If there's a big weight difference between lead climber and belayer, the Edelrid Ohm offers a genuine safety gain. Rob Greenwood's initial scepticism was blown out of the water when he got to use this ingenious device in anger...
It's funny, I had the same reaction Rob had when first seeing the Ohm, dismissing it as just another "innovation" that was in fact pretty useless and a bit of a gimmick. Actually, it's VERY good and if you're a lightweight climber like myself, especially if you climb with heavier partners down the wall, you should definitely look into one of these.
When we did the test, myself belaying Rob at Awesome Walls, without the Ohm I was rather unsurprisingly yanked directly up into the 2nd quickdraw. Probably about 8 to 10 feet in the air and my plate was fixed against the draw. With the Ohm it was basically like belaying someone of equivalent weight. When Rob fell I was about a foot or so off the ground without the violent yank.
I actually recently had a pretty horribly experience at my local wall while belaying my brother. I had some slack out for him to clip, he was slightly above the previous draw although hadn't yet clipped it, he fell and I was yanked horizontally and vertically into the first draw. His feet touched the ground on rope stretch from about 35 feet. I'm pretty sure had I been using one of these that would not have happened.
I'm pretty accustomed to belaying heavier climbers, not many people weigh less than 55kg, but as soon as someone is significantly heavier than me it can become a real problem, especially at my local wall as the routes are short and there is very little margin for error. That extra tug upwards can make the difference between the deck and hanging on the rope.
Does it let the belayer move about much? I like to step in and out from the wall while lead belaying, in order to give or take slack more quickly and easily. My usual climbing partner is lighter than me by enough that she doesn't like to do that because if I fall while she's further from the wall she gets dragged in alarmingly. Would the Ohm help with that? I've read that moving out from the wall would make the Ohm more likely to stick when giving slack (due to the angle the rope takes through the device and the way it adds friction).
Is anybody doing demo days? Might be useful for a new and unique bit of kit.
>My usual climbing partner is lighter than me by enough that she doesn't like to do that because if I fall while she's further from the wall she gets dragged in alarmingly. Would the Ohm help with that?
It would indeed.
We tried really hard to find a shortfall in the device, and when I first saw it this was my primary concern - that it would just jam up and create an obscene amount of friction in the system. The only time this happened was when people were giving a poor belay (i.e. not paying out enough slack), but if belaying properly - like you suggest - it should be fine.
In terms of demo days I'll give the guys at Edelrid UK a shout. If they haven't got any dates in the diary this might persuade them to, as it really is a device that makes a lot more sense once you've actually used one.
Hi Rob, good write up, one question though: did any of the belayers deliberately try giving a soft catch i.e a dynamic belay, and if so, any comments on any effect (or not) that you noticed when using the device?
The Ohm definitely minimised the effect of a soft catch/dynamic belay, insofar as the belayer in question wouldn't be dragged upwards + forwards as much as they might have otherwise.
From a climbers perspective, you'd have thought this would mean a horrifically hard catch, but for some reason it didn't (which is counter-intuitive). My conclusion as to why this was comes down to two factors: the first being that the device lets the rope through slowly, so it's not as on/off and jolting as a hard catch and the second being that my belayers knew what they were doing and had a bit extra in the system.
Definitely interesting, but my first thought is that all that energy that would normally send Martin 20 feet into the air has to go somewhere. I can't find much information on what safety tests have been done - but presumably that extra energy manifests as heat and is absorbed by the rope. In which case - is there some risk that extended use of a device like this could shorten the lifespan of a rope? ( though presumably it's a similar principle to a Gri Gri, which have been used for years without any such concerns ).
All very interesting, when someone told me about the Ohm back at the start of the year I was pretty skeptical too but I did very much want to find out that it works because I'm frequently 100% heavier than my partner and even tying people down is not great at such a disparity (for the belayer that is, soft catches are just fine for me).
I was very tempted to buy one in Wales back in April but I just couldn't bring myself to part with so much money for something so new and unproven where I didn't even really know anyone who had used one. Maybe I can get to some sort of Edelrid demo session to try it out, there are not a lot of walls in the NW of Scotland though...
The energy dissipated during any fall is mostly not converted to gravitational potential energy of the belayer; It is mostly heat (as you said) and some elastic potential energy as the rope is stretched. Heat generation by friction is primarily in the metal components rather than the rope for two reasons:
1) The metal absorbs heat readily as it is a conductor, the rope does not as it is an insulator.
