Mega jul top belay

Anyone understand why there is a difference between 2 ropes and 1 rope in top belay?

I think I know. With only one rope it is possible for the carabiner to rotate 180 degrees and the self blocking feature to be defeated. The result is basically the same as threading the rope into the belay backwards. This can't happen with the bd or petzl device by design, but I've actually seen this happen before with the mega jul if you thread it the two rope method with only one rope. I think it's a pretty dangerous failure mode. It can occur if you're rocking the carabiner to inch out slack / lower a follower. Good to see how to prevent it. Stay safe!

The problem is known for users of the Gi-gi plate; see elevationoutdoors.com/the-k… for a clear explanation accompanied by step-by-step pictures of the single-rope failure mode.

The Gi-gi problem occurs for ropes thin enough for the strands to swap positions in the slots. I don't know what the threshold for such swapping might be for the Mega Jul, but if the strands can swap when the braking carabiner twists, then the braking function of the device will be lost and you're just holding the second over a carabiner. If there is an issue, it would presumably be with single ropes in the 9mm range.

Another possibility, not so catastrophic, is that the strands could jam in the slot with a partial twist of the braking biner and prevent the belayer from taking in or paying out rope.

Apparently Edelrid is worried enough about these scenarios to put warnings, both pictorial and verbal, about them into the instruction manual, but of course few people actually read it. Interestingly, Edelrid doesn't label the incorrect threading with the skull and crossbones, they simply X it out and put a "no" in the diagram, so maybe they don't think a complete failure is possible with their slot widths.

The book Rock Climbing, 2nd Ed., Mastering Basic Skills by Topher Donahue and Craig Luebben (dec) has a picture of a Mega Jul incorrectly rigged, and I found some more such shots in a cursory internet search, so it is pretty clear that either the word is not out, or folks don't think it is an issue with the ropes they are using.

rgold wrote:The problem is known for users of the Gi-gi plate; see elevationoutdoors.com/the-k… for a clear explanation accompanied by step-by-step pictures of the single-rope failure mode. The Gi-gi problem occurs for ropes thin enough for the strands to swap positions in the slots. I don't know what the threshold for such swapping might be for the Mega Jul, but if the strands can swap when the braking carabiner twists, then the braking function of the device will be lost and you're just holding the second over a carabiner. If there is an issue, it would presumably be with single ropes in the 9mm range. Another possibility, not so catastrophic, is that the strands could jam in the slot with a partial twist of the braking biner and prevent the belayer from taking in or paying out rope. Apparently Edelrid is worried enough about these scenarios to put warnings, both pictorial and verbal, about them into the instruction manual, but of course few people actually read it. Interestingly, Edelrid doesn't label the incorrect threading with the skull and crossbones, they simply X it out and put a "no" in the diagram, so maybe they don't think a complete failure is possible with their slot widths. The book Rock Climbing, 2nd Ed., Mastering Basic Skills by Topher Donahue and Craig Luebben (dec) has a picture of a Mega Jul incorrectly rigged, and I found some more such shots in a cursory internet search, so it is pretty clear that either the word is not out, or folks don't think it is an issue with the ropes they are using.

Thanks for the additional info, Rgold. I know I read the instructions when I first got the mega jul and I'm pretty sure they did not show it this way. This must be something that they found out about after the initial release, which is probably why people who would likely do things correctly are doing it differently.

Thanks guys!

