Biktrix Juggernaut Ultra Duo 4 Step-Over Review: Two Wheelsets and 160 Nm of Torque for $3,499
The Biktrix Juggernaut Ultra Duo 4 pairs a torque-heavy Bafang motor with two tire sets and a big battery, so it climbs and hauls where lighter e-bikes give up.
If your idea of a good ride means steep, loose climbs, muddy trails, or getting a heavy load somewhere a normal bike can't go, the Biktrix Juggernaut Ultra Duo 4 Step-Over is built for exactly that. It runs a Bafang Ultra motor with , one of the highest figures on any production e-bike. At $3,499 it's a serious outlay, and the range of terrain it opens up is what justifies the number.
It's a bike as it ships, so it has a and you can ride up to 20 mph without pedaling, which is handy for launching from a stop on a hill or through soft sand. The honest catch is range. A motor this hungry burns through even the decent-sized well before the 95-mile claim would suggest, so plan conservatively or budget for a bigger pack.
Pros & cons
What we like
- from the Bafang Ultra mid-drive is enough to haul a heavy, loaded bike up grades that stall weaker motors.
- Genuinely strong output, with and on tap.
- A lets you pull away from a stop or cruise up to 20 mph without pedaling.
- Two wheelsets included: 26x4 fat tires for snow, sand, and gravel, or 27.5x3 for pavement and groomed trails.
- A 380 lb leaves room for a larger rider plus gear or cargo.
Worth weighing
- The base paired with such a power-hungry motor means real range comes in far under the 95-mile claim, and going long distances means paying for a larger pack.
- The drivetrain is a modest Shimano Alivio 9-speed, plainer than you'd expect on a bike at this price.
Key specs
The motor & power
The engine here is a Bafang Ultra M620, a motor. That's what gives it real climbing muscle: with , it drags a heavy, loaded bike up steep and loose terrain without straining.
It's rated at with , about as strong as production e-bike motors get. Power is one of this bike's standout strengths.
Out of the box it ships limited to 500W and 20 mph, which makes it a e-bike with a you can ride without pedaling. The settings are programmable, so you can unlock the full power for off-road and private-land use where the higher speeds and wattage are legal.
The throttle earns its keep on a bike like this, getting you moving from a dead stop on a hill or through soft sand where pedaling is a slog. Riding on it does drain the battery faster than , and that matters here given how range shakes out.
Range & battery
The standard build includes a 52V , and Biktrix quotes on a charge. That figure assumes gentle, low-power riding on flat ground.
In the real world, a 1000W mid-drive pulls hard and pulls often, especially on the climbs this bike is made for, so expect meaningfully fewer miles than the headline. Real range comes down to terrain, your weight, and whether you ride on the throttle or pedal along.
Range is this bike's soft spot, so if you're planning long backcountry days far from an outlet, the larger battery options are worth the extra money.
Biktrix lists a whole menu of battery sizes on this page, from a 728Wh option up to a 1794Wh dual-battery setup. The Duo 4 we're reviewing includes the 910Wh internal pack as standard; the bigger numbers are paid upgrades, so double-check which battery a listed price actually includes before you buy.
Ride & components
What really sets this bike apart on the trail is flexibility. It comes with two wheelsets: 26x4 fat tires for snow, sand, and gravel, and 27.5x3 for pavement and groomed trails. Swapping between them changes what kind of riding the bike is good at, which is rare to get in a single purchase.
Stopping is handled by Biktrix dual-piston on 180mm rotors, which is appropriate braking power for a heavy bike carrying a load down a grade.
The drivetrain is a Shimano Alivio 9-speed. It shifts reliably, but for a bike at this price it feels plain, and it's the one part that lags behind the motor.
At around 88 pounds it's a heavy machine, which is par for the course with a fat-tire bike carrying a motor and battery this size. You won't notice the weight while riding; it only matters when you need to lift it onto a rack or up a set of stairs.
With a 380 lb , there's plenty of headroom for a bigger rider plus panniers, tools, and trail gear. One thing worth confirming before you buy: suspension travel isn't spelled out in the specs we have, so ask about it if you'll be hitting genuinely rough terrain.
Heads up on a spec mismatch: Biktrix's marketing text mentions an 11-speed drivetrain, but the spec table lists a Shimano Alivio 9-speed. We go with the 9-speed from the spec sheet, so confirm the gearing with the seller before ordering.
Price & value
At $3,499 the Juggernaut Ultra Duo 4 sits firmly in premium territory, and what you're paying for is the motor and the terrain versatility rather than fancy finishing parts. For the level of climbing power, payload, and range of surfaces you get, it's priced fairly against other heavy-duty off-road builds.
That balance is why it lands at a Genius Score of 73 out of 100: strong on capability, held back a bit by real-world range and a plain drivetrain. If you'll actually use the power off-road, it's money well spent. If you mostly ride flat pavement, you're paying for muscle you won't ever touch.
Who it's for
The go-anywhere trail rider
If you ride steep, technical, or loose terrain and you're tired of motors that bog down on climbs, the 160 Nm mid-drive here has the muscle to keep pulling. Between the fat tires and the MTB wheelset, it takes on snow, sand, gravel, and singletrack, so one bike covers most of the ground you'd want to explore.
The heavy-duty hauler
If you're a bigger rider, or you load up with gear and tools on rough ground, the 380 lb capacity and strong motor mean you won't feel like you're overloading it. It's also happy to move you along on the up to 20 mph when you don't feel like pedaling a heavy load uphill.
The all-day explorer
If your rides are long backcountry days far from an outlet, look hard at the battery first. The standard 910Wh pack won't get near the 95-mile claim under hard trail use, so you'll likely want to pay up for one of the larger batteries before you commit.
The flat-city commuter
If most of your miles are flat streets and bike paths, this is far more machine than you need. You'd be spending $3,499 on climbing power and off-road grip you won't use, and a lighter, simpler commuter would be easier to park, carry, and live with.
Frequently asked
Does the Biktrix Juggernaut Ultra Duo 4 Step-Over have a throttle?
Yes. It has a , so you can ride without pedaling up to 20 mph in its standard Class 2 setting.
What class is the Biktrix Juggernaut Ultra Duo 4 Step-Over?
As it ships, it's a e-bike, limited to 500W and 20 mph with a throttle. The settings are programmable, so you can unlock more power and speed for off-road or private-land use where that's legal.
How far does the Biktrix Juggernaut Ultra Duo 4 Step-Over go on a charge?
Biktrix claims up to 95 miles on the standard , but that's a best-case number. Hard trail riding with this powerful motor brings real range down considerably, and larger battery options are available if you need more.
How much weight can the Biktrix Juggernaut Ultra Duo 4 Step-Over carry?
Its is 380 pounds, enough for a heavier rider plus gear or cargo.
How powerful is the Biktrix Juggernaut Ultra Duo 4 Step-Over motor?
It uses a Bafang Ultra M620 rated at 1000W continuous and 1500W peak, with , which is among the strongest setups you'll find on a production e-bike.
How much does the Biktrix Juggernaut Ultra Duo 4 Step-Over weigh?
About 88 pounds with the battery, which is normal for a fat-tire e-bike carrying a motor and battery this size.
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Read the reviewHow we score: the Genius Score blends a bike's capability against same-price peers with its value for the money, weighted for what this off-road buyer prioritises. Specs are pulled from the manufacturer's live page and normalised (nominal vs peak watts, true weight with battery). Ratings are our estimate from specs, not a lab test.