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Chockstone Forum - General Discussion

General Climbing Discussion

 Page 2 of 3. Messages 1 to 20 | 21 to 40 | 41 to 42
Author
top roping from rap anchors

nmonteith
5/08/2005
2:42:35 PM
This is an example of what happens to well used lower-off bolts. The wear is very visible on the lower
part of this u-bolt. This example is from the Blue Mtns.


steph
5/08/2005
5:37:48 PM
The simplest way to set a toprope up if you don't want to muck around with statics is to clip quickdraws into the fixed bolts, set up a single sling, tie a knot and clip a screw-gate biner to it. Rope runs through biner, all is good, no wear on fixed bolts. We usually use statics though - it just makes life a lot easier after its all set up.
Ronny
5/08/2005
5:40:25 PM
Two draws is probably fine almost all of the time, but you can't sensibly argue that two locking biners isn't safer. Then you think about how much difference in time there is between setting up the two (possibly 1/2 a second at best for doing up the gate?) and its a no brainer that you might as well put one on.

Its horses for courses though, if you've got to the top without locking biners, plannign on lowering of and letting someone else lead, and then they decide to toprope instead, the above doesn't apply and you probably wouldnt' bother to climb it again, or lower a rope for a locking biner or something like that.

Oh and I reakon that thinking that relative beginner might not make it to the top is not a reason for toproping off the rings. just climb it again or something, or give them a jumar, or tell them to try a more suitable route (not necessarily easier, but one that you can get to the top of some other way to clean up).

The basic deal i rekon is *never* toprope on non-replaceable fixed gear, abseil whereever possible (including when cleaning), and add replaceable components where possible to remove the problem. I lower off fixed stuff occasionally when i have to, but just try to avoid it where possible.
J

aikibujin
5/08/2005
9:42:25 PM
I'm obviously pretty ignorant when it comes to climbing, so please excuse all the stupid questions I'll be asking.

>You should equalise to avoid cross loading the bolts.

What exactly is "cross loading", and how do you cross load bolts?

>No mater what the propper practice is you see many people simply top
>ropeing through the bolts (if they are rings which i understand there is
>no many of in the states) This is bad because it creates a large death triangle and also puts wear on a non redundant part of the system.

Besides putting wear on the anchor (which I agree is bad), I don't quite understand how you can create a death triangle when you top rope through the bolts directly. Could someone explain to me, in simple high school level physics so I could understand, how threading the rope through the fixed anchor directly creates a death triangle?

Paulie
5/08/2005
11:16:58 PM
On 5/08/2005 manacubus wrote:
>C'mon guys, two opposed quickdraws are fine!

Not when you're guiding they're not.

Another option is to replace the 4 clip gates on 2 of your (long) quickdraws with locking 'biners. That way it's easy and you also have 4 x locking krabs that will not (potentially) twist open.

Paul
patto
6/08/2005
12:53:16 AM
On 5/08/2005 aikibujin wrote:
>I'm obviously pretty ignorant when it comes to climbing, so please excuse
>all the stupid questions I'll be asking.
>
>What exactly is "cross loading", and how do you cross load bolts?
>
>Besides putting wear on the anchor (which I agree is bad), I don't quite
>understand how you can create a death triangle when you top rope through
>the bolts directly. Could someone explain to me, in simple high school
>level physics so I could understand, how threading the rope through the
>fixed anchor directly creates a death triangle?

Your confusion is valid. Your questions are not stupid.

Threading rope throught the bolts does not create a death triangle, or any other dangerouse polygon. In fact by threading the rope through the bolts you are minimising the forces on the bolts. (assuming the bolts are level).


Threaded through the bolts your are putting 1x climbers body weight on each bolt. Whereas with a quickdraw/sling setup your are putting >1x climbers body weight on each bolt. Eg if your slings have a 90degree angle between them then your putting 1.4x climbers body weight on EACH bolt. Though of course these bolts can happy handle alot more than climbers body weight, so due to wear I agree that threading the bolts is bad.
WM
6/08/2005
9:07:47 AM
This seems to be an opportune moment to remind everyone to chip in a few bucks for a few more of these, especially on routes which get toproped:

http://www.chockstone.org/Forum/Forum.asp?Action=Display&ForumID=11&MessageID=1875


Hatman
6/08/2005
9:19:07 AM
I supose that the threaded situation is not a death triangle. However corss loading is still present. And exagerated depending on where the belayer and climber are situated.

