Edelrid MegaJul Belay Device

The deeper a hole Brian digs himself, the more I enjoy this thread.

Brian - do you have any idea of the background and knowledge of the individuals with whom you're rapidly losing an argument?

Richard and Jim - thank you for your tireless and timeless contributions to the climbing world. Your posts here are always valued and appreciated.

Jon H wrote:The deeper a hole Brian digs himself, the more I enjoy this thread. Brian - do you have any idea of the background and knowledge of the individuals with whom you're rapidly losing an argument? Richard and Jim - thank you for your tireless and timeless contributions to the climbing world. Your posts here are always valued and appreciated.

+1

Brian wrote: So in a factor 2 fall the assisted locking of a MegaJul doesn't lock-up and assist in braking and the rope in any way and the rope will go screaming through the device as rapidly as a regular ATC? And a BD ATC is easier to hold a factor 2 fall? Unless we are talking about different things, I find that to be incredible. I probably can't convince any of my climbing partners to take a factor 2 fall for me to test it so I will have to continue to disbelieve it until I see verifiable published tests.

Two comments Brian.

(1) Jim has already mentioned that factor-2 fall testing is out. In a way, this is too bad, because factor-2 falls are a real possibility on lots of pitches if the belayer doesn't clip the anchor, and (oh-oh, a whole separate argument: there are good reasons at least in some cases not to clip the anchor). The reason factor-2 falls are out is because neither the MegaJul nor an ATC nor the Smart nor the Alpine Up stands a chance of holding them unless the belayer brings the braking hand up to the chest so that braking action can be invoked.

(2) Ok, factor 1.9 then. Jim may have to correct me, but I don't see his results implying quite the catastrophic alternatives you discuss. Here's what I think Jim's results imply.

(a) ATC. The load will build up on the ATC until the belayer can no longer hold it, after which some rope will run through the device. As Jim mentioned, once the rope is running, the energy absorbtion method changes form rope stretching, which is "scalable" and so is described by the fall factor, to work done against the (inadequate) resisting force of the belay device and belayer's hand, which is not scalable and will be greater and greater as the fall distance increases. Nothing about this is hypothetical---it has been tested over and over.

(b) MegaJul and others. The device will initially lock until the load builds up past its locking capacity. After that the rope will run through the device and the belayer's hands, and at that point the resisting force supplied by the device will be less than would have been obtained from an ATC. As I wrote above, this appears to give rise to two possibilities:

(i) The extra rope stretch occurring during the locked phase will absorb enough fall energy that, even with less power, the amount of rope that runs through the device is less than what would have occurred with the ATC.

(ii) The opposite of (i), which is that the reduced power of the device forces more rope to run through it then would have occurred with the ATC.

My guess is Item~(i), in which case the "assisted locker" is still a better bet. But all this is pure speculation (read: mathematical bullshit), and without dynamic testing we won't know which scenario happens or in fact whether neither of them are accurate.

rgold wrote: Two comments Brian. (1) Jim has already mentioned that factor-2 fall testing is out. In a way, this is too bad, because factor-2 falls are a real possibility on lots of pitches if the belayer doesn't clip the anchor, and (oh-oh, a whole separate argument: there are good reasons at least in some cases not to clip the anchor). The reason factor-2 falls are out is because neither the MegaJul nor an ATC nor the Smart nor the Alpine Up stands a chance of holding them unless the belayer brings the braking hand up to the chest so that braking action can be invoked. (2) Ok, factor 1.9 then. Jim may have to correct me, but I don't see his results implying quite the catastrophic alternatives you discuss. Here's what I think Jim's results imply. (a) ATC. The load will build up on the ATC until the belayer can no longer hold it, after which some rope will run through the device. As Jim mentioned, once the rope is running, the energy absorbtion method changes form rope stretching, which is "scalable" and so is described by the fall factor, to work done against the (inadequate) resisting force of the belay device and belayer's hand, which is not scalable and will be greater and greater as the fall distance increases. Nothing about this is hypothetical---it has been tested over and over. (b) MegaJul and others. The device will initially lock until the load builds up past its locking capacity. After that the rope will run through the device and the belayer's hands, and at that point the resisting force supplied by the device will be less than would have been obtained from an ATC. As I wrote above, this appears to give rise to two possibilities: (i) The extra rope stretch occurring during the locked phase will absorb enough fall energy that, even with less power, the amount of rope that runs through the device is less than what would have occurred with the ATC. (ii) The opposite of (i), which is that the reduced power of the device forces more rope to run through it then would have occurred with the ATC. My guess is Item~(i), in which case the "assisted locker" is still a better bet. But all this is pure speculation (read: mathematical bullshit), and without dynamic testing we won't know which scenario happens or in fact whether neither of them are accurate.

But both devices are locked up in the early phase, one by it´s locking ability plus hand force and the other purely by hand force. Until they slip the rope does the work and after that the braking resistance so then it is a simple question of which slips at a higher force and does the most work.

I was assuming that the "assisted locking" devices would at least have the good grace to begin slipping at higher loads than the ATC. If that turns out not to be true I guess I'll be shelving some very expensive gadgets...

