I placed it higher than low fall factor falls. This isn't enough to activate a screamer or move a truck. I don't think it is essential to my point either way.

I think Sty is right.

I would like a link to rgold's post that you referred to or a better explanation. You are just giving the jt512 validation right now.

Nope. Even if he was correct that the peak force from sitting back on a dynamic line is not higher than the weight of the climber, he is still wrong about his calculation on the force the top piece feels. It would not feel 2X the weight of the climber, but ~ 1.6X. Do you know why?

I suppose I am just trying to learn from others' experiences.

I believe it is possible to generate 3 times my weight with a sling.

I don't think a tug approaches three times our weight. It definitely would be much less.

Everyone that says tugs are worthless hasn't had any reasoning to back that up.

All of the above logic is why I was hesitant to believe your figures earlier. I believe it is possible to generate 3 times my weight with a sling. You didn't, and I don't have a screamer to test my theory.

Perhaps we should go dig up rgold's force calculations, and then we can prove it with numbers? Probably not worth the effort. This is a branch of the discussion that doesn't really even relate to the thread.

granite_grrl, I agree that that level of precision in calculating a toprope fall is not relevant to this discussion. It was merely part of a larger point I was making.

But I hope you're not suggest that 2 is *more* accurate than 1.6-1.7. In simplest terms, at rest, a belayer standing on the ground will put approximately (that's what the little "~" sign means) 2/3 the amount of force on the belay strand as the climber at rest puts on the other strand (irrelevant to any intermediate protection between the belayer and the top piece, or any friction between the rope and rock between the belayer and top piece).

Of course, if the belayer sits down and holds herself up with the friction on the belay device, the top piece will feel the weight of the belayer plus the weight of the climber, which would indeed be ~ 2X the weight of the climber.

Make sense?

GO

Sure doesn't sound like it. My experience (and the experience of others on this thread) has shown that the force applied on a cam (in the direction of the stem) is nowhere near enough to rip it out of a poor placement unless the placement is obviously crap. I'm telling you, when I was testing Aliens, I placed a bunch of cams, tugged on 'em all, they held great. Until I found good enough placements, none could hold the 3-4kN that I was testing them to. Ripped 'em all right out.

How much force do you think your tug is putting on your gear? I really don't know what you think. You say both: and
So which do you actually think? Go ahead - take my earlier suggestion: Go to the gym, take a stack of the big 45 lb iron weights. The kind that fit on a barbell. Put your sling through the middle of them, and give them a nice upward tug, just like you would give your gear a downward tug. See if they budge. If they do, congratulations, you can generate 2kN of peak force with a tug. Please let me know I'm wrong, and I'll send you a beer. If they don't - I'm sorry you've bruised your hand trying. Next time, think about it a little harder.

Nonsense. I gave specific examples, and so have other posters.


Can you please explain what is wrong with my logic?

I brought it up, so if it doesn't relate to the thread, I apologize. But I thought you wanted to know if tugging was useful. Your premise is that it is, because it generates a force equivalent to a small fall. I tried to explain the amount of force various things put on the gear, to show that you were mistaken, and to give both real-world examples and mathematical explanations.

Static test versus dynamic test of climbing protection


To compare the 2 methods of testing protection we need to make some assumptions:

1. How strong is a static test.

Since this is more controlled than a dynamic test we can use more of our body mass to pull. If we were to perform a dynamic test with all our power it would put us in a very dangerous position if the piece failed. Real world experience shows that a dynamic test (tug) is performed mostly with the arm.

A strong pull could probably lift a 90 lb (40 Kg) load off the ground an inch or so. This corresponds to a force of 400 Newton.

2. Dynamic test.

How fast is the protection traveling during the tug?

A baseball pitcher throws a baseball at a velocity of 44 m/s, and gravity would have the pro traveling at 3 m/s after 50 cm. I used 50 cm to simulate a 25 cm sling being pulled up then down. Assuming that our tug will not be anywhere near as fast as a baseball from a pitcher the velocity of the pro is assumed to be 10 m/s.

Nylon slings will stretch about 5% under small loads (more under heavier loads. I have stretched slings 100% before they broke) which will give us a stretch of 1.25 cm. This is the distance over with the braking will occur and allows us to calculate the acceleration during the application of the tug.

a=(v.v)/2x = 100/0.025 = 4000 m/s

Assuming a mass of 100g for sling and pro this gives a force of

F = ma = 0.1 x 4000 = 400 Newton

Comparing the 2 forces we can see that they are the same, therefore I would suggest that it is better to exert a controlled force rather than a dynamic one.

This assumes the intent is to generate the maximum force on the pro. It is interesting to note that the forces are about 1/5th the force that could theoretically be generated in a fall.

You weren't posting any of this unprompted. I am playing devil's advocate to a great extent to hear people's reasoning.

Your weight + height fallen + jumping + no elongation = enormous force for a split second....I would be surprised it this wasn't at least 3 times the weight of the person executing it.

Your example of lifting the weights does not apply because all of the above utilizes gravity.