rgold wrote:The problem is known for users of the Gi-gi plate; see elevationoutdoors.com/the-k… for a clear explanation accompanied by step-by-step pictures of the single-rope failure mode. The Gi-gi problem occurs for ropes thin enough for the strands to swap positions in the slots. I don't know what the threshold for such swapping might be for the Mega Jul, but if the strands can swap when the braking carabiner twists, then the braking function of the device will be lost and you're just holding the second over a carabiner. If there is an issue, it would presumably be with single ropes in the 9mm range. Another possibility, not so catastrophic, is that the strands could jam in the slot with a partial twist of the braking biner and prevent the belayer from taking in or paying out rope. Apparently Edelrid is worried enough about these scenarios to put warnings, both pictorial and verbal, about them into the instruction manual, but of course few people actually read it. Interestingly, Edelrid doesn't label the incorrect threading with the skull and crossbones, they simply X it out and put a "no" in the diagram, so maybe they don't think a complete failure is possible with their slot widths. The book Rock Climbing, 2nd Ed., Mastering Basic Skills by Topher Donahue and Craig Luebben (dec) has a picture of a Mega Jul incorrectly rigged, and I found some more such shots in a cursory internet search, so it is pretty clear that either the word is not out, or folks don't think it is an issue with the ropes they are using.

I read the instructions and still missed it. After using the device and rigging the biner outside of the loop I did not experience any type of failure. I used 9.5 and larger ropes. Not indicative of all scenarios but my experience.

It looks like they've updated the manual. My device was manufactured mid 2015 and the instructions that came with it do not mention this.

I tried forcing my 9.5 rope to flip like the gi-gi failure but was unsuccessful. My guess is you need a sub 9 rope for this to be even theoretically possible.

If it is an issue with the Mega Jul, and I have no idea whether it is or not, you probably have to have a 9mm rope and a situation in which the belayer doesn't keep up and the second takes a little "leader fall." The ropes stretch and as a consequence get thinner, so things happen at higher loads that you aren't going to see in moderate testing. Of course, attentive belaying would keep any such an episode from ever happening, but a major "advantage" of the guide plates is that they enable and encourage inattentive belaying.

Jim Titt did some tests after people started speaking of using the guide plate orientation for rope-solo self-belaying. Here are his results ( mountainproject.com/v/atc-g…)
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First Fail Mode:
The trapped rope escapes sideways from under the tensioned rope and gets trapped between the tensioned rope and the side of the slot.This is very difficult to free off and you have to dismantle everything and twist the locking krab brutally to release the rope. Take your Prusiks.

Second fail mode:
Apply yet more load and the trapped rope where it crosses the tensioned rope goes down through the slot with a bang. At this point the holding power drops off considerably but not catastrophically, though pretty near!
Easy to release, just unclip the krab when unweighted. Still need to take your Prusiks!

ATC Guide. 10.2 Mammut, used, non-treated. First fail mode 4.8kN. No second fail mode, rope sheath cut at ca 9kN.
ATC Guide. 9mm Edelrid, used, non treated. First fail mode 2.96kN. Max fail load 5.58kN. Residual load 1.6kN
ATC Guide. 8.2mm Edelrid, new,treated. First fail mode 2.05kN. Max fail load 4.06kN. Residual load 1.2kN

Reverso³. 10.2 Mammut, used, non treated. First fail mode 3.68kN. No second fail mode. Rope sheath cut ca 9kN
Reverso³. 9mm Edelrid, used, non treated. First fail mode 2.25kN. Max fail load 3.60kN. Residual load 0.9kN
Reverso³. 8.2mm Edelrid, new,treated. First fail mode 1.6kN. Max fail load 2.38kN. Residual load 0.7kN
All with Petzl Attache 12mm round profile karabiner.
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For the present discussion, the take-home is that with enough load even fat ropes (up to 10.2mm in the tests) can switch places, although, realistically speaking, the belayer would have to be really inattentive at a time when the follower is close to the belay to create such loads. The issue with the Mega Jul, whose braking carabiner is not clipped through the attachment wire loop as with every other tube-style device, is that if (when) strand displacement happens, the carabiner can twist and then I think much of the "residual" braking power will be gone.

The fact that the carabiner positioning advice wasn't in the earlier manuals and then appeared in later ones does suggest something happened, either in the real world or in a testing situation, to make Edelrid add to the instructions.

