spring length depends on particular manufacturer.
It will vary from 3 to 6 inches.

Good luck.

Getting one of these porch swing springs and putting in inline between two butterfly knots seems like it would work. Appears to be the same as one of the yacht snubber designs but it's available at Ace Hardware:

$11.99 porch swing spring

(Edit to add: Oh. You're in the UK. No Ace Hardware for you.)