American Death Triangle is a Myth 

Check out our new store! hownot2.store/

Ahhh.... the good ol' 60-60-70 triangle! Buy yourself one today! _(offer only good on convex surfaces)_

In Australia, I was always taught that the ADT was called such because there was no redundancy built in.

When I started climbing at Josh in the late 70's, I learned that the Death Triangle was the typical arrangement of 3 button head bolts, center being higher, with countless loops of sun bleached webbing threaded through them. Often so many webbing loops that you couldn't get anything more through the eye of the bolt. Bolts were commonly all within 2 ft and the webbing was looped in a triangle through all three. It was practice at the time to just connect through the webbing loops without equalizing the anchor at all ( (3:58) picture the loop of webbing around the piranha in the video). Pulling on the longest span of webbing often left the angle at less than 30 deg. which greatly increases the load on all angled legs of the "system". The basic idea being that it was very easy to exceed the ability of the system since all aspects of that system were pretty sketchy to begin with. Manky webbing (albeit a lot of webbing) and 1/4 button head bolts. This did not inspire a lot of confidence. So NOT a myth just a safety tip that has probably outlived its necessity.

Is that a dynamometer in your pocket or are you happy to see me…

Just a note that was never explained in the video: the top side of the triangle will always have lower force than the two other sides due to the friction of the rope/webbing going around the corners at the anchor dynamometers. Each of the readings that are on the top length of the triangle are probably around 70-80% of the force felt on the two sides that are directly pulled. All the math problems we ever did in geometry classes are lies! They (thankfully) removed friction from the problems.

Makes sense that the ADT performs worse than a sliding X with the same masterpoint angle. However, if you only have one sling, you can get a more acute masterpoint angle with the ADT than a sliding X. It would be interesting to compare the ADT to the sliding X if the same length of sling is used, rather than the same masterpoint angle.

Thanks for helping us be less obtuse about our anchors.

Explanation of what's happening with belay setups, starting around @17:00: (For clarity of language, imagine the setup on a wall or rock face instead of on the floor, so that we have a clear "up", "down", "left", and "right".) In the up-down direction, each leg of the triangle IS supporting 1/2 of the force on the static line. But in addition to that, they are also experiencing force in the left-right direction. The belay device is pulling both chains down, but it's also pulling them toward each other. And the angle of the "legs" of the triangle determines exactly how much. You can intuitively understand this if you think about a 50-lb. static load on the end of a rope hanging at your waist level in front of you from a point a few feet above you. If you want the rope to be at an angle instead of straight up-and-down, you can pull sideways on it. The harder you pull sideways, the more of an angle you can put in the rope. If you pull with just a couple of pounds, you will give the rope a slight angle. And if you pull with a whole bunch of force, you can make the rope almost horizontal. As we increase the angle of the rope, the up-down force remains the same - it's just the 50-lb weight. But the left-right force increases. Which means the total force being resisted by the rope is always at least 50-lb., and can be a lot more if we're really pulling it hard sideways. It's the same any time a rope (or chain) is at an angle. It's always resisting force in the up-down direction, and force in the left-right direction. How much exactly is a little more complicated, because trigonometry. If you're super curious and want a quick sanity check in a "death triangle" or anchor situation, you can use the formula below (or consult the cheat sheet at the end of this comment). In a two-anchor situation like at @17:00, the total force on each chain is 1/2 x F x sec(Ø ÷ 2) where F is the force on the line and Ø is the angle the ropes or chains make where they meet. sec is the notation for secant (pronounced see-kuhnt), which is one of the trigonometric functions like sin and cos. So if the angle at the belay device is 90°, the force on each chain is 1/2 x 1.83kN x sec(45°) = 1.294kN. If the angle is 60° (a narrower triangle), then it's 1/2 x 1.83kN x sec(30°) = 1.057kN. If the angle is 120° (a wider triangle), then it's 1/2 x 1.83kN x sec(60°) = 1.83kN. Which means with a wide, 30-30-120 triangle, the total force in each leg of an anchor should be exactly the same as the total load on the line! If the angle is 133°, which is the angle in the setup at @20:42, then the force on each anchor should be 1/2 * 2.16kN * sec(66.5°) = 2.708kN, which is very close to what you found. At 178° (meaning the chains are so far apart they're being pulled just 1° down from directly horizontal), the total force on each anchor would be 1/2 x 1.83kN x sec(89°) = 51.43kN!!!!!!! So don't do that. Obviously, the value of sec(Ø) increases a LOT between 133° and 178°, i.e., when the triangle is super-duper wide, but that's beyond the angle most people would try and get away with. However, this kind of multiple does come into play when calculating the total tension on a slack line. Finally, here is a bit of a cheat sheet for equal-length dual-anchor setups with approximate values: Angle Force on each Anchor ------------------------------------------------ 20° 0.5 x load 60° 0.6 x load 90° 0.7 x load 120° 1 x load 140° 1.5 x load 160° 3 x load 170° 6 x load 176° 15 x load (pretty close to horizontal, like a stiff slack line) 178° 30 x load (nearly horizontal, like hanging something from the middle of a very tight line or chain)

