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Why “Bounce Testing” should be avoided

Kyle Tarry · · Portland, OR · Joined Mar 2015 · Points: 448
Mark Pilate wrote:

Thesis (that I stand behind) was that the higher force “shock” load of the bounce at “N” on non-uniform, highly variable materials resulted in greater subsequent variation and unpredictablilty at N+1 vs lower a more static load with the rope involved in the other case resulting ina statistically better out at N+1

You have not provided a single source of data or a single valid theory to explain this thesis.  The data that we do have shows the exact opposite (material strength is not significantly reduced after one hard pull or bounce).

edit to Ian and Kyle: post and time limited, but you are mistaken. Follow up later. It’s easy to be a google engineer and look things up and post. Harder to immediately collate decades of experience and data. Find and post stuff you did 5yrs ago vs look it up now. You both missed the logical solution (as I did) in your fools errand to disprove the irrelevant semantics of the technical

There is no substance here.  I've made multiple specific points, asked specific questions, and provided data that directly conflicts with your claim.  You've haven't responded to a single specific question or provided a bit of data, you've just used logical fallacies and ad hominem attacks to try to delegitimize people who disagree with you.  Either provide data supporting your claim, back it up with legitimate science, or just stop arguing.  Ideally, you just delete this whole thread and we're all the better for it.

irrelevant semantics of the technical

All of the "irrelevant semantics" I responded to were your bullet points that you based your theory on.  If they are irrelevant, then why did you bring them up in the first place?

Cherokee Nunes · · Unknown Hometown · Joined May 2015 · Points: 0

It was an N+1 troll from the start.

J C · · Unknown Hometown · Joined May 2015 · Points: 477

If cyclic loading affected webbing the way you guys think it does, there would be a lot of dead highliners.

Has anyone posting here encountered an anchor that took more than a moment of inspection to decide whether it's good or not? I realize edge cases are what is interesting, but this is like using a dynamometer to get your shoelace tension correct.

jt newgard · · San Diego, CA · Joined Jul 2016 · Points: 446
J C wrote:

Has anyone posting here encountered an anchor that took more than a moment of inspection to decide whether it's good or not?

yes !!!!!!!!!!

This thread is in the general forum, but for context, we have had two fatal accidents in SoCal in the past year where a tat anchor failed.

My thinking on this has evolved as a result, and it seems I'm now in a more conservative camp of being strongly inclined to leave my own gear and being extremely distrustful of in situ anchor materials. Yes I understand the concept of testing and see its utility.

Whatever helps remind you to back it up, I'm all for it. However I'll leave it to y'all to have fun bouncing around on failed anchors (perhaps leaving the backup, perhaps not) either with the heavy man on rap or dance partying on your tether at the anchor.

...

...

P.S. Matt N, your comment is pure gold :D

J C · · Unknown Hometown · Joined May 2015 · Points: 477
jt newgard wrote:

yes !!!!!!!!!!

This thread is in the general forum, but for context, we have had two fatal accidents in SoCal in the past year where a tat anchor failed.

Well, based on the photo of the webbing, I'd say that would take about half a second to evaluate on route.

Ian Lauer · · Yakima, WA · Joined Jan 2014 · Points: 15
Mark Pilate wrote:

... Therefore, there is actually a belt and suspenders approach and I’d totally agree, that if a bounce passed AND then a regular test load test passed with the first person, then the risk to the last guy is ultimately lower than if no bounce. 


edit to Ian and Kyle: post and time limited, but you are mistaken. Follow up later. It’s easy to be a google engineer and look things up and post. Harder to immediately collate decades of experience and data. Find and post stuff you did 5yrs ago vs look it up now. You both missed the logical solution (as I did) in your fools errand to disprove the irrelevant semantics of the technical 

Glad you worked it out, but nothing stinks like a narcissist more than criticizing your opponent in the same breath after saying you were wrong

Micah Hoover · · Seattle, WA · Joined Oct 2016 · Points: 1
Kevin DeWeese wrote:

Except for this part of the accident analysis

While being wet explains part of that, I'd consider white webbing to always be a red flag. I don't know that I've ever seen "new" white tubular webbing and I suspect there's a reason for that.

Occasionally I'll come across some pure dyneema (white) cord tat on remote cascades routes. I always back it up because I just don't trust it.

