Rope Solo w/Gri-gri
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Even if you use dynamic ropes for solo toproping, when you near the top anchor, there is little rope to stretch and the remaining rope is essentially static. A fall here is going to be a factor-2. This could be an argument for using a Screamer to connect your harness to the ascender. |
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George Bracksieck wrote:Even if you use dynamic ropes for solo toproping, when you near the top anchor, there is little rope to stretch and the remaining rope is essentially static. A fall here is going to be a factor-2. Some ascenders will inflict more damage to the rope during the impact created by a sudden solo-toprope fall. The Mini-Traxion has sharp teeth, which can shred a rope. Even the Microscender, which I used for years, have a relatively long lever arm to drive its benignly toothed cam into the rope. Now, my gadgets of choice for solo toproping are the uAscend and the Cinch, one on each of two separately anchored ropes. The uAscend is the resurrected Ushba Basic and acts as a cam bending the rope to hold a fall. The Cinch also operates by bending he rope. The Grigri (as well as the Microscender) has a camming lever to pinch the rope, whereas neither the uAscender nor the Cinch do. The uAscender slides easily up an unweighted rope. The Cinch generates some friction when sliding up, but not nearly as much as the Gri does. As with the Gri, the Cinch can be used to descend the same rope. The uAscender is rated to only 4kN, so backing it up with the Cinch on another strand is important. I bought my uAscender from GrandWall Equipment (www.grandwallequipment.ca or 6045187432). The Cinch is made by Trango.the uascend spring can fail ... one of my partners had that happen ... fortunately he caught it when he was on the ground dirt can also get into the spring mechanism ... also the old ushba cut the rope at 6-7 KN the microcender essentially has no moving parts beyond the lever arm and has been tested on a factor 2 fall ;) |
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I edited this tweak into my previous post while bb was making his post: Generally, connecting your harness to any ascender with a Screamer would reduce potential impacts. |
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bb said: "also the old ushba cut the rope at 6-7 KN." |
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I just got out my uAscender and operated it on a rope. Contrary to my earlier statement, the camming of the device (to bend the rope) also presses the rope against one end of an internal lever, which pinches the rope with the other end of that internal lever. This process appears to be independent of the spring action of that lever. (You have to open the spring-tensioned lever so as to put the rope into the uAscender.) |
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George Bracksieck wrote:bb said: "also the old ushba cut the rope at 6-7 KN." Was that with the Ushba Basic, or with the Ushba ascender with the handle, which has a longer lever arm?the model tested is basically the same as the uAscend thats sold now except it was the titanium version ... cut the rope at 5.5 KN Industrial rope access - Investigation into items of personal protective equipment Prepared by Lyon Equipment Limited for the Health and Safety Executive the microcender and the larger rescue version were some of the best performers ... Industrial rope access - Investigation into items of personal protective equipment summary of slippage points of various devices .. Industrial rope access - Investigation into items of personal protective equipment George Bracksieck wrote:I edited this tweak into my previous post while bb was making his post: Generally, connecting your harness to any ascender with a Screamer would reduce potential impacts.yes and no ... the knot at the end of the dynamic rope should be more than sufficient for reducing the impacts ... and in fact a short length of knotted dynmic rope as a tether may be more effective also remember that with a screamer or tether you are INCREASING the fall height/factor the main reason to use a dynamic tether is in the not infrequent situation in TR soloing (and setting up TRs) when your anchors are right on the edge of the cliff/slab ... if you were to fall setting up you would be above your anchors also when topping out those kind of climbs as well DAISY CHAINS AND OTHER LANYARDS: Some Shocking Results when Shock Loaded Series of tests on Cow's Tails used for progression on semi-static ropes the uAscend will work just fine as long as you know its limitations ... however any mechanical device can fail ... a friend of mine was working bruce lee (13- trad overhung) out here and fell on his uAscend .... the device might have gotten a bit twisted when he was pulling the roof and it zoomed down the rope for 20 feet or so before it caught him off the deck the only "certain" way is to use a secondary device, clip in point or knot backup ;) |
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I'd recommend a skinny 9.2 or less and supple, weight the end with your approach shoes gri-gri on and good to go, no pulling slack required. |
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bb, thanks for the docs. I have a few questions/comments. |
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Larry S wrote: The difference is your belayer has a hand on the brake strand and is maintaining the device. In top rope soloing, the grigri is flopping around on your belay loop, it could potentially get into a position where the cam is obstructed, the carabiner is crossloaded, etc.Tape the brake down.,,obv backing it up is ideal 😉 |
