Yeah, it would be very interesting to see on real rock... especially the difference between granite vs sandstone if possible! I'd think friction might not matter as much on sandstone though: the rock itself might shear more easily under those forces which would make obsolete any frictional resistance the rope might encounter.
Also the difference between hard sandstone and the soft sandstone where these are used. Sometimes it feels like grabbing sand not actual rock. I think the rock is likely to break
Sandstone in Czech Republic, Poland and Germany is delicate. Using metal pro leads to rockfall and changes cracks into lines made of holes. Moreover people often climb after rainfall and break the rock. That's long & short :)
@@marekholub8668 It would be interesting to see actual drop tests that proves if this actually happens. I've climbed in Germany's Pfalz mountains on sandstone and didn't observe that. What if you place a cam deep into a crack system? Perhaps longer stemmed cams could increase safety in soft sandstone. I liked someone's comments below. He said that using such gear as knots and climbing in Czechia is a lifestyle and adventure. Others have said it is about the cost of gear. Others have said that the American use of cams is more about a desire for a label and shiny metal. I'd like to see tests comparing cams and knots on actual cracks in Czechia. That will chase my skepticism away and replace it with scientific fact.
@@Davidadventures Nah, the point of not using cams is that we don't have enough sandstone for everyone, which means we have to be gentle, otherwise there won't be any left for the next generation. And no chalk allowed for the same reason.
I have a feeling that these rely on frictional forces to a great deal, especially since they are being placed in soft sandstone. I think it would be great to see some real rock tests, or maybe you could add some sandpaper to the inside of "your crack"?
@@antonf.9278 These are quite specific, here the sandstone is very rough (about 40 sandpaper) and sometimes you want your sling to really hold and stay on smaller tips (sorry, I have just realised that I have never heard English phrase which would describe throwing sling over a pointy rock feature). The slings then work as velcro and are far less likely to fall off the point when you pull on them with a rope as you climb further.
I think they could try getting the faces if the cam crusher sandblasted. It would give a more realistic rough face without the problems that sticking sandpaper to it would cause.
As a climber from Czech republic, who uses these a lot, I can share following two remarks: first, yes, the knots indeed do rely on friction a great deal and second and foremost, there is a fundamental error in your test machine setup. I can clearly see, that you screw the one end as tight as possible, so the knot can not be pulled through, but once you start the machine the far ends of the contraption are not kept in place, they get closer to each other and that makes the gap with the knot to become slightly wider and the knot gets pulled through. I think you should have used something to keep the far end the same width. Also, this kind of strain does not occur during climbing, there is no steady pull with increased force, instead there is a really short twitch, so the knot does not have time to deform that well. Once you complete your tower, much more representative tests could by done by throwing weights from the top to the anchor made of the knots.
I live and climb in Czech republic. Rock in some crags is actually that much soft, that if you don't have a hold and you'd rub your foot for 5 minutes in one place, you'd have a pretty good foothold. Friction makes a difference, but it's not all. Placement is key. On a great placement you actually can whip. It's not that uncommon, to put several knots close to each other and clip them the way, that they all are weighted in a single moment in case of fall and weight distributes. Knots don't work all that well when they are on they own, I tend to put more knots in the rock than I would with metal protection. A lot of the routes have metal protection hammered into the rock that is usually pretty good and you can whip on it all day long. If you'd ever have a trip to Europe, definitely come to Czech republic and have a look on how that work!
You could try replacing the steel with concrete paving slab type things tho the slabs themselves might not be able to take the stress of a pull. I would love to see both this in real rock and it done dynamically in the drop tower. I can see the results of a dynamic drop being very different from these results.
Guess, when its about knotslings, soft Sandstone will be way different from steel or concrete areas. The more grip, the more friction, the more Power -Transmission.
@@cutt7837 yes that's who I was thinking. A paving supplier may even just give you various rock types as you only need a few small scrap bits to them. Sandstone and limestone paving common. Granite less so.
Good idea, but like you mentioned concrete don't like pull forces. But small concrete pieces inside of the crack would one dive them pressure force. Which concrete is very good at.
