Rock Machine Vyöry e70 – comparing and reviewing a fatbike

Intended Use
Exploring & mountainbiking
Shimano EP6 85 Nm
500 Wh
25.77 kg with pedals and studded tyres
Varies, starts at a little over €3.000
It’s still winter and snow around here, so we decided to test a fatbike. We’re used to riding full suspension emtbs with 2.6 to 3” wide studded tyres. How much better is the Rock Machine Vyöry with 4.8” tyres on snow?

About the Rock Machine Vyöry​

This fatbike is supposed to come with wide Maxxis Minion FBF/FBR 26x4.8” tyres. But on the demo bike, those were swapped for the Schwalbe Al Mighty 26x4.8” studded tyres. Riding on dry snow, studs aren’t needed. But for riding throughout the winter in various conditions, these tyres are a great choice.

There’s something raw and simple about a fatbike. It’s a tractor and it doesn’t need expensive, lightweight, high-performance components. It needs solid and durable components. The Microshift AdventX 10 – 10-speed drivetrain served us well. An 11-48t cassette gave us all the gear ratios we needed. I’ve never seen the Clarks Clout+ brakes before, and I’m sure they aren’t as nice as the more expensive models from Magura, Sram and Shimano. But I don’t care. They were perfectly fine for this use-case.

Microshift AdventX 10 with an 11-48t cassette
Clarcs Clout+ brakes

The only luxury item found on the Vyöry is the dropper seat post. That’s great because you can ride down steep stuff with a fatbike. But it’s great for a less obvious reason too. If you ride loose conditions and you have to dismount the bike you risk sinking into the snow. It’s difficult getting back on the bike when you’re knee-deep in snow and the bike sits half a meter higher than you. Dropping the saddle 150 mm helps.

Motor and battery​

The Shimano EP6 85 Nm is a nice choice of motor, I think. It’s a bit cheaper than the other full-power motors and it’s very powerful at lower speeds. I wish the battery was bigger though. The 500 Wh detachable battery isn’t ideal for riding in the cold. As the internal temperature of the battery drops, so does its ability to deliver power. A bigger battery has more battery cells in parallel, allowing it to deliver more power when it’s cold.

Shimano EP6 - 85 Nm motor
Fitting a cover will increase the temperature in the battery compartment.

In properly cold conditions, chances are the BMS will turn off a small battery before it’s empty. This can be remedied to some extent by using a neoprene cover. And if you enjoy going on long rides, we would definitely consider getting a second battery that we kept wrapped in a blanket in the backpack.

No suspension?​

You don’t need suspension on a fatbike, the tyres offer all the cushioning you need, right? Well, that depends. Running lower air-pressures, the tyres will soak up a lot of the bumps and provide a comfortable ride. But they have basically no rebound damping, so the ride can end up being quite bouncy. One would think suspension makes the bike more settled. But the bouncy tyres are still there. Increasing the tyre pressure removes much of the bounce and would allow the suspension to do its job in peace. I think running low pressures is what fatbiking is all about though, at least in winter conditions.

A rigid fork with a Vyöry sticker

Riding the bike​

We probably never went above 10 psi. I say probably because our high-volume minipump doesn’t have a manometer showing the pressure. When going for a ride, you will usually encounter a variety of conditions and you need a pump. My little high-volume pump is usable when trying to fill these huge tyres back up again.

Our rides started off on asphalt and roads covered in hard packed snow. It’s nice having reasonably hard tyres on the transport sections. The bike rolls considerably faster, and the steering is relatively precise. But as we approached the forest, the surface was soon covered by a layer of fluffy snow. We stopped to reduce the tyre pressure. This improves rear wheel traction, and it makes the steering more stable. The twitchiness of the front wheel that makes us constantly correct the steering disappears.

The Topeak Mini Morph is usable when trying to inflate a fatbike tyre.

As we entered the forest and got properly off-road, conditions got much softer. So, we stopped to let out more air. It’s a matter of trial and error, how low do we have to go to keep riding. A 4.8” tyre isn’t that wide for a fatbike and it won’t let us ride the most extreme conditions. I’ve seen people ride with 0 psi in extremely powdery snow. You need big tyres for that, like 6” . When getting on the bike with such a big tyre, the pressure builds up enough to have some clearance between the tyre and rim.

We settled for what seemed like a few psi in relatively deep, fluffy snow. It made the bike so slow and bouncy. We struggled to keep the rear wheel calm so it would find grip. The steering takes “sluggish” to a new level. It becomes heavy and imprecise as the rim floats inside the tyre. For many, this is what fatbiking is all about. Getting out in extreme conditions.

How low can you go?
In conditions like these, a motor is nice, but 4.8 tyres isn't enough.

Compared to a regular emtb with plus-tyres​

We fitted Suomi 29x2.8” studded tyres on an Orbea Wild H10. This offers a nice amount of float and decent stability on snow. And we fitted a narrower 45Nrth 29x2.6” tyre up front on a Marine Alpine Trail E1, along with a wider 45Nrth 3” tyre on the 27.5 rear wheel. These provide great traction and precision, but less stability.

We took these two bikes out with the Rock Machine Vyöry e70 to do a comparison. And there is no doubt, the fatbike is just much more stable and less twitchy in fluffy snow and over tracks from other trail users. When riding the fatbike, we didn’t understand why the guys on the other two bikes were struggling and going left and right. The 2.8” tyres on the Orbea Wild has a decent amount of volume though. It can be ridden with less pressure than the 2.6” tyre on the Marin, making it reasonably stable.

