This topic has been archived, and won't accept reply postings.
A friend of mine is sport climbing in Germany, and she's found that they lower off/abseil off single bolt anchors. Her friends said she was being paranoid to expect 2 bolts.
I've asked her to send me a picture, so I don't know any more details. However, this doesn't seem the best idea, and it would appear most other places agree with the use of double bolt anchors everywhere I've climbed.
Does anyone have any comments on single bolt anchors, or has anyone experienced this in Germany?
I've asked her to send me a picture, so I don't know any more details. However, this doesn't seem the best idea, and it would appear most other places agree with the use of double bolt anchors everywhere I've climbed.
Does anyone have any comments on single bolt anchors, or has anyone experienced this in Germany?
In reply to JuneBob:
Sure, it´s standard practice most places I climb in Germany. In fact I´m not sure where I would find a two-bolt anchor around here (Frankenjura).
The UIAA recommend two bolts for multi-pitch belays NOT for single pitch and this is pretty standard in a lot of Europe.
Climbers from other areas are used to two bolts because of a) the appalling quality of some countries earlier bolting, b)two bolts are required for climbing walls as the individual bolts are far weaker than outdoors (12kN instead of 25kN).
As the lower-off is the lightest loaded bolt by far then one bolt is sufficient and the accident statistics show this is correct.
Sure, it´s standard practice most places I climb in Germany. In fact I´m not sure where I would find a two-bolt anchor around here (Frankenjura).
The UIAA recommend two bolts for multi-pitch belays NOT for single pitch and this is pretty standard in a lot of Europe.
Climbers from other areas are used to two bolts because of a) the appalling quality of some countries earlier bolting, b)two bolts are required for climbing walls as the individual bolts are far weaker than outdoors (12kN instead of 25kN).
As the lower-off is the lightest loaded bolt by far then one bolt is sufficient and the accident statistics show this is correct.
In reply to jimtitt:
Ok, interesting. I have only ever seen double bolt top anchors also on single pitch routes, hence why I was surprised.
I suppose because I am used to double bolt anchors (as is my friend) it does make me uncomfortable to abseil off just one.
Anyway, your reply and your profile indicate you know what you're talking about, so thanks for the comment!
Ok, interesting. I have only ever seen double bolt top anchors also on single pitch routes, hence why I was surprised.
I suppose because I am used to double bolt anchors (as is my friend) it does make me uncomfortable to abseil off just one.
Anyway, your reply and your profile indicate you know what you're talking about, so thanks for the comment!
In reply to JuneBob:
Whack a klemheist on the live rope as you lower. If the top bolt goes you'll theoretically only go as far as the next bolt.
Whack a klemheist on the live rope as you lower. If the top bolt goes you'll theoretically only go as far as the next bolt.
In reply to jimtitt:
What's the logic of that? Is it that you have two people hanging on a multipitch belay (but if someone falls on a single pitch and pulls their second off the ground you have that anyway)?
Or do they just think that only falling the height of one pitch isn't too serious?
> (In reply to JuneBob)
>
> The UIAA recommend two bolts for multi-pitch belays NOT for single pitch and this is pretty standard in a lot of Europe.
>
> The UIAA recommend two bolts for multi-pitch belays NOT for single pitch and this is pretty standard in a lot of Europe.
What's the logic of that? Is it that you have two people hanging on a multipitch belay (but if someone falls on a single pitch and pulls their second off the ground you have that anyway)?
Or do they just think that only falling the height of one pitch isn't too serious?
Post edited at 11:35
In reply to Dave Garnett:
Presumably because a multi-pitch belay might take a factor 2 fall, whereas the lower off on a single pitch on takes body weight (you don't fall on the loweroff...)
Presumably because a multi-pitch belay might take a factor 2 fall, whereas the lower off on a single pitch on takes body weight (you don't fall on the loweroff...)
In reply to Mick r:
however you have already had plenty of opportunity to check the lower-off bolt is sound and intact in safety before you strip the route.
> not if your stripping the route on the way back down
however you have already had plenty of opportunity to check the lower-off bolt is sound and intact in safety before you strip the route.
In reply to Mick r:
Uh that's exactly what it's for. It should catch you at the next bolt down. The klemheist goes onto the rope that runs through the draws.
http://www.ascenttraining.co.uk/wp-content/uploads/2013/08/Lowering-of-a-si...
Uh that's exactly what it's for. It should catch you at the next bolt down. The klemheist goes onto the rope that runs through the draws.
http://www.ascenttraining.co.uk/wp-content/uploads/2013/08/Lowering-of-a-si...
In reply to Kid Spatula:
I've just learnt something new, cheers.
Yep as above, have experienced mainly single bolt top anchors throughout the F'jura, although they are usually in good condition.
I've just learnt something new, cheers.
Yep as above, have experienced mainly single bolt top anchors throughout the F'jura, although they are usually in good condition.
In reply to JuneBob:
The single bot belays I have come come across tend to be massive things, cemented into the rock - not 10mm parabolts. They look like they would hold an elephant,
Chris
The single bot belays I have come come across tend to be massive things, cemented into the rock - not 10mm parabolts. They look like they would hold an elephant,
Chris
In reply to bigbobbyking:
Well, two people's bodyweights sometimes, but I take the point if you mean a lower off.
I guess I was being hopelessly old-fashioned thinking that it was perfectly possible for someone to fall off and for this force to be transmitted to a belay above a single pitch.
> (In reply to Dave Garnett)
>
> Presumably because a multi-pitch belay might take a factor 2 fall, whereas the lower off on a single pitch on takes body weight (you don't fall on the loweroff...)
>
> Presumably because a multi-pitch belay might take a factor 2 fall, whereas the lower off on a single pitch on takes body weight (you don't fall on the loweroff...)
Well, two people's bodyweights sometimes, but I take the point if you mean a lower off.
I guess I was being hopelessly old-fashioned thinking that it was perfectly possible for someone to fall off and for this force to be transmitted to a belay above a single pitch.
In reply to Kid Spatula:
I'm learning new stuff too! Cheers!
Is a kleimheist simply a prussik? (attached to harness)
I'm learning new stuff too! Cheers!