Same rules of using knots over hardware are in southern Poland where the sandstone rocks are present. Also no chalk allowed. Some examples of such gear placement are here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-HXTgPUOEQbs.html
It is sweet indeed, just please be careful, most of the placements you would consider absolute bomber in granite are still rubbish in sandstone. The angle at which the sides are joining should be over 30 degrees and you should place in a slot where the loaded end hardly passes through the tight end. And everything crumbles. Don't be afraid to spend evening before in pub - making some local friends and getting tips, mabye even a experienced lead climber :)
Yes please. I almost exclusively use monkeys fists in sandstone (sometimes also in other rocks). I was hoping to see those here, but maybe another time then ;)
8:30 Yes friction would make a huge difference. Friction also makes the figure 8 much stronger I believe because the knot folds in on itself while beeing as slim as an overhand while placing it.
It is the same in saxonia, there is a long-standing tradition of climbing with rope as protection. I am no geologist. But probably a similar sandstone. Works apparently well and all the top anchors are bolted. Locals get really grouchy if you climb with other gear and it does actually damage the sandstone which is considered a heritage site... welcome to European climbing
The problem with German and Czech sandstone, which are one geological unit, is not really that it is to soft. In some places it is actually quite hard because of regional metamorphosis I suppose. But even in regions with hard sandstone metal protection does not work, because when taking a fall on it, the surrounding surface just gets broken out of the rock. Because the real problem of the sandstone over there, no matter how hard or how soft it is, is the overall porosity of the stone. The porosity is so high, that climbing is forbidden, if it rained in the past 24 hours, because the rock is just too wet and therefore more likely to fail/break. From my own experience I can say, that I have never climbed on better rock than the sandstone in the Bielatal in Saxony, Germany and it is definitely a recommendation for everyone, as long as you have a lead climber, who knows his way around.
@@edwinmahlo427 Porosity isn't a measure of the weakness of the rock, it is the property of friability. However, you are correct that porosity increases the failure of rock when it is wet. If you want to make a landslide happen, add water. If you want your rock to fail, add water. Therefore you have multiple problems. You can't use cams because the rock is friable and you can't climb after rains because the porosity decreases the rock strength. Here in California's North Bay we have cemented rhyolites, some of them are like sedimentary conglomerates, but occur through igneous processes. We can't climb on them after rains for the same reason. But since it hasn't rained here in a few years, the climbing is good, except when the fires sweep through the climbing areas and destroy the bolts. I am an engineering geologist by the way.
@@edwinmahlo427 Actually there was an short investigation considering metal gear (at that time = nuts) on saxony sandstone. It didn't find the the often citated rock failure, at least not different to slings. Back then it was decided to stop testing nuts to preserve the tradition. It was definitely not a fact based decision to ban metal gear but rather a highly emotional one (as it's the case for many of the saxony climbing rules). If you look closer it's an repeating pattern to argue based on "facts" that have never been proven in most of the discussions surrounding climbing in Saxony. The funny thing is even evidence often times can't change the believe in these alternative facts...
@@Davidadventures the problem in saxon or bohemian sandstone (its the same) is that the compuond that holds it together is water solvable, so basicly it falls apart when wet because there is no „glue“ holding it together, assoon as it dries its solid again. This happens less with sandstone that has a major metal component like the dark sandstone found all over bilathal (lots of iron working as „glue“) so you can climb those towers pretty shortly after rain, just 20km away the „rathener gebiet“ is called cookies or „rathener keks“ among locals as its so likely to break, even when dry. Sandstone geology is wild 😂
Just came back from a beautiful day in Elbe valley, climbing some fun sandstone and what a pleasant surprise I found in the subscriptions. Great job, nice to see these tested.
