Very sad accident today...

moss said:
Globe 3000 or whatever special cordage sauce the TM bridge is has Dyneema SK78 in the core, very abrasion and bend/flex resilient.
-AJ
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@moss not arguing, just asking: isn't dyneema usually too slippery to knot or splice well, and isn't it sometimes paired with a sheath that keeps it from picking, and lends it some functionality in splicing/knotting? I remember TS carrying amsteel blue (with a very long bury spec for splicing), then remarketing it as a winch line and instead offering an expensive sheathed dyneema cored rope for a while. Seemed like the sheath was to mitigate picking and make it "termination-friendly"... I can pull 2.2mm zingit through a tight figure 8 with a slip termination. I think the strength of dyneema is great for a bridge, but feel like other materials provide sufficient strength without these lesser characteristics of dyneema. Is there a difference in the sk78 spec and where does one go for information on it?
 
Can we perhaps differentiate between an adjustable rope bridge and an extendable rope bridge? Adjustable just means I can take pretty much the standard length but shorten it down to almost nothing to eliminate movement on the bridge. There are good reasons for that in rope walking, limb walking and work positioning.
I do agree that an extendable bridge may not be the best option and if for some strange reason I was going for that I would probably incorporate my lanyard.
 
colb said:
@moss not arguing, just asking: isn't dyneema usually too slippery to knot or splice well, and isn't it sometimes paired with a sheath that keeps it from picking, and lends it some functionality in splicing/knotting? I remember TS carrying amsteel blue (with a very long bury spec for splicing), then remarketing it as a winch line and instead offering an expensive sheathed dyneema cored rope for a while. Seemed like the sheath was to mitigate picking and make it "termination-friendly"... I can pull 2.2mm zingit through a tight figure 8 with a slip termination. I think the strength of dyneema is great for a bridge, but feel like other materials provide sufficient strength without these lesser characteristics of dyneema. Is there a difference in the sk78 spec and where does one go for information on it?
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Absolutely no worries, clarification is always good.

I found technical information on Dyneema by looking through specs on rope manufacturers web sites and simple searches on different types of Dyneema.

I've read through a ton of specs on rope manufacturers sites and documentation, apparently there are many varieties of Dyneema with different characteristics. SK78 is renowned for it's ability to withstand load and unload cycles, flex and other damaging conditions which can destroy "high modulus" fibers. Dyneema is very slippery as you mention. Which is why, I think, Teufelberger doesn't like people building their own bridges with Globe 3000. They set the termination knots in production and add stitching on the knot tails to stabilize the core, as well as indicator stitching so the user can monitor any slippage occurring in the termination knots. When Globe 3000 was available by the foot I did similar stitching to prevent core slippage on the tail of the termination knots for my custom length TM bridges. Very wise to do so if a climber is building their own knot terminated bridges with any kernmantle construction cordage.
-AJ
 
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@TimBr and Who ever else.
Yes the TM bridge is a dyneema core, which is where the strength comes from, with a cover for abrasion.
Dyneema is a very slippery fiber, and when used with a core it can slip through the knot at much lower loads than breaking strengths. I assume Globe3000 bulk was pulled from the arborist market because of this specific issue. That is why the ends of the TM bridges have a few inches of stitches running down the rope so the core cannot pull through the cover milking thought the stopper knot.
I stick with stock, and yes it's annoying to pay $20 for a $5 piece of rope. IF I were to use a different rope it would be a parallel strand static line with good a abrasion resistant cover.
 
evo said:
@TimBr and Who ever else.
Yes the TM bridge is a dyneema core, which is where the strength comes from, with a cover for abrasion.
Dyneema is a very slippery fiber, and when used with a core it can slip through the knot at much lower loads than breaking strengths. I assume Globe3000 bulk was pulled from the arborist market because of this specific issue. That is why the ends of the TM bridges have a few inches of stitches running down the rope so the core cannot pull through the cover milking thought the stopper knot.
I stick with stock, and yes it's annoying to pay $20 for a $5 piece of rope. IF I were to use a different rope it would be a parallel strand static line with good a abrasion resistant cover.
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So does this mean that if one buys a replacement TreeMotion rope bridge that it's a requirement to stitch both sides of the bridge after pulling it through and tying the stopper knots, or it is just not a safe install? If so, I would hope such instructions come with the replacement bridge. Thanks.
 
evo said:
It comes stitched, that’s why you can’t find it in bulk.
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I'm assuming only one side is stitched, so that the new bridge can be threaded through the plates, correct? And that once you do tie your stopper knot on the second side, it is advisable to stitch that end also? Thanks for your time, evo, it is much appreciated.

Tim

Edit: Nevermind, @evo, I just answered my own question by looking it up on TreeStuff. It does come stitched on only one side. Here's the link.

http://www.treestuff.com/store/catalog.asp?item=260#detail
 
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TimBr said:
I'm assuming only one side is stitched, so that the new bridge can be threaded through the plates, correct? And that once you do tie your stopper knot on the second side, it is advisable to stitch that end also? Thanks for your time, evo, it is much appreciated.

Tim

Edit: Nevermind, @evo, I just answered my own question by looking it up on TreeStuff. It does come stitched on only one side. Here's the link.

http://www.treestuff.com/store/catalog.asp?item=260#detail
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no.. The knot is stitched and pre tied on one side. I am not sure why they throw a stitch in the knot. The TAILS on both ends have a long bar tac style stitch, not unlike a sewn eye stitching pattern in the smack dab middle of the cord. THIS is what I'm speaking about, it locks core to cover. I also think that it's overdone, to insure proper tail lenght as well.. Leave it to the damn Germans to think of everything

I should bill you for my research time..

TEUFELBERGER+TREEMOTION+REPLACEMENT+BRIDGE_R.jpg
 
evo said:
no.. The knot is stitched and pre tied on one side. I am not sure why they throw a stitch in the knot. The TAILS on both ends have a long bar tac style stitch, not unlike a sewn eye stitching pattern in the smack dab middle of the cord. THIS is what I'm speaking about, it locks core to cover. I also think that it's overdone, to insure proper tail lenght as well.. Leave it to the damn Germans to think of everything

I should bill you for my research time..

TEUFELBERGER+TREEMOTION+REPLACEMENT+BRIDGE_R.jpg
Click to expand...

Ah, that is interesting. If you look at the link I posted to the TreeStuff web page for the replacement rope bridge, it shows no such bar tac/sewn eye style stitching. Only the stopper knot is shown with a stitch through it. Maybe it is an old photo, or maybe it is possible that different companies do it differently. I suspect the former. Thanks for your time.

Tim

P.S. I could not afford your rates.
 
evo said:
This brings up a very interesting point. Should the details of accidents leading to serious injuries or death be open source? Personally I feel they should
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Totally agree.

If my CTSP Ass gets wasted doing tree work someday, I want all of you to know how it happened because I guarantee you that it is because of something that I fucked up doing and not because of some "freak" accident.

Sorry to be such a doom and gloom. Just the way that I see it.
 
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