Russ Walling · · Flaky Foont, WI. Redacted… · Joined Oct 2004 · Points: 1,216
Micah Hoover wrote:

While being wet explains part of that, I'd consider white webbing to always be a red flag. I don't know that I've ever seen "new" white tubular webbing and I suspect there's a reason for that.

Occasionally I'll come across some pure dyneema (white) cord tat on remote cascades routes. I always back it up because I just don't trust it.

White nylon webbing is not that uncommon.  Using color as your guide for tat is not a sound choice.

Matt N · · CA · Joined Oct 2010 · Points: 425
jt newgard wrote:

P.S. Matt N, your comment is pure gold :D

thanks  =)

Just thought of another one:

There are two kinds of trad climbers: those who've rapped off of tat, and liars.

A few more tangents and maybe the memes will start and this thread will finally get useful. 

Micah Hoover · · Seattle, WA · Joined Oct 2016 · Points: 1
Russ Walling wrote:

White nylon webbing is not that uncommon.  Using color as your guide for tat is not a sound choice.

I never suggested using color as a guide. I said white webbing would be cause for me to doubt it's integrity as most often, in the context of in-situ climbing anchors, white webbing = degraded. That's it.

Mark Pilate · · MN · Joined Jun 2013 · Points: 25
Ian Lauer wrote:

Glad you worked it out, but nothing stinks like a narcissist more than criticizing your opponent in the same breath after saying you were wrong

I’m getting to that.  For one, the only people being “snotty” in this thread are you and Kyle for some reason.  Also, Kyle was not right in his analysis or understanding of this argument.  He posted only from the top 5 google searches that did not apply to this analysis.  It applies to uniform test specimens for new material.  Not in debate.  That is never what this has been about.   I specifically stated in the original post the context to try and avoid being dragged into irrelevant issues.  

Big Red was drilling in on the point.  He got it, Kyle didn’t.  While wrong in the end, my error was based on the logical makeup and capabilities of a two person team, not wrong in the engineering analysis of the risks of predicting the results of a test N+1 given test result N of a deteriorated, non uniform material.  My original post stands as is (it’s basic mat sci) obviously with some to be added modified takeaways of a good test protocol.  

Just an example of Kyle’s lack of understanding here and misapplication of his google searches —

He had heartburn over my original graph and disputed my showing a delta between two consecutive tests at 1kN.    Then he gloats over posting pics of the RMRU test showing what?  A 1.1 kN delta between two consecutive tests.  —thanks for validating my thesis.   He also erroneously assumes the victims didn’t do a bounce test of the anchor before committing.  They didn’t trust just one of their own biners and used 2, but implicitly trusted a single piece of old tat without testing it?  His logic is at least as bad as mine, lol.   He makes a lot of baseless assumptions on that old webbing test.  This could just as easily been a case of a bad bounce test protocol where the erroneously trusted the results.   I’d like to know if any of Chelsea’s partners would expect her to blindly trust old tat or did she have a tendency to bounce test.  

Tradiban · · 951-527-7959 · Joined Jul 2020 · Points: 212
Ian Lauer wrote:

Glad you worked it out, but nothing stinks like a narcissist more than criticizing your opponent in the same breath after saying you were wrong

I think you owe Mark an apology for your behavior on this thread, very disrespectful.

J C · · Unknown Hometown · Joined May 2015 · Points: 477
Kevin DeWeese wrote:

Except for this part of the accident analysis

I don't buy it that wetting that sample would change how it looks. Sure, things get darker when wet, but that stuff is pure white. If I saw it, I'd say it looked exactly like wet, sun bleached 1" mil-spec. I own a few hundred meters of white webbing, so I know it's out there, but one look at that thing and you should know it's garbage.

If that's not enough, check out that knot it was tied around the tree with. Can you tell what it is? If I can't ID a knot, I basically don't trust it. This is all in the context of rapping off a single piece of unknown tat.

Being wet might make it more supple in hand, but that sample can be fully evaluated without touching it.

Mark Pilate · · MN · Joined Jun 2013 · Points: 25
Kyle Tarry wrote:

You have not provided a single source of data or a single valid theory to explain this thesis.  The data that we do have shows the exact opposite (material strength is not significantly reduced after one hard pull or bounce).

