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I suggest revisiting this strictly using the winch. It seems you are just measuring shock loads with just pulling with manpower. You want a repeatable same force applied during each test.

When you have a long rope and your doing short jerking pulls, you'll get lower peak values at the other end. If you statically load the long rope you'll get rid of that difference (for the most part). When you're jerking on the rope you'll see that the elasticity effects the force that the other end experiences. I loved this video and think it does a great job at demonstrating how mechanical advantage really works!

Dynamic loading and peak force measurement are somewhat incompatible here. The springiness of the rope act as a damper, widening the peak force in a broader peak, while the force shockwaves may also be interfering which each other. You should do the same thing, but while keeping a constant force (maybe do 2kN and 4kN)

"Mechanical Advantage is a Myth" is definitely the better "get views" title, but I suppose what you're saying is "Mechanical Advantage is Oversimplified" and I love your investigation into real-world variables and results. Great work!

For the next test, I would suggest one of the follwing: - constant pulling force (such as a weight in free space) - progress capture device, again providing static load to the rope

To reduce the length of rope needed, you could extend the pulley block away from the anchor tree to just a couple of feet from the other end. This way, the back and forth between the pulleys is only a few feet of rope instead of 100+ feet. Less stretch and less elastic losses, and less rope length and weight.

There's one more variable that you threw in by accident, it's the duration of the pull. A single straight line should have equal values, unless you're yanking on it quickly, without giving it the time for the forces to equalize. With the 13:1, the rope is so long that the pull takes a while to travel all the way to the end, and if the pulls are so sharp, you aren't using all the pulleys, you're just fighting against the inertia of the rope. Slow pull the next one?

I think bouncing is having the effect of systematically increasing the input force more for the least dynamic cords. Also you could pick up a short length 1.5 to 2" thick wooden dowel to make a pulling 'handlebar'. I'm using a portable fingerboard similarly for tightening my longer slackline setups. I can get way more force without the finger pain.

I have been so curious to see this series of tests done. Thanks for doing this!

Awesome content my dude! You guys are constantly growing and learning and sharing it all with us. Much appreciated!

It would be interesting to repeat the tests with different total length of rope per configuration. Suspect doing 1to1 testing with very short length of rope incrementally increasing the length would give you a factor reduction in efficiency per meter length. Probably best to use mechanical clamps to remove variance in knot tying between each test.

I'd love to see if you get closer to the exact ratios with slow/constant force pulls.

This channel is amazing. Thanks for all your hard work and dedication. You are making the world a better place. This is like myth busters of rated gear!

Love the vid Ryan, very informative. Hope there's one delving into multipliers too at some point. One thing I think would help: A bar chart at the end displaying all the different % results from each rope type and pulley setup. Every result on one graph would make it much easier to compare the results I think, rather than trying to keep them in my head.

Thanks for another great video. The physics 101 graphic at the beginning of video assumes frictionless (as you noted) but also a constant force being pulled with zero stretch line. Bouncy dynamic inputs are damped out by the stretchy rope, less by the semi-static and even less by the Dyneema. I'd be interested to see the Input v Output when using the portable winch set up as it's less bouncy. Appreciate the video and look forward to more content from the drop tower and testing of sailing components.

Great videos Ryan & Bobby, thank you!

Will be nice to see calibration of those linescales. Worked with load cells and is important to do the calibration process often if you are putting a lot o stress on them.

I’ve been a subscriber for a few years thanks for the great content

Haven’t seen that many comments appreciating the fact that this is helpful to understand why it’s soo hard to pull someone out of a crevasse. Yes there’s stretch and yes I am yarding on the rope just like he does here. So now thanks to him I’m considering separate static for glacier travel even with a dynamic for the climb.

You’d have better results with complex/compound systems. Put a 2:1 or even a 3:1 on the tail of a 5:1 and you can get some huge forces.

Efficiency of pulleys in a system is a compound problem seen in the video. For example, if 90% of the force is redirected from a pulley. If you haave a 5:1 system. The ropes will pull at: 100%, 90% 81%, 73%, 65%. These forces are added up 309%, so 40% of the systems total pulling force is lost in friction. So.. pulley efficiency in series is pretty important. A dynamic rope basically adds rope to the system upstream under tension, which means you'll have less opposing force and therefore less pulling power. I'm a engineer btw, and I do enjoy this backyard science, and trying to explain the results.

Best video! Love the pulley science! More please

This was very helpful, just like all of your videos. Thank you!