Why does that guy ask us "IF" we want to see real rock test ? Shouldn't he ask about "WHEN" we want to see it instead ?? We are not gym climber here, we want rock by the roll of course !! PS : greetings from Chamonix, keep up the great work guys
@@marekholub8668 knot stuck in cracks have been wildly used for climbing all over the world in all sort of rocks long before metal protections been on market (just read old books from Bonatti or Rebuffa and al.). As of the present, fact is it is lighter, it is much much cheaper, and it has better availability. So having test that show if it can be a viable option is indeed of great interest far beyond the particular case of one small portion of one country. From this video i can see some potential for it. So yes any test in any type of rocks makes us all advance, no matter the country.
@@lolaa2200 Yeah, I know it has been used on all types of rock. I'm just saying the tests in other rock wouldn't be relevant to Jenny's videos. If you can use cams and nuts on your climb, you are safer using them over textile pro. If you can't, they are definitely better than nothing.
I imagine these would hold up better on real rock, especially when being pulled from an angle. Super entertaining video though! Probably one of my favs!
In a moment of desperation i have placed a prussic into a crack an fell with it at my hip height. And it held. It was really hard to remove it though... So I know for a fact that it can work. But i like my solid cams better. Or even the emergency BD guide stopper like you instructed on one of your videos! LOL
Well, anything metal might also be likely to rip or break out enough stone as to come loose. An expanding dynamically loaded knot might hold a lot better.
Hey Rian, maybe your jig isn't that optimal for soft nuts. The side plates change angle when pulled (good to see at 08:00) . Therefore the front of the gap opens for smaller knots. Maybe you could test the small pieces again with a jig with fixed angles? Best regards from germany :)
Yep, exactly what I noticed. The knots actually pushed the side plates open. Should be easily fixable by fixing the rear of the plate so that it doesn't move.
Stoked for all the engagement so far! The ground is prepped for drop tower, crane is 100% working and all the parts are painted. We "just" have to assemble it now, lift it up and decorate it. Donations really appreciated while we take the drop tower project over the finish line. 😀 www.slackline.com/donate
just fyi - "How does the comparison of knot loop and cam look like? The discussion about local usage bans should be disregarded here. Therefore, the range from loosely pushing through to tight is very small. The range of extensions 30mm is better covered; cams are also easier and quicker to lay. With Friends you can then secure completely parallel cracks. A knot loop is softer and therefore has a larger contact surface. This means that the risk of rock damage is lower with soft rock. Knot loops are a bit more complex to lay, you shouldn't forget that there is a certain range from lying well to pulling through. A knot loop has more friction with the rock. This has the advantage that a knot loop does not loosen as quickly as a cam through rope movement. Knot loops can also be placed in relatively open cracks and holes, in places where a cam would immediately fall out again. The experiments were carried out by Jörg Brutscher, André Hoose and Jens Freudenberger. We would like to thank the Institute for Materials Science for making the tensile testing machine available for these experiments. Thanks also to Martin Lange for reviewing the article. Further details of the experiments are available from the author." [1] See diss. Helmut Mägdefrau: The stress on the human body when falling into a rope and its consequences, available from the DAV safety group. Also: More safety in mountain sports, part 10, Bavarian State Ministry for Labor and Social Affairs - www.joergbrutscher.homepage.t-online.de/knoten.htm
Hi guys, I just had an idea, you might be able to create a more rock like surface in your clamp by coating the steel with epoxy and dusting it with sand while still wet. Kinda like non slip epoxy floor coating.
I don't know much about the whole using knots in rock vs in that clamp, but I do know that some rock like limestone and such, don't look anything like that clamp, with all those grooves and whatnot, on account of how smooth it is, and in some cases probably even more cushioning than that metal clamp... If I'm wrong in any of this, please correct me, but just given what little I know about rock, I know that different types of rocks might have different grip properties and characteristics, the same as testing out those forces in a metal clamp will likely behave differently in rock
yeah, do it in real rock...and also if you're ever going to use it again, put some texture in the cam-crusher! (maybe epoxy some flat pieces of actual rock into the jaws of your cam-crusher)
@@kevinmcdonough9097 uh, yes...? epoxy is good for thousands of PSI which should be super-good-enough if the force is distributed by a flat piece of rock above it -- we epoxy in bolts that hold >40kN. I dunno if that's even a great solution, just that slippery grooved metal plates are NOT the right medium for this type of test. Maybe the steel can be textured directly, but I'm pretty convinced rock has different enough friction characteristics compared to metal as to be a poor facsimile.
