UKC

Out of curiosity I've ran a few braking tests for some belay devices.

Test set-up, similar to in DAV halbe sache oder optimal (P6 in PDF). Hand force 16.8kg, load angle 165°, rope is 1x Beal Cobra 8.6 golden dry. Pulled manually (smoothly as possible) with a 5:1 progress capture system, peak force recorded with load cell. At least 2 runs averaged for each device. Numbers below are braking force/hand force, so force multiplier.

BD ATC Alpine Guide: 11.6

BD ATC XP: 8.4

CT Be Up: 8.1

DMM Mantis: 7.9

Ocun Habu: 7.8 

Petzl Reverso 3: 7.5

DMM Pivot: 7.3 

WC VC Pro 2: 6.7

Cassin Piu 2: 6.5

BD ATC Guide: 6.4

BD ATC Guide (highly worn): 5.1

CT Alpine Up (dynamic mode): 5.0

DMM Bug: 4.5

I don't have a full test rig so probably not super scientific, but interesting so thought I'd share as not a lot of belay device performance info out there!

Similar work/further reading:

https://www.alpenverein.at/bergundsteigen_wAssets/archiv/2020/2/62-69(halbe...

https://mra.org/wp-content/uploads/2016/05/Hang_Em_High_Final.pdf

https://www.mountainproject.com/forum/topic/112357901/the-deadly-atc?page=1...

https://www.alpenverein.de/artikel/risiko-tubes-und-duenne-seile_87e77817-0...

In reply to Alpenglow:

Thanks. An interesting point to me is the guide mode version of the the high performing ATC XP apparently has a significantly lower test result for braking a leader.

This is also true for what I have regarded as the guide mode version of the Mantis (ie the Pivot). However in this case both Mantis and Pivot perform better in both modes than the ATC Guide.

Presumably there is a necessary compromise in designing a device with an additional guide mode.

In reply to oldie:

Yeah it is interesting, the slots are different dimensions in the vertical museum link, perhaps the bigger slots give better feeding in guide mode but slightly compromise braking performance? (ATC guide was v.C and worn ATC guide was v.A in below link)

http://www.verticalmuseum.com/VerticalDevicesPage/Belay/BelayTubes.php

Weirdly for the Mantis/Pivot the slots measure the same dimensions, but the website reports the carabiner sits slightly differently and DMM say Pivot is rated for 8.7mm+ single ropes and Mantis is 8.5mm+ single ropes.

Perhaps someone in the know can shed some more light!

In reply to Alpenglow:

I missed the fact that the BD ATC Alpine Guide apparently outperforms everything else in your group for braking a leader fall and still permits guide mode. Obviously difficulty/impossibility in handling thicker ropes is a drawback. Braking with all the devices would be improved using two krabs but personally I've almost never seen this used.

Edit. One seller only recommends this device for ropes up to 8mm and if this is correct perhaps the 8.6 mm rope used in the test means the result is not the best comparison.

In reply to Alpenglow:

So a bigger number is less good? Are the differences between 11 and say 8 actually perceivable to a human being?

In reply to TobyA:

Surely a bigger number means more braking force? So big number better in that respect.

In reply to TobyA:

Bigger number is more braking force, so better in that respect.

There may be some inverse correlation with braking force and ease of handling/grabbiness, however I compared the DMM Mantis and CT Be Up at the wall top roping, which both have similar braking force and the Mantis was smoother to belay with. Perhaps there are some clever design tricks to have both high braking force and smooth handling?

Happy to do some more tests if anyone has some spare rope offcuts, need about 10-15m, or old belay devices. Would be interesting to see changes with 8mm rope etc.

In reply to Alpenglow:

I can send in 15mm of Edelrid Parrot 9.8mm (pretty worn, on verge of being retired) along with a sticht plate if that would be helpful.

What are you using for load cell? I've been thinking of how to build test rig for gear and was thinking of using crane scales.

In reply to Alpenglow:

Is this less desirable with marginal protection?

In reply to abcdef:

I wouldn't think so, especially if the belay isn't wearing gloves. If the braking force of the belay device is exceeded it means the rope will run. Once the rope is running (which will reduce peak forces) an ungloved belayer is likely to get rope burns which massively increases the chances of the belay failing completely.

I feel like there are loads of factors at play, including the belayers hand strength. A particularly weak-handed belayer might still have the rope running with the grippiest device and a strong-handed belayer might be able to fully lock off a device with less multiplication factor.

I've read a whole bunch of threads about the geometry-style assisted-tube devices (megajul, mammut smart etc) over on mountain project and their low-multiplication factor is a problem when dealing with violent falls. They'll catch low-FF sport falls all day easily, but a high-FF fall on a multipitch and the rope is very likely to slip.