Ryan's oww makes him a human torque wrench.

Great video as always! The only way to get a perfect 50/50 load sharing is to have an angle of 0° between the bolts, in every other case the sum of the load on the bolts will be more than 100%. The load multiplication of the death triangle has to do with the top strand being free and allowing the bolts to pull on each other. The numbers from the calculations assume no friction, to get similar results on the dynos as expected you will have to add pulleys on the top angles (not really a real world scenario though...).

This angle stuff is super important if using ice screws.

This video reminded me of something I’ve wondered about (and also a possible video idea). I’ve seen AMGA certified RU-vidrs suggesting the use of dedicated top-roping quick-draws with locking carabiners. If you orient them with both spines against the rock will you compromise strength of the dogbone (which would have a 90deg twist)? Note: I believe the benefit of using them in this orientation is to keep the rope away from the rock to prevent it from being pinched or rubbing, thus adding a lot of friction to the system and prematurely wearing your rope. Additionally, since they are both locking quick-draws the concern about the rope unclipping itself is eliminated (barring human error).

You have to go pretty extreme to get cosine losses eating up much of your force. At a 30 degree angle (equilateral triangle), you are only weakening the whole thing by around 13.4% on paper. At 45 degrees, so a right triangle, you reduce the strength by 29.3%. That's significant but still allows a decent safety factor. At 60 degrees, you're basically reducing the strength in half. Keep in mind though, that is 120 degrees for the bottom angle on the triangle. In reality, harsh angles are needed for any severe loss of performance.

I’m a qualified mountaineer, and commercial rope technician and think your channel is awesome and has definitely added to my knowledge and understanding. At the moment I’m seeing so many American videos on RU-vid or Instagram posted by “rock guides” or so called IFMGA guides, that are doing so many dodgy things and posting them as educational. Such as unequalized, unloaded systems, using dual fixed point bolt anchors but then putting the load on one bolt. Anchor points that include a triangle of death, but in a belaying scenario that could end up shock loaded. It seems, all in the name of speed, lightweight, “innovation”. What is going on with the climbing instructors?

This video is super educational enough!

As a French guy who has been taught to use the "European death knot" I am curious about the result of the test with that one. And to add a comment on the ADT since that is the subject the death part is really the one you mentioned, there is no redudency and fi you break the sling due to a rock falling on it or rubbing against the rock you go all the way down.

The biggest issue is the direction of force vector in an ADT. Bolts or attachment points are usually designed to pulled toward the load, not horizontally toward each other. This can cause failure. Mathematically, force amplification won’t occur until the interior angles are greater than 120. 90 degrees is a good rule of thumb. The angle doesn’t matter on the chain when they are connected across the top. This was a rough one.

You could use a marlinspike hitch for when you need to pull on the line manually. Wrapping it around your hand and yarding on it is no fun!

