Mountain Project Logo

Self-Equalizing Figure 8 with rope anchor--correct tying method?


Original Post
ebmudder · · Bronx, NY · Joined Jul 2011 · Points: 50

Hi All: I have used the self-equalizing figure 8 tie in at 2-bolt anchors, by tying the 8-on-a-bight and then wrapping the loop over and through the knot a second time, and collapsing the extra strand:

But I frequently see instructions online that instead of looping over and through again, you should rethread the loop through the knot like this:

These come up at the top of the list when you google "using rope for climbing anchor"

Climbing.com equalizing figure 8

thoughtco.com equalizing figure 8

Someone actually pointed out in the comments on the climbing.com entry that if the gear on both loops on the left pull (or if you collapse the 2nd left loop, and the remaining left loop fails), then the entire knot comes undone. I think this is easy to see in the 2nd pic, although in reality the 'biners and/or gear might prevent the loop to get pulled through the knot.

But this can't happen with the first method, which I learned from a book, although I don't remember which one at this point.

Even if the left loops slipped through the knot and it untied, you would still be held by the last piece, although if you're the belayer you would likely get pulled into it and at best, bad things would happen.

My question is, am I tying it correctly, and the other method is wrong? And if so, why is it commonly shown this way? Or will it work either way and I'm overthinking the problem?

John Wilder · · Las Vegas, NV · Joined Feb 2004 · Points: 1,530

Never seen the method you use before. Looks like it's fine. 

The second method is for three piece anchors, not bolts. It's rarely used because if the rope gets cut, you're hosed. 

For two bolt anchors, I use the super 8 (or bunny ears 8). It doesn't equalize (but then, neither do either of your examples), but it's fast, easy, and you don't have to do anything fancy. 

Muscrat · · Unknown Hometown · Joined Oct 2011 · Points: 3,610

I see potential for FUBAR here. Just learn the super 8.

Jim Titt · · Germany · Joined Nov 2009 · Points: 490

Climbing .com don´t know the difference between equalising and equalised.

ebmudder · · Bronx, NY · Joined Jul 2011 · Points: 50
John Wilder wrote:

Never seen the method you use before. Looks like it's fine. 

The second method is for three piece anchors, not bolts. It's rarely used because if the rope gets cut, you're hosed. 

For two bolt anchors, I use the super 8 (or bunny ears 8). It doesn't equalize (but then, neither do either of your examples), but it's fast, easy, and you don't have to do anything fancy. 

Thanks John...the method I use works for 2- or 3-piece anchors, but is also vulnerable to the rope getting cut...but I'm not sure the bunny ears 8 is any less vulnerable to the rope getting cut?

walmongr · · Gilbert AZ · Joined Aug 2015 · Points: 85

Never seen it tied like that... for 2 bolt anchors my partner and I always just use the "bunny ears 8" you can  equalize buy tying is loose and clipping it to both bolts then snuggin everything up. Off belay pull up the slack and clip a quick draw through the shelf and put your partner on belay in less then 2 mins...  sure speeds things up!! Here is a pretty good thing on back country how to tie it.  Animated knots also has it. 

https://www.backcountry.com/explore/bunny-ears-the-best-multi-pitch-climbing-knot-youve-never-heard-of

John Wilder · · Las Vegas, NV · Joined Feb 2004 · Points: 1,530
ebmudder wrote:

Thanks John...the method I use works for 2- or 3-piece anchors, but is also vulnerable to the rope getting cut...but I'm not sure the bunny ears 8 is any less vulnerable to the rope getting cut?

It won't fail if a loop is cut. 

I would also point out that the rope getting cut on a two bolt anchor on a trade route is pretty low on my list of worries when building an anchor. 

Jorge Jordan · · Unknown Hometown · Joined May 2011 · Points: 25

You're tying it correctly.  You can verify that in Craig Luebben's excellent book "Rock Climbing Anchors", it's in the appendix.

Nathan Hui · · San Diego, CA · Joined Feb 2016 · Points: 0
John Wilder wrote:

It won't fail if a loop is cut. 

I would also point out that the rope getting cut on a two bolt anchor on a trade route is pretty low on my list of worries when building an anchor. 

Have pull tests been done to determine the affect on knot strength if one loop is cut?  Intuitively, I don't buy the it won't fail if a loop is cut, since both loops are connected in the bight that's passed over the ears, but I don't have an intuition for the internal friction of the knot.

