Backwards C-rigging

[Mike Hopley]

I've been using a "backwards C-rig" to thread my descender. I can't see any problem with this, but I'd like to know what other people think -- because maybe I missed something!

So my question is this: in terms of safety, how does backwards C-rigging compare to normal C-rigging?

The known hazards of C-rigging are (1) the possibility of going too fast and losing control and (2) disabling the auto-lock on a Stop. Both of these apply to backwards C-rigging too; I want to know if there's any additional hazard.

I prefer backwards C-rigging because it's easier to flip the rope over the descender, creating a half-lock. It also lets me spread the wear on the descender sideplate. Note that backwards C-rigging doesn't work well with a traditional braking krab position (on the right of the descender), and is more suited to using a Freino or similar.

To clarify the discussion, I made pictures of C-rigging and backwards C-rigging

**EDIT**
Can't seem to get the image embedding right, so links instead.

 

[Stu]

Is c rigging a simple necessary? Don't use one so inquisitive. Would have thought they're slick enough. 

 

[Mike Hopley]

Is c rigging a simple necessary? Don't use one so inquisitive. Would have thought they're slick enough. 

Semi-necessary on 11 mm rope, especially old, fuzzy stuff.

Not necessary on 10 or 9 mm, but very smooth and fun. I started routinely C-rigging last expedition and loved it. But this could be very dangerous if one is not used to it, so obviously test it in a safe environment first (belayed, etc.).

Really quite fast on 8 mm, which I still prefer to S-rig!

 

[ianball11]

On the backwards C, does the rope scrape on the body of the bobbin before it goes into the freino?

 

[Stu]

Thanks Mike that makes sense.

 

[Mike Hopley]

On the backwards C, does the rope scrape on the body of the bobbin before it goes into the freino?

The rope always rubs on the bobbin sideplate when using a Freino. In those photos, you can see the existing wear mark from previous S- and C-rigging.

With the backwards C, the same thing happens, just on the left side rather than the right. That's one reason for my using a backwards C: I can divide the wear more evenly, to make the Simple last longer.

 

[ianball11]

It seems a bit silly to have more rubbing than necessary in normal use  :-\

You could just have normal s rigging and not use the freino on a sticky rope?

 

[Mike Hopley]

It seems a bit silly to have more rubbing than necessary in normal use  :-\

That is a disadvantage of the Freino, yes.

You could just have normal s rigging and not use the freino on a sticky rope?

True. But I like the Freino!

...and if you're referring to not using a braking krab at all, I consider that dangerous, even on fat rope.

 

[ianball11]

I can't think of ever seeing any abseil without a braking krab  :-\

 

[Stu]

On the backwards C, does the rope scrape on the body of the bobbin before it goes into the freino?

Petzl now don't recommend placing the braking krab alongside the Stop/Simple krab. Their recommendation is a Freino or the braking krab clipped onto the Stop/Simple krab 7B. Basically their recommendation means rubbing is inevitable.

 

[badger]

Cavers do amaze me, even me included, in how tight we all seem, we would rather rig a abseil devise in way not recommended by the manufacturer, when both spare parts are available, or even that in the great scheme of things they are relatively in expensive (certain parts of kit), and even on heavy use last a very long time. 

 

[Stu]

To be fair to Mike I suspect that any sharing out of the wear in use is incidental to the fact that sometimes there is just too much friction in a "normal"  set up.

Alternate rigging methods are certainly shown in quite esteemed technical tomes.

 

[Mike Hopley]

Cavers do amaze me, even me included, in how tight we all seem, we would rather rig a abseil devise in way not recommended by the manufacturer, when both spare parts are available, or even that in the great scheme of things they are relatively in expensive (certain parts of kit), and even on heavy use last a very long time. 

As Stu said, balancing out the wear is an incidental benefit. I C-rig because I like the smoothness; I backwards C-rig because I feel it's safer and more convenient than C-rigging, since I can more easily make a half-lock.

Nevertheless, backwards C-rigging is unusual, so I thought it worth asking around about any safety implications I might have missed.