@9:50 - I checked my local climbing store, but I couldn't find an alien like you've got.

These results are important, because if you watch to the angles of the forces, one can see that this is the same with those lifting loops - the purple one in the background on the mashine. The wider the angle the more multiplies the force on both ends. In this case the force mashuring devise is the climber and the other two ends are the ankers, if one want to compare with a crane lifting a load up with a rope which is in such a wide angle. In your experiment, if the rope was tide down on each chain sepearedly, the force onto the ankerpoints should be sharing the load by almost half, when these rings are still close together. Because the rope is going though, the effect is like those lifting loops used in a very wide angle. Sorry for my English, but it is not my first language. You guys are the best. Your topics are great and with the breaking test is so much to learn about "gear fear" and what to keep in mind, if one is using those equipment. Best wishes and be save. Jan v. Baumbach - Germany

Hey! Try the death triangle combined with other common issue: carabiners with open gate. See how hard you need to pull to break an open carabiner on anchor with death triangle.

when you visualize the forces in your anchor, it helps to see the forces in between the two bolts, separately from the forces along the axis of pull. So you have a) the axial force through the master point and b) the force between the bolts. The Cosine of the angle, gives you the horizontal force between the two bolts. With that, you can easily see how all the forces add up.

I feel that the ADT is a lot more concerning on ice or rock routes where you've placed your own protection as it can pull at less predictable angles as compared to other anchors. I've never been concerned when I'm on well bolted anchors of anything breaking. I have been concerned that trad gear might pop if pulled at an angle other than downward.

Hey ! I'm 2 years late for commenting but I just discovered your channel 😅. Anyway, this stuff is kinda basic for me being a mechanical engineer but I love that you're taking the time to test it all ! I laughed a bit when you thought that when using chains and basically just moving your measurement point you'd get a different result with the same angle ! Anyway, keep it up !

From about 12:00 on, running a rappel rope through two rings that are separate does magnify the loads on each bolt. Ideally, the solution is to have chains long enough to hang down far enough to make a lesser angle - but not have two separate rings, at all. Instead, join the two chains with one or two links, and have the rope run just through that, eliminating the horizontal section of rope altogether. Visualize the chains as two lengths of webbing, and the idea is clear. There is no purpose served by creating rings apart. Once again, modern practices have arisen without thorough considerations of the various consequences, and just because bolts ordinarily are assumed "bombproof" does not mean one should routinely use them in ways that tend to multiply forces.

Would love to see this with pulleys instead of carabiners at the corners of the triangle.

When you're climbing on an old route whose bolts are sketchier than poorly placed micro nuts, it surely deserves the name "Death Triangle".

NOTE!! What is shown at 12:00 is very different from the test setup. There are no force magnifying triangles at 12:00, but the test setup using 1 atc creates a triangle. Force wise the 12:00 setup is just fine.

Hey guys I have a few simple rules when setting anchors. I sure you already know this but just to say my thing. FYI I come from a climbing but predominantly industrial background. Anchors should be installed at a minimum of 10 x the diameter of the bolt apart, the further the better thus minimizing the conning effect. If you want to form an equilateral triangle of 60 degrees than all you need is three sides of the same length. Ryan how come you don’t use a jumar to tighten your pulley system instead of your hand? Have you guys come across the Harkin hand winch built for a rope access application? One side gives you a 3:1 mechanical advantage and the 2nd configuration gives you a 10:1 mechanical advantage. Bolts to the ground and is compact and great for compressed (small) mechanical advantage.

