Edelrid’s Ohm: the solution for climbing partners of different weights

The German brand Edelrid has come up with a real innovation this year, the Ohm. This clever device compensates for weight differences between climbing partners. A definite plus in terms of belaying safety. La Fabrique verticale was asked to test it, so we put it through its paces. Here’s our verdict.

The Ohm: for whom? Why?

The Ohm is unique in its field, since it compensates for weight differences between climbing partners. As it happens, we at La Fabrique Verticale are ideal candidates for trying out this type of equipment. There’s a weight difference of over 30% between us. Which is nothing exceptional! We’re pretty representative of many couples that climb together, in fact.

So, what usually happens in this type of case? Either the lead climber doesn’t dare push him/herself to the point of falling, because he/she doesn’t have confidence in the belayer. Or, he/she commits and climbs as hard as possible, but if he/she falls, the belayer is pulled upwards, which obviously raises some safety concerns.

If it is a big fall, the belayer can be lifted off their feet and hurled against the wall or the rock. Or get slapped into the first quickdraw. The lead climber can even land on the belayer. In all of these situations, there’s a real risk of being injured and/or dropping the rope.

To get round the problem, you could of course tether yourself at the foot of the route, if there’s a bolt. But you can still get quite a shake, and it’s not always an option.

The Ohm: problem solved

The Ohm provides the solution to the problem AT LAST! So how does it work? The Ohm has a V-shaped neck, which increases friction on the rope if there’s a fall. You place it on the first bolt on the route. The rope glides freely within the mechanism as the lead climber climbs upwards. If he takes some slack to clip a draw, for example, there’s nothing to hamper the rope’s movement.


But, if there is a fall, the Ohm will do its thing. It is pulled upwards by the laws of mechanics, adopts a horizontal position, and its design, with the V-shaped neck, reduces the effort required by the belayer. Instead of getting stuck in the 1st draw, the belayer will be able to stay on his/her feet, as if he/she were the same weight as the lead climber. And when the climber sets off again, the Ohm’s weight causes it to drops back into its normal position.

Obviously, this doesn’t always happen. There is always a gap between theory and practice. And depending on the type of route, the Ohm can sometimes remain in its upright position. For example, if there is a sharp overhang just above the first draw, where the Ohm is installed. It’s probably one of the only reserves that we have for this device. Thankfully, the belayer can fix this from below, and flick it back into position with a simple shake of the rope. This is necessary, otherwise the leader could really struggle to pull up the slack when clipping.

Other solution, which we would recommend in this kind of situation, is to place the Ohm on the 2nd draw on the route.

Ohm: installation and use

In practical terms, it is really simple. You place the rope in the Ohm to start with. The direction of the rope is shown on the mechanism.


Clip the Ohm on to your harness then install it on the first draw on the route. Be careful where you put the Ohm on the harness though so you don’t get confused, and make sure you install it the right way up (climber’s rope at the top).


On the belayer’s side, belaying technique is exactly the same, and use of the Ohm does not mean you can be less vigilant, you still need to be a competent belayer. Once the Ohm is in place on the 1st draw, if the leader wants to have another run in the same route, he can run the rope through the Ohm on the way back up. It’s not quite as easy as on the ground, but it is possible with a bit of practice.

If the lighter climber wants to have a go at the same route meantime, they can clip another draw in the same bolt as the Ohm (or on the upper section of the Ohm itself). When the belayer brings the lead climber down, the Ohm can be very useful again in taking the strain of the weight difference.


The Ohm is a great invention, with real added value in terms of safety. Especially at the start of a route, when there is a real risk of hitting the ground if you fall. Obviously, and this is the logical effect of the system, any falls will be a little more static. Which can be what you want when the climber is close to the ground. If the climber is a little higher, for a more dynamic fall, you could give a little hop when he/she falls to limit the static grab, or take a step forward.

What’s really great with the Ohm is:
1. The extra security when there is a significant weight difference
2. The psychological advantage it gives the climber to go for it, knowing they can fall safely
3. The fact that you can use it with all types of single ropes (from 8.6 to 11mm)

The only downside is its weight (nearly 400g). But you only feel it in your bag on the way to the crag. Once you’re climbing, it’s a weight off your shoulders in more ways than one.

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