Is a kleimheist simply a prussik? (attached to harness)
Post edited at 15:20
In reply to JuneBob:
I was on some single-pitch climbs in the Black Forest area (Albbruck crag), and all the top-anchors that I saw were two-bolt anchors.
I have encountered single-bolt anchors upon occasion, and it makes me nervous, too. Especially for setting up a top-rope, rather than just rapping/lowering-off.
I was on some single-pitch climbs in the Black Forest area (Albbruck crag), and all the top-anchors that I saw were two-bolt anchors.
I have encountered single-bolt anchors upon occasion, and it makes me nervous, too. Especially for setting up a top-rope, rather than just rapping/lowering-off.
In reply to Mark Bannan:
A klemheist is a specific type of friction knot - tied like a French Prusik, but instead of clipping the two ends together you pass the bottom one through the top one and clip that instead.
A klemheist is a specific type of friction knot - tied like a French Prusik, but instead of clipping the two ends together you pass the bottom one through the top one and clip that instead.
In reply to jimtitt:
Just come back from the Frankenjura, and echo all of the above - with the exception that in some cases, you're lucky to find even one bolt, never mind two.
JW
Just come back from the Frankenjura, and echo all of the above - with the exception that in some cases, you're lucky to find even one bolt, never mind two.
JW
In reply to John Ww:
That´s generally a feature of the retro-bolting policy, older routes the pegs were replaced with bolts but none added (for a lower-off)so you have to top out. But mostly you aren´t allowed to top-out as it´s a nature park so it´s a bit complicated. It´s what happens when climbing dogma meets the rest of the world.
> Just come back from the Frankenjura, and echo all of the above - with the exception that in some cases, you're lucky to find even one bolt, never mind two.
> JW
That´s generally a feature of the retro-bolting policy, older routes the pegs were replaced with bolts but none added (for a lower-off)so you have to top out. But mostly you aren´t allowed to top-out as it´s a nature park so it´s a bit complicated. It´s what happens when climbing dogma meets the rest of the world.
In reply to JuneBob:
A loweroff should have two bolts, not one, always.
At the average single pitch sport crag, I see as many people top roping as leading and if you want to toprope, leaving the last bolt and anchor clipped is pretty inferior to just having a proper anchor with two bolts.
You don't have to go far to find people who will tell you about bolts or carabiners that have failed on them (or to have experienced it yourself). I've never yet seen someone being lowered with a klemheist backup for quickdraw retrieval (further still, I'd guess that only a small minority of sport climbers would have ever heard of this technique, let alone used it).
The chance that a bolt will fail might be low, but there are a hell of a lot of climbers on a hell of a lot of routes, so the math goes something like this: [low probability of failing] x [many climbers] x [many routes] = appreciable risk.
With two bolts, you are squaring the probability of anchor failure, so the risk becomes tiny: [low probability of failing] x [low probability of failing] x [many climbers] x [many routes] = small risk.
This is a bit wishy washy, so, if I hypothesis what is probably a high probability of bolt failure: 1 time in 10 000. This would mean that even if you contend that your special, cemented adamantium superbolt is 100 times as safe as a normal bolt, it is still 100 times less safe than a two bolt anchor (assuming that the bolts are sufficiently separated to be considered to have an independent chance of failure).
Everyone has been at crags where the 8a has bolts every 1.5 metres and the 6a has bolts every 4.5 metres. Single bolt anchors are just an extension of this; lazyness, lack of funds or elitism on behalf of the bolters.
And no, I have never put in a bolt in my life, before anyone asks ;D
A loweroff should have two bolts, not one, always.
At the average single pitch sport crag, I see as many people top roping as leading and if you want to toprope, leaving the last bolt and anchor clipped is pretty inferior to just having a proper anchor with two bolts.
You don't have to go far to find people who will tell you about bolts or carabiners that have failed on them (or to have experienced it yourself). I've never yet seen someone being lowered with a klemheist backup for quickdraw retrieval (further still, I'd guess that only a small minority of sport climbers would have ever heard of this technique, let alone used it).
The chance that a bolt will fail might be low, but there are a hell of a lot of climbers on a hell of a lot of routes, so the math goes something like this: [low probability of failing] x [many climbers] x [many routes] = appreciable risk.
With two bolts, you are squaring the probability of anchor failure, so the risk becomes tiny: [low probability of failing] x [low probability of failing] x [many climbers] x [many routes] = small risk.
This is a bit wishy washy, so, if I hypothesis what is probably a high probability of bolt failure: 1 time in 10 000. This would mean that even if you contend that your special, cemented adamantium superbolt is 100 times as safe as a normal bolt, it is still 100 times less safe than a two bolt anchor (assuming that the bolts are sufficiently separated to be considered to have an independent chance of failure).
Everyone has been at crags where the 8a has bolts every 1.5 metres and the 6a has bolts every 4.5 metres. Single bolt anchors are just an extension of this; lazyness, lack of funds or elitism on behalf of the bolters.
And no, I have never put in a bolt in my life, before anyone asks ;D
1
In reply to JuneBob:
I guess bounce-testing the lower-off should be a pretty safe way of testing it before committing to it...
I guess bounce-testing the lower-off should be a pretty safe way of testing it before committing to it...
In reply to Jon W:
Reminds me of my favorite F'jura description:
On the right wall you’ll find the best routes, the protection in the left part of the main wall is in parts very dangerous. The rock is a bit fragile here. The route no 3 on the “Vorturm” is fragile, overgrown, the protection is extremely dangerous and at the top the adventure continues as there is no lower-off why you’ll have to downclimb again
Reminds me of my favorite F'jura description:
On the right wall you’ll find the best routes, the protection in the left part of the main wall is in parts very dangerous. The rock is a bit fragile here. The route no 3 on the “Vorturm” is fragile, overgrown, the protection is extremely dangerous and at the top the adventure continues as there is no lower-off why you’ll have to downclimb again
In reply to Sankey:
Albatros on the Gernerfels near Gössweinstein has no lower off either. As the guidebook says, the clue is in the name: Climb until your feet are above the last bolt, then spread your wings and fly.....
Doesn´t matter though, the route goes up the nose on the right next to Supernase
http://www.frankenjura.com/klettern/poi/334
http://routen.climbing.de/gebiete/frankenjura/gifs/20070502163512Supernase....