15:25 lookits like a 5:1 ratio , fer every foot wide, youd want it at least five foot long

This is first year classical mechanics, applications of newtons laws. If you vary the angle then the force of tension will be different. All you need to know to calculate the forces in terms of that tension is the angles and the kilo newton reading. You can decompose the forces acting on the angled straps summing the x and y components to zero assuming the system is at some point in equilibrium. Then you can set up a system of equations and substitute one of the angled forces in terms of another. Then with this A=T/(cos(theta)tan(theta)+sin(theta)) you can vary the angle and see mathematically what the forces will be without doing this experimentation. If you don't make that assumption then you would need to calculate the acceleration by using the 1D position equation in kinematics. Which is the approach I would use when you do those drop tests

Not sure if I got it right, but here goes: Assume X is the master point force, Y is each bolt's force, and A is the angle between the lines coming from the master point and going to the bolts. Take the vertical components of the angled lines and add them together. That equals the downward force. 2*Y*cos(A/2)=X The force on each bolt Y = X / (2 * cos (A/2))

It's a nice episode, but understanding/explaining the theory behind all these numbers could've make it a great one. In general, it can be awsome to show theoretical calculations vs. the outcomes of the various tests in the videos...

Can you just redo every single test you've ever done, but on the drop tower?

American death triangle depending upon it being a V you have a equivalent weight lifting ability but when you do use it in a triangle 🔺️ connection you are adding a mechanical advantage to one side or the other. Mechanical Advantage look it up.

25:54 well this is an acute episode 👌👌👌😎🚬

I think you’re not taking into consideration that when you make the triangle you’re making two pulleys that are pulling towards each other multiplying the force. Look up an example where someone uses a winch to pull a vehicle that is stuck off road. If the winch is rated at 12,000 pounds that’s what it can pull. If you take the winch line and take it through a pulley back to the vehicle with the winch on it it pulls double because you’re reeling in 1’ of cable but only moving 6” with nearly twice the force.

Try testing Edelrid's "ADJUSTABLE BELAY STATION SLING", if you can get a hold on that. It should behave kinda like sliding-x.

There's a reason that the tension in the ADT anchors at 60° angles doesn't match up with the sliding X at 60° angles. When you have the equilateral triangle tensioned, if you look at the angles that the anchor point load cells are being pulled at, they are NOT 60° with respect to the master point vertical line, even though the ADT angles themselves are. I suspect that if you set up a sliding X so that the pull angle of the anchor lines are the same as the pull angles of the ADT anchor lines, they would be a much closer match in tension numbers.

FYI it's MUCH easier to measure an equilateral triangle by comparing side-length.

Here's something to try. Put a line between 2 hitches of a 2 cars and pull it taught. Now put a biner and a rope to the middle. Pull the rope and you'll move the cars! Yhat's the force multiplier you are talking about. It's the tangent of the half angle and as it gets close to 180 degrees (a straight line) the half angle is 90 degrees. The tangent of 90 degrees is infininte.

Loved watching this video, but the book “ on rope” ( which has been around since the 80’s) has discussed this in thorough.

The closer you get to 180 the closer the force will approach infinity. naturally you can not have a line perfectly horizontal because it will be forced out of perfect horizontal or the line will fail realistically.

Interesting video. I had never considered the vector forces at play here. I always though the American Death Triangle got its name because it has no redundancy.

7:57 can anyone please explain this relationship of angles to greater forces… 8:41 shows it practically and i must admit its baffling me… I don’t understand where/how the force is multiplied from in the diagram… Thank you

23:34 im knot a professional, but eye play one on RU-vid 🤣

:thinking: Huh, good point on “you almost may as well be using just one anchor” with the American Death Triangle, which I suppose is the whole point of avoiding it. It’s not that you’ll be absolutely overloading your anchors or slings, if it were that bad, no one would ever be using death triangles because they would just be so inherently dangerous that trying it even once would kill you. One can get lucky a whole bunch and manage to avoid injury just by using one anchor all the time as well, it’s all about preparing for that time when things _do_ go wrong, and in the death triangle, you just don’t have an redundancy, _and_ you’re loading your anchors more than 100% of the actual load.

A question about the anchor you build at the end: Doesn't the knot you put in the sling for redundancy prevent it from properly load sharing?

To get 50% you'd need both bolts to be in line with each other (which isn't physically possible since they'd have to pass through each other). Having the extensions doesn't change anything.

