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Big Bro unscrewed as I climbed by?
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By Rich Farnham
Jan 12, 2010
I'm wondering if this has ever happened to anyone else...

(NOTE: This thread is not intended to bash the Big Bro. I like the device, and feel that I just need to understand its limitations to be able to use it safely--just like any piece of gear.)

Yesterday I placed a blue Big Bro (#4), set it with a few hard tugs, and climbed past. When my partner got to it, he said, "Hey watch this" and yanked it right out with one tug. Apparently when he got to it, the locking collar was completely unscrewed, meaning that only the spring was holding it in place. Obviously, with only the spring holding it, an easy tug pulled it right out.

Initially we thought I had just forgotten to screw the collar tight before clipping it and climbing on, but the more we thought about it, we both remembered me aggressively tugging on it to set it before I clipped it. I have a visual recollection of testing how tight the collar was after tugging on the sling. I had tried to place the same piece a bit lower, so it is certainly possible that I am making a mistake and recall this from the earlier placement; but I think there is a very low chance of this.

So, here's what I think happened. I placed the unit as deep into the crack as I could to allow me room to squirm past. Despite this, I know my leg rubbed it as I went by. All I can figure is this was enough to loosen the collar. The unit was probably an inch from being fully retracted, so I don't think my leg would have contacted it enough to completely unscrew the collar, but once it is loose, even the rope running over it might be capable of moving the collar.

This placement was higher on the right than the left. In this orientation, the outside (front) of the collar needs to be turned up to loosen the collar. I think my leg did this, and then the rope running upwards might have continued the action. If I spun the device 180 degrees, so that the left side were higher, the collar would need to be turned downwards to loosen it. My leg would be less likely to do this.

Has anyone ever seen this before? Am I crazy? Should we always place these units with the left side higher (or maybe only if we expect to contact it as we climb by). Of note, the directions show the unit placed with the left side higher, and suggest the orientation "so the moving rope tends to tighten the collar". I had seen this before and thought it seemed like a non-issue given how tight the collar is once you set the device with a hard tug.

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By tooTALLtim
From Boulder, CO
Jan 12, 2010
Loving it up in the Creek!
Woah, no wonder you were less than enthusiastic when I saw you after the climb.

Glad you didn't get hurt, and good to see ya!

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By Brian Scoggins
From Eugene, OR
Jan 12, 2010
Rich Farnham wrote:
Should we always place these units with the left side higher (or maybe only if we expect to contact it as we climb by). Of note, the directions show the unit placed with the left side higher, and suggest the orientation "so the moving rope tends to tighten the collar". I had seen this before and thought it seemed like a non-issue given how tight the collar is once you set the device with a hard tug.


It is a legitimate issue. One thing you should try (although your second will curse you for it) is to dog the collar down so tight that it is difficult to move. And sling it long. Even a little bit of rope movement can walk it enough that the collar springs free.

I've definitely had it happen before.

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By Casey Bernal
From Arvada, CO
Jan 12, 2010
Yes, this is certainly a known quirk - one that Craig educated me on.

The collar-end does need to be on right side of the crack. The rope running upwards should tighten the collar. (and it shouldn't be an issue if the rope isn't running over it)

I have found that it works best to NOT tighten the collar TOO TIGHT, but to have it just snug, so pulling on the cord will set it into place. Different cracks/rock-types/features change everything.

Also, since the Bros are the same strength through the entire range of the device, it is better to set them in the upper end of extension. Obvoiusly this doesn't make any difference with it unscrewing, just another tip.

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By brenta
From Boulder, CO
Jan 12, 2010
Cima Margherita and Cima Tosa in the Dolomiti di Brenta.  October 1977.
Two observations:

1. I just looked again at the Trango instructional video. In spite of what the written instructions recommend, around 2:40 it shows two placements with the inner tube touching the left side of the crack.

2. My understanding is that the problem is not the climbing rope running over the BigBro, but the effect of the climbing rope pulling on the cord threaded through the BigBro. If the rope is sufficiently far from the BigBro, the cord tends to assume a horizontal position. Because of the way the cord is threaded through the BigBro (the holes are vertical) when the cord is pulled out it applies a torque which may either tighten or loosen the collar depending on how the BigBro was placed.

Rich says he placed the BigBro deep into the crack, which means that the rope might have run sufficiently far from the anchor to stretch the cord, especially if the connection to the BigBro was not extended.

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By Rich Farnham
Jan 12, 2010
tooTALLtim wrote:
Woah, no wonder you were less than enthusiastic when I saw you after the climb.


Yeah, that plus the questionable flake that some of the other gear was behind made the lead a little sporty. The climbing was good though. I TR'd it later and enjoyed the moves without the mental baggage of the lead. Go do it on TR some time.

brenta wrote:
Because of the way the cord is threaded through the BigBro (the holes are vertical) when the cord is pulled out it applies a torque which may either tighten or loosen the collar depending on how the BigBro was placed. Rich says he placed the BigBro deep into the crack, which means that the rope might have run sufficiently far from the anchor to stretch the cord, especially if the connection to the BigBro was not extended.


Interesting. That was not the issue here, but that's not to say it couldn't be a problem in some placements. The rope ran close to the piece and may even have been running over it (although no significant change of direction on the piece).

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By Malcolm Daly
From Boulder, CO
Jan 12, 2010
Hey brenta,
Thanks for pointing that out. it is definitely better to have the inner tube on the right than the left and that fact is not clear in the video. When we re-shoot we'll fix it.
Mal

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By Rich Farnham
Jan 12, 2010
Malcolm, I was hoping you might comment on this thread. Have you heard of ropes loosening the collar when it has been securely set? Or, is it only if I got it started by bumping it with my leg (or didn't have it tight in the first place)? Again, I'm not trying to knock the Big Bro, I'm just trying to lead more wide cracks and want to know as much as I can about how to make the Big Bro work as well as possible.

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By Malcolm Daly
From Boulder, CO
Jan 12, 2010
Rich, Craig would always warn about the possibility of the rope loosening the locking collar but I never have had it happen personally. That's probably because I suck at OW climbing. But Craig climbed OW all the time and it didn't sound like he had ever experienced it either. I suspect that if you place the 'Bro with the inner tube to the right, as he recommends, and are aware of the possibility of unscrewing the collar with your leg or arm, you may never experience it again. I'd rank the problem somewhere below the possibility of dislodging a cam with your foot when you're climbing by it.

Climb safe,
Mal

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By Rich Farnham
Jan 12, 2010
Malcolm Daly wrote:
...dislodging a cam with your foot when you're climbing by it.

I've definitely done that one before!

Thanks for the info. I think this was a pretty rare thing, but good to know it can happen so I know to watch for it.

FLAG


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