The gear lasts a very long time in the UK. But each expedition in the Spanish Picos, I wear through about one descender, plus one spare set of spools, plus one Freino. Now, what was that about being tight?

The descender wear could be avoided by using a Raumer Handy, but I prefer the Freino for its ease of use, particularly in locking off. The lock-off is so fast that it's almost as good as having a Stop, without the downsides of a Stop.

Petzl now don't recommend placing the braking krab alongside the Stop/Simple krab. Their recommendation is a Freino or the braking krab clipped onto the Stop/Simple krab 7B.

Yes, and this is also the current recommendation of the French Caving School -- although they also permit using a Raumer Handy or similar, or using the Vertaco method with an auto-locking krab.

Basically their recommendation means rubbing is inevitable.

Sort of...

Rubbing is inevitable with the Freino, or with the Vertaco method (where the rope is passed through the descender krab itself).

I think rubbing would not occur when the braking krab is attached to the descender krab; and it definitely doesn't happen when using a Handy.

 

[ianball11]

I've seen the Petzl paperwork and got to admit I read it as the stop is ok for descent and for added braking use a freino or a krab attached to the descender attachment krab along with the notion that added braking through a krab on the d-ring was dangerous (which it can be but usually if you load your stop with a load of slack)  The Simple bobbin though isn't and a freino is considered essential.  2&2A  [on an interestsing side note, 2m/s max speed is also noted on the simple paperwork!]
When I first starting caving everyone had the braking krab on their leg loop, I went to a conference and felt an idiot, all that crawling with a karabina flapping about and sliding around when everyone else has it on the harness attachment to the d-maillon.
Then it was on the d-ring and now it's on the attachment krab.
I feel a little silly in admitting that I last used it on my leg loop again to see what it was like and I liked it.
But through all of it, everyone used a braking krab, just disagreed about where to put it.

 

[Mike Hopley]

I've seen the Petzl paperwork and got to admit I read it as the stop is ok for descent and for added braking use a freino or a krab attached to the descender attachment krab along with the notion that added braking through a krab on the d-ring was dangerous. The Simple bobbin though isn't and a freino is considered essential.

Yes, I think that's a correct interpretation of Petzl's recommendations (except that it doesn't have to be a Freino, it could be any suitable braking krab).

...although having said that, their text doesn't quite agree with their diagrams on this matter, and implies that a Simple may be used without a braking krab.

Personally I disagree with them: I believe a braking krab should always be used, even with the Stop. This is also what the EFS say.

[on an interestsing side note, 2m/s max speed is also noted on the simple paperwork!]

And there's no corresponding speed limit on the Stop paperwork!

 

[Jon]

A friction krab is useful and beneficial but it's certainly not essential. You can prove this by learning to abseil smoothly without one.

 

[Mike Hopley]

A friction krab is useful and beneficial but it's certainly not essential. You can prove this by learning to abseil smoothly without one.

I consider them "essential" because they afford a much greater degree of control, and protect cavers against situations where their abseiling speed increases unexpectedly. It's not a matter of "proof", it's a matter of judgement -- and of course, different people will make different judgements! Your "proof" is easily repurposed:

A descender is useful and beneficial, but it's certainly not essential. You can prove this by learning to abseil without one.

A harness...

 

[Jon]

Blimey! And I thought my reply was pedantic! A friction krab is a minor, non essential addon, you can't put it in the same category as a harness.

 

[Mike Hopley]

Blimey! And I thought my reply was pedantic! A friction krab is a minor, non essential addon, you can't put it in the same category as a harness.

Apologies -- that word "proof" brings me out in a rash, which is my personal allergy and nothing to do with you. It leads to dark corridors of pedantry. It also leads to profound philosophy. Unfortunately the former is often the route to the latter.

I must try to remember that reductios are not appropriate or enlightening in general conversation. :-[

If none of that made sense, here's a translation: don't take up philosophy, kids; it will leave you with mental problems.

 

[owd git]

If none of that made sense, here's a translation: don't take up philosophy, kids; it will leave you with mental problems.
[/quote]
Do you have any proof of that statement? :
O.G.