In reply to Alpenglow:

Dmm bug was never designed for single ropes that thin.

Wonder if the other devices in their instructions state rope diameter guidance. 

In reply to kl4543j:

Using a Rock Exotica Enforcer load cell.

Drop me a message, would be interested to test sticht plate and a different rope.

In reply to ExiledScot:

True, the DMM Bug instructions say 8.5-11mm single and half ropes. In theory if you fall off using half ropes then only one of your ropes may get loaded, then the Beal Cobra 8.6 is within the device's specification, so my test isn't too unrealistic?

In reply to Alpenglow

Incidentally Sticht plates used to have 2 sizes of slots specifically for 11mm or 9mm which were once the only 2 climbing ropes in general use. One could get single 11mm, double 9mm, or 11 + 9mm plates. So the plate would probably not work as well with some different diameter ropes.

Would still be interesting to test. I've read that the braking performance for severe falls is much better than almost all similar modern devices. I suppose the modern devices must be able to be used with a range of rope sizes which may involve compromise. Personally I found Sticht plates an effort to feed the rope through and carried on usually using a waist belay for many years.

In reply to Alpenglow:

Arguably right on the limit, use a rope diameter that matches as near as practical the middle of the working range of each device? 

If you use a rope which is optimum on one device(certain atc's?), but then almost (0.1mm) out of range then your results are skewed. I'm not saying worthless, but as a bug user with primarily 10mm rope I'm quite confident on it's stopping power or rope grab ability even on newer shiny ropes. 

In reply to ExiledScot:

Unfortunately I don't have 10 separate bits of 10/15m rope to perfectly match the middle of each devices' stated diameter range! Also myself and most other climbing partners use half ropes around 8.0-8.5mm, not many use thicker 9mm half ropes.

Of course I'd happily test other ropes/devices if you send them to me.

In reply to Alpenglow:

Bugs were developed in a time when most climbed on single 10mm, the obsession with using double or twin ropes for every route hadn't arrived. Bit like sprung sticht plates were in the 11mm era, although they are still great smooth devices for use with slightly thinner ropes, especially by novices. 

In reply to ExiledScot:

Really? My first belay device was a DMM Betabrake - which after the BD ATC came out, DMM used as the basis of the Bug, their first bucket device if I remember it correctly. Anyway in early 1992 I bought my first half rope - at the time where I was (Glasgow) it seemed like everybody got a half rope as their first rope. So wherever you climbed and whoever you climbed with, you used double ropes. 

In reply to TobyA:

Love to see an early ATC on these tests, they were a little lively. 

I had an 11mm, which once worn was more like 12+, it would probably brake itself through a stich plate or inverted tuber. 

In reply to Alpenglow:

Interesting. I have to say that's pushing gear junkie geekery to new level.

In reply to Alpenglow:

FYI, UIAA 101 & EN 892 both allow a +/- 0.2mm on top of a rounding to the nearest 0.1mm on the mean of the six diameter measurements. So your 8.6mm rope could be anything 8.35 to 8.84mm.

(Just to re-iterate that when thinking about using a rope/belay device combo, aiming for the middle of the range is a good idea!)

In reply to Alpenglow:

Some more tests completed, this time with Beal Iceline 8.1mm golden dry, same hand force of 16.8kg and same load angle as previous. All tests in duplicate and averaged. For the 8.1mm rope, on average the power ratio is 20% less than the 8.6mm rope. Similar trends to previous test, a couple of the mid-pack devices have swapped places.

BD ATC Alpine Guide: 9.2

BD ATC XP: 6.7

CT Be Up: 6.2

Petzl Reverso 3: 6.1

DMM Mantis: 5.9

DMM Pivot: 5.8

Ocun Habu: 5.7

WC VC Pro 2: 5.7

BD ATC Guide: 5.2

Cassin Piu 2: 5.1

BD ATC Guide (worn): 4.7

DMM Bug: 3.9

CT Alpine Up (dynamic mode): 3.6

In reply to ExiledScot:

That's bollocks, when I became interested in climbing in '91 people were using 9mm halves all the time. Bug didn't come out until after that.

In reply to Alpenglow:

I once abbed on a pair of used 8.4mm halves with a bug, I changed to a Metolius BRD after that, the friction provided by the Bug was scarily poor. I wasn't aware of the rope diameter was out of spec at the time. It's why the Bugette was invented!  If you want, I can send you my BRD to test? It's pretty powerful, and test results back up my experience http://www.paci.com.au/downloads_public/PPE/18_Belay-Device-Test.pdf