Please please do monkey fists. Both with 3 wraps with 1 strand, and 2 double wraps with 2 strands (Both ends of the rope in the knot) I've been setting up hammocks and rodeos like that for a long, cant wait to know how they hold up.
Yes, also testing the monkeyfist vs crown knot?? in a soft shackle - is it less crucial to fully tighten / dress or not?? NB a monkey fist can be made pretty-much as bulky as one wants, 2,3.,4 wraps, easy to bulk up....
The sandstone mountains are actually a national park split by the German/Czech border. The park service allows climbers but prohibits the use of chalk or any metal-on-rock trad protection. Some of the routes are bolted, mostly only at the anchor or every 30m with a thick metal ring.
Definitely think it makes sense to test these in real rock; seems like friction plays a huuuge role on how the knots hold up vs. slip through under max kN.
Love this! I love the conventional stuff, but these obscure gear tests are such a nice bonus. I have always wondered about these and other odd pieces of gear like the beal escape and I loved the video on that too. Please test these in real rock!
So glad you did this! Definitely somewhat surprising results. I'd love to see these tests done on the drop tower, maybe between cinderblocks or something rock-like that you could still adjust the gap on (maybe the same as your rig in this video, but with some sort of rock-like tiles/patio stones?). I bet the friction really matters, and falling forces are probably more like prolonged spikes, compared to steady forces seen in the slacksnap machine. If the knot moves a little at high impact, but the impact dies down before it manages to slip out, these knots might perform better than expected.
Climbing sandstone in Czech republic or in Germany is more a lifestyle or adventure than technical pro climbing. I'm happy when my sling holds 6kN because dynamic rope doesn't allow to generate more. Knot will slip away rather than break the cord.
Great work, both yourselve and the local climbers who developed this tradition to look after a fragile resource. I look forward to the friction version.
You should get various stone sample pairs and a good stone drill bit, drill 4 holes like those metal plates you're using and secure them with the bolts. Then you could determine how the type of rock, and their respective coefficient of friction, affects breaking point using a consistent anchor type. Great video! Love to see these tested in a controlled environment.
I am really looking forward to seeing your drop-tower in action! Super curious to see the differences between those dynamic forces and the static / slow ones.
I did that in the day. It's depicted in Royal Robbins' Basic Rockcraft, so I tried it with many regular pieces for back up. It worked. In those days you never expected that a helicopter was going to come and rescue you. Nor was some gym employee telling you that this is a "safe" sport so we learned everything we could since knowledge weighs nothing and could, at the least, save you from the embarrassment of having skilled people have to rescue you due to your ineptitude.
I feel like some kind of coating or liner to ad some friction on the jaws would make a difference and possibly reducing the angle of the plates would help because you’re not getting as much contact between rope and the jaws as you could and the compressive force between the plates would be distributed over a larger portion of the rope thus giving more pportunity for the knot to catch or get hung up further up the jaws
I finally followed your advice and climbed with my totem cams with the tag still on! Was nice to have something to read on the belay. Thanks for the tip
Thanks for all your work! It would be pretty interesting if you would test all that in real sandstone. I am sometimes climbing in the german sandstone of Sachsen, that's on the other side of the Chzech Republic. People there are crazy climbing with this stuff and without chalk.
In 1983 in the kitchen of Wolfgang Güllich and Kurt Albert, Wolfgang held up a piece of rope with a figure 8 to show everyone at the table how knots are used in what was then East Germany (I climbed in the Elbsandsteingebirge twice in 1983, once in 1985, and once in 1994, plus in 1983 in what was then Czechoslovakia, on the soft white sandstone of the Böhmische Paradies, where the rock is much softer than in the Elbsandsteingebirge): "You make ze knot theen, like so, and zen put in ze crack, and pool ze rope so ze knot gets bigger. Just like a Friend, except it does not hold ze bodyveight." 😆😬☺️
Yeah! Please do it in real rock. I’m most interested is seeing monkey fists done. Some with no solid core and some with a solid core (likes a bearing or metal marble)
Would love to see these get some testing in actual rock to see if it makes a difference; more friction may bind them a bit more but the knots deforming could be the main issue!
