Tugging on Cams Rant

The cams like to be tugged. 

Can I step on em too?

Harumpfster Boondogglewrote:

Why do nubs tug on their cams? I swear to the ghosts of Bachar and Bridwell that it's an accident waiting to happen and does nothing to test them.

Yet the noobosity persists!

It's a very sensible practice.  Here's the thing.  Cams are friction devices.  The physics involved in the cam's logarithmic spiral shape says, remarkably, that the frictional force scales with the applied load in such a way that if the cam works for any one load, it works for all loads.  (That's not what the physics actually says.  It actually says that the cam will hold if the tangent of the cam angle is less than the aluminum/rock coefficient of friction, then the cam will hold.  Note that there is nothing in that statement about the magnitude of the applied load,)

It follows that a decent jerk on a cam will test whether the frictional forces will hold a fall, and so jerking on cams is an intelligent way to estimate one aspect of holding ability.

There is, of course, a rub, because friction isn't the only consideration.

• There can be issues with a placement that cause cam failure, A cam can walk with rope motions and might arrive at an unfavorable position. A cam that is undercammed is particularly vulnerable. Placements in which the cam stem is not aligned with the load direction may be less effective.
• There can be issues with the rock that cause cam failure. A crack can expand, the feature can shatter, or the surface can crumble. All of these can cause cam failure, and a jerk can detect none of them. Perhaps more insidious is that sliding friction is lower than static friction, so that a cam that holds when the load does not cause it to move might fail with a load that also puts the cam in motion. 
• There can be issues with the cam itself. Very occasionally, we hear of the main cable stem breaking. This might be the result of wear from placements whose loading severely bent the cable. More often, we get some kind of shear load failure, in which the cam surface shears off in layers.  Cams that fail and display a gouged surface have probably experienced such a failure.

So a jerk is a good way to test one aspect of cam reliability, but cannot be relied on to be decisive. Of course, you had better be holding on well with the other hand so that a cam failure does not cause a fall. 

If you are used to the rock you're climbing on and you can see that your placement is not lubricated with water, dirt, or rock dust, then a frictional failure is unlikely, you already know the jerk test will be passed, and no such testing is likely to be needed.  That said, I recall a reference, which I cannot now find, that claimed, after a series of tests, that jerked cams had higher holding power.  This result, if true, can't have anything to do with friction.  It is possible that a good jerk "sets" a cam by allowing crack rugosities to slightly embed in the metal surface.  This is pure speculation on my part.

Bottom line: if your stance allows it, a good jerk eliminates one possible aspect of cam failure and might just barely contribute to holding power. In many cases, you won't have good enough holds to give a good jerk and resist the outward force of a failure, so we can't promulgate a universal rule.

Power to the noobs.

Edit: This post has been read as advocating the tug test as a decisive test of cam reliability.  That's not what I said above, and I don't believe that to be true.

It feels nice

Like slapping a fully weighted lifting rig lol

You're overthinking it and being a dick about it at the same time. Good effort 

I like to wiggle cams gently to help them set and see if they might move in a bad position with the rope tugging. I'd rather be the biggest MP nubz than a pr0climbz0r on the deck.

Loic Prstwrote:

I like to wiggle cams gently to help them set and see if they might move in a bad position with the rope tugging. I'd rather be the biggest MP nubz than a pr0climbz0r on the deck.

I do the same. IME a wiggle tells me a lot more than an inline tug.

rgoldwrote:

It's a very sensible practice.  Here's the thing.  ...

Hopefully this information is making into anchor books, on-the-rock training sessions, etc.

Exceptionally good post, as usual.

philip bonewrote:

Can I step on em too?

only if you say degrading things to the cam while you do it

Cosmic Hotdogwrote:

only if you say degrading things to the cam while you do it

Oh, I do that while kicking them.  
And simultaneously cursing the rope caught against my knee on a 5.8 fist/OW bulge. 

Put me in the camp that says tugging/wiggling has some value. So I think it makes sense to do it. 

