Non-Newtonian Skis Adapt to Speed: Renoun Citadel 107 Review

I was on lap number seven on Grouse Mountain, and I wasn’t about to stop anytime soon. My breath was heavy. I was sweating through my baselayers and covered in snow. Beaver Creek had gotten 10 inches overnight, and it didn’t seem like anyone else was there to ski it. Every single run, snow was exploding over me all the way down.

It was an ideal day to test the Renoun Citadel 107 — a light, floaty, and easy-to-maneuver powder ski with one very techy attribute. According to Renoun, thanks to a patented non-Newtonian anti-vibration polymer called “VibeStop,” this ski self-adjusts its own stiffness or softness based on the skier’s speed and terrain.

That’s the kind of claim that makes the hair on my arms stand up. So, I’d gotten a testing pair of the Citadel 107s at the beginning of the 2024/25 ski season. This was my first real pow day to test them in their element. I’d busted them out for some initial impressions on hardpack and groomers. But that wasn’t what these skis were made for.

Now that I had them in the deep stuff, their true personality was emerging. I was having so much fun on them that I kept getting back on that lift until they closed it.

In short: The Renoun Citadel 107 is a powder ski through and through. It has all-mountain capability, but its nimbleness, fat waist, and shovel tips are best suited for slashing blower cold smoke turns in deeper snow. They’re middle-weight contenders for backcountry skiing but still well-suited for touring and shredding backcountry stashes. At higher speeds, they’re damp and seem to mitigate vibration well. They’re not a quiver killer, but as a specialized powder tool or backcountry ski, they’re a great option.

Check out our guide to the Best Backcountry Skis.

Renoun Citadel 107 Powder Ski Review

Renoun is a Vermont brand that’s been around since 2011, but I only really started noticing their skis in small mountain town ski shops within the last few years. It isn’t a mass producer like K2 or Atomic. Since 2015, most of Renoun’s skis have been hand-pressed by the same guy (JF Bouchard) and his small crew in the brand’s Canadian manufacturing facility.

Construction & Weight

The Citadel 107 is the brand’s latest “powder weapon.” Redesigned for 2024/25, this ski uses Renoun’s patented VibeStop tech, bidirectional carbon fiber, a titanal binding reinforcement plate, and an aspen wood core.

The materials used are all light, contributing to the ski’s 1,635 g/ski weight. Compared to the other skis in our guide to the Best Backcountry Skis, that’s pretty squarely in the middle-weight class. But for a standard all-mountain or powder ski, it’s light. I mounted my Renoun Citadel 107s with a Dynafit Speed Radical binding. The setup only weighs 1,968 g/ski. It’s one of the lightest I own.

Shape

The Citadel 107 uses a rocker/camber/rocker shape (30%/60%/10%) with early-rise shovel tips. Its 107mm waist is just on the threshold of too-big-for-a-regular-day. You can get away with using it as an all-mountain ski when the snow is chalky or soft. But the Citadels will only truly shine in powder. It’s what they are made for.

The tail of the ski is shaped with a notch for skin clips. So they were clearly designed with uphill travel in mind, even though you can mount them with downhill bindings.

VibeStop Tech

This is where the rubber meets the road. Or, rather, where the non-Newtonian polymer hits the snow. VibeStop is a patented polymer developed specifically to enhance the dampness of Renoun’s skis. It’s a non-Newtonian substance.

So, when it is subjected to stress at speed, VibeStop allegedly stiffens up, providing more stability. At lower speeds or in softer snow, it softens under less stress. The polymer is also 50% lighter than the aspen it replaces within the wood core.

According to Cyrus Schenck, Renoun’s founder, Vibestop changes almost instantaneously, without delay. “It’s adapting in under one second,” he told GearJunkie.

Schenck said the stiffness of the ski changes by up to 300% thanks to this technology. When the original Citadel ski came out, he said they actually pulled back the amount of VibeStop used because the ski was changing almost too much.

In the Field: Renoun Citadel 107

The first few days I took the Citadel 107s out were not powder days. I skied a mix of chalky bumps and corduroy and hit more than a few patches of ice. Their light weight makes them extremely maneuverable. I had no issues navigating tight spaces as I darted around to my favorite runs on the mountain.

On softer snow (i.e., chalk or slush), they performed like an all-mountain ski. I could grab an edge fairly easily, despite the fat 107mm waist, and carve fairly aggressive turns on groomers. But as soon as ice or chunder entered the mix, these skis lost some control. I got bucked around by icy bumps or chunks of frozen snow. It was tough to get the Citadel 107s to carve or grab a solid edge on ice or chunky hardpack.

But in powder, the Citadel 107s opened up. That first deep day I took them to Beaver Creek and ripped Grouse Mountain I had so much fun on them. They floated without much effort. I could kick into patches of fresh and blow explosions of snow over myself. They turned and maneuvered well. When I jumped into a patch of fresh snow, they popped me out energetically into my next turn.

And the changing stiffness? Here’s what I’ll say: As you transition from going slow to going fast, it’s most noticeable. When I would start skiing from a dead stop, the first few skates I made definitely felt different than those I made when the skis started picking up speed.

Once I got going, though, it was hard to really tell a difference. Even in chopped powder, there was enough force that I can’t say the skis were softening up between turns.

If you had a fresh slope of uncut champagne powder, you’d probably notice less stiffness in the ski. But they felt as though they skied pretty consistently for most of the conditions I was riding, even in softer, deeper snow. It wasn’t like they were turning into noodles in soft stuff and hardening back up on firm snow. But they were damp when I needed them to be at speed, which is the whole point (and namesake) of VibeStop.

Limitations

As I mentioned, when you get onto ice, it’s hard to grab a solid edge and slash a turn with the Citadel 107s. More than once, as I was skiing, if the snow changed under me from chalk to ice, my edge would slide out. They don’t have the heft to hew into hard snow and ice, which can be a limiting attribute in the variable conditions of the backcountry.

But that also isn’t what these skis were made to do. They aren’t carving skis. They aren’t even technically listed as “all-mountain” skis on Renoun’s website (although they can work just about anywhere on the mountain). These are powder skis — a specialized tool for deep resort days or for hunting backcountry stashes. That’s where you’ll get the most out of them.

Renoun Citadel 107: Who Are They For?

If you’re looking for a powder ski to add to your resort or backcountry quiver, the Renoun Citadel 107 is a fun and very techy ski. What it lacks in power, it makes up for with flotation, maneuverability, light weight, and the unique ability to adapt its stiffness.

On powder days, I looked forward to busting this setup out. On the skin track, they’re light enough to save both energy and stamina.

It is not a quiver killer. There are some days when I wouldn’t consider riding my Citadel 107s — if it’s icy, exceptionally crusty, or chop and chunder. This is a specific tool that performs well within its range of functionality.

That said, I’m excited to continue using this ski in the resort and the backcountry when there is enough snow. Any excuse to break out my Citadel 107s is a good one.