Hey, have you ever thought about testing a petzle ASAP fall arrestor for use in rope soloing? Its been a topic of debate around the shop recently!

Alway have loved the content man❤️keep it up

When I pull my soft shackles to 10KN+ on my theoretical “15:1” system I found I can maximize the force of my “1” by putting on my harness and clipping to my belay loop. Like a saddle on a horse!! Helps especially when you have no homies to pull with you. I’d need an extra linescale if I want to do a similar test like this one though. Thanks for this info I’ve been waiting for some good MA testing!!!

Boby: It's excatly same if you are dyslexic. me, dyslexic: no joke, that's static, and they are same, OH SHII

Any plans on testing multipliers in the future? also, an interesting experiment would be side pulling a tight line, maybe in conjunction to a pulley system

If using a loaded dynamic rope with a progress capture (like when you're hauling), wouldn't that eliminate a lot of the effect of stretch you're seeing? Because the rope would already be pre-stretched?

This was very informative. Thank you for making this video.

Keep up the good work guys

Good work. I would be interested to see if a ratchet, like a micro traction, would allow you to eliminate some of the losses from the dynamic rope.

Great video! Interesting results 😲

Great video as always! I'd love to see this applied in more climbing-specific scenarios, mainly giving a boost to a second while belaying from above, as well as in crevasse rescue!

Do those pulleys have ball bearings? You should look into sailboat hardware, they make some pretty trick stuff. The nicer stuff rides on ball bearings and has almost no friction, even under load.

As a sailor first and a climber second, I appreciate this video. Could you test some sailing-oriented line for us? I think most of it will have a dyneema core for strength and being static, but covers for this core vary widely depending on friction needed, pulleys being used, the handfeel, and workability of the rope. An interesting experiment would be to see how much extra force we get on a jibsheet for every extra wrap around a winch we take. More wraps takes more time to do and undo, but also lets you hold hundreds of pounds of force. Too few wraps means your winch will slip against the rope, and you won't be able to pull the sail in anymore.

Also, do the readings depend on which way you link up the linescales? Because this time you had the pulley system attached to the top of the "yanking" scale on one end, and to the bottom side of the "stationary" scale. Of course this wouldn't matter for a slow loading, but might be one of the confounding factors when yanking.

Can you do a test on ice screws and while you are at it snow anchors where you literally only snow. I’ve seen it before and was wondering if it was super good enough.

I was thinking about this whenever choosing between 3to1 and 5to1, thanks for sharing! Do you still keep collecting the results in a spreadsheet or similar? I cannot find it. I like graphs! - would love to see a comparison of both linescales' graphs for some more insight. :)

Can you zoom in on the force graph to see the shape of the peak? Is there just one data point at the sharp peak, or are there two or more points and the peak is kinda rounded by them?

Now I wonna know what would happen with static load ...

If stretch is the issue, wouldn’t compound MA have better results since there would be less material (shorter legs of cord)?

Do you think the 9:1 is greater than the 13:1 could be something to do with losing a percentage of the pull at each pulley meaning you want you most efficient pulleys first and the 13:1 has those small pulleys first?

Awesome Vid. Thank you!

Would a vertical orientation also have an effect on results? My instinct thinks it definitely would, in part because of the jerking. I also wonder if angles on pulleys/gravity/leverage would have much effect.

Lol i like the set up in this video, there's no way I'm pulling at a constant and consistent way myself

That’s gotta be sore next day! 😆 thanks for pulling

Serious question: hope someone can answer seriously, what if you were to capture the stretch in the rope not allowing it back into the system. As you jerk the input side you are taking up the stretch but then you let it return into the system. Is it still such high loses when you’re slow pulling with say a winch or a van where that stretch is continually being taken up…would you not eventually reach the point where the stretch is stretched and then acts like a semi static or static rope where your input more closely matches the theory or would there alway be loses to keep the stretch stretched. Sorry wish I knew more technical terms but hopefully it’s clear enough.

How often and by what method do you calibrate the scale? Why didn't you properly rig the rigging bar for the 9and 13 to 1 tests?

do you have any information about the power wench? Are rescue team is looking into them.

What's your progress capture for hollow braid UHMWPE ?