It was supposed to be another classic day on another classic route. “Good gear, easy climbing, you should go for the lead.” My partner Hamster Bongwaffle was anything but a sandbagger so I racked up and began to climb.

Halfway up the pitch, I reached for a small cam and placed it in the crack. It looked fine. Not great, not inspiring, but probably fine. You’ve all been there.

I gave it the standard visual inspection, as Hamster had taught me: lobes engaged, rock looked solid. “Should be fine” I thought to myself.

Then I heard Rob Dillon’s voice in my head: “Connor Herson would tug on that cam.” But like a devil on my other shoulder I heard Daniel Shively whisper “it’s micro resting bro, don’t you want this send to count????”

Not sure which path to take I stared at this questionable placement. I know what Caleb, Dow, and Julian would do, but Tal and Tristan said it was just a nervous habit. Should I clip it and gun it? Or is today a day meant for some cam tugging. What a predicament! “Good gear, easy climbing,” he had said…

My gaze cast downward towards Hamster. He shouts up: “looks bomber!”

Long my friend and mentor I trusted Hamster’s words and clipped the rope. My eyes began to scan the small edges above. Right hand on a crimp, left hand on a sidepull, right foot on a dimple thing, right hand up to a small downpulling crimp. “This looks pretty difficult,” I thought. Fuck it. Today is a day for tugging.

I look down at the cam and prepare for the ritual that we’ve all partaken in.

One little tug - looks solid.

Caleb’s voice enter’s my head: “tug wiggle push, whatever it takes.”

So I tug, I wiggle, and I push. “Great! It does look bomber!” My confidence begins to bloom.

I look down at my mentor Hamster and remember he’d once said “tugging is useless, when aiding we bounce test with full body weight plus.” So I clip a sling to the cam and stomp my foot into it with all my might.

The cam ripped out of the crack like it had been waiting for that moment all it’s life! And when I say ripped out, I don’t mean a grainy slide, I mean it exploded, like an Iranian missile in the skies of Tel Aviv.

I hung on to that crimp and sidepull, eyes bulging from my face. Hamster looked up at me in silence and with astonishment.  “So… not bomber?”

“Yeah,” I said, “it failed the test.”

Hamster: “good thing you tested it.”

I took several deep breaths, internalizing the philosophical implications of cam tugging, before reaching down to retrieve another cam from my harness, a totem this time.

I placed the cam in the crack and looked down inquisitively at Hamster. “Looks bomber," he said.

I ignored him.

rgoldwrote:

It's a very sensible practice.  Here's the thing.  Cams are friction devices.  The physics involved in the cam's logarithmic spiral shape says, remarkably, that the frictional force scales with the applied load in such a way that if the cam works for any one load, it works for all loads.  (That's not what the physics actually says.  It actually says that the cam will hold if the tangent of the cam angle is less than the aluminum/rock coefficient of friction, then the cam will hold.  Note that there is nothing in that statement about the magnitude of the applied load,)

It follows that a decent jerk on a cam will test whether the frictional forces will hold a fall, and so jerking on cams is an intelligent way to estimate one aspect of holding ability.

There is, of course, a rub, because friction isn't the only consideration.

• There can be issues with a placement that cause cam failure, A cam can walk with rope motions and might arrive at an unfavorable position. A cam that is undercammed is particularly vulnerable. Placements in which the cam stem is not aligned with the load direction may be less effective.
• There can be issues with the rock that cause cam failure. A crack can expand, the feature can shatter, or the surface can crumble. All of these can cause cam failure, and a jerk can detect none of them. Perhaps more insidious is that sliding friction is lower than static friction, so that a cam that holds when the load does not cause it to move might fail with a load that also puts the cam in motion. 
• There can be issues with the cam itself. Very occasionally, we hear of the main cable stem breaking. This might be the result of wear from placements whose loading severely bent the cable. More often, we get some kind of shear load failure, in which the cam surface shears off in layers.  Cams that fail and display a gouged surface have probably experienced such a failure.