From your recent posts, I now gather that you meant the force on the top piece of gear. Earlier, I was taking your statements to mean the force on the climber. This is probably my mistake in reading too quickly. Above I explained where I expect the bounce test forces to be much higher than your findings.

My premise is not that a tug generates a force equivalent to a small fall...

1) holds its own weight and the weight of the rope.
2) holds body weight and a slow transition onto the piece is required
3) holds a top rope fall (body weight applied quickly)
4) holds a fall with a low fall factor
5) holds a sharp tug from the climber
6) holds any fall

... but that there is some non-negligible force that a tug generates.

and that is the benefit of tugging in my eyes. You at least rule out that there is something obviously wrong. If you don't tug on those pieces, then you are possibly climbing into dangerous situations thinking you are well protected.

Is there anything else that you want to say with respect to this?

I would like to point out that "Gear Tugging" is a euphemism for masturbation.

You seem determined to mix bounce test forces with tugging forces. I give up arguing with you on that front. I see these two as distinct items, but above you mingle everything with no distinction.

Others in this thread are saying good looking placements are failing under loads of a good yank: (my bold)


Your only response to this seems to be "MY placements either hold or they look really bad." Did I miss another response to this? Is there anything else that you want to say with respect to this?

"microbarn"]copying your equation from your 'dynamic' section and altering:

F = ma = (0.1 + mass of arm) x 4000 + (your definition of 'static force') = way more force

I will leave it to you to make up the numbers.

The main point is that the magnitude of the forces generated either by tugging or by pulling, in a real world situation, are in the same realm. Therefore, it is better to perform a controlled pull to test the placement.

Whether 1/5th the fall force is sufficient is up to debate. In some cases, insufficient force will not give an accurate representation of what will happen under full force. How many times have you seen climbers test a foot hold by placing the shoe on the hold without weighting it, only to have the foot slip off. However, confident climbers will use the same hold by committing their weight to it. The amount of holding power is dependant on the force applied. The same may apply with cams since their holding power is generated by friction.

I am aware of a number of instances where climbers have fallen while tugging on gear and decked as a result - interestingly they seem to happen frequently in positions where a fall would not have occured without the tug.

It is an important consideration I think - if you are a tugger, make sure that your balance will not be jeopardised if the piece comes out while you're tugging.

Apologies if this has already been covered, but gear tuggers know if their cams will hold in a horizontal flare or if the angle is just too wide.

I am aware of a number of instances where climbers have fallen while tugging on gear and decked as a result - interestingly they seem to happen frequently in positions where a fall would not have occured without the tug.

It is an important consideration I think - if you are a tugger, make sure that your balance will not be jeopardised if the piece comes out while you're tugging.

Cheers tuggers!

Adam

Tugging should be avoided since it serves no better purpose than a simply pull and it places the climber in a potential situation where they could be put off balance should the piece pull out. Climbing is about control and tugging is wrong.

I would respectfully suggest that notapplicable was either not yet proficient at analyzing his gear in general, or on that specific rock, at the time that this happened. Simply put - even halfway good cams can't get yanked out in the direction of force. As I've said several times (and perhaps this is what notapplicable meant in relation to his failing cams) if you have a marginal cam, and you're not sure about the contact of one or more of the lobes, yanking it sideways *can* produce enough torque to show that those lobes aren't biting. Even though yanking it directly probably would not cause it to fail! That's how useless a direct yank is! The piece will often stay in place on just one lobe!
GO

We aren't running hard numbers, so let's make the assumption that you are correct. A given placement will not hold a tug, but it will hold a fall.

cracklover,
Perhaps you are right. Maybe you have a better eye for placements than ALL the guides, and ALL the other trad climbers that have pulled out good looking placements.

If I am currently well protected and the crux is coming up, I will probably continue to tug on that piece. I will probably tug on blindly placed pieces. I may tug on others too. I will probably continue to avoid tugging on the first piece after a run out or mid crux. I will probably tug more often on the polished Seneca climbs and on limestone. I won't assume the piece is bomber just because it held a tug, but I will be able to quiet my mind just a little bit. It will make the unknowns with respect to that placement slightly smaller.

(I still am interested in the rgold link if you have it.)

That just doesn't happen. You display a fundamental lack of understanding here that may be at the root of your larger misunderstanding. As the force in the direction of the stem increases, the cam becomes more, not less likely to pull out. That's what makes a weak pull so useless in determining if the cam will hold a fall.

Further, there is a very real downside if the piece rips. If there's no benefit, it's just not worth it.

Okay, sorry I couldn't add to your peace of mind as a gear tugger. That's obviously all you were interested in/capable of getting out of this thread. Your understanding of the degrees of force put on your gear by various different stressors, and the behavior of cams under different stressors, is so far divorced from reality that trying to discuss the single element of gear tugging within the context of the larger realm is a completely worthless endeavor.

Apologies if this has already been covered, but gear tuggers know if their cams will hold in a horizontal flare or if the angle is just too wide.