You are still loading the bolts in a week orientation. Even though the forces aplied are much less than a sling triangle.

That said there are still some dodge bolts out there that would not like a cross load like this. For example if as quite often happens some wally new to the game puts in some rings on his first new route and does not cut a notch for them to sit in.

This would considerably weaken the bolts cross loading strength. If the bolt twists at all the brittle glue will snap letting go of the bolt. This applys to lots of bolts. As there are some crap ones that you just dont realise.

I have met some of these bolts and have used them as top rope anchors but only with an equalised system. I would hessitate to use a rope threaded through them. An would never abseil off them as this creates a triangle again no? Any how abseiling SUX

U bolts are great! you can cross load them with no hope of twisting due to the two holes!

tepas
6/08/2005
9:32:37 AM
ask a simple question... :)

Hatman
6/08/2005
9:39:49 AM
gat a long, varied and confusing arguement! what else did you expect on chockstone??

Did it help?
Ronny
6/08/2005
1:54:10 PM
The difference is between u bolts and 'p' bolts which are welded rod that only has one shaft going into the rock, and are hence susceptible to being twisted.

Toproping directly off one bolt does not just simply put a single climbers wieght on each bolt. The rope maintains an equal tension over the entire length, including the part between the bolts. This means that the force on the bolt is the resolution of two vectors, one in teh direction of the rope to the climber (or belayer) and one in the direction fo the other bolt. (the two vectors are equal in size). This means that if the bolts are level the resultant force is at 45deg to horizontal. Excluding friction, if the climber is remaining still, there must be an equal weight on the belayers end, and hence the total weight being held up by the anchor is twice the wieght of the climber. Each bolt takes half the weight, but being pulled at 45deg, that makes the total force on each bolt in teh static system about 1.4 timest the wieght of each climber.

The 'death triangle' problem occurs when one bolt fails. (this isn't a real 'death triangle' but as i understand it is the same problem for which death trianbles are named). All of a sudden there is slack in the system (being the amount of rope between the two bolts, and so there will be a shockloading of the remaining bolt. This may not be very much, especially if the bolts are close together, but that is the issue ppl are refering to.

J

anthonyk
6/08/2005
2:15:19 PM
On 6/08/2005 WM wrote:
>This seems to be an opportune moment to remind everyone to chip in a few
>bucks for a few more of these, especially on routes which get toproped:
>
>http://www.chockstone.org/Forum/Forum.asp?Action=Display&ForumID=11&MessageID=1875

sorry couldn't read that, its not open unless you get permission or something. but how much do those things cost? is there an effort to put them on most popular lower-offs?

also how often are these things stolen? seems they disappear a bit in the blueys and nowra, i'm really surprised that climbers would do such a thing. there was a post from someone on the cragx forum suggesting to "inact a law that anyone found with twist shackles and no proof of purchase can be @ss f*3ked with a housebrick...". nice..

Hatman
6/08/2005
2:30:30 PM
>I am confused that you mention U bolts are great. (which of course they
>are) I thought we were talking about U bolts, all the pics have been U
>bolts. How would you thread a bolt if it wasn't a U bolt? You certainly
>wouldn't want to thread a hanger, unless you want you rope cut!


Many people put a shackle on the hangers so they can be treaded. This I thinks is done a bit in USA? So same things aply.

Rings similar to an eye bolt and are just about as good U's long as they are recesed properly.

I get my twisties for about 7 bucks. They are a good investment. A dab of glue on the thread will deter all except the most determined of hardware fleecer. If you catch such a person do not hesitate to throw rocks at them!
patto
6/08/2005
3:39:52 PM
On 6/08/2005 Ronny wrote:
>The difference is between u bolts and 'p' bolts which are welded rod that
>only has one shaft going into the rock, and are hence susceptible to being
>twisted.
>
>Toproping directly off one bolt does not just simply put a single climbers
>wieght on each bolt. The rope maintains an equal tension over the entire
>length, including the part between the bolts. This means that the force
>on the bolt is the resolution of two vectors, one in teh direction of the
>rope to the climber (or belayer) and one in the direction fo the other
>bolt. (the two vectors are equal in size). This means that if the bolts
>are level the resultant force is at 45deg to horizontal. Excluding friction,
>if the climber is remaining still, there must be an equal weight on the
>belayers end, and hence the total weight being held up by the anchor is
>twice the wieght of the climber. Each bolt takes half the weight, but
>being pulled at 45deg, that makes the total force on each bolt in teh static
>system about 1.4 timest the wieght of each climber.
>
>The 'death triangle' problem occurs when one bolt fails. (this isn't a
>real 'death triangle' but as i understand it is the same problem for which
>death trianbles are named). All of a sudden there is slack in the system
>(being the amount of rope between the two bolts, and so there will be a
>shockloading of the remaining bolt. This may not be very much, especially
>if the bolts are close together, but that is the issue ppl are refering
>to.
>
>J