Albatros on the Gernerfels near Gössweinstein has no lower off either. As the guidebook says, the clue is in the name: Climb until your feet are above the last bolt, then spread your wings and fly.....
Doesn´t matter though, the route goes up the nose on the right next to Supernase
http://www.frankenjura.com/klettern/poi/334
http://routen.climbing.de/gebiete/frankenjura/gifs/20070502163512Supernase....
In reply to henwardian:
Your argument and your maths are flawed. One correctly installed certified bolt is sufficient. We know this because theoretically this is so and there are no records of failure in practice.
> A loweroff should have two bolts, not one, always.
> At the average single pitch sport crag, I see as many people top roping as leading and if you want to toprope, leaving the last bolt and anchor clipped is pretty inferior to just having a proper anchor with two bolts.
> You don't have to go far to find people who will tell you about bolts or carabiners that have failed on them (or to have experienced it yourself). I've never yet seen someone being lowered with a klemheist backup for quickdraw retrieval (further still, I'd guess that only a small minority of sport climbers would have ever heard of this technique, let alone used it).
> The chance that a bolt will fail might be low, but there are a hell of a lot of climbers on a hell of a lot of routes, so the math goes something like this: [low probability of failing] x [many climbers] x [many routes] = appreciable risk.
> With two bolts, you are squaring the probability of anchor failure, so the risk becomes tiny: [low probability of failing] x [low probability of failing] x [many climbers] x [many routes] = small risk.
> This is a bit wishy washy, so, if I hypothesis what is probably a high probability of bolt failure: 1 time in 10 000. This would mean that even if you contend that your special, cemented adamantium superbolt is 100 times as safe as a normal bolt, it is still 100 times less safe than a two bolt anchor (assuming that the bolts are sufficiently separated to be considered to have an independent chance of failure).
> Everyone has been at crags where the 8a has bolts every 1.5 metres and the 6a has bolts every 4.5 metres. Single bolt anchors are just an extension of this; lazyness, lack of funds or elitism on behalf of the bolters.
> And no, I have never put in a bolt in my life, before anyone asks ;D
Your argument and your maths are flawed. One correctly installed certified bolt is sufficient. We know this because theoretically this is so and there are no records of failure in practice.
In reply to jimtitt:
I'd be interested to know where you think henwardian's maths is flawed. His argument looks pretty sound to me. Having at least two points of attachment seems pretty sensible. It's what I would routinely do when taking a stance trad climbing.
I appreciate that your experience equipping and climbing sport routes is vastly greater than my own, and that all your lower-offs will be equipped with correctly installed and certified bolts. But is that universally the case? I've seen some fairly dodgy looking lower offs even at well frequented venues like Kalymnos, and I'm always reassured when there are two bolts to lower from. Fortunately, in my fairly limited sport climbing experience this is generally the case.
Martin
I'd be interested to know where you think henwardian's maths is flawed. His argument looks pretty sound to me. Having at least two points of attachment seems pretty sensible. It's what I would routinely do when taking a stance trad climbing.
I appreciate that your experience equipping and climbing sport routes is vastly greater than my own, and that all your lower-offs will be equipped with correctly installed and certified bolts. But is that universally the case? I've seen some fairly dodgy looking lower offs even at well frequented venues like Kalymnos, and I'm always reassured when there are two bolts to lower from. Fortunately, in my fairly limited sport climbing experience this is generally the case.
Martin
In reply to Martin Hore:
henwardian kind of gave the game away: "assuming that the bolts are sufficiently separated to be considered to have an independent chance of failure"
The distance isn't the only issue. We are talking about bolts installed on the same day, in the same lump rock, drilled by the same person, probably with bolts from the same manufacturer, and possibly the same batch, with the same wrong glue or other tools.
This make it a long way from independent variables. The nuclear industry for one has suffered failures from considering things as independent, multiplying 1 in a 100 x 1 in a 100 ......... then watched the whole thing burn. (Three mile island as an example).
Once upon a time belay bolts were placed a long way apart with a length rope connecting them. Now one finds bolts only 10cm apart with a link between them. It would be interesting to know if spending the same drill time to drill deeper is safer than two less-deep bolts.
> I'd be interested to know where you think henwardian's maths is flawed. His argument looks pretty sound to me.
henwardian kind of gave the game away: "assuming that the bolts are sufficiently separated to be considered to have an independent chance of failure"
The distance isn't the only issue. We are talking about bolts installed on the same day, in the same lump rock, drilled by the same person, probably with bolts from the same manufacturer, and possibly the same batch, with the same wrong glue or other tools.
This make it a long way from independent variables. The nuclear industry for one has suffered failures from considering things as independent, multiplying 1 in a 100 x 1 in a 100 ......... then watched the whole thing burn. (Three mile island as an example).
Once upon a time belay bolts were placed a long way apart with a length rope connecting them. Now one finds bolts only 10cm apart with a link between them. It would be interesting to know if spending the same drill time to drill deeper is safer than two less-deep bolts.
1
In reply to jimtitt:
I love it when folk argue with you, Jim! Like whats his face... can't remember the name - which prompted your reply 'You'll have realised that I know a lot more than you do...!'
I love it when folk argue with you, Jim! Like whats his face... can't remember the name - which prompted your reply 'You'll have realised that I know a lot more than you do...!'
In reply to David Coley:
The redundancy principle, hard to argue against, two has to be better than one. But is it totally justified ? Probably.
Regarding the Klemheist/prussik back up on lower. If you lower on a Reverso you can get the same safety back up, but is the Reverso OK for a low fall factor fall or too harsh on the rope ? I think it might be kinder than a prussik but have not seen any testing? Jim / David?
The redundancy principle, hard to argue against, two has to be better than one. But is it totally justified ? Probably.
Regarding the Klemheist/prussik back up on lower. If you lower on a Reverso you can get the same safety back up, but is the Reverso OK for a low fall factor fall or too harsh on the rope ? I think it might be kinder than a prussik but have not seen any testing? Jim / David?
In reply to jimtitt:
There are three possible issues here:
1) someone does not correctly install a bolt (fails to clean the bolt holes for a gluein etc)
2) someone installs a single unsuitable/unreliable bolt type (e.g. rubbish expansion bolt)
3) it may not be the bolt that is the problem, but the lump of rock it is installed in...