I fell already few times on stuff like that. We climb in Saxony, Germany only with textile. The biggest problem is the stability of the rock, you can never know.
These tests are nonsense. You can clearly see how the metal plates move backwards during loading and thus enlarge the opening at the front. In addition, the friction of the metal plates cannot be compared with that in sandstone
i have sandstone near my place, and, at least here, its abrasive as hell, i dont know if a knot would stand the forces of a dinamic fall before the rock tear it apart, or if, on the contrary, it would hold because the knot will be stuck in it, seeing that the people there use for climbing, maybe the second one??
The smaller diameters feel a bit sketchy on the rope/shackles as they're impossible to place, but webbings and the bigger diameters I'd whip on. As with other trad gear I'd want two or three of them as placement can be make or break even if you're careful: whipping through one should break enough force even if it fails early to give the next one an independent chance of catching you again.
- Sand friction is different.. - Any metal stuff is not allowed to be used on sand rock. (Most of sands are kind of National Monument or protected zone) - You always fall with angel 60-80 degree - Its possible that second or 3 knot catch you - we call this zipping :) (the first 1-2 can go out and just slow your motion ) - I think this need to be tested with real sand rock but nice video... - You wanna fall to ring not to knot :P but some knots are better than nothing you know :P Because distance between rings are sometimes length of route itself :D
Definitely need to drop test. The slow pull looks like it's generating a lot of heat from friction over time, allowing the plastic to soften and deform. With a drop test, the heat from friction should be negligible and it should simulate the real world conditions a little better. Plus, your metal tester is more like polished granite than sandstone, and I don't know any place that uses soft pro on polished granite haha.
I think you need to add some nuts on the inside of the bolts on the wide part of the slot. It seems like that wide side is closing up like a lever when the knot is sliding through the narrow side. Maybe try adding some nuts to keep it from moving. Because in some of the slowmo tests you can see the "narrow end" of the slot opening up slightly and allowing the knot to slide through easier.
Would also think about using dry treated ropes vs non. At least for mammut, their dry treated ropes are significantly more abrasion resistant vs normal ropes.
I think the friction from the sandstone (== sandpaper) might abrade and compromise the rope pro much faster than in your nice clean metal device. Would be interesting to try with a sheet of sand paper on each side of the cam crusher
Have you considered possibly adding grip tape to one or both sides of that setup so it has a more similar texture and friction coefficient to real rock instead of relatively smooth steel?
Since there are currently 400 and some comments saying to try it on real rock, I will answer in the opposite. I don't want to see it done in real rock, because there is enough granite in the world to put my lovely rack of cams into. If I can dig a foothold into it while climbing, it's not my thing. I'd rather see a DMM Pivot go head to head with a BD ATC Guide. Speaking of such places, isn't Garden of the Gods in Colorado very similar? I climbed there once many years ago and decided that rock wasn't for me. It seemed that the rock was so friable that no removable protection felt secure. In West Virginia, at places like Seneca Rocks, they metamorphose the sandstone with some heat and pressure to form more like a quartzite. While they still call it sandstone, that is some tough rock. Perhaps Czech Republic should consider holding another mountain building event to toughen up their sandstone.
I feel like the angle of the metal plates is unrealistic compared to real world placements. The constriction used seemed much tighter than most you will run into on a route. The tests just seemed to measure the knots strength rather than how well it would hold when placed in a constricting crack like a nut. Friction probably has a greater impact for these types of "protection". Thanks for the video, I hope y'all can test the on real rock soon.
I'm late to the party, but I think that rock due to it's porous surface would provide much more holding strength at least to the slippage. Breaking strength I imagine would be very similar or perhaps slightly lower due to abrasion.
