Sterling Fusion Nano IX Rope

Anneke Door reviews the Sterling Fusion Nano IX for Blister Gear Review
Sterling Fusion Nano IX

Sterling Fusion Nano IX


Diameter: 9.0

UIAA Falls: 6

Weight: 52 g/m

Dynamic Elongation: 33.1%

Static Elongation: 7%

Certified use: single, half, twin

Impact force: 8.5 kN

Sheath Proportion: 27%

Lengths Available: 50m, 60m, 70m, 80m

Length Tested: 60m

MSRP: $224

Test Locations: City of Rocks, Idaho; Wind River Range, Tetons, Wyoming


The Sterling Fusion Nano IX is an excellent example of a specialty rope designed for light & fast alpine pursuits and hard red-pointing. Its light weight and small diameter position if for use in the mountains, and its handling characteristics should appeal to mountain guides and recreational climbers alike.


Much like the flex ratings for ski boots, diameter measurement for ropes varies greatly from manufacturer to manufacturer.

For a 9.0mm rope, the Fusion Nano is surprisingly thin compared to its competitors. Side by side, it is noticeably thinner than the 8.9mm and 8.7mm Mammut Serenity (I’ve used both of these ropes for years), though the Serenity 8.7 weighs in at 51g/m, compared to the Nano’s 52g/m. Most likely, this is due to the way the rope is constructed. I.e.,  the Fusion Nano IX probably has a tighter weave, and whether the rope was weighted or not during the diameter measurement, and thus measured smaller than it actually is when unweighted. Whatever the case may be, everyone I’ve climbed with has commented on how skinny the Fusion Nano feels for a 9mm rope.


Sterling boasts that they make the “best handling ropes in the world,” and I actually have found the Fusion Nano IX to handle as well or better than any other rope in its class. I’ve used it with both Petzl Reverso and the Black Diamond ATC Guide belay devices, and it pulls through both effortlessly.

That said, with its dry coating and tiny diameter, it also can be more difficult to belay a leader, catch a fall, or lower a climber with the Nano IX in these tube-style belay devices. For this reason, I often have my belayer use a GriGri 2 with the Fusion Nano IX, which works great, especially in conjunction with the Freino carabiner. (The Freino is a GriGri specific carabiner from Petzl which has an extra hook for additional friction while lowering. At $50, it’s the most expensive carabiner you’ll ever buy, but totally worth it if you’re lowering people heavier than you on skinny ropes).

Even with the GriGri 2, you must be very attentive belaying with the Fusion Nano IX (or any small-diameter rope), since it’s more prone to allow rope to slip through the device before the cam engages.

Anneka Door reviews the Sterling Nano IX for Blister Gear Review
Anneka Door with the Sterling Fusion Nano IX.

Many ropes these days are sold in a butterfly coil off the shelves. The Nano IX is not, so it takes some time and care to unravel the rope to make sure it will handle smoothly on your first climb. But this is just a one-time thing. Aside from a couple initial kinks from the factory coil, I have not noticed the rope to have any unreasonable twists or kinks even after dozens of munter hitches and kiwi coils, which is another testament to how well this rope handles.

Middle Mark

The Fusion Nano IX came without a middle mark of any kind. I find this both annoying, time consuming, and arguably dangerous. Of course there are ways to mark your rope, but finding a rope-specific pen can be difficult, and using an old marker isn’t totally confidence-inspiring. I almost always spend the extra money on a bi-pattern rope, and fortunately, the Fusion Nano IX does come in bi-pattern option for an extra ~$67. Well worth it in my opinion.

Dry Treatment

The Fusion Nano IX is a dry-treated rope. Dry treatment reduces the amount of water your rope will absorb which keeps it it lighter when wet, as well as making it more durable and less susceptible to holding dirt.

Nylon ropes lose a significant amount of their dynamic properties when saturated, making dry treatment a must for ice climbers, and a good idea for anyone else. The tradeoff is that dry treatments can make your rope feel more “slippery” at first, which can make it more difficult to hold a fall, especially when combined with a smaller diameter rope like the Nano IX


As you might expect from a high-end rope, the Nano doesn’t come cheap. However, at $224 USD, it falls into the same range as its competitors like the Mammut Serenity ($229) and the Beal Joker ($219).


The concern with any skinny rope is, of course, durability. A 9.0mm cord is simply not going to be as durable as 10mm one, but that’s why we have different ropes for different applications. You wouldn’t want to haul your fat 10.2mm into the backcountry any more than you’d want to have a group top rope session on the Fusion Nano IX. The core in a 9.0mm rope is often the same as that of a 10mm, but the sheath will have fewer fibers in the smaller rope, resulting in less durability.

The ratio of core to sheath in a rope is called sheath proportion. Most fatter ropes from about 9.5-10mm, come in somewhere around a 40% sheath proportion. Compared to the Mammut Serenity 8.7 (38%), and the Beal Joker 9.1 (35%), the Fusion Nano IX has a very low sheath proportion of only 27%. Despite this fact, I have found the rope to be surprisingly durable. While I have not abused the Nano like a dedicated sport climber would, I have run it over coarse granite in the Wind River Range, the City of Rocks in Idaho, and the Tetons, and so far I can hardly even tell that it’s gotten fuzzy.

Bottom Line

The Sterling Fusion Nano IX is right up there with the best thin, lightweight ropes I have used. I am impressed by its durability and handling, and it has earned a place in my quiver for alpine objectives and any other situation where weight and size take a priority. I do, however, recommend investing in the available bi-pattern version.

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