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

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Climb Safe: Dangers of Worn Lowering Anchors

By Kolin Powick

The following article is courtesy of Black Diamond Equipment.

The used cold shuts with rope grooves. Trust it?

Whether it's at the local gym or a dreamy vacation cliff in the Mediterranean, we've all been there: You finish a sport climb and are ready to clip your rope through the anchors (e.g., cold shuts, leaver biners, chain links, etc.) when you notice that countless lowerings and top roping have left gnarly rope grooves in the anchors. Will these grooved-out anchors hold? Will the sharp edges trash my rope?

Recently a friend of mine was doing his part at a local sport crag by replacing old bolts and rope-grooved anchors. He pulled these off and wanted me to test them to see how weak they were. (I'm not going to get into the technicalities, pluses or minuses of different kinds of anchors and am not condoning anything in anyway—I'm just looking at only one style of cold shut, one test, two data points, just out of curiosity more than anything.)



The cold shuts after testing (the new one is on the left).Measuring the rope groove of the test samples, the reduction in thickness was about 25%. Therefore, the used cold shuts would be 25% weaker, right? Wrong.

  • The two rope-grooved samples tested to 2330 lbf and 2522 lbf, before they deformed and slipped open.
  • The new cold shut stretched all the way open at a load of only 1466 lbf.

So how and why did the rope-grooved cold shuts withstand a higher load than a brand new one? Take a look at these testing photos (the new cold shut is on the left):

The rope groove forces the rope to stay in line with the main axis and direction of load of the cold shut, whereas with a new cold shut, as the load increases, the rope is able to slide out and cantilevers it open at a reduced load. So rather than reduce the tensile strength of the shut due to removal of material, the groove seats the rope onto the spine so that the shut holds more weight before it starts to deform.


Conclusions, Comments, Remarks
  • Rope-grooved cold shuts keep the load in line with the strongest axis and therefore can withstand a higher load before deformation.

Just because a rope-grooved anchor may be stronger, however, doesn't make it better. The sharp edges of rope-grooved anchors and biners can potentially damage the rope's sheath. If you see anchors or biners out in the field that look beat up, do your part and replace them. You can also use your own quickdraws or biners at anchors in order to save on wear and tear of the fixed anchors.

Be 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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