In either case, having two bolts significantly reduces the risks. It is true that the chance of a pair of dodgy bolts is correlated, and if one is dodgy there is a good chance the other is too, but I would much rather have two dodgy bolts than one dodgy bolt!
I know there are no records of failure in practice, but it would probably be best if it stayed that way. The argument may be a bit moot, though. I'm not sure you can say exactly how safe the practice is compared to double bolts, however, because of the low number statistics (beyond saying 'it is at least very safe'). It is hard to say that two bolts is X times safer than one bolt when there are so few bolt failures...
> One correctly installed certified bolt is sufficient.
There are three possible issues here:
1) someone does not correctly install a bolt (fails to clean the bolt holes for a gluein etc)
2) someone installs a single unsuitable/unreliable bolt type (e.g. rubbish expansion bolt)
3) it may not be the bolt that is the problem, but the lump of rock it is installed in...
In either case, having two bolts significantly reduces the risks. It is true that the chance of a pair of dodgy bolts is correlated, and if one is dodgy there is a good chance the other is too, but I would much rather have two dodgy bolts than one dodgy bolt!
> We know this because theoretically this is so and there are no records of failure in practice.
I know there are no records of failure in practice, but it would probably be best if it stayed that way. The argument may be a bit moot, though. I'm not sure you can say exactly how safe the practice is compared to double bolts, however, because of the low number statistics (beyond saying 'it is at least very safe'). It is hard to say that two bolts is X times safer than one bolt when there are so few bolt failures...
Post edited at 23:13
In reply to tehmarks:
Where the 'top' loop in this specific case would actually be the bottom of the knot/hitch(?) as you assembled it.
jk
> A klemheist is a specific type of friction knot - tied like a French Prusik, but instead of clipping the two ends together you pass the bottom one through the top one and clip that instead.
Where the 'top' loop in this specific case would actually be the bottom of the knot/hitch(?) as you assembled it.
jk
In reply to JuneBob:
My one and only bolt failure experience, was sitting at a two bolt anchor rigging an abseil on granite. All sorted, gave it a stern tug before I set off. One of the bolts pulled out.
I too get nervous at single bolt anchors. Glue ins are confidence inspiring, expansion style on the other hand not so much.
Japan has very interesting bolts. Some anchors maybe made of 4 of these tiny things, and even with 4 you're not so sure (I'd guess they're 7mm thick, go in 15 maybe 20 mm with a wedge at the end).
My one and only bolt failure experience, was sitting at a two bolt anchor rigging an abseil on granite. All sorted, gave it a stern tug before I set off. One of the bolts pulled out.
I too get nervous at single bolt anchors. Glue ins are confidence inspiring, expansion style on the other hand not so much.
Japan has very interesting bolts. Some anchors maybe made of 4 of these tiny things, and even with 4 you're not so sure (I'd guess they're 7mm thick, go in 15 maybe 20 mm with a wedge at the end).
Post edited at 04:02
In reply to henwardian:
So what you are saying is that top roping anchors should have two bolts, not that lower offs should. Horses for courses and all that...
So what you are saying is that top roping anchors should have two bolts, not that lower offs should. Horses for courses and all that...
In reply to David Coley:
Sounds like an argument for five bolt belays and always lowering off with a prussik to me.
> (In reply to Martin Hore)
>
> [...]
>
> henwardian kind of gave the game away: "assuming that the bolts are sufficiently separated to be considered to have an independent chance of failure"
>
> The distance isn't the only issue. We are talking about bolts installed on the same day, in the same lump rock, drilled by the same person, probably with bolts from the same manufacturer, and possibly the same batch, with the same wrong glue or other tools.
>
> This make it a long way from independent variables. The nuclear industry for one has suffered failures from considering things as independent, multiplying 1 in a 100 x 1 in a 100 ......... then watched the whole thing burn. (Three mile island as an example).
>
> Once upon a time belay bolts were placed a long way apart with a length rope connecting them. Now one finds bolts only 10cm apart with a link between them. It would be interesting to know if spending the same drill time to drill deeper is safer than two less-deep bolts.
>
> [...]
>
> henwardian kind of gave the game away: "assuming that the bolts are sufficiently separated to be considered to have an independent chance of failure"
>
> The distance isn't the only issue. We are talking about bolts installed on the same day, in the same lump rock, drilled by the same person, probably with bolts from the same manufacturer, and possibly the same batch, with the same wrong glue or other tools.
>
> This make it a long way from independent variables. The nuclear industry for one has suffered failures from considering things as independent, multiplying 1 in a 100 x 1 in a 100 ......... then watched the whole thing burn. (Three mile island as an example).
>
> Once upon a time belay bolts were placed a long way apart with a length rope connecting them. Now one finds bolts only 10cm apart with a link between them. It would be interesting to know if spending the same drill time to drill deeper is safer than two less-deep bolts.
Sounds like an argument for five bolt belays and always lowering off with a prussik to me.
In reply to Rick Graham:
Sorry Rick, I'm not sure I understand where you are placing the Reverso or how you are using it. Please elaborate. Thanks.
> Regarding the Klemheist/prussik back up on lower. If you lower on a Reverso you can get the same safety back up, but is the Reverso OK for a low fall factor fall or too harsh on the rope ? I think it might be kinder than a prussik but have not seen any testing? Jim / David?
Sorry Rick, I'm not sure I understand where you are placing the Reverso or how you are using it. Please elaborate. Thanks.
In reply to Kid Spatula:
Nifty technique and very useful information but I note that they don't recommend the klemheist knot in the document but they recommend the standard prussik instead. It seems to me it would be quite easy to get the klemheist the wrong way up as the instinct for most would be to tie it going up the live rope when in fact it would need to go down.
Perhaps in this case the std prussik is safer.
> (In reply to Mick r)
>
> Uh that's exactly what it's for. It should catch you at the next bolt down. The klemheist goes onto the rope that runs through the draws.
>
> http://www.ascenttraining.co.uk/wp-content/uploads/2013/08/Lowering-of-a-si...
>
> Uh that's exactly what it's for. It should catch you at the next bolt down. The klemheist goes onto the rope that runs through the draws.