Might be time for another buying guide now that you got the new site goin. Also new climbers like me would love your opinion on good gear to buy right now. Keep up the good work

After 8:1 the friction overcomes the efficiency of adding more parts. . .most of the time. Cranes will have more than 8 parts but use super efficient sheaves to do so.

it would be awesome to see a repeat of this with the same length of rope in used in all the tests.

what if you had a 3 to 1 pulling the end of another separate 3 to 1 system, would we see a proper mechanical advantage of a 6 to 1 without any losses cause your reducing theoretical friction of one system info 2 separate smaller systems? i have no idea but it may work??

It would be interesting if you where to apply a progress capture and compare using one early/(before the pulleys) in the system or last.

Very good, man!

You need a repeatable force method of tension using the recommended pullley / block system for rope / line size and if dynamic or fail point is your criteria then you must. Load vertically with a uniform dead load to create dynamic or live load

Most would never read the boring studies on the advantages of elevator music. Your channel allows us without a music degrees to see how effective the musical advantage really is.

I wonder if you have let's say 5 guys pulling by one rope vs 5 guys pulling each by one rope will there be a diference? It's because when i pull one rope with other people i feel like my strengh isn't used as efficient as when i pull alone

Can u please test the breaking force of Amazon "climbing" ropes. Thanks.

so the sweetspot for max power is somewhere between 13:1 and 5:1. would love to see 6,7,8 and 11 to 1 tested.

Have you thought about using a progress capture pulley on the tail end? I'm not sure how much additional force youd be able to generate, but it would at least keep the rope between the pulleys tensioned between pulls so you don't have to pull that extra slack each time

How strong is the belay loop in the harness? I can't seem to find a direct answer for that question. I'd love to see you test some.

Can you put up a link to your capstan winch? Id buy one of those

Should the scale be on the other end of the rope

Great idea!

How much should one worry about overloading stuff when using big ratio systems(yall? Big big much? Or nah?

One way to get repeatable static pulls with systems like this is to add two redirect pulleys, one at the anchor you are standing next to and one above the anchor you are standing next to. Run the rope up and back down then use your body weight by hanging or standing on the rope instead of relying on your arms.

Have you tried an aluminum framed come a long for input power. I pull trees over with a 5 to 1 and a 1 ton come a long. Great videos. Always good info. Thanks

I tend to use a 4:1 with a 4:1 jag on the end. The key is constant pull with a progress capture. Next time I do it I'll put a meter on it and see how it compares.

This is exactly why we use Dynamic rope for climbing, Semi static rope for where it is possible to fall, or a super Static rope where there is zero/no chance of falling. Lets see the difference of a FF1 and a FF2 on each type of rope. I think it's an eye opener!! Keep up the great work.

Has anyone found the code? Ive looked through the book of numbers and haven't spotted it. If someone could just tell me where it's hidden ill go look again.

I know this is an old video, but just curious about what knots you used for the to attach the dyneema to the ends.

Nice! More tests!

What if you try making a gearbox for mechanical advantage instead of ropes and pulleys, maybe less losses or more overall multiplication?

I'd like to see you try a compound pulley set up? I bet it would dramatically increase your force.

Nice use of pulleys on the straight pull.

I loved that video, I think all this info super usefull

So I think you should definitely do this test again but this time use a steady increase of pull to see if the energy at the other end of the system levels out with time. My theory is that you’re jerking motion put only a momentary pull on one end of the rope which didn’t have time to work its way through to the other end. Still not going to be a perfect result but I’ll bet it’s a lot closer. Awesome video thank you

Hey please break some ice wall stuff! How strong are ice bolts and ice itself?

looking forward to the v-threads in ice so much!

Fantastic! Sometimes I use a 3:1 or a 5:1 when working. I thought I'd be getting much more pull than your results show. I will have to take this in to account when I'm tipping trees over in the future 🤔