On further inspection the reason the locking force doesn´t increase with an increasing load has nothing to do with rope dynamics or anything technical, the karabiner is physically unable to move nearer the pressure point. On the MegaJul it stops leaving an eye shaped hole 6mm high and more or less as wide as the slot, on the Smart it´s bigger so it´s just a matter of how much effort it takes to pull a rope through a hole this big. There´s a reason that both Edelrid and Mammut have to make different plates for larger and smaller ropes.

rgold wrote: My guess is Item~(i), in which case the "assisted locker" is still a better bet. But all this is pure speculation (read: mathematical bullshit), and without dynamic testing we won't know which scenario happens or in fact whether neither of them are accurate.

I totally agree with this. I can't test it but it is just logical that the assisted locking, however minimum, would be better than the rope running through an ATC. Or at least it would run more slowly through the assisted locking device allowing the belayer to retain control of it more easily than it screaming through an ATC.

D.Buffum wrote:...On an "assisted braking" device - the Smarts and Juls - there is actually a change in the amount of friction that depends on the interaction between the biner, device and rope. As the rope pulls, the biner is forced into a position that pinches the rope between the device and the biner, and increases the bends int he rope. However, theoretically (but not yet tested), a large and sudden enough force can cause the device to fail to engage in a way that the friction is minimized rather than maximized. Similar to the problem that the Cinch had when it did not engage at high factor falls. Am I getting this right? Not "logical," but "intuitive." If anecdotal first-hand experience plus intuitive extrapolation were an accurate measurement of the world, then Columbus would have sailed off the edge of the sea.

Yeah I find this hard to believe, logically or intuitively.

Logic
(of an action, development, decision, etc.) natural or sensible given the circumstances.
"it is a logical progression from the job before"
synonyms: natural, reasonable, sensible, understandable;

D.Buffum wrote: . . . Not "logical," but "intuitive." If anecdotal first-hand experience plus intuitive extrapolation were an accurate measurement of the world, then Columbus would have sailed off the edge of the sea.

I suppose that's the type of "reasoning" that is causing many of you to believe Jim's rather fantastic theory that the rope will go streaming through a Mega Jul in a sufficiently hard (but not FF2) fall, when absolutely no one who uses them as experienced anything like that.
Jim may be right and I don't completely reject his theory, but I think we're in an "extraordinary claims require extraordinary evidence."

I just tried to explain, perhaps incorrectly but surely not all that unclearly, that what Jim is saying does not necessarily mean the rope will go "streaming through the MegaJul."

There are plenty of people out there who will tell you the rope doesn't run through a ATC either in their experience, but there is no question at this point that it will in a big fall with high fall-factor and little system friction. One of the problems with these discussions is the difference, already present before "assisted locking" devices entered the picture, between the behavior of belay devices in "ordinary" circumstances and "extreme" circumstances. Most folks have never had to deal with an "extreme" circumstance and end up claiming the device behavior associated with such circumstances doesn't happen.

The situation with "assisted lockers" is further muddied by the fact that they are new and so experience from the field, is even less likely to have exposed issues and anomalies.

By the way, I say all this as someone who has used and promoted "assisted locking" devices (I use the Alpine Up) for about two years now.

I thought my megajul was awesome, after reading this thread I am tossing all of my tube style devices ( except for my Toucan ) and using a munter exclusively.

D.Buffum wrote: See, that's the problem, you're conflating the informal definition of "logical" (which is synonymous with "sensible") with the formal definition which is "based on rigorous reasoning from known facts." Just because the informal definition is applicable, does not mean the formal one is. "Logic" in it's informal sense is not proof of anything; only formal logic provides rigorous proof. It may be "sensible" to believe that increasing fall forces will affect an assisted braking device in the same manner as the lesser fall forces, but that is not rigorous reasoning. It is also "sensible" to suppose the Earth is flat because it appears so to the unaided eye. It doesn't make it true. I will try to come back tonight and break down the syllogism you're relying on to show why it's faulty. I don't have time right now because I have to get to court in 20 minutes.

You don't need to "break down the syllogism." Please don't. We don't need to get into a semantics debate here on a climbing forum. I found that there are actually multiple definitions to the word logical. If it soothes your ego, yours is the correct definition and you win the semantics debate. I give. So now we can get back to talking about the belay device. (You mean the earth isn't flat?)

D.Buffum wrote:This is a fascinating and slightly troubling discussion. If I understand correctly, in a "traditional" ATC device (paired with a particular rope and caribiner), the amount of friction created is fairly constant, created by large bends in the rope. The "slippage point" is reached when the forces in the fall are great enough to overcome the combined friction in the system and grip strength of the belayer. On an "assisted braking" device - the Smarts and Juls - there is actually a change in the amount of friction that depends on the interaction between the biner, device and rope. As the rope pulls, the biner is forced into a position that pinches the rope between the device and the biner, and increases the bends int he rope. However, theoretically (but not yet tested), a large and sudden enough force can cause the device to fail to engage in a way that the friction is minimized rather than maximized. Similar to the problem that the Cinch had when it did not engage at high factor falls. Am I getting this right? Not "logical," but "intuitive." If anecdotal first-hand experience plus intuitive extrapolation were an accurate measurement of the world, then Columbus would have sailed off the edge of the sea.