2) The point of heat production is at the same location for the entire braking event on the metal surface whereas the rope is moving past the point of heat production so no one rope location gets excessively heated until the rope stops (at which point in an extreme event the hot carabiner/Ohm/belay device could melt the stationary rope). This is the same rationale as it being ok to pull two ropes past each other quite vigorously when they are both moving but not ok to pull one rope vigorously over another that is stationary.
Any sort of heat production by individual rope fillaments moving against one another in the event of normal use/fall must fall significantly short of the level needed to damage the rope or else ropes would fail a lot more often without warning. i.e. I've never yet heard of a rope being damaged due to overheating through the action of stretching alone in a climbing situation. (I'm happy to be corrected though!).
The metal part of the Ohm is pretty chunky and I suspect that part of the reason for that is rapid heat dissipation. Personally I'd be much more worried about rope life shortening when you are abseiling because in that situation you are dissipating considerably more energy (50m of grav pot energy for a short/average abseil vs 10 to 20m of grav pot energy for a big fall) and the entire dissipation is at one location (the belay device/rope interface) compared to a lead fall situation where the dissipation is at the belay device/rope interface and the Ohm/rope interface and the quickdraw karabiner/rope interfaces and the internal stretching of the rope. I know I frequently come off a full-length abseil with a device that is hot enough to hurt my fingers but I've never experienced the same thing on the device or quickdraw karabiner from a leader fall.
Had a trial with it at a wall this week and it does what everyone above has said it does. Took a little getting used to at the start, but like all unfamiliar bits of gear, the more you use it the easier it gets. One point that doesn't get mentioned in your review or in the Edelrid film is when you are being lowered and stripping the route and reach the first bolt again the Ohm is under tension so I had to clip into the first bolt with my belay loop to unweight the Ohm. If you are stripping a route of quickdraws, then a cow's tail would be handy, and on outdoor sports routes you'd probably have one anyway. Retrieving it from the first bolt is the only issue that needed a bit of extra practice, unless someone has found an easier solution?
In reply to Martin McKenna - Rockfax: Martin, you clearly need to eat some more pies! I hope UKC is paying you enough for a less healthy diet.
More seriously, I guess the pull on the device is upwards so it really needs to be attached to a bolt? I've had my older son belay me a few times on trad routes and mainly focused on climbing like I was soloing, but attached him to the floor in some way just in case. But I suppose this couldn't be used trad climbing?
A multi-directional gear placement like an absolutely sinker cam in good quality rock would function in much the same way as a bolt for the purposes of the Ohm I would think. BUT 1) Is the Ohm rated for use with half-ropes? 2) How many routes can you be sure your first piece is both multi-directional and absolutely bomber? 3) Are you going to take two Ohms and clip them both to the first piece?!
Maybe it's more feasible for a relatively straight trad line where you can use a single rope.
Great device, one thing I was aware of though, with the extra resistance of the device is on 1st bolt..as the climber climbed up I saw the device pulled up, with karabiner then pushing against the bolt...and it opened slightly!! So from then on used it with a screwgate on the first bolt, as actually there was enough resistance to pull karabiner up against the bolt, and enough pressure to open the karabiner. After making this change I felt a lot more confident. Also did notice, on the lead, if a panicky, snappy attempt to clip was made, the rope jammed a little, and slack was being called for...despite slack below the first bolt being available for the clip....however, if you're clipping smoothly and confidently there's no issue at all.
> Also did notice, on the lead, if a panicky, snappy attempt to clip was made, the rope jammed a little, and slack was being called for...despite slack below the first bolt being available for the clip....however, if you're clipping smoothly and confidently there's no issue at all.
Is that maybe accentuated the further out the belayer stands?
Quite possibly, I wasn't standing more than 2m out from the wall though, not a great deal...it felt more like the climber was locking out the OHM with snappy rope pulls, a bit under pressure on the crux going for the clip. It's not autolocking obviously, but it seemed the resistence in the device was preventing rope for a quick (less than smooth) clip. I guess it's just if you're climbing a bit above your level...and panicking a bit on the clip, then it might knock your confidence when you can't pull up the rope you need for the clip quickly as it slows and slightly jams rope....could I guess potentially knock some confidence for someone only beginning to lead s'all...
My (lightweight) wife and I have used the OHM for two days of single pitch cragging so far and are both impressed with its performance being exactly as 'it sys on the tin'. I do think some extra care needs to be taken while stripping the device from the first bolt while being lowered. Full weight comes back onto the whole length of rope and there could be ground fall potential on rope stretch. No problem once aware, but may be an issue when introducing the device to a new partner.