You are simply wrong. Both from a fundamental engineering understanding of degraded materials and statistics.   And you yourself posted data that proved my original graph delta of 1 kN  (which you disputed then too).  If I wait long enough and you study enough, youll prove more of me correct … but I’ll cite sources upcoming  

There is no substance here.  I've made multiple specific points, asked specific questions, and provided data that directly conflicts with your claim.  You've haven't responded to a single specific question or provided a bit of data, you've just used logical fallacies and ad hominem attacks to try to delegitimize people who disagree with you.  Either provide data supporting your claim, back it up with legitimate science, or just stop arguing.  Ideally, you just delete this whole thread and we're all the better for it.

Sorry Kyle, this thread actually has some good info and people should have a more uniform protocol for testing.   And I will address you points.  You simply were not correct in the application of the info you found.  I will clarify, don’t worry- my technical points are valid.  (As you yourself posted) 

All of the "irrelevant semantics" I responded to were your bullet points that you based your theory on.  If they are irrelevant, then why did you bring them up in the first place?

My bullets aren’t irrelevant, your tangential out of context arguments against them are.   You seem to be focused on new material and uniform test specimens.   My point has always been — goalpost never moved-  the unpredictable nature of test results of non-uniform, non-homogeneous or highly degraded materials.  Applying your lab test specimen info and understanding (correct in the context of lab test specimens) to the real world can be dangerous 

Stay tuned.  I’ll address your questions.  There’s just no easy way with post limits

James W · · Unknown Hometown · Joined Aug 2021 · Points: 0
Mark Pilate wrote:

They didn’t trust just one of their own biners and used 2, but implicitly trusted a single piece of old tat without testing it?  … This could just as easily been a case of a bad bounce test protocol where the erroneously trusted the results.

That’s what I see as the highest probability scenario given all the known facts - he to some degree bounce tested the sling, inspiring enough confidence for both to lean back on it.  

However - as discussed in countless recent posts - his test was tragically worthless.  

He likely performed it while still on belay while leading up from below - next lead pro down was his backup - likely little more than 2x bodyweight applied.

Ian Lauer · · Yakima, WA · Joined Jan 2014 · Points: 15
Tradiban wrote:

I think you owe Mark an apology for your behavior on this thread, very disrespectful.

I think Mark owes the group an apology for continuing to push his faulty analysis without any material proof nor backing from a legitimate source.

I am dumbfounded by his behavior given the fact he apparently works in the engineering field. You would get absolutely trashed in a professional setting for attempting to provide this level of analysis on something you have zero experience in and can't reference reputable sources for.

I'll be happy to change that opinion once he actually provides some kind of reference to back his analysis. 

Tradiban · · 951-527-7959 · Joined Jul 2020 · Points: 212
Ian Lauer wrote:

I think Mark owes the group an apology for continuing to push his faulty analysis without any material proof nor backing from a legitimate source.

I am dumbfounded by his behavior given the fact he apparently works in the engineering field. You would get absolutely trashed in a professional setting for attempting to provide this level of analysis on something you have zero experience in and can't reference reputable sources for.

I'll be happy to change that opinion once he actually provides some kind of reference to back his analysis. 

So what makes you an expert?

And isn’t “trashing” someone in a professional setting unprofessional?

Kyle Tarry · · Portland, OR · Joined Mar 2015 · Points: 448
Mark Pilate wrote:

Stay tuned.  I’ll address your questions.  There’s just no easy way with post limits

You can choose to use your allotted daily posts for actual facts and data, instead of ad hominem attacks.  This is 100% up to you.

You could also just edit an existing post to add more content, you've already done that in this thread a bunch of times.

And you yourself posted data that proved my original graph delta of 1 kN  (which you disputed then too)

The data I posted showed a 1 kN strength INCREASE.  Your whole theory is that an anchor will fail below the strength it bounce tests at.  That data shows that after testing to failure, it got STRONGER.  It's literally the opposite of your theory.

Micah Hoover · · Seattle, WA · Joined Oct 2016 · Points: 1
Kevin DeWeese wrote:

Using color as a reason to "doubt it's integrity" is literally what "using color as a guide" means. 

Are we honestly arguing that seeing white webbing shouldn't cause one to be just a bit more diligent than say, a bright fluorescent color?

Russ Walling · · Flaky Foont, WI. Redacted… · Joined Oct 2004 · Points: 1,216
Kevin DeWeese wrote:

No, we're arguing semantics. Keep up. 

lol… yep

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