So a jerk is a good way to test one aspect of cam reliability, but cannot be relied on to be decisive. Of course, you had better be holding on well with the other hand so that a cam failure does not cause a fall. 

If you are used to the rock you're climbing on and you can see that your placement is not lubricated with water, dirt, or rock dust, then a frictional failure is unlikely, you already know the jerk test will be passed, and no such testing is likely to be needed.  That said, I recall a reference, which I cannot now find, that claimed, after a series of tests, that jerked cams had higher holding power.  This result, if true, can't have anything to do with friction.  It is possible that a good jerk "sets" a cam by allowing crack rugosities to slightly embed in the metal surface.  This is pure speculation on my part.

Bottom line: if your stance allows it, a good jerk eliminates one possible aspect of cam failure and might just barely contribute to holding power. In many cases, you won't have good enough holds to give a good jerk and resist the outward force of a failure, so we can't promulgate a universal rule.

Power to the noobs.

Ah, at last a thoughtful response!

I respectfully disagree in the utility, Ser Gold, for the following reasons:

1. As noted, rock quality is highly variable, and rugosities that may survive a tug easily are crushed by the cam with lead fall forces leading to failure. 

2. Expansion of flakes (area dependent) as the cam itself forces the flake wider leading to cam failure but still passes tug test.

3. Lobes misaligned ie two lobes in good orientation can withstand a tug, but higher forces or tiny deviations in direction of pull will lead to cam failure due to poor engagement.

4. Any experienced aid climber will tell you that many flared or otherwise less than ideal placements will hold in precisely one ideal angle, but the cam fails if any rotation occurs. These even pass bounce tests.

You suggest that "a jerk is a good to test ONE aspect of cam reliability", but the number of additional factors that remain untested may lead to a false sense that security is present.

One poster even suggested that the newfound confidence of the "tug test" would embolden them to go for it.... this is the height of false security. Even if a cam passes a bounce test all of the above factors listed can result in failure. Visually assessing the quality of the rock, the lack of wet/lichen/rugosity, the angle of cam engagement, relative degree of parallel of the crack walls, the solidness of the flake etc etc all are factors that a light tug tests do not assess.  I honestly think we are dealing with a "tug test myth" that does not hold up to the real world where cam failure is a leading cause of injury accidents. Remember when "equalization" was a thing?

Cam failure is of course due to the leader's failure to assess the overall picture of the cam placement and it's integrity as he/she climbs above. (and can change from the rope's action etc). That complete assessment is undervalued when we tell the noobs a tug test is a reliable indicator the cam will hold a fall. Watching beginner climber video after video on youtubes we see bad cam placement after bad cam placement for all of the above reasons withstand tugs. It's a false indicator giving a false sense of security, imo.

In your defense, I do recall similarly that in very coarse rock a "setting" of the crystals into the softer cam materials some makers have chosen did lead to better holding. But this was due to less rotation of the cam in the placement iirc. There are also probably micro vibrations during the instant of force application that may be contributing to holding/failure to hold in this case of coarse rock too.

In addition, if you were to say "I set my cams so that they resist walking and maintain lobe orientation better" I would have no problem with that. But you are not testing their holding power in any meaningful way as my experience bounce testing hundreds of cam placements on Yosemite big walls has taught me.

Noob it up, as you were.

Thx Rich!

almostradwrote:

And isn't it embarrassing that I can still flash your proj while wasting all that energy?

This is kinda a sad flex, really, don't you think?

Climbing, like most human things, is filled with this sort of hubris that associates relative youth and one's current (yet mediocre) ability with carrying more weight than decades of experience.

Rob Dillonwrote:

Come to think of it, I did notice that rank n00b Connor Herson tugging on a cam in the film of him leading a .15a crack on bullet granite. Kids these days!

Can we get him to come on the forum and ‘splain himself?

Could be part of a running series on pros doing things that the MP forum deems bad practice. 