The idea that the top of the triangle is experiencing some kind of force greater than the tension in either of the other legs is a bit odd. There's only two points acting on that part of the triangle - the tension in the sling pulling each end out until it's balanced. So the tension in that rope should only be about the same as the tension in any other point of the sling (otherwise, the sling would move through the karabiner at each end until it equalized.) It's only when there's some force acting on the middle of the rope or if a knot was jammed up against one of the points that it could change much. A tip: You can analyze a system of rope or chain *fairly* well by considering each bolt/piece of gear/pulley/karabiner as a point in space, then considering each point separately and drawing the forces on the ropes as vectors pointing in the directions that the ropes travel away from the point. This neglects friction and the weight of the ropes/gear, but in a lot of cases those are negligible (and when they're not, you can add those in, too). If you do this with any of the anchor systems you tested, you'd find that the force on each bolt is not just the force required to hold the climber up, but also some force pulling out to the side because of the angle. That's why you'll never see the load being shared all the way down to 50% unless the bolts are exactly in a vertical line.

Dude Pythagoras. If Y is the direction of the load, then the y force on each bolt will be 50% of y. For a given angle away from Y the total force on each of the the bolts (along the hypothesis) would be (1/2* y)/cos(angle). Then use Pythagoras to work out the x portion of the force.

For bad ideas that are irrelevant to climbing: what about tensioned dyneema between the two bolts? That seems like the closest to the mythical 180 degrees that you can get.

basic bridle math there, it starts adding up really quick the longer to make the base of that triangle, and can get really odd when you make it shift and start shortening one leg of it say with single legs rather than a looped sling

9:00 What a background!

What if the ADT is tied with an EDK??

Why the cast(s)? What happened?

Where did u get that bombshell shirt lol

Horizontal opposite, I’ve used them at Tahoe lovers leap routes on the friction climbing flake sections a lot, keep away from using mechanical pro. 33 years climbing and I ain’t dead yet !!!

equiangular means equal angles equilateral means equal sides and that results in equal angles

As my high school physics teacher used to say in her Texas accent.. “If you know eF-mAH, you know physics” FYI Bobby “Anglenometer “ = Combination Square

For the rappel test, you need to put the bolts right next to each other to share the load. Extending with chains still preserves the angles on the legs, and it's the angle that controls the amplification of force. If you have the bolts immediately next to each other, the angle between the chains would be basically zero, and then they'd share the load. Edit: oh good, you did that!

Something with cosinus alpha and stuff

My inner geek,if a triangles side dimensions are equal the inside angles are 60 degrees

In the video, he said something like, when slack-lining we take factor 2 falls...I think he meant 1, right or did I missheard or missing something?

ELLIOT love the E.T.

Ah, American triangle. I get it. Do twice the work, to get the same results. Same loading as if had just done 1 anchor.

very interesting tests

Doesn't the knot you tie at the end impede good force division between the bolts? The sliding X would have a wide angle where it would divide the load between the bolts, but after you tied the knot, even a slight lateral shoft of the master point would put one all force on just one bolt.

If you want your diagram from the beginning of your video to be true, you need to loose the top of your triangle. It's a diagram when you have two separate ropes and no top liaison between the two. Or one with o knot in the middle and two knots on top. You reduce a lot the load on your points with that top sling.

Not done watching the video...clicked like because Ryan used Celsius to cover the weather. Good job man. Proud of you. Next convince your countrymen to switch to the logical date format of DD MM YY 🤣. Bobby looking well!

You should do static analysis first tu have a theory to compare to

1:41 wait what?

Ill never call a protractor the correct name again.. its an angel-o-mometer

Calling it an American Death Triangle is hyperbole but it's still a silly way to build an anchor.

LOL, sponsor of SERENE!

Likewise, I appreciate everything you guys do. Amazing. That said, the results from this one are all more in less keeping with what a basic statics free body diagram would show. It shouldn’t have been surprising. It’s making me realize that not knowing engineering actually reduces climbing safety. Let me know anytime you need a more thorough analysis done prior to an episode to raise production value…

glad to see Bobby

Equalateral Triangle: if you measure the first angle, and it's 60-degress, then no need to measure the others, because they MUST also be 60. Physics.

