Thinnest Static Rope for extended achors


Original Post
ebmudder · · Bronx, NY · Joined Jul 2011 · Points: 0

Hi All: I have a mess of old 1" tubular webbing that I used for rigging extended toprope anchors (like trees 25' from the edge of a route). If I wanted to replace it with static cord, what would be the minimum diameter I should consider? Is 7 or 8mm nylon acceptable?

Does anyone routinely use tech-cord for this purpose, or is nylon preferred?

I don't top-rope that frequently, so durability is not a primary concern.Obviously safety is primary.

Jon H · · MD/DC · Joined Nov 2009 · Points: 13

7mm is adequately strong provided it's a redundant setup (e.g. 2 independent cords going to 2 independent anchors).  Note that 7mm cord (and even 8mm) is quite thin, so you need to be diligent about inspecting it for abrasion before and after each use.  Top roping is prone to causing anchor rub when the anchor material is draped over an edge.


You could use tech cord which is extremely strong and less prone to abrasion, but it's stiffer so it does a poorer job holding knots. Keep an eye on the knots.

Matt Kuehl · · Las Vegas · Joined Nov 2010 · Points: 1,425

1" webbing is probably the most suited, and cheap.  But 7mm would be good too.  Anything less its going to get abrasions pretty easy over edges like already mentioned. Tech cord is great but mostly much more expensive for 25" than webbing. 

Stephen Bittner · · Unknown Hometown · Joined Nov 2012 · Points: 35

Unless you're hiking in super far and only want to be able to use it a few times, the thinnest I would consider is 9mm. Even that can get beat quickly if you have your anchor over an edge. 7-8mm will get worked super fast. I have a length of 9mm for my infrequent personal use- it packs down quite small. For work I use 10mm for my TR anchor set ups and after a year the cord can get well fluffed.

Considering that unless you're using directionals, your anchor point is going to be pulled side to side as you climb in different directions and abrading against the rock with the weight of two people on it, I wouldn't use anything smaller than 9mm for your own safety. If you've never seen it, you wouldn't believe how easily a loaded rope cuts when pulled across sharp rock. 

Rich zz · · california · Joined Oct 2012 · Points: 0

i use 6mm lines. that's about 8.5kN. more than enough.

JasonSH · · unknown · Joined Apr 2015 · Points: 0

Sterling 5.9mm powercord. 

Chris treggE · · Madison, WI · Joined May 2007 · Points: 8,590

Seems like 9mm is recommendation by some courses and groups.  Any idea why, if the strength is less than 8mm?  Why is 8mm stronger than 9mm?  The chart is from a sterling display at a local shop. If the recommendation is for higher durability, then why would the 9mm be more durable?  

Random Climber · · Burke, VA · Joined Apr 2017 · Points: 0

I thought that was a typo but I looked on the Sterling site and the 9mm figure conveys. My guess would be the CE EN 564 standard that it is tested too (which is the only items that I'd buy). Also, possibly the 9mm has a thicker sheath for abrasion resistance? No idea... just throwing that out there.

that guy named seb · · Britland · Joined Oct 2015 · Points: 0

9mm is probably tested under en 1891 which would explain why on the chart it gives odd results.

Gunkiemike · · Unknown Hometown · Joined Jul 2009 · Points: 1,865
Rich zz wrote:

i use 6mm lines. that's about 8.5kN. more than enough.

Maybe "strong enough" but no way I'd go any smaller than 8mm, in the interest of durability and cut resistance.  Most of what I use is 10mm, but weight and bulk are not a real concern here.

Idaho Bob · · McCall, ID · Joined Apr 2013 · Points: 53

And if the extension is going over a sharp edge, pad it.  I use an aluminum SAM splint which attaches to the rope ( I use 10mm for long extensions).  The splint weighs about 150 grams.

Ted Pinson · · Chicago, IL · Joined Jul 2014 · Points: 45
Stephen Bittner wrote:

Considering that unless you're using directionals, your anchor point is going to be pulled side to side as you climb in different directions and abrading against the rock with the weight of two people on it, I wouldn't use anything smaller than 9mm for your own safety.

Do what now?

timinthehouse · · Unknown Hometown · Joined Jun 2016 · Points: 0

Just my 2 cents, I used to use hose that I had cut down the middle to protect the rope going over sharp edges. Then I got lazy and bought those rubber rope protector things which seem to prevent excessive abrasion. Sometimes I would use them for protecting my fixed rap line when rappeling down to the anchor from above. But I would only really use the rope protectors when TR soloing because extra caution and all.

Jaren Watson · · Boise, Idaho · Joined May 2010 · Points: 1,195

The OP said he top ropes infrequently. 7 mm is fine. 

Brian Carver · · Boulder, Co · Joined Jul 2015 · Points: 10

I once bought a 80' 7mm static line for this exact reason. Thank god I bought it from REI because I had to take it back within a month. I replaced it with a 100' 10.2 that was amazing. It made anchor building very quick and very safe. Obvious downside is the carrying weight.  I don't find myself extending TR anchors much anymore so when I do it's usually just easier to use a couple rolls of webbing. 

Guideline #1: Don't be a jerk.

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