I've seen this happen in a real-world setting. I had a hanging follower who needed to be lowered a small amount since he was having trouble pulling a small roof. I started ratcheting the carabiner to inch him down. The rope was loaded and I think it's a 9.8 or 9.4. At some point, the carabiner rotated 180 degrees and the "loaded" and "unloaded" sides of the rope switched positions in the belay device. I noticed this happened and quickly put a munter behind the Mega Jul and everything worked out fine. Since then, I've been wary of using the Mega Jul for followers. I'm very glad to see how they recommend to prevent this.

I feel like they should have tried to inform the climbing public that they changed the instructions.

Yikes, that's pretty scary---I'd say worth a skull and crossbones in the manual.

I wonder how well ratcheting works with the carabiner correctly installed. At best it look as if it might be more awkward...

you basically wouldnt be able to ratchet ... same with a gigi

its not the end of the world as several other autoblock devices dont ratchet or are quite hard to do so (alpine smart im looking at you)

but it does complicated escaping the belay a bit

;)

I would like to add that the instructions for a Mega Jul purchased in Sept 2015 don't make a distinction between single and double ropes in auto-block mode. So this change must be pretty recent.

Also, there is another device where the braking carabiner is supposed to be clipped outside the attachment loop when in auto-block mode, the Mammut Alpine Smart. It will work inside but there is significantly more friction.

Has anyone else noticed that the Mega Jul, no matter how it's configured, has way more friction than any other devices in auto-block mode? To me this is its largest drawback and something I can't really get over because belaying with it destroys my elbows.

Here's some comparative info on that from Jim Titt ( mountainproject.com/v/edelr…), who writes

Jim Titt wrote:I measured the force in kg to pull a single strand of rope through feeding with the other hand as normal for some of the commoner devices used for belaying a second off the anchor (N.A means the device is not rated for this rope diameter so not tested).

EDIT:

And here are the results of similar tests by Blake Harrington ( cascadeclimbers.com/elbow-s…) as referenced later in the thread by Jack Cramer.

theres really only 4 autoblocking devices that i know of if you use "fatty and stiffy" ropes and dont want elbow tendonitis

- gigi and copies

- grigri (includes cinch, etc)

- smart alpine

- autoblock munter

as mistah titts (got that sounds awwwwsum) data shows ... once a 10mm+ rope gets worn and stiff, pulling it through the other devices is a biatch

to be blunt ... its a great way for the climbing rope "industrial complex" to keep selling folks thin slick dry treated ropes for moderate multi

;)

For those with older instructions, here is the diagram (correctly rotated) and the accompanying text. Relevant to the current discussion is the last paragraph.

Sure didn't take long for the luster to fade from the MegaJul.

Thanks for that auto-block resistance chart rgold (and Jim Titt).

I'm currently working on an update for the belay device review at OutdoorGearLab. We ran a similar test with 8 devices, including 5 of the same, and I can confirm similar results to those reported. Our full analysis, with graphs and discussion, should be posted within the next few weeks.

It really is a shame though because the Mega Jul is light, durable, and includes some innovative features. I just wish it wasn't such a pain to actually belay with.

Blake Herrington at Cascade Climbers has also run similar tests but with somewhat different results.

Jack Cramer wrote:Thanks for that auto-block resistance chart rgold (and Jim Tett). I'm currently working on an update for the belay device review at OutdoorGearLab. We ran a similar test with 8 devices, including 5 of the same, and I can confirm similar results to those reported. Our full analysis, with graphs and discussion, should be posted within the next few weeks. It really is a shame though because the Mega Jul is light, durable, and includes some innovative features. I just wish it wasn't such a pain to actually belay with. Blake Herrington at Cascade Climbers has also run similar tests but with somewhat different results.

are you writing about the various "failure" modes of the devices?

for example the alpine smart has at least 2 possible failure modes that most users dont know about and arent in the documentation ... thats in addition to multiple "cautions", not failure modes per se but various ways the device can easily have issues

;)

I added Blake Harrington's chart to the same post with Jim Titt's in order to have the info all in one spot.