True. I concede the point.
WM
6/08/2005
4:04:16 PM
On 6/08/2005 anthonyk wrote:
>>http://www.chockstone.org/Forum/Forum.asp?Action=Display&ForumID=11&MessageID=1875
>sorry couldn't read that, its not open unless you get permission or something.

That thread is in the SCV forum - contact info@safercliffs.org to get access permission.

> but how much do those things cost?

~$7.50 each from www.climbinganchors.com

>is there an effort to put them on most popular lower-offs?

As much effort as the climbing community is willing to put in! You can be part of the problem, or part
of the solution!
This is the text of a notice which has been placed on the toilet block notice board at the Pines:
________________________________________________________________________


U-BOLT & RING BOLT ANCHORS - PLEASE NOTE

THE PROBLEM:
U-Bolt anchors (& some ringbolts) have been installed above many routes at Mt. Arapiles in recent
years.

However, climbers threading ropes directly through the U-bolts for abseils or for toproping (as shown in
this picture) have caused significant wear on many of these U-bolts.

If the U-bolts continue to wear through, they will soon be damaged beyond repair and will need to be
removed and replaced.

Removing and/or replacing U-bolts causes significant damage to the rock, is expensive, and takes a
lot of time and effort.
________________________________________________________________________

THE SOLUTION:

To extend the life of the U-Bolts, high strength 10mm stainless steel twisted shackles are gradually
being added. THE TWISTED SHACKLES ARE PERMANENT INSTALLATIONS - DO NOT
ATTEMPT TO REMOVE THEM. They should be replaced in future only when they have worn out.

All Climbers are asked to extend the life of the U-bolts by adopting these practices:

1. Where shackles have been provided, always thread your ropes for abseils through the shackles
(as shown in this picture), and not through the U-bolts.

2. Use your own carabiners for all toproping. A weighted rope running through the U-bolts (e.g. when
lowering a climber) causes by far the most wear on the bolts

3. Abseil off, don't lower off

4. 'Put something back' - next time you visit, bring some 10mm stainless steel twisted shackles to
place on bare U-bolt anchors.

Shackles already placed: Muldoon (9/7/05), Collision Course (9/7/05), Megalomaniac (10/7/05)

For further information contact Safer Cliffs Victoria at info@safercliffs.org or visit www.safercliffs.org

tepas
7/08/2005
8:13:16 AM
Can't say that I'm keen on two x quickdraws.. too many failure points for my liking.

However, two x screwgates, one through each anchor would be hard to stuff up, unlikely to fail and easy to prepare and use. Does that sound like a goer?

Alternatively, two of those shackles, which one could leave behind. Thing which concerns me there, is the potential of people (unintentionally) buying innapropriate shackles and leaving them behind. A lot of people would just assume they're safe... So what's a good shackle look like?

rodw
7/08/2005
12:07:26 PM
You trust the home made U bolt (where most of it concealed in the rock) and not a shackle...interesting.

Rupert
7/08/2005
12:42:01 PM
speaking of which, Neil that sample from the blue Mountains looks like it is only embedded about half the depth of the sample with the shackles a few posts later.

Hatman
8/08/2005
7:03:33 AM
Dont listen to rodw he is a U basher!

He performs secret voodoo dances at crags to keep the U bolters away.

That worn out U does look ultra bodge! If it were the length of the U's I get there would be only 2-3cm in the rock. Just goes to show how strong they are.

Nick Kaz
8/08/2005
8:20:46 AM
Sometimes larger U's are placed as the anchors to make them less crowded when rethreading, the legs are longer it just looks like it hanging out a long way.

 Page 2 of 3. Messages 1 to 20 | 21 to 40 | 41 to 42
There are 42 messages in this topic.

 

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