Michael Vaillwrote:

It was supposed to be another classic day on another classic route. “Good gear, easy climbing, you should go for the lead.” My partner Hamster Bongwaffle was anything but a sandbagger so I racked up and began to climb.

Halfway up the pitch, I reached for a small cam and placed it in the crack. It looked fine. Not great, not inspiring, but probably fine. You’ve all been there.

I gave it the standard visual inspection, as Hamster had taught me: lobes engaged, rock looked solid. “Should be fine” I thought to myself.

Then I heard Rob Dillon’s voice in my head: “Connor Herson would tug on that cam.” But like a devil on my other shoulder I heard Daniel Shively whisper “it’s micro resting bro, don’t you want this send to count????”

Not sure which path to take I stared at this questionable placement. I know what Caleb, Dow, and Julian would do, but Tal and Tristan said it was just a nervous habit. Should I clip it and gun it? Or is today a day meant for some cam tugging. What a predicament! “Good gear, easy climbing,” he had said…

My gaze cast downward towards Hamster. He shouts up: “looks bomber!”

Long my friend and mentor I trusted Hamster’s words and clipped the rope. My eyes began to scan the small edges above. Right hand on a crimp, left hand on a sidepull, right foot on a dimple thing, right hand up to a small downpulling crimp. “This looks pretty difficult,” I thought. Fuck it. Today is a day for tugging.

I look down at the cam and prepare for the ritual that we’ve all partaken in.

One little tug - looks solid.

Caleb’s voice enter’s my head: “tug wiggle push, whatever it takes.”

So I tug, I wiggle, and I push. “Great! It does look bomber!” My confidence begins to bloom.

I look down at my mentor Hamster and remember he’d once said “tugging is useless, when aiding we bounce test with full body weight plus.” So I clip a sling to the cam and stomp my foot into it with all my might.

The cam ripped out of the crack like it had been waiting for that moment all it’s life! And when I say ripped out, I don’t mean a grainy slide, I mean it exploded, like an Iranian missile in the skies of Tel Aviv.

I hung on to that crimp and sidepull, eyes bulging from my face. Hamster looked up at me in silence and with astonishment.  “So… not bomber?”

“Yeah,” I said, “it failed the test.”

Hamster: “good thing you tested it.”

I took several deep breaths, internalizing the philosophical implications of cam tugging, before reaching down to retrieve another cam from my harness, a totem this time.

I placed the cam in the crack and looked down inquisitively at Hamster. “Looks bomber," he said.

I ignored him.

LOL, props for actually making the effort. Sincerely appreciated.

I think you just made my point. 

A better placement, with a more suitable choice of cam and assessment by the leader. Little tug was useless. Bounce told a tale.

Now, don't fall or we both go. These old, fixed pins down here are mank.

(maybe the issue is that most of these nubs have never stood on cams for days aiding walls like we have in Yosemite and have learned how even bounce tested cams fail in a leader fall?).

Alex C wrote:

"Can we get him to come on the forum and ‘splain himself?

Could be part of a running series on pros doing things that the MP forum deems bad practice."

In the short of Conor that I saw, which I cannot post for some reason, he may be setting it due to the well-known coarseness of Squamish cracks for reasons we have discussed. Well, leave aside the "dab" that weighting pro might taint an ascent. I personally don't care about such things one bit.

I do care about the safety of nublings.

But word to the wise: don't equate pure climbing ability (or depth of experience for that matter) with knowledge of the mechanics of cam function. My experience with many world class climbers is that they know no more or less than others about gear. Some are very thoughtful about it, some completely ignorant.

The people you really want to talk to about testing cams are people that have bounce tested thousands of placements ie Yosemite Big Wallers. I am no longer active but have bounced tested hundreds of placements. I assure you, tug testing doesn't mean shit.

Note: It's very rare for a world class climber to be a gear innovator unless ie like Jardine, they also happen to be engineers/scientists.

Harumpfster Boondogglewrote:

A better placement, with a more suitable choice of cam and assessment by the leader. Little tug was useless. Bounce told a tale.

