Sterling Rope Factory Tour

Ever wonder what goes into making your climbing rope? Yesterday I had the opportunity to head over to Sterling Rope in Biddeford, ME with 6 other EMS Guides for a tour of their factory.


It is one thing to read a companies credo in a catalog or on their website. It’s quite another to experience it in person.

We left EMS North Conway around 8 yesterday morning and arrived at the factory at 9:30 where Sterling’s Market Manager, Matt, and head of Research & Development, Josh, greeted us and gave us a quick briefing before passing out safety goggles and leading us out to the factory floor. The first two things you’ll notice when passing through the factory doors are the immense size of the factory and the constant loud drum of dozens of machines producing some of the best ropes in the world.

Sterling Rope Factory Tour

We started on the far end where huge pallets held tons of spider-silk-thin nylon, dyneema, and polypropylene awaiting various treatments and processing before they would be braided into different styles of core for dynamic and static ropes. We were reminded to keep our hands away from machines since you would not see this thin material being spun at such high RPMs.

Sterling Rope Factory Tour
Lots of spinning & whizzing

I got to climb up a small ladder and watch as the rope cores were treated with Sterling’s proprietary DryCoat Treatment. Many rope manufacturer’s only treat the sheath of the rope. Sterling’s treatment of both the core and the sheath greatly increase the water resistance of your rope, which effects just about every property of the material from strength to durability.

Next we made our way over to one of the coolest machines, the “braider”. After all the work that goes into making the core of our climbing ropes is finished, these machines artfully braid the protective sheaths over the core at a mesmerizing speed. This machine is off while we are shown the core strands.

Sterling Rope Tour Braider
Sterling Rope Tour Braider

Then I captured some slow motion video on a nearby machine to see the process. You can see the final product sliding out inch by inch, at probably about an inch every 2 seconds in real time…

We then got to walk though the final product areas. Who needs 700 meters of the amazing Fusion Nano IX 9mm rope?

Sterling Rope Factory Tour
700 meters of 9mm? It would retail for over $2000 if cut to standard lengths.

After touring the distribution center we made our way over to the highly anticipated Sterling Drop Test tower. This tower allows Sterling ropes to pass rigorous UIAA tests that simulate a really bad fall onto a rope. Most climbers notice when purchasing a rope how many of these “worst case” scenario falls their rope is rated for. Off the top of my head I’d say I have owned and used ropes that passed anywhere from 6-12 of these falls. The fall imitates a fall factor around 1.77 with a 80Kn weight (about 176lbs).

And again in slow motion:

On the 7th drop the rope failed (and I was not ready with the camera). The snap was loud and impressive. It was interesting to feel how flat and warm to the touch the abused rope had become after multiple test falls, especially since we did not let the rope rest between drops.

After that we made our way to the Pull Test machine. This hydraulic beast can exert over 222Kn (50,000 pounds!) of force on ropes & gear in a measurable and controlled environment. We were encouraged to bring old slings and gear to destroy here in the name of science. Well, maybe in the name of pure fun. But science too.

Our school manager, Keith, had a plethora of slings and belay loops to test, with an emphasis on investigating the different rappel extension options we choose to use on such a regular basis while guiding and recreating. We also wanted to see if worn belay devices could pose a threat when pre-rigged on a rope. Ian had brought a damaged fixed quickdraw from the last bolt on the classic hard Predator route at Rumney NH. Jeff had a pine sap infused sling he wanted to test. Over the next hour or so we broke about 20 pieces of gear in the machine.

Sterling Factory Tour
Snapped Dyneema smells like burning nylon
Sterling Rope Tour
Ready to test
Sterling Rope Tour
That’s science son!

Some video of the tests:

The Results:

Sterling Rope Tour
The Results

So what were the main take home points?

Most methods of rappel extension are more than strong enough.

The single girth hitched dyneema sling actually broke at a slightly higher force than the nylon. While strength isn’t the biggest issue with this method I will often choose to girth-hitch the enforced tie-in point of the harness rather than the belay loop, namely to increase the life of the harness. While belay loops are incredibly strong one well documented fatality from a belay loop breaking after prolonged wear always lingers in the back of my head. I would also keep in mind the lower melting temperature of dyneema and watch those rappel speeds when the rope is passing close to the loaded dyneema sling.

A well used belay device that has developed a relatively sharper edge on the “outgoing” side significantly reduces the load needed to cause failure

Tthough still under a relatively high load (more than 10Kn). Even so while pre-rigging 3 people on a steep rappel it would be a bit more comforting to know belay devices where in good condition and not heavily worn. No need to be the “first” to draw attention to this potential catastrophic failure. Replace your belay device when it develops an edge on the out-going side.

The frayed quickdraw from Predator failed under 4Kn

This definitely draws attention to the quality of fixed draws that might be hanging on your project. Inspect fixed draws!

Thanks to Jeff Lea I also now know that sap does not weaken my slings. It’s still pretty messy so I’ll continue to avoid it when possible.

This visit to Sterling was highly educational and informative. I’ve been climbing almost exclusively on Sterling ropes for the last 3-4 years. I have regularly used the Sterling Evolution Velocity for cragging and top-roping and reserve my Sterling Fusion Nano for leading waterfall ice. Sterling also happens to be the official supplier of rope for EMS Schools. If you are in the market for a new rope this is a company you should be considering!

Do you own a Sterling rope? Which one and how do you like it? What other brands/models do you like? Let me know in the comments below!

See you in the mountains,


Sterling Rope Factory Tour

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