Ascender Safety 101

       Ascending Rappel Ropes 101

       Autoblock Misuse (ATC-Guide)

       Avalanche Safety

       Belay School - Why Dynamic Matters

       Can A Hot Belay Device Melt My Slings?

       Carabiner Off-Axis and Tri/Quad-Axial Loading

       Choosing the Right Carabiner

       Common Belay Screw-ups

       Connecting Two Slings Together

       Daisy Chain Dangers

       Dangers of Rope Worn Carabiners

       Dangers of Worn Lowering Anchors

       Do Ropes Need to Rest Between Falls

       Draws in a Gym

       Extending a Cam Sling

       Fall Factors Explained

       Full Strength Haul Loops

       Gear Doesn't Last Forever—Crampons

       Gear Doesn't Last Forever—Ice Tool Picks

       Gear Doesn't Last Forever—Slings & Draws

       Girth Hitching a Stopper

       How Sketchy Is a Sharp-Edged Carabiner?

       How Strong are Himalayan Fixed Lines?

       How Strong is the Spinner Leash?

       How To Belay, Part 1

       How To Extend a Rappel Device

       Knot Passing 101

       Rappelling - Climbing's Diciest Business

       Re-Slinging Cams

       Rethinking the Double-Loop Bowline

       Retiring Old Ropes

       Sharpie for Marking the Middle of a Rope?

       Sling Strength In Three Anchor Configurations

       Spectra versus Nylon

       Spotting for Bouldering

       Surviving Bad Weather on El Cap

       The Dangers of Modifying Your Gear

       The Dangers of Short Static Falls

       The Electric Harness Acid Test

       The Skinny on Super Light Ropes

       Top Roping is Not So Safe

       To Screamer Or Not To Screamer

       Via Ferrata

       Weakness of Nose-hooked Carabiners

       What is the Safest Rappel Knot?

       Worn Belay Loops and Retiring a Harness

Video Spotlight
The Full Send Footage of Ethan Pringle's Jumbo Love (5.15b) Ascent
The Full Send Footage of Ethan Pringle's Jumbo Love (5.15b) Ascent

Climb Safe: Autoblock Belay Device Misuse

By Kolin Powick

The following article is courtesy of Black Diamond Equipment.

I've seen some curious/scary autoblock uses/misuses out there and I had the boys in the QA lab test a couple of the setups I've seen, which were:

a) Incorrectly using a standard belay device as an autoblock device.
b) Using multiple biners as the "brake bar" in order to make taking in rope easier.



The Black Diamond ATC-Guide is an example of an "autoblock"-style belay device.An autoblock-type belay device is awesome for belaying up one or two people on a multi-pitch route. When used correctly (utilizing a SOLID anchor, threaded correctly, always having your brake hand on the rope, etc.) it is easy to take in rope and lock one or both strands should the seconding climber(s) happen to fall. However, I think the recent popularity in these devices has caused some confusion. 

A few weeks ago I was at Red Rock on a super classic (read: crowded) route belaying my partner as he led upward. A climber below us joined me at the belay ledge and set up his belay system by equalizing the two-bolt anchor with a cordelette (the tie-in point was at chest height) and used a standard ATC device as an autoblock. I politely suggested that the belay setup wasn't ideal as the belayer would need to raise their arm up above their chest (see photo) in order to lock off the climber, and they may not be able to hold the fall. The climber assured me that they "do this all the time" and that the seconding climber wouldn't fall anyway because the climbing was "so easy."

Now whether this was a case of not understanding exactly how an autoblock device works, I'm not sure. I hope that it's obvious to most people reading this that when using a standard belay device as described above it DOES NOT LOCK automatically if a second falls, and is VERY DIFFICULT to hold the climber by hand if he/she were to weight the rope. When using a standard belay device to bring up a second, I always belay off my harness' belay loop, with the rope running through the anchor as a directional—that way if the seconding climber were to fall, the load is on the anchor. Some people belay off the harness straight down to the climber, but in the case of a fall, the belayer is now being yanked off the ledge and being pulled in two directions (the belayer is tied off to the anchor, but the pull from the fallen climber is downwards).

The correct setup of an autoblock device is shown below.

Correctly using an autoblock device off the anchor. Incorrectly setting up a standard belay device off the anchor.
























Take-Up Force setup.

I've had a few people write me claiming that, while using an autoblock device such as the ATC-Guide, they get pumped taking in rope when belaying their seconding climber up. It's true that pulling up fat ropes (i.e. 10.5 mm and greater) has increased friction and therefore requires more effort than pulling up skinny cords. So other than not using such a fat rope, what are the options to make life a little easier?

Well, I've had several people claim that they use multiple carabiners as the brake bar to help save the pump, but they're worried about the potential loss of locking ability should their seconding climber fall. So I asked one of the members of the crack-crew of QA engineers here at Black Diamond to run a few quick, unofficial tests using two of our most popular models of locking carabiners, the RockLock (rounder cross section) and the VaporLock (flatter cross section). Here are the results:


Take-Up Force:

Carabiner Quantity/Style                Force (lbf)        
1 RockLock 25
2 RockLocks 29
1 VaporLock 28
2 VaporLocks 35


In the testing we did, using multiple (two) biners actually INCREASES the amount of force required to take rope in.

  • I believe this is because though the radius of the rope going over at the top of the device is larger, the radius at the bottom, where the rope pinches, is tighter. As well, I think multiple biners are assisting in forcing the rope harder into the grooves of the device, therefore causing more friction and thus more force required to take up rope.
  • What the data also showed is something that is pretty intuitive and many have noticed and realized in the field: the shape of a biner's cross section had an impact on the amount of take-up force required. (i.e. round cross section biner = easier to take rope in; flat cross section biner = harder to take rope in).

Holding Force setup.

Holding Force:

Carabiner Quantity/Style            Force (lbf)        
        1 RockLock               1218
        2 RockLocks               1316
        1 VaporLock               1466
        2 VaporLocks               1825

We found, once again in the limited testing we did, that using two biners actually INCREASES the amount of holding force.

  • Once again, for the same reasoning, though the radius the rope takes at the top of the setup is larger and you would think reduces the amount of holding force, the multiple biners cause the radius at the bottom of the setup, where it clamps on itself in the device, to be tighter and therefore INCREASES the holding force.
  • And once again, the data showed that flatter cross section biners had a greater holding force than rounder cross section biners.


Bottom Line

What is the ultimate solution? You need to find a balance that works for the given situation. I'm usually climbing on anywhere from two 8.1s, to a single 9.1 mm, 9.7 mm or even a 10.2 mm. I typically use a VaporLock (flatter cross section) when using skinnier ropes, and a RockLock (rounder cross section) when using fatter ropes.

Again, this is pretty rough stuff; as always don't take it as the Gospel. More in-depth testing would need to be performed to come to any concrete conclusions. I'm sure there's a point where more biners would reduce the take-up force and reduce the clamping force. Is it three biners? (No, because we tested that. Could it be four or five? Not sure, as we didn't take it that far. And it goes without saying that I'm not a climbing guide and I don't even play one on TV. If you want official instruction get it from a qualified, certified instructor.

Climb safe out there,



Kolin Powick (KP) is a mechanical engineer hailing from Calgary, Canada. He has over 20 years of experience in the engineering field and served as Black Diamond’s Director of Quality for over 11 years. He is currently their Climbing Category Director. If you have a technical question for KP, please email him at and he will TRY to respond.

To help make more climbers safer climbers, Rock and Ice has teamed up with Black Diamond Equipment to present the information here.

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