>
> http://www.ascenttraining.co.uk/wp-content/uploads/2013/08/Lowering-of-a-si...
Nifty technique and very useful information but I note that they don't recommend the klemheist knot in the document but they recommend the standard prussik instead. It seems to me it would be quite easy to get the klemheist the wrong way up as the instinct for most would be to tie it going up the live rope when in fact it would need to go down.
Perhaps in this case the std prussik is safer.
In reply to Martin Hore:
The possible reasons for bolt failure aren´t random, as has been pointed out what effects one bolt in a pair is very likely to effect the other. If you tested 100 bolts and two failed you have a failure chance of 1:50 so using simple statistics the chance of two bolts failing is 1 in 2500. However simplistic statistics of that type can´t identify grouping of events or external effects and so doesn´t know that of the 100 bolts tested two were side by side. The tester would/should have identified this but statistics won´t.
Laying down the law to the climbing world;- "A loweroff should have two bolts, not one, always." is in direct contradiction to the opinion of the UIAA, DAV, IG Klettern, CAI, CMBEL and just about anyone else you can think of. One good bolt is preferable to two or more bad ones and in a sport-climbing environment there is no reason or need to have bad bolts or use them, if a lower-off looks `dodgy´then either test it or change it.
> I'd be interested to know where you think henwardian's maths is flawed. His argument looks pretty sound to me. Having at least two points of attachment seems pretty sensible. It's what I would routinely do when taking a stance trad climbing.
> I appreciate that your experience equipping and climbing sport routes is vastly greater than my own, and that all your lower-offs will be equipped with correctly installed and certified bolts. But is that universally the case? I've seen some fairly dodgy looking lower offs even at well frequented venues like Kalymnos, and I'm always reassured when there are two bolts to lower from. Fortunately, in my fairly limited sport climbing experience this is generally the case.
> Martin
The possible reasons for bolt failure aren´t random, as has been pointed out what effects one bolt in a pair is very likely to effect the other. If you tested 100 bolts and two failed you have a failure chance of 1:50 so using simple statistics the chance of two bolts failing is 1 in 2500. However simplistic statistics of that type can´t identify grouping of events or external effects and so doesn´t know that of the 100 bolts tested two were side by side. The tester would/should have identified this but statistics won´t.
Laying down the law to the climbing world;- "A loweroff should have two bolts, not one, always." is in direct contradiction to the opinion of the UIAA, DAV, IG Klettern, CAI, CMBEL and just about anyone else you can think of. One good bolt is preferable to two or more bad ones and in a sport-climbing environment there is no reason or need to have bad bolts or use them, if a lower-off looks `dodgy´then either test it or change it.
In reply to Mick r:
Nope, have a look at page 3 here:
http://www.petzl.com/files/all/en/activities/sport/Solutions-Sport-climbing...
You only go as far as ~2 distance the the nearest (unstripped) bolt.
Nope, have a look at page 3 here:
http://www.petzl.com/files/all/en/activities/sport/Solutions-Sport-climbing...
You only go as far as ~2 distance the the nearest (unstripped) bolt.
In reply to jimtitt:
Indeed. The only accident from lower off failure I have ever witnessed happened because the entire summit block (roughly fridge sized) fell off.
Arguably, the climber would have been better off if the bolt had failed: As is happened he got hit by the block on the way down, and then fell on top of the rubble afterwards. I still have no idea how he survived this, albeit with both arms, both legs, and pelvis broken.
To be on any use, the two bolts would have had to be spaced several meters apart and strong enough to keep the block in place.
CB
> The possible reasons for bolt failure aren´t random, as has been pointed out what effects one bolt in a pair is very likely to effect the other.
Indeed. The only accident from lower off failure I have ever witnessed happened because the entire summit block (roughly fridge sized) fell off.
Arguably, the climber would have been better off if the bolt had failed: As is happened he got hit by the block on the way down, and then fell on top of the rubble afterwards. I still have no idea how he survived this, albeit with both arms, both legs, and pelvis broken.
To be on any use, the two bolts would have had to be spaced several meters apart and strong enough to keep the block in place.
CB
In reply to jimtitt:
So the two bolts on the belay are doubling the strengh not increasing redundancy?
So the two bolts on the belay are doubling the strengh not increasing redundancy?
In reply to JuneBob:
So why 2 bolts for a multipitch? A single 25kn bolt is supposed to support a factor 2 fall?
So, if placed correctly shouldn't it be strong enough?
That just leaves arguments about poor placement/rock/etc, which is the same for single pitch.
The only remaining argument then is that on multipitch there's a lot more gear being attached.
So why 2 bolts for a multipitch? A single 25kn bolt is supposed to support a factor 2 fall?
So, if placed correctly shouldn't it be strong enough?
That just leaves arguments about poor placement/rock/etc, which is the same for single pitch.
The only remaining argument then is that on multipitch there's a lot more gear being attached.
In reply to JuneBob:
To be fair, if you are referring to the Frankenjura in Germany then I was told by a few local bolters there years ago not to worry as its Germany and in usual fashion they tend to do things properly haha
their top bolts are apparently monsters, and go in really, really, really deep (more than the rest of the route) and compared to some of the marginal bolts you'll find elsewhere, one proper german bolt vs 2 old crappy bolts is a no contest IMHO (think I was quoted like 10-12 inches but could be mistaken!), but like others have said, given top bolts don't take any major fall factors, they are fine providing in good condition!
Goes without saying to check yourselves before lowering off and inspect the metal, glue, looseness etc and critically that the rest of the rock surrounding it is ok (which even if there were 2 bolts would cause you to die if it all failed), as it would on any route regardless on number of anchors.....remember you belay off just one krab, so its not the bolt failing you need to worry about but the placement and rock itself
Stay safe
To be fair, if you are referring to the Frankenjura in Germany then I was told by a few local bolters there years ago not to worry as its Germany and in usual fashion they tend to do things properly haha
their top bolts are apparently monsters, and go in really, really, really deep (more than the rest of the route) and compared to some of the marginal bolts you'll find elsewhere, one proper german bolt vs 2 old crappy bolts is a no contest IMHO (think I was quoted like 10-12 inches but could be mistaken!), but like others have said, given top bolts don't take any major fall factors, they are fine providing in good condition!