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George Bracksieck wrote:bb, thanks for the docs. I have a few questions/comments. re: test of the Ushba Stop-Lock ("Basic"), how were tests performed? I'm not doubting the validity; I'm just curious. re: test of the other gadgets, in which there was slippage of the Microcender, etc. Did slippage continue down the rope while under load? Did slippage cause rope damage? re: test of Shorty Screamers. Failure was the result of an unusually heavy weight (100kg) dropped onto a Shorty, which has little impact-absorption capacity. John Yates once told me that the biggest, heaviest Screamer was the best choice for energy absorption. I've watched drop tests on ice screws, with the same conclusion. Consequently, I've always used those as draws on my screws. I agree that keeping the attachment to the device as short as possible is a good idea.full report here ... the methods are in the appendix hse.gov.uk/research/crr_pdf… basically the HSE tried to determine whether the device was suitable for workplace fall arrest protection ... which is the same concept as TR soloing, just with a lot more liability on a dynamic rope you really dont need a screamer with a microcender ... the knot will absorb a significant amount of energy as well as the rope itself ... not to mention itll slip around 3-4 KN the absence of stripped sheaths or cut ropes when using toothed ascenders and ushbas should tell us that 4 KN (5.5 KN ushba) is likely the upper limit of what a TR solo fall impact force realistically is ... the one exception though is if the device fails to catch and hits the inline knot, using 2 devices will solve this problem however the main disadvantage of toothed ascenders is that if it hits the knot as you reach the anchors, its an absolute biatch to take the ascender off ... ;) |
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George Bracksieck wrote:Even if you use dynamic ropes for solo toproping, when you near the top anchor, there is little rope to stretch and the remaining rope is essentially static. A fall here is going to be a factor-2.If you are below the anchor, the fall can NOT be factor-2. You may approach a factor-1 fall as you get close to the anchor, but not a factor-2 unless you climb above your anchor. |
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JSharpe wrote: Tape the brake down.,,obv backing it up is ideal 😉Tapping a grigri would prevent it from braking... you really don't want to do that. |
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David Gibbs wrote: If you are below the anchor, the fall can NOT be factor-2. You may approach a factor-1 fall as you get close to the anchor, but not a factor-2 unless you climb above your anchor.If you are climbing above the ascender (that you are dragging behind you) and fall, then you will fall from above the ascender to below it, which I think would be a factor-2. That's a good reason to clip your harness directly to your ascender/Cinch/Grigri/whatever to shorten or eliminate such a potential fall. Unless you push the gadget above your attachment with each move, it could be below your attachment. Edit/addition: Even if the fixed rope(s) that you are using for your solo toprope are dynamic, you aren't going to have nearly the give/stretch in the system as you near the anchors, when compared to a toprope or lead belayed by a human. |
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George Bracksieck wrote: If you are climbing above the ascender (that you are dragging behind you) and fall, then you will fall from above the ascender to below it, which I think would be a factor-2. That's a good reason to clip your harness directly to your ascender/Cinch/Grigri/whatever to shorten or eliminate such a potential fall. Unless you push the gadget above your attachment with each move, it could be below your attachment.Fall factor is the ratio of fall distance over the amount of rope in the system. |
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Larry S wrote: Fall factor is the ratio of fall distance over the amount of rope in the system.Say you have a 12-inch tether attaching your harness to the ascender. If you fall from 12 inches above the ascender down to 12 inches below your ascender, that's a 24-inch fall; 24 divided by 12 is 2. Same if you clip a locker directly into the device, so that you could fall from 3 inches above the device down to 3 inches below it. |
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In climbing (specifically in lead climbing) using a dynamic rope, the fall factor (f) is the ratio of the height (h) a climber falls before the climber's rope begins to stretch and the rope length (L) available to absorb the energy of the fall. |
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George Bracksieck wrote: Say you have a 12-inch tether attaching your harness to the ascender. If you fall from 12 inches above the ascender down to 12 inches below your ascender, that's a 24-inch fall; 24 divided by 12 is 2. Same if you clip a locker directly into the device, so that you could fall from 3 inches above the device down to 3 inches below it.The FF is the distance you fall divided by the rope out in the system. If you are attached to an ascender by a tether and climb 12 inches above it, you fall 24 inches. But you do not have 12 inches of rope in the system. You have whatever amount of rope is between your ascender and the anchor (assuming a static tether, add 12 inches if using dynamic rope for the tether). That is why the fall factor increases as you approach the anchor. There is less rope in the system to absorb (denominator). So in this scenario, a FF2 could occur with the 24 inch fall when you are 12 inches below the anchor (static attachment). And it could even exceed 2 if you fell twice the length of your tether (24 inches) with less than 12 inches of rope between the ascender and the anchor. |
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csproul wrote: The FF is the distance you fall divided by the rope out in the system. If you are attached to an ascender by a tether and climb 12 inches above it, you fall 24 inches. But you do not have 12 inches of rope in the system. You have whatever amount of rope is between your ascender and the anchor (assuming a static tether, add 12 inches if using dynamic rope for the tether). That is why the fall factor increases as you approach the anchor. There is less rope in the system to absorb (denominator). So in this scenario, a FF2 could occur with the 24 inch fall when you are 12 inches below the anchor (static attachment). And it could even exceed 2 if you fell twice the length of your tether (24 inches) with less than 12 inches of rope between the ascender and the anchor.For the purposes of calculating fall factor when approaching the anchors, your tether does behave as a short rope. In my earliest post, I was addressing the "approaching the anchors" situation, in which there is little give in the system. |
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I don't know if anyone has ever truly calculated factor 2 fall when your system is built with taking into account multi factor 2 falls on alot of leashes built together with ascenders / breaking devices. |
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posted today ... skaha incident ... |