Biktrix Juggernaut Ultra Duo Pro Step-Thru Review: A 160 Nm Step-Thru Fat-Tire Climber for $3,046
The Biktrix Juggernaut Ultra Duo Pro Step-Thru packs a Bafang Ultra mid-drive and a huge battery into a low, easy-mount frame built for steep, rough terrain.
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What the stars are rated against
The stars compare this bike with other off-road e-bikes we have scored — 25 of them, priced $1,828–$4,264. They are a ranking inside that group, not an absolute grade: four stars means it beats most of that set on the measure, not that it hits some fixed standard.
Peers are drawn from a tight price band around this bike, so a $1,000 commuter is judged against other $1,000 commuters rather than against machines costing three times as much. Change the group and the stars would change with it.
The headline Genius Score is not decided by that group alone. It blends the category ranking above with a market-wide view across every bike we publish, so a bike cannot climb simply by sitting in a weak category. How we score.
If your rides involve real climbing, the kind of steep fire roads and loose pitches that stall a lesser bike, the Biktrix Juggernaut Ultra Duo Pro Step-Thru was built for exactly that. Its Bafang Ultra motor pushes 1,000 watts and a stout through the gears, so it keeps pulling when the trail points sharply uphill. The step-through frame is the twist: all that off-road muscle in a frame you step onto at ground level.
It's a bike, so it has a and you can ride up to 20 mph without pedaling. That 20 mph ceiling is the main thing to make peace with, because a motor this strong could clearly go faster. What you get in return is a big 1,040Wh for long days out and a Genius Score of 73, which puts it firmly in strong-buy territory for a premium off-road machine.
Pros & cons
What we like
- The Bafang Ultra puts down , enough grunt to climb steep, loose grades that would bog down a weaker motor.
- The 1,040Wh is genuinely large, and an optional 910Wh extender bolts on for much longer backcountry days.
- The low step-through frame lets you get on and off easily, a real help on a heavy fat-tire bike loaded with gear.
- Quad-piston on big 203mm rotors give you strong, controllable stopping on steep descents and under load.
- A lets you pull away from a dead stop mid-climb or cruise without pedaling when your legs are done.
Worth weighing
- As a bike the assist cuts out at 20 mph, which feels conservative for a motor with this much muscle.
- The Shimano Alivio 9-speed drivetrain is a rung below what you'd expect alongside a premium motor and battery.
Key specs
The motor & power
The heart of this bike is the Bafang Ultra M620 , one of the strongest units you'll find on a production e-bike. It's rated at with , so you can drop into a low gear and let the motor multiply your effort straight up a wall of a hill.
This is exactly the setup you want off-road. On a steep, loose climb all that twist keeps you moving where a hub bike might spin out or stall, and the mid-drive's efficiency helps the battery stretch a little further while it does the work.
It's a bike with a , so you can ride up to 20 mph without turning the pedals. The throttle earns its keep getting a heavy, loaded bike rolling from a standstill on a grade. The trade-off is that the assist stops at 20 mph, and that ceiling is what keeps it Class 2 and shapes where you're allowed to ride.
One gap to note: Biktrix doesn't publish a output, so judge the motor on the 1,000-watt continuous number, which is already plenty for serious climbing.
Range & battery
The single battery is big by any measure, and it needs to be, because a 1,000-watt mid-drive and fat tires ask a lot of it.
Biktrix estimates on a charge. That number assumes easy, efficient riding, so on real off-road terrain with climbing, a loaded bike, and time on the , plan on landing well short of it. Steady on gentler ground is where you'll get closest to the claim.
If you routinely ride longer than one charge holds, the optional 910Wh extender roughly doubles your capacity, which turns this into a true all-day machine for backcountry trips.
You'll spot three battery numbers around this bike. It ships with the 1,040Wh pack. Biktrix also sells a 910Wh add-on, and the two together are the 1,924Wh figure you might see quoted. Judge range on the 1,040Wh you actually get unless you pay for the extender.
Ride & components
You roll on 24x4 Kenda Krusade fat tires, which is what gives this bike its footing on sand, dirt, gravel, and snow. The fat rubber also takes the edge off rough ground on its own.