Goes without saying to check yourselves before lowering off and inspect the metal, glue, looseness etc and critically that the rest of the rock surrounding it is ok (which even if there were 2 bolts would cause you to die if it all failed), as it would on any route regardless on number of anchors.....remember you belay off just one krab, so its not the bolt failing you need to worry about but the placement and rock itself
Stay safe
In reply to JuneBob:
On a multi-pitch route the amount of gear attatched is certainly to be considered (on a cramped stance I usually fit a third bolt as well) but normally it´s the amount of people we worry about, half-a-dozen on one belay isn´t exactly unusual.
> So why 2 bolts for a multipitch? A single 25kn bolt is supposed to support a factor 2 fall?
> So, if placed correctly shouldn't it be strong enough?
> That just leaves arguments about poor placement/rock/etc, which is the same for single pitch.
> The only remaining argument then is that on multipitch there's a lot more gear being attached.
On a multi-pitch route the amount of gear attatched is certainly to be considered (on a cramped stance I usually fit a third bolt as well) but normally it´s the amount of people we worry about, half-a-dozen on one belay isn´t exactly unusual.
Post edited at 11:58
In reply to cb294:
Reminds me of the tale of the labourer, the pulley, and the barrel of bricks
> As is happened he got hit by the block on the way down, and then fell on top of the rubble afterwards. I still have no idea how he survived this, albeit with both arms, both legs, and pelvis broken.
Reminds me of the tale of the labourer, the pulley, and the barrel of bricks
In reply to David Coley:
Sorry late night post.
It goes like this.
Lead a pitch clipping all the gear.
The belayer keeps you on their plate.
Lower yourself off the single/dubious belay with a reverso/guide plate set up so if the belay fails the reverso goes automatically into locking mode.
In effect the reverso does the job of the petzl prussik.
I just wonder which is stronger/more reliable, the 7mm prussik or the reverso?
The fall factor in the petzl test is quite low.
> Sorry Rick, I'm not sure I understand where you are placing the Reverso or how you are using it. Please elaborate. Thanks.
Sorry late night post.
It goes like this.
Lead a pitch clipping all the gear.
The belayer keeps you on their plate.
Lower yourself off the single/dubious belay with a reverso/guide plate set up so if the belay fails the reverso goes automatically into locking mode.
In effect the reverso does the job of the petzl prussik.
I just wonder which is stronger/more reliable, the 7mm prussik or the reverso?
The fall factor in the petzl test is quite low.
In reply to jimtitt:
I know your Bolt products are fully tested and tick all the boxes.
I would also like to state I am in awe of your products and the depth of research and testing you have done on even unrelated products and techniques.
But..
regarding the redundancy discussions, engineering, quality control, statistics and possible user error in installation and use.
I don't think anybody yet has taken into account the "consequences " of any failure/ f*ck up.
I know your Bolt products are fully tested and tick all the boxes.
I would also like to state I am in awe of your products and the depth of research and testing you have done on even unrelated products and techniques.
But..
regarding the redundancy discussions, engineering, quality control, statistics and possible user error in installation and use.
I don't think anybody yet has taken into account the "consequences " of any failure/ f*ck up.
In reply to Rick Graham:
Rick, this is interesting. I will play at the wall on Sunday - and hopefully I won't end up being thrown out. It will be interesting to see if the climber even descends given the friction.
By the way Jim has done some testing on using a Reverso as a lead self belay device, so there is some data. Basicly, it can work, but if the force is high enough the ropes can switch places inside the reverso. Which = not good.
> The belayer keeps you on their plate.
> Lower yourself off the single/dubious belay with a reverso/guide plate set up so if the belay fails the reverso goes automatically into locking mode.
Rick, this is interesting. I will play at the wall on Sunday - and hopefully I won't end up being thrown out. It will be interesting to see if the climber even descends given the friction.
By the way Jim has done some testing on using a Reverso as a lead self belay device, so there is some data. Basicly, it can work, but if the force is high enough the ropes can switch places inside the reverso. Which = not good.
In reply to David Coley:
Take a few guide plate types. I find the longer slot flat ones best. You are lowering yourself mainly, the belayer just watches the rope.
This technique can also be very reassuring when applied to dodgy abseils off multi pitch routes. First person down puts in some runners, and keeps the plate on the rope at the next stance.
> Rick, this is interesting. I will play at the wall on Sunday - and hopefully I won't end up being thrown out. It will be interesting to see if the climber even descends given the friction.
Take a few guide plate types. I find the longer slot flat ones best. You are lowering yourself mainly, the belayer just watches the rope.
This technique can also be very reassuring when applied to dodgy abseils off multi pitch routes. First person down puts in some runners, and keeps the plate on the rope at the next stance.
In reply to David Coley:
Version one Reverso has worked quite well for me used this way the last 13 years. Just never sure how hard a fall it will take.
> By the way Jim has done some testing on using a Reverso as a lead self belay device, so there is some data. Basicly, it can work, but if the force is high enough the ropes can switch places inside the reverso. Which = not good.
Version one Reverso has worked quite well for me used this way the last 13 years. Just never sure how hard a fall it will take.
In reply to Rick Graham:
Have you taken many falls on it? It is such a simple approach, I've always been tempted, but never brave enough.
> Version one Reverso has worked quite well for me used this way the last 13 years. Just never sure how hard a fall it will take.
Have you taken many falls on it? It is such a simple approach, I've always been tempted, but never brave enough.
In reply to JuneBob:
St.Bees has many single bolt lower offs. I used to do a fair bit of caving and friends testing p hangers reassured me when they said even wobbly hangers were nearly indestructible, the rock blew before the resin bond, so being lowered off "one" is fine. I would prefer 2 though.
St.Bees has many single bolt lower offs. I used to do a fair bit of caving and friends testing p hangers reassured me when they said even wobbly hangers were nearly indestructible, the rock blew before the resin bond, so being lowered off "one" is fine. I would prefer 2 though.
In reply to petegunn:
The ones at St Bees (if they are ones with large shiny eyes) are some mean things! They are 300mm long and made of 1.4462 duplex stainless steel, I´ll admit I don´t actually know how strong they are as our tester will only read 12tons but the smaller 6mm ones hang on in to about 75kN so those will probably be good for 140kN.