Jack, in addition to the issues Bearbreeder mentions, you should be and perhaps are aware to the tests done by Jim Titt on the hand-force multiplying power assisted and non-assisted braking devices. Briefly, one should not assume that because the devices take little or no hand pressure at the the relatively low loads that are commmon for "ordinary" climbing falls, that it follows that they will be better (or at least as good) as non-assisted braking devices for the rare but very high loads that can occur with severe multipitch falls.

In fact, the assisted braking devices do not work as hand-force multipliers and do not provide progressively more resistance as the hand force is increased. The results are in the MP thread at mountainproject.com/v/edelr… and later pages, but there is a tremendous amount of static there to be endured. Here are the graphs:

For explanations, I recommend two of Jim's posts on UKC, reproduced below ( ukclimbing.com/forums/t.php…):

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With a normal plate the braking force you achieve is (roughly) proportional to the force the belayers hand applies. With devices like the MegaJul the total braking force is made up from a) the device jamming the rope b) the normal hand force multiplication as with a standard plate. The amount of braking force the device itself produces is a fixed amount and is added to the normal braking force which increases with hand force to produce the total braking effect. The MJ itself is an extremely ineffective belay plate when it comes to the hand-force generated braking effect and so the sum of the combined forces is surprisingly low at higher loads. The Smart Alpine has a higher rope jamming component and by virtue of it´s design (it is designed for a lower rope diameter range than the MJ which attempts to cover far too large a variation in rope diameter) is a more powerful belay device in it´s own right so performs considerably better with thin ropes.

The traditional way of viewing belay plate effectiveness is the ratio between the hand force applied and the resulting braking force and with twin 7.8mm ropes the difference is dramatic, removing the jamming part of the braking force the MegaJul achieves a ratio of 1:3 and the ATC XP a ratio of 1:16, with thin ropes like this the jamming effect is also minimal so the overall braking effect is poor. In a situation where maximum braking force is required the ATC XP provides 4 times as much power as the MegaJul.
The Alpine Up on the other hand is an astoundingly weak belay device (try the "dynamic" mode to see how bad) BUT has an enormous jamming effect so when it comes to braking force far superior to any of the other devices of this type.

I have an extensive collection of belay devices which I have tested over the years and use an ATC XP or GriGri as appropriate....

...Tube-style devices took over from simple plates because the extra height gave better braking performance which allowed the manufacturers to then make the device more usable by opening the slots to give better feeding and reduce the grabbiness Sticht plates tend to exhibit. Taller devices like the ATC have always performed better than say the Reversos, the penalty for saving weight and a "sexier" design.

Having a shallower plate certainly reduces the wrap angle but more critically there is a point where separating the bends increases the bending resistance of the rope, moving the radii apart by a multiple of 7 diameters seems to be roughly the optimum and the better conventional plates seem to follow this roughly. With the current crop of assisted plates the problem is worse because the locking slot allows the karabiner to go even higher than normal and the plate has anyway to be de-powered by enlarging the slots since grabbiness isn´t just inconvenient any more like it is with normal plates but a real problem if unlocking is awkward. Unfortunately some of the better ways of overcoming involuntary locking are protected by patent which only CT have found a way round so far.

To prevent the plate locking to the extent it is unreleasable or starts to damage the rope there has to be a gap left between the karabiner and the body of the plate in the locked position, with the Megajul it is possible to pass a 6mm dia steel rod through the gap which is more than any other device and explains the poor performance under high forces, we dye-tested the contact areas and with my thin ropes at high loads there is no locking effect whatsoever which is why the overall braking is so poor. CT went the other way by physically preventing involuntary locking which allowed them to vastly increase the jamming effect, the downside is unlocking means the device has to be physically large to get the necessary leverage, rope feed is poorer than a normal device and when loaded to extremes the rope starts to suffer.

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Ray Pinpillage wrote:Sure didn't take long for the luster to fade from the MegaJul.

I´ve learnt over the years to not bother debating belay devices until they are at least two years on the market to let the initial enthusiasm die down and reality to start creeping in :-)

rgold what does CT stand for?