Thing about ×4 safety margins. They are there, so when you do mistakes, like using this triangle anchor, you still have ×2 safety margin. It doesn't mean you should, it just means you'll probably be safe. Combine it with some other mistake, like not locking a carabiner (strength goes down to ~8 kN), and you'll still probably be safe, but we're already approaching the ×4 safety margin!

confirmed: E.T.

20:06 ok but how do we get less than 50%?

Looks like the bermuda triangle

I mean, there's a lot of difference between 130, and say, 170. A lot.

Good

Thanks for posting, this video is an interesting start to a rabbit hole run around the internet.

As the Angle approaches zero the load share approaches 50%

Clinometer

Gonna share a thought here on the differences between the American and European way of building an anchor on bolted routes. So you guys in the states usually always spread the load on two bolts using a quad or something like it, right? Which is why these two bolts are placed at the same height. In Europe (German living in Austria speaking here), common practice is building bolted anchors in a way that places all the force on one bolt, with the second bolt being connected, but not weighted. The second bolt is considered a "cold" redundancy, a backup, in case the first one fails. Thus, you'll usually find that the two bolt of an anchor are spaced out mostly vertically. (It'll usually look something like this: www.bergwelten.com/files/article/images/1-klettern-stand-reihenverankerung.jpg?impolicy=gallerie_pictures) I've had a discussion with a bunch of Canadians in Mexico before on what way makes more sense, and I ended up thinking that the "American way" actually makes more sense, but the European one is still super good enough and is just common practice. Having seen this video sort of made me reconsider this conclusion, because now I understand that it really depends on how you set up your "American" anchor. If you end up having a rather large angle between the two strands, you'll load the same force or even a higher one on both bolts. So as Ryan said (21:42): Why not just use one bolt? That is, have all the load on one bolt AND have a backup in place. Of course this doesn't apply if you build your American anchor properly with an adequate angle in the system. Hit me up, I'd be interested to hear what someone from the other side of the pond has to say on that :D (Btw, if no "safe" points are involved, that is, if you build a trad anchor, it's also common practice here to build a system that has the load shared between these points.)

RU-vid in a nutshell...18:27

So your hands mbs is decreased after a number of falls? Lol

A good way to think about it is that the anchors must not only support the vertical load, but also the load against each other. One anchor is loading the other horizontally, hence the higher load than 50%

If you look up crane rigging deductions and theories, it explains in great detail how sling angle changes forces in relation to vertical load. 45 degree angle in sling multiplies force by 1.41 compared to a vertical force. So 1 kn vertical force will produce 1.41( barring strange friction forces in the rig) kn of force.

You guys are idols of mine. I appreciate how selfless, generous, & absorbed in the science you guys are. I appreciate that you guys live life for fun, but also work hard to improve the fun of others

I want Bobby to be 100% again!

Your opening comment about taking F2 falls on American Death Triangles on unsheathed ropes is literally something I think about every time I rig slacklines and then I just say to myself "hmmmm it seems like people have been doing this and been just fine for decades so its probably alright" but this episode is what I have been waiting for all along!!!

It would be pretty cool if you could get a physics teacher to explain the theory and compare it to the empirical data :)

Blake’s hitch drop test. As well as any other arborist climbing nots.

This is obviously more of a warning about vector forces in anchors, but you can also use the vector force multiplication to your advantage. It's a rescue technique that is taught to tower climbers and I've used it when we rigged the 1km in Oregon to pull in just a bit of slack. If you have a rope that is anchored at one end and a casualty on the other end that needs to be lifted slightly before being lowered, you can put your body weight on the tensioned rope and it will lift your casualty up slightly allowing you to detach them from whatever they are weighting before being lowered.

Ryan's ouch is now a unit of measurement 😃