The ones at St Bees (if they are ones with large shiny eyes) are some mean things! They are 300mm long and made of 1.4462 duplex stainless steel, I´ll admit I don´t actually know how strong they are as our tester will only read 12tons but the smaller 6mm ones hang on in to about 75kN so those will probably be good for 140kN.
In reply to jimtitt:
The original staples at St Bees (early 90's) used 100mm deep holes.
There was a scare a few years ago about them pulling out of the holes as they were far prouder from the rock than when first placed.
When they still tested OK it dawned on everybody that it was rock erosion.
The bolts stayed put , the rock face was moving inland!
The original staples at St Bees (early 90's) used 100mm deep holes.
There was a scare a few years ago about them pulling out of the holes as they were far prouder from the rock than when first placed.
When they still tested OK it dawned on everybody that it was rock erosion.
The bolts stayed put , the rock face was moving inland!
In reply to David Coley:
Not for the faint hearted, I can confirm. But prefer the reverso to the Soloist and modified Gri gri I've also used.
Just a few test falls. I'm an old school trad climber. Most falls I have taken are from snapping holds.
> Have you taken many falls on it? It is such a simple approach, I've always been tempted, but never brave enough.
Not for the faint hearted, I can confirm. But prefer the reverso to the Soloist and modified Gri gri I've also used.
Just a few test falls. I'm an old school trad climber. Most falls I have taken are from snapping holds.
In reply to jimtitt:
Do you mean "effects" or "affects"? affects would make more sense but if the English was changed a bit then "effects" could also make sense but mean something a bit different.
Can you link the relevant pages please, or at least copypaste quotes. I'm suprised that so many organisations advocate single bolt loweroffs.
On a tufa covered wall, there might not be any certainty that "one good bolt" is available anywhere". Nobody aims to put in "two bad bolts", obviously everyone aims to place a "good bolt" when they place it in the first place, the very reason for placing two is that if one turns out to be bad, there is a good chance that the other will not. So yes, I know that in many cases, the chance of failure of one bolt is not totally independent of the other, but what you seem to be saying is that making an anchor with two bolts makes the anchor no more reliable than with one and this simply is not true.
In reply to GrahamD:
I would think that "lower off" and "top rope anchor" are the same thing at almost all crags because the use of the anchor depends on the inclination of the climber using the route. As we are talking about cemi-permanent bolts and not something set up for personal use on the day, they really must be designed with both uses in mind.
> The possible reasons for bolt failure aren´t random, as has been pointed out what effects one bolt in a pair is very likely to effect the other.
Do you mean "effects" or "affects"? affects would make more sense but if the English was changed a bit then "effects" could also make sense but mean something a bit different.
> Laying down the law to the climbing world;- "A loweroff should have two bolts, not one, always." is in direct contradiction to the opinion of the UIAA, DAV, IG Klettern, CAI, CMBEL and just about anyone else you can think of.
Can you link the relevant pages please, or at least copypaste quotes. I'm suprised that so many organisations advocate single bolt loweroffs.
> One good bolt is preferable to two or more bad ones and in a sport-climbing environment there is no reason or need to have bad bolts or use them, if a lower-off looks `dodgy´then either test it or change it.
On a tufa covered wall, there might not be any certainty that "one good bolt" is available anywhere". Nobody aims to put in "two bad bolts", obviously everyone aims to place a "good bolt" when they place it in the first place, the very reason for placing two is that if one turns out to be bad, there is a good chance that the other will not. So yes, I know that in many cases, the chance of failure of one bolt is not totally independent of the other, but what you seem to be saying is that making an anchor with two bolts makes the anchor no more reliable than with one and this simply is not true.
In reply to GrahamD:
> So what you are saying is that top roping anchors should have two bolts, not that lower offs should. Horses for courses and all that...
I would think that "lower off" and "top rope anchor" are the same thing at almost all crags because the use of the anchor depends on the inclination of the climber using the route. As we are talking about cemi-permanent bolts and not something set up for personal use on the day, they really must be designed with both uses in mind.
In reply to henwardian:
I think in a well engineered climbing world this might be true. But in reality, routes are equipped by a volunteer who does it for their own motives - not because they are working to a ratified plan of any sort.
> I would think that "lower off" and "top rope anchor" are the same thing at almost all crags because the use of the anchor depends on the inclination of the climber using the route. As we are talking about cemi-permanent bolts and not something set up for personal use on the day, they really must be designed with both uses in mind.
I think in a well engineered climbing world this might be true. But in reality, routes are equipped by a volunteer who does it for their own motives - not because they are working to a ratified plan of any sort.
In reply to henwardian:
You´re correct, affect would be right!
They don´t "advocate" single bolts, that is what they fit. The DAV say two bolts is standard but then they don´t fit them themselves, you can go to their safety training facility in the Franken and lower off single bolts. The UIAA only mention 2 bolts belays in a multi-pitch belay context.
Bolting in tufa is notoriously unreliable, if it has to be done then drilling right through and fitting one bolt into the bedrock is better than two bolts in the tufa.
The difference is whether the top anchor was designed for top-roping to be carried out using it or it was installed for lowering/abseiling only. The bolt(s) don´t change since there is only one bolt standard anyway but the rest does.
> Do you mean "effects" or "affects"? affects would make more sense but if the English was changed a bit then "effects" could also make sense but mean something a bit different.
You´re correct, affect would be right!
> Can you link the relevant pages please, or at least copypaste quotes. I'm suprised that so many organisations advocate single bolt loweroffs.
They don´t "advocate" single bolts, that is what they fit. The DAV say two bolts is standard but then they don´t fit them themselves, you can go to their safety training facility in the Franken and lower off single bolts. The UIAA only mention 2 bolts belays in a multi-pitch belay context.
> On a tufa covered wall, there might not be any certainty that "one good bolt" is available anywhere". Nobody aims to put in "two bad bolts", obviously everyone aims to place a "good bolt" when they place it in the first place, the very reason for placing two is that if one turns out to be bad, there is a good chance that the other will not. So yes, I know that in many cases, the chance of failure of one bolt is not totally independent of the other, but what you seem to be saying is that making an anchor with two bolts makes the anchor no more reliable than with one and this simply is not true.