No, this is incorrect and not what I have said.
The locking friction in the Smart/MegaJul stays constant (or near enough), the additional friction you require for higher force falls which you apply by hand strength is proportional to the grip strength as in a normal plate. The sum of the locking friction and the hand force friction is the total braking force.
As these plates produce a low hand force component the initial total force is better as there is the locking force to be added, at higher loads the higher hand generated friction obtained though an ATC XP outweighs the benefits of the locking force.
Both types of plate exhibit progressive and consistent (as far as belay plates can) increase in braking power with increased hand force, just the Smart/MegaJul start higher and end up lower. With a single 8.5mm strand the MegaJul is superior up to about 5kg hand force and after that the ATC XP takes over, this represents a braking force of ca 90kg. With other ropes this point is different.
There is nothing "sudden" happening and no catastrophic loss of braking power, the MegaJul and the Smart are perfectly adequate belay devices with a braking power comparable with a large number of the currently available devices. What they DO NOT do is provide extra braking power in high force falls and less than other better performing conventional plates. Unassisted as in your belayer is knocked out by a falling rock they provide minimal if any extra security and in that respect are totally different to a GriGri.
The loss of braking power which the Cinch exhibits is a completely different problem.

pfwein wrote: I suppose that's the type of "reasoning" that is causing many of you to believe Jim's rather fantastic theory that the rope will go streaming through a Mega Jul in a sufficiently hard (but not FF2) fall, when absolutely no one who uses them as experienced anything like that. Jim may be right and I don't completely reject his theory, but I think we're in an "extraordinary claims require extraordinary evidence."

That was Brian, I wrote that the MegaJul has 87% of the braking power of an ATC XP when tested with two strands of 9mm rope and a 17kg hand force. How he reasoned that to "screaming through" I can´t imagine.

Jim Titt wrote: That was Brian, I wrote that the MegaJul has 87% of the braking power of an ATC XP when tested with two strands of 9mm rope and a 17kg hand force. How he reasoned that to "screaming through" I can´t imagine.

What I refer to is if the rope should get out of the control of the belayer in a factor 2 then it would go screaming through the ATC where as (I believe) it would be at least somewhat slowed down by the rope pinching effect using a MegaJul. We can debate this ad nauseam but I guess we will never solve this conjecture unless someone actually tests it. Anyway, as someone else mentioned, a factor 2 fall is an extreme case and I wouldn't necessarily base my use of a belay device on this sole criteria. I don't think many belayers could hold a factor 2 fall with an ATC and no gloves.

Brian wrote: What I refer to is if the rope should get out of the control of the belayer in a factor 2 then it would go screaming through the ATC where as (I believe) it would be at least somewhat slowed down by the rope pinching effect using a MegaJul. We can debate this ad nauseam but I guess we will never solve this conjecture unless someone actually tests it. Anyway, as someone else mentioned, a factor 2 fall is an extreme case and I wouldn't necessarily base my use of a belay device on this sole criteria. I don't think many belayers could hold a factor 2 fall with an ATC and no gloves.

There I will agree with you:-)
If you take the gigantic enormous whipper and your belayer lets go of the rope because he´s got rope burns then you are going to plummet downwards slower with a MegaJul than with an ATC since the locking part still works. Depending on the rope you are using you´ll either slow down a bit or speed up a bit.
The alternatives are of course don´t fall off (the one I choose), climb with a belayer with enormous hand strength or wear gloves. A big furry, non treated rope is probably the biggest single factor apart from not falling off in the first place.

Jim Titt wrote: A big furry, non treated rope is probably the biggest single factor apart from not falling off in the first place.

Blammo! JUST what I was waiting to hear!
Big untreated ropes are cheap and resilient and now they are safer too.
Now I have ammo to counter with when my friends among whom 9.2's and 9.5's are de rigueur poke fun at my cheap, trusty 10.2.

Jim Titt wrote: The locking friction in the Smart/MegaJul stays constant (or near enough), the additional friction you require for higher force falls which you apply by hand strength is proportional to the grip strength as in a normal plate. As these plates produce a low hand force component the initial total force is better as there is the locking force to be added, at higher loads the higher hand generated friction obtained though an ATC XP outweighs the benefits of the locking force.

This actually sounds quite disconcerting. It's not so much the 87% braking power vs the ATC XP in a high factor fall (which I imagine would still be better than the ATC guide), but the none progressive nature of hand force required. You get used to not having to grab the rope very hard at all in baby sport falls (since it's like there's always a relatively weak hand helping you), and never practice things like swinging the brake hand around the hip to increase braking power. Then when you do try catching a big fall, it requires brake force equivalent to a good plate device. That would be quite an expectation shock.

Hand Force/belay Force 9mm rope.

Jim, pardon my ignorance of your testing method, but I assume that these results are from a static measure of grip force vs the load on the climber end. Do you have any testing planned to show the grip strength requirements during a dymanic test (say a given falling mass, height and FF) by belay device and the associated slippage?