More than three tugs, you are just playing with yourself, that's what Bounce said.
Nice lady, wouldn't take her to meet the parents.

Michael Vaillwrote:

It was supposed to be another classic day on another classic route. “Good gear, easy climbing, you should go for the lead.” My partner Hamster Bongwaffle was anything but a sandbagger so I racked up and began to climb.

Halfway up the pitch, I reached for a small cam and placed it in the crack. It looked fine. Not great, not inspiring, but probably fine. You’ve all been there.

I gave it the standard visual inspection, as Hamster had taught me: lobes engaged, rock looked solid. “Should be fine” I thought to myself.

Then I heard Rob Dillon’s voice in my head: “Connor Herson would tug on that cam.” But like a devil on my other shoulder I heard Daniel Shively whisper “it’s micro resting bro, don’t you want this send to count????”

Not sure which path to take I stared at this questionable placement. I know what Caleb, Dow, and Julian would do, but Tal and Tristan said it was just a nervous habit. Should I clip it and gun it? Or is today a day meant for some cam tugging. What a predicament! “Good gear, easy climbing,” he had said…

My gaze cast downward towards Hamster. He shouts up: “looks bomber!”

Long my friend and mentor I trusted Hamster’s words and clipped the rope. My eyes began to scan the small edges above. Right hand on a crimp, left hand on a sidepull, right foot on a dimple thing, right hand up to a small downpulling crimp. “This looks pretty difficult,” I thought. Fuck it. Today is a day for tugging.

I look down at the cam and prepare for the ritual that we’ve all partaken in.

One little tug - looks solid.

Caleb’s voice enter’s my head: “tug wiggle push, whatever it takes.”

So I tug, I wiggle, and I push. “Great! It does look bomber!” My confidence begins to bloom.

I look down at my mentor Hamster and remember he’d once said “tugging is useless, when aiding we bounce test with full body weight plus.” So I clip a sling to the cam and stomp my foot into it with all my might.

The cam ripped out of the crack like it had been waiting for that moment all it’s life! And when I say ripped out, I don’t mean a grainy slide, I mean it exploded, like an Iranian missile in the skies of Tel Aviv.

I hung on to that crimp and sidepull, eyes bulging from my face. Hamster looked up at me in silence and with astonishment.  “So… not bomber?”

“Yeah,” I said, “it failed the test.”

Hamster: “good thing you tested it.”

I took several deep breaths, internalizing the philosophical implications of cam tugging, before reaching down to retrieve another cam from my harness, a totem this time.

I placed the cam in the crack and looked down inquisitively at Hamster. “Looks bomber," he said.

I ignored him.

Nice post! What’s interesting to me is that I often take the micro rest too, and my interpretation of a free ascent is predicated by my own ego. When I take my exploration of a truly free ascent to the literal limits, over my long love affair with climbing, I’ve only succeeded on a few fleeting occasions, but those climbs definitely stand out in my memories. 

Climbing is Fun!

Harumpfster Boondogglewrote:

Ah, at last a thoughtful response!

I respectfully disagree in the utility, Ser Gold, for the following reasons...

I  thought I covered all your objections in my post, and the point was that we have to consider a lot more than the outcome of a jerk test.  The idea that eliminating one possible source of cam failure might induce a false sense of security is your only remaining point.  That addresses the mentality of the individual, and is beyond the realm of technical considerations.  Depending on the person, you might be right. 

Long and somewhat sad experience suggests that an overconfident attitude obtained from partial information is not an exclusive feature of noob activity.

philip bonewrote:

Can I step on em too?

Only the big bros

Harumpfster Boondogglewrote:

This is kinda a sad flex, really, don't you think?

Climbing, like most human things, is filled with this sort of hubris that associates relative youth and one's current (yet mediocre) ability with carrying more weight than decades of experience.

If it lacked the sarcasm intended, totally.

However it's worth noting that I'm not as young or new as you might suspect.  I too have decades of experience, just stronger fingers (for now) too