Biktrix doesn't specify the setup on the spec sheet, so if a plush fork matters to you, confirm what this build ships with before you buy rather than assuming.
Stopping comes from IIIPro E500 quad-piston with 203mm rotors. That's serious hardware, and it matters on a bike this heavy, especially when you're hauling gear down a steep grade.
At 88.5 lb this is a substantial machine, which is normal for a fat-tire mid-drive, and the step-through frame is the practical answer to it, letting you mount and dismount without lifting a leg high. The Shimano Alivio 9-speed drivetrain shifts fine, though it's a modest pick sitting next to the premium motor and battery.
Biktrix lists both a 380 lb and a 330 lb load capacity for this bike. To be safe when you're loading up cargo or a passenger, plan around the lower 330 lb figure.
Price & value
At $3,046 this sits squarely in premium off-road territory, and for the money you're getting a lot of hardware: a top-tier Bafang Ultra motor, a 1,040Wh battery, and quad-piston brakes.
That's why value holds up so well here. Few bikes hand you this much climbing power and battery for the price, so what you're paying for is genuine capability rather than marketing.
Who it's for
The steep-country climber
If your local rides involve real elevation, grinding fire-road climbs and loose rocky pitches, this is the bike that keeps pulling instead of bogging down. The mid-drive and low gearing were made for dragging a loaded bike uphill.
The easy-mount off-roader
If raising a leg high to get aboard is awkward, whether from a stiff hip, a shorter inseam, or a bike piled with gear, the low frame lets you step straight through. You get full fat-tire capability without the clumsy climb-on.
The 28-mph rider
If you were hoping to cruise faster than 20 mph, this one tops out there as a bike, and all. The motor could clearly do more, so if outright speed is the goal, look at a Class 3 build instead.
The flat-pavement cruiser
If your riding is mostly flat streets and bike paths with no real hills, you're paying a premium for climbing muscle you'll rarely tap. A simpler hub-motor bike would cover that ground for a lot less money.
Frequently asked
Does the Biktrix Juggernaut Ultra Duo Pro Step-Thru have a throttle?
Yes. It's a e-bike with a , so you can get moving or cruise without pedaling up to 20 mph.
Can you ride the Biktrix Juggernaut Ultra Duo Pro Step-Thru without pedaling?
You can. The throttle lets you ride up to 20 mph without turning the pedals, which is handy for pulling a loaded bike away from a stop on a climb. Riding on the throttle does drain the battery faster than pedaling.
How far does the Biktrix Juggernaut Ultra Duo Pro Step-Thru go on a charge?
Biktrix estimates up to 55 miles from the 1,040Wh battery. Expect less on steep, loose terrain or with heavy throttle use, and note that an optional 910Wh extender roughly doubles capacity.
How fast does the Biktrix Juggernaut Ultra Duo Pro Step-Thru go?
The motor assists up to 20 mph, which is the Class 2 limit.
How much does the Biktrix Juggernaut Ultra Duo Pro Step-Thru weigh?
About 88.5 pounds with the battery, which is typical for a fat-tire mid-drive bike. The low step-through frame makes getting on and off easy despite the size.
How much torque does the Biktrix Juggernaut Ultra Duo Pro Step-Thru have?
160 Nm from the Bafang Ultra M620 mid-drive, which is why it handles steep, loose climbs so well.
How it compares to its siblings
This is the step-thru version of the family, and at $3046 it's the cheapest mid-drive Juggernaut here. It also carries the family's highest Genius score (73), the largest battery (1040Wh), the top payload rating (380 lb), and the same quad-piston 203mm brakes as the much pricier Eagle 2. If you want mid-drive torque and strong stopping power without paying Eagle 2 money, this is it — you just stay in Class 2, with no higher-speed mode.
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Biktrix Juggernaut Ultra Duo Pro Step-Thru is ranked on:
Guides worth reading
- Mid-drive vs hub motorWhere the motor sits changes how the bike climbs, what it costs, and what wears out. Neither is better everywhere.
- E-bike classes explained: Class 1, 2 and 3Three classes, two questions: does it have a throttle, and how fast does the motor keep helping.
- Nominal vs peak watts on an e-bikeThe wattage in the headline is usually the peak figure, which can be roughly double the number the motor actually sustains.
How 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.