Should be big difference with some friction! Contact with hard Placements is punctual, and by this the impact force is led into the surronding Material on a very small area. Soft material builds up form fit, which is rather the opposite of punctual fit. By this ,i guess , it is absolutely crucial to keep friction in mind , testing knotsling gear. Would really appreciate testing on some soft sandstone, cause the Routes of sächsische Schweiz traditionally need this technique. Maybe the softshackles suddenly perform great?!! Give it a go, please!😉
Might be a dumb question but if you were to line the inside of your gripper device with say 80 or 100 grit sandpaper, would that make a difference? Find a sandstone "analog" and use spray adhesive or something to secure it to the inside of the jaws. Hmm...interesting stuff!!
Note that the metal plates open up, once the knot is in between the left two bolts. You can easily see this as the right two bolts lose tension. This effectively means that the distance between the plates at the location of the bolts controls the size of the slit. Would recommend to fully lock the two metal plates, during further testing.
Hey, actually I`ve some experience in sandstone but in saxony, not in czech republic. Here in germany in this area, even fever bolts are placed and therefore we rely even more on knots (and UFOs) :D Well and it`s not so secure like bolts or friends or nuts. Buts actually I think it`s necessary. Sandstone is really soft, so you could damage it with harness or with too many people climbing on it. So there is a debate about how much protection we allow, because the more protection, the more people will climb. This is a difficult consideration. (Fun fact: There are some people severely injured or even dead each year in this area. Most of them made mistakes during abseiling, not with the knots ) But at the end, its an ideological thing. We learn that climbing is something you should have respect for. I will not start a route if i´m not sure that I can do it. I don´t want to fall under all circumstances. My protection is there to save me from death, and its working. With some experience and the right eye for knot placement (and the friction of sand stone of couse :D) it is a lot saver than it looks. And for me it has to do with appreciation and not to overestimate myself. But how I said: You should not fall (At least I don´t want to fall, there are some people without this kind if concern). So its not classic sport climbing. It is a developed traditional climbing with some real special moves. Thanks for the video, it was quite interesting. How others said, friction is key regarding this topic. Would be really interesting to see what happens with real sandstone (maybe some stone plates in the testing device?). For me it would be nice to not rely only on experience or feeling, but on facts :D
I live in the Czech Republic, used to climb on sandstone sometimes. The friction from sandstone is vital to how the knot works, as you pull the rope and the knot tightens, it should try to expand against the rock and 'mold' to the crack's shape, speading the load. These knots are not for big falls with high kN values, if you are worried you will fall you put a knot every meter or so. The sandstone is too soft for metal placements. In a fall, they do not mold to the sandstone so all the pressure is on a small area (the grains which are in actual contact with the metal), which will crumble or snap off. Maybe you could test with some sandstone blocks?
3 года назад
There is also stuff called "Uforing", ment to be fabric equivalent to cams. It is made from webbing expanding in rubber outer. This soft sandstone is very beautiful (and solid from climbing perspective), pity that local ethics forbids bolting from rappel
300 to 400 grit sand paper glued to the Knot Buster 5000 steel plates may help give a more grippy surface to test the ropes with since steel on rope has low friction. It may help with the slippage. I would also love to see the rock results because if its better then nothing. How bad is it when you h a be nothing, if ya dig bro
Disregarding the friction aspect missing in the test, I would suggest that the test jig itself is flawed. This is best seen in the test at around 7:20. In that test, you can see that the wide end of the test jig/fixture is closing which correspondingly causes the narrow end/mouth of the fixture to open wider. This results in creating a condition which doesn't exist in real rock. If you secured the rear bolts by placing stop nuts on them (inside of the plates) so the rear plates are set at a more fixed position, you would most likely eliminate this condition. The "loosey-goosey" rear end of the fixture not only causes the narrow end to widen, it thereby also reduces the plates' angle where the "rubber meets the road". Less angle would also make less resistance to the knot.
Definitely do the monkey fist I do some light climbing for photography and use monkey fists when I don’t have any metal nuts (I have to order them thanks to a lack of shops in my area)