That capstan winch is awesome

There are two separate issue going on that are incorrectly getting linked together here. These are (1) how impulse loads are generated on a system and (2) the sum of all forces acting on a system (each rope end) incorrectly not equaling zero. These actions exist independently. Regarding the force generated from the duration of the dynamic loading. This deals with Newtons second law. In this case you placed kinetic energy into the rope by pulling on it. The amount of time the rope takes to absorb this kinetic energy determines the peak impulse force placed on the rope. The more stretch, the longer the time duration, the lower the force. The less stretch, the shorter the time duration, the higher peak force. This is why the static rope saw a larger impulse load. The second issue is the question of “will a rope that is fully constrained by one end ( with no other external forces restraining it) and loaded at the other end see different force values at its end”? Newtons 3rd law states no. The tensile load throughout the entire segment is equal at all points regardless of the load being dynamic or static. This exact rope problem is littered throughout intro level physics text books and commonly appears on midterm exams. With regard to the different measured values at each rope end it is not that Newtons 3rd law is incorrect, it is more likly that the way you set up and performed the test failed to collect representative data points, for all forces acting within the system. There is probably a couple reason why your load cell values are different Load cells only measure force in a predefined axis. Placing the rope horizontally causes the anchored load cell to rotate more when loaded the force vector of the rope was not always concentric with the anchored load cell axis. The way you held the input load cell when loading the system placed the force aplied ro the rope directly inline with the loading load cells axis . Because the load was more in line with this load cell a higher value was recorded more often. With regard to the end of the rope you were not continually measuring the total force placed on the rope. Form most of the time you were only measuring the vector component that was acting in line with the end load cell’s axis. This would not be an issue if you had a load cell with an extremely high sampling rate and where then downloading this data into a laptop running data acquisition software. As the duration of the peak impulses can be very very short. However it is highly probable your load cells were not sampling at a high enough rate to capture the peak data point at the exact instance it was 100% aligned with the end load cell. I would recommend re doing this experiment and see if you get more accurate data. Anchor the rope overhead and perform this test by pulling straight down with the force being transferred straight through both load cells axis. Crank the sampling rate to the highest value you can and try and apply the dynamic force at a rate that will not exceed the sampling rate of the load cell. It would be interesting to see the results I love you channel and it has lots of great information

Great testing! I'm not stoked about the title though and hope that's worth it for the views. I'll never understand it, but i'll live with it. Cheers!

I thought you only counted the Xtra lines, like when you were saying 9 to 1, it would be 8 Xtra lines to 1 cause you would always have the 1 to start with

I loved the Lounge Music.

the stretch definitely makes a difference but only because the force is not constant, energy is being put into stretching the rope and that doesnt come out as force on the other side of the pully system. Once the rope is stretched out the force would look quite similar to the static rope if you had a constant load: perhaps hanging a weight on the drop tower with the reduction pully system?

You have to add in the divided values of stretch as well as the effect of gravity pulling down on the rope... This is why by the time you got to 13:1 you had slack ropes dangling...

I don’t think you are supposed to count the line you are pulling. So your 5 to 1 was only 4 to 1. On the 3 to 1 the pulley furthest from you is just a change of direction. If you have 1 pulley you get 2 lines but it’s not 2 to 1 it’s 1 to 1.

It is a good reminder that the pulleys in your crevasse rescue kit are very important :)

Did you try pulling one scale directly hooked up to the other to see if you get any difference? I wonder if there is a 'calibration issue' between the two devices. Or run tests swapping scales end for end with the same line/pulley set-up to see if your readings are accurate. Also, like others have stated, either repeat the test vertically with a static hanging weight or use the capstan winch for a steady pull for each test.

The relationship would be closer to 5:1 or 3:1 or whatever arrangement there is if it was equating total work on each side of the pulleys. Work being equivalent to force by distance (w=F•d) this also means we could add other variables onto this function such as the stretch of the rope. The stretch of the rope is ultimately the limiting factor when applied to multi pulley systems. That’s why cranes will utilize dyneema (amsteel) on a winch

Excelente tema. Es importante derribar todos esos mitos comerciales. Felicidades desde la Ciudad de México a todo el equipo del canal.

Great vid and interesting results! Certainly using the capstan will give more control over loading, perhaps invest in some ground anchors to avoid "towing error". Regarding technique (and haters) I used to teach experimental technique as a Physics teacher and see no problem in what you do. You are looking for the big picture not the fine detail, I love it.

I wonder if you used the ratio of your 1:1 with any rope that you could calculate what you should actually expect from a 5:1, 9:1 etc.

Hay rayen. Garage video. It will be also interesting to see 3:1 multiple by 3:1 (9:1 with less rope).

As many below are saying, dynamic loading is wasting a bunch of the force/energy into friction and heat as the rope stretches. You will also find that putting the linescale currently on the tree on the opposite side (using an even number multiplier/pulling from the same side as the "load"), it will register even less, considerably less when using carabiners, since that first carabiner will eat a bunch of the force/energy as the highest friction point. As the force put into the rope goes up, the amount of that force required to even just start moving the rope around the carabiner will go up. . To prove out the actual advantage you should add the second linescale between the van/anchor and portable winch in that last break test.