John Wilder · · Las Vegas, NV · Joined Feb 2004 · Points: 1,530
Nathan Hui wrote:

Have pull tests been done to determine the affect on knot strength if one loop is cut?  Intuitively, I don't buy the it won't fail if a loop is cut, since both loops are connected in the bight that's passed over the ears, but I don't have an intuition for the internal friction of the knot.

No idea if pull tests have been done. 

My vague recollection is that someone, probably Jim has done them or knows who has. 

If you tie the knot and load it by pulling on the load strand, you'll see that the wrap around the ears is what's loaded, not the bottom half of the knot. The 8 only needs to be half tied to work, so the same applies here. You could cut both ears and the knot would still hold together. 

Jeremy B. · · Unknown Hometown · Joined May 2013 · Points: 0
Nathan Hui wrote:

Have pull tests been done to determine the affect on knot strength if one loop is cut?  Intuitively, I don't buy the it won't fail if a loop is cut, since both loops are connected in the bight that's passed over the ears, but I don't have an intuition for the internal friction of the knot.

I get the same iffy feeling when looking at it.  The guy at RopeLab has pull-tested the figure eight bunny ears, and it seems to hold:

http://www.ropelab.com.au/figure-of-8-bunny-ears/

ebmudder · · Bronx, NY · Joined Jul 2011 · Points: 50
John Wilder wrote:

It won't fail if a loop is cut. 

I would also point out that the rope getting cut on a two bolt anchor on a trade route is pretty low on my list of worries when building an anchor. 

I don't get too worried about that either, although there was a story last year in AAJ about a trade route in Little Cottonwood Canyon where the leader set off from a two-bolt anchor and pulled off a large block, shearing through the left arm of the sling that had been tied into a cordelette, leaving them hanging off one bolt. If it wasn't FF2 onto a single bolt/sling it was pretty close.

Gunkiemike · · Unknown Hometown · Joined Jul 2009 · Points: 2,745
Nathan Hui wrote:

Have pull tests been done to determine the affect on knot strength if one loop is cut?  Intuitively, I don't buy the it won't fail if a loop is cut, since both loops are connected in the bight that's passed over the ears, but I don't have an intuition for the internal friction of the knot.

It's been tested  a few times that I'm aware of.  It holds on just one loop.  This is super easy to replicate yourself BTW.  Just tie the knot and pull one loop.

The only mode for total failure would be to cut the exact spot where the "over the top" bight passes around the base of the knot - not that likely, and not something I ever worry about.

David Kerkeslager · · Brooklyn, NY · Joined Jan 2017 · Points: 55

If the rope gets cut in one of the loops, I've very little faith in either of those knots, but it's not something I'm particularly concerned about. Aren't you trusting the rope not to get cut below this anyway?

The second knot seems pretty sketch in the case where the left anchor blows. That seems only marginally better than having no redundancy at all.

rgold · · Poughkeepsie, NY · Joined Feb 2008 · Points: 525

I've never found any use for any of the bunny ears knots.  Clove hitch "technology" is better because it is quickly and easily adjustable.  I'm already belaying while the bunny-ears user is still fiddling with the lengths of the ears and the tie-in.

jaredj · · Unknown Hometown · Joined Jan 2013 · Points: 165
rgold wrote:

I've never found any use for any of the bunny ears knots.  Clove hitch "technology" is better because it is quickly and easily adjustable.  I'm already belaying while the bunny-ears user is still fiddling with the lengths of the ears and the tie-in.

I agree, finding it at least as fiddly as an "auxillary cord" method  (e.g. cordelette, quad) with none of the advantages (ease of escape / block leading without untying).

However, the bunny ears / super figure 8 has become my "go-to" anchor setup for toprope soloing from a two-bolt anchor (pretty common at the crags where I do toprope soloing). 

John Wilder · · Las Vegas, NV · Joined Feb 2004 · Points: 1,530
rgold wrote:

I've never found any use for any of the bunny ears knots.  Clove hitch "technology" is better because it is quickly and easily adjustable.  I'm already belaying while the bunny-ears user is still fiddling with the lengths of the ears and the tie-in.

Two horizontal bolts takes about 7 seconds to set up for belay. Tie knot, hang grigri, belay. 

It has limitations, but for short fixing or moving quickly swapping leads up routes with bolted belays, it's my go to anchor setup. 

Guideline #1: Don't be a jerk.

Post a Reply

Log In to Reply