Bolting in tufa is notoriously unreliable, if it has to be done then drilling right through and fitting one bolt into the bedrock is better than two bolts in the tufa.
> In reply to GrahamD:
> I would think that "lower off" and "top rope anchor" are the same thing at almost all crags because the use of the anchor depends on the inclination of the climber using the route. As we are talking about cemi-permanent bolts and not something set up for personal use on the day, they really must be designed with both uses in mind.
The difference is whether the top anchor was designed for top-roping to be carried out using it or it was installed for lowering/abseiling only. The bolt(s) don´t change since there is only one bolt standard anyway but the rest does.
In reply to jimtitt:
What would the Germans think of home-made Portland staples then?
While I have been convinced by your arguments that a single bomber German-installed and certified bolt is indeed sufficiently bomber, I'm not sure lowering off a single Portland-type staple would give quite the same level of reassurance...
The only place I have encountered 'single' loweroffs was actually at Winspit Quarry. They were the sort you don't need to thread, but a type I haven't seen elsewhere - they had a big spike which went through a square hole? (they weren't really single loweroffs since there were older bolts that could also be threaded - which I threaded). Even ignoring the generally loose nature of some of the rock, the loweroffs would have been more reassuring if several of them weren't broken, with the square gate having snapped off somehow...
PS as expected they don't match anything in your catalogue
What would the Germans think of home-made Portland staples then?
While I have been convinced by your arguments that a single bomber German-installed and certified bolt is indeed sufficiently bomber, I'm not sure lowering off a single Portland-type staple would give quite the same level of reassurance...
The only place I have encountered 'single' loweroffs was actually at Winspit Quarry. They were the sort you don't need to thread, but a type I haven't seen elsewhere - they had a big spike which went through a square hole? (they weren't really single loweroffs since there were older bolts that could also be threaded - which I threaded). Even ignoring the generally loose nature of some of the rock, the loweroffs would have been more reassuring if several of them weren't broken, with the square gate having snapped off somehow...
PS as expected they don't match anything in your catalogue
In reply to andrewmcleod:
They were in fact a product of mine. Climbers were confused by them and clipped onto the gate which was only there to stop the rope coming out. And as you say we did provide a second bolt as well They held about 78kN on a good day but like some other lower-off solutions climber intelligence is hard to judge sometimes!
It´s something we all learn in the industry in the end, when you are surrounded by experienced and active climbers mostly with some mechanical knowledge it´s a bit hard to realise there are people out there who literally climb by numbers and have little or no innate feeling for what´s going on. It´s also hard to know how far to cater for them!
As for Portland staples, well they aren´t a certified product so who knows?
They were in fact a product of mine. Climbers were confused by them and clipped onto the gate which was only there to stop the rope coming out. And as you say we did provide a second bolt as well They held about 78kN on a good day but like some other lower-off solutions climber intelligence is hard to judge sometimes!
It´s something we all learn in the industry in the end, when you are surrounded by experienced and active climbers mostly with some mechanical knowledge it´s a bit hard to realise there are people out there who literally climb by numbers and have little or no innate feeling for what´s going on. It´s also hard to know how far to cater for them!
As for Portland staples, well they aren´t a certified product so who knows?
Post edited at 19:22
In reply to jimtitt:
Fair enough, as usual the weakest link isn't the product...
> They were in fact a product of mine. Climbers were confused by them and clipped onto the gate which was only there to stop the rope coming out. And as you say we did provide a second bolt as well They held about 78kN on a good day but like some other lower-off solutions climber intelligence is hard to judge sometimes!
Fair enough, as usual the weakest link isn't the product...
In reply to jimtitt:
Thats why we have 10 kg strength tags on harness gear loops.
I had it explained to me once as the PF rule.
" If it is physically possible to f**k it up, some f**kwit will manage it eventually "
Thats why we have 10 kg strength tags on harness gear loops.
I had it explained to me once as the PF rule.
" If it is physically possible to f**k it up, some f**kwit will manage it eventually "
In reply to andrewmcleod:
I thought that staple type bolts were first used in Germany.
> What would the Germans think of home-made Portland staples then?
I thought that staple type bolts were first used in Germany.
In reply to Rick Graham:
Possible but I´d have thought unlikely, I´ve not seen one. There have been various kinds of ring bolt in use for over a hundred years like the Muni and the DAV ones and the Buhler´s around for about 50. I´d have guessed S.Africa myself since they seemed to have been using railway U´s for a fair time.
Possible but I´d have thought unlikely, I´ve not seen one. There have been various kinds of ring bolt in use for over a hundred years like the Muni and the DAV ones and the Buhler´s around for about 50. I´d have guessed S.Africa myself since they seemed to have been using railway U´s for a fair time.
In reply to jimtitt:
I got the idea for the Lakes staples after seeing some in the Donautal in 89.
Unless they were just well embedded Buhler bolts.
Looked at using industrial U's but all a bit short legged for comfort.
I got the idea for the Lakes staples after seeing some in the Donautal in 89.
Unless they were just well embedded Buhler bolts.
Looked at using industrial U's but all a bit short legged for comfort.
In reply to Rick Graham:
I remember Johnny Adams telling me about putting staples in St Bees. Were you two working together?
I remember Johnny Adams telling me about putting staples in St Bees. Were you two working together?
In reply to Rick Graham:
He told me the he found that they corroded at the point where he'd tapped them in with a hammer. After that wasn't the hammer wrapped in a towel or something?
He told me the he found that they corroded at the point where he'd tapped them in with a hammer. After that wasn't the hammer wrapped in a towel or something?
In reply to jon:
Special leather capped hammer.
Apparently if you hit stainless with a different steel hammer some local alloying or other phenomena occurs which will corrode. Jim will probably explain better.
At St Bees , lots of climbers involved, not just JA.
Special leather capped hammer.
Apparently if you hit stainless with a different steel hammer some local alloying or other phenomena occurs which will corrode. Jim will probably explain better.
At St Bees , lots of climbers involved, not just JA.
This topic has been archived, and won't accept reply postings.
Elsewhere on the site
Loading Notifications...