The Orbea Wild with 29x2.8 tyres. Photo: Øyvind Wold

Photo: Øyvind Wold
Marin Alpine Trail E1 with 2.6+3 tyres alongside the fatbike. Photo: Øyvind Wold

Photo: Øyvind Wold
The Marin Alpine Trail E1. Photo: Øyvind Wold

Photo: Øyvind Wold

The fatbike could struggle a bit in the climbs. We had to concentrate and pedal evenly in the correct gear to avoid rear wheel bounce. If there’s too much bounce, traction is lost and the fatbike comes to a halt. The lower volume tyres on the other bikes won’t bounce as much and the rear suspension is able to control it. Therefore, the plus-tyre bikes are better in slippery conditions.

And the full suspension bikes win again on most descents. The narrower tyres are more precise in turns, they will provide a minimum of feedback to let you know how the front wheel traction is coming along. Thus giving you an idea of how to position your body weight over the bike. When going over rough sections, the full suspension emtbs tracked well while the fatbike keept on bouncing.

Not as fast as it looks.
The Rock Machine Vyöry e70 fatbike

Verdict & conclusion​

An electric fatbike and a full suspension emtb are obviously two very different tools. But for winter riding in places like Norway, they definitely overlap. A full suspension emtb with room for 2.8-3” tyres can be used most of the winter season. But make sure you get a bike that will take these wide tyres. You’re sacrificing quite a bit of usability in snow by going 2.6” or below.

The fatbike has an advantage for riding cross country ski tracks. It will leave less of a trace and less skiers angry. The 4.8” tyres are better and more stable in lose conditions. But the plus-tyre bikes went along for most of the rides we did. When challenging the fatbike in properly deep, powdery snow, it didn’t get far. This means there weren't that many places and conditions we could ride the fatbike and not the two others. If you dream about plowing through a meter of powder, you need even bigger tyres, 4.8” isn’t enough.

Leaving barely a trace
Will it float? The rim floats around inside the tyre at these pressures.

For us that love to ride full suspension emtbs at a bit of speed, we probably would stick to our bikes running plus tyres. That doesn't mean the fatbike is pointless! The fatbike shines at lower speeds and it can be ridden so effortlessly over loose surfaces. It’s nice going out on a ride an early morning before the snowplow has cleared the roads. This is a perfect bike for exploring and riding far, provided you brought a second battery.

But couldn’t you buy a full suspension fatbike? I guess you could, but it would very likely still struggle with the bounce when riding low tyre pressure. And as far as I know, the full suspension fatbikes can’t take as big tyres. The full suspension Haibike FullFatSix ships with 4” tyres. To me, a fatbike makes a lot of sense as a simple and durable bike with no suspension and room for the biggest tyres possible. The Rock Machine Vyöry e70 at just over 25 kg is such a bike.

The Rock Machine Vyöry e70 fatbike

And it’s surprisingly cheap these days. In Norway, it’s currently sold for 35.000 NOK, which means just over €3.000. That’s a great price I think, a nice fatbike without a motor can cost almost the same. But according to me, an unmotorized fatbike doesn’t make half as much sense. The places you can ride with a motor assisted fatbike is just impressive! The Rock Machine Vyöry e70 is a proper no-nonsense workhorse and a great choice for exploring the winter landscape.
About author
Started mountainbiking in the 90s. Moved to emtbs in 2014 and have been reviewing them since 2016. Contact me here


Thanks for the review!
This means there weren't that many places and conditions we could ride the fatbike and not the two others.
I ride a full suspension with 5" studded tires in the winter and the conditions where it makes a real difference is when there is a solid crust on the snow. With narrow tires it passes through and then it's over.
Good review, but it lacks a bit of "fatbike usage knowledge". ;)

I have a similar e-fatbike (EP8 motor, 5" wide tires) and a Orbea Rise. Unless the snow in Québec is very different from the snow in Norway (I doubt that), I don't agree with the statement that "2.8-3” tyres can be used most of the winter season". In fact, the minimum width to ride on trails in fatbike centers is 4.5 inches, the reason being that small tires destroy the trails. I wouldn't even think of using with a smaller width, because you want flotation on snow. I fact, we rarely ride with more that 7 PSI. Also, you want a tire that is studdable in the winter.

Also, I can't agree with the statement that "fatbike has an advantage for riding cross country ski tracks" . Anybody that does that is called an "a**hole" here, specially if it's a E-Fat. Cross country ski tracks are for cross-country skiing, let's not make them "less angry" because a fatbike messes up "less" their tracks
Good review, but
It seems Canada is more different than I imagined. Riding ski tracks is a thing in Norway, and I believe it's similar in Sweden and Finland. Sure, people get p*ssed if we ruin the tracks. But as long as the bikers are careful not to destroy anything and stay out of the actual classic track, most skiers seem happy. I guess they're getting used to the fatbikes. We used to have a couple of bike loops nearby that was kept open during the winter. One was made by a guy or two pulling a car tyre, the other was maintained by a snowmobile. Both tracks are (were?) open for both fatbikes, non-fats, dog walkers, etc.

In 2014-2016, I owned a fatbike with a retrofitted Bafang BB01 motor and DIllinger 5 (4,8") tyres. But I sold it when I started riding a Merida eOne-Sixty gen1 with the Suomi Fat Freddie 3" tyres. Having i38mm rims, the tyres was about 75 mm wide. It would occasionally work on hard packed ski trakcs, but it wasn't ideal. But the Merida was great for riding forrest roads and snow trails from the walkers. The wide tyres made it easier staying on the straight and narrow. Riding a fatbike again after 7-8 years, my impression hadn't changed. I'm not losing many days of riding with a plus-tyre emtb. If we had fatbike-only loops around here, the situation would of course be different.
Well Knut7, I does look like we have a very different situation in Québec. We have specific trails for cross-country skiing (classic and skaters have their specific trails) , fatbikers have their own. Only Class 1 E-Fats are allowed. Everybody's happy because we all have optimal trail conditions:


Different worlds, I guess!