Biktrix Juggernaut Ultra Duo Pro Step-Thru Review: A 160 Nm Step-Thru Climber for $3,046
The Bafang Ultra motor and a big 1,040Wh battery make this one of the most capable climbers you can get on a step-thru fat bike, and the price is fair for what's in it.
If your idea of a good ride involves steep fire roads, loose gravel, and hauling gear up grades that make most e-bikes give up, the Biktrix Juggernaut Ultra Duo Pro Step-Thru is built for exactly that. The motor puts out , a huge amount of low-end pulling power, and it feeds that through the gears so you can drop into a low gear and grind up a loose climb steadily. The step-thru frame just makes getting on and off easier, loaded or not.
It earns a Genius Score of 83 out of 100, and the value holds up. You're paying premium money, but you're getting a serious mid-drive, a big battery, and brakes that can actually rein in a heavy bike. The one thing to make peace with is the 20 mph cap: with this much power, plenty of riders will wish it went faster, but as a bike it stops assisting at 20.
Pros & cons
What we like
- The Bafang Ultra M620 is one of the strongest climbing motors on any production e-bike, with to haul you and a full load up grades that flatten lesser bikes.
- A large 1,040Wh gives you room for long days out, with an optional range extender if you want even more.
- The lets you pull away from a dead stop or crawl up a rough pitch without pedaling at all.
- IIIPro quad-piston with 203mm rotors give you the stopping power a heavy, fast fat bike really needs.
- The low step-thru frame is easy to mount, and it's rated up to 380 lb , enough for a big rider plus a fully loaded rack.
Worth weighing
- The 24-inch wheels keep the standover low, but they're smaller than the 26-inch fat tires on some rivals, so they don't roll over big rocks and roots quite as smoothly.
- The headline 1,924Wh capacity you'll see advertised only shows up if you pay extra for the range extender. The built-in pack is 1,040Wh, so plan around that unless you buy the second battery.
Key specs
The motor & power
The heart of this bike is the Bafang Ultra M620, a rated at . On this setup you can drop into a low gear and let the motor multiply your effort, which is exactly what you want when a climb turns steep and loose.
The number that matters most here is , near the top of what any e-bike offers. That's the muscle that drags a loaded bike up a steep grade without bogging down. A hub motor pushed up the same pitch would overheat and quit, while this one just keeps pulling.
Biktrix doesn't publish a figure, so judge the motor on its 1,000-watt continuous rating and that torque number. Both sit near the top of the class.
Range & battery
The 52V is big, and Biktrix estimates on a charge. That's a solid number rather than a huge one, and the reason is simple: a 1,000-watt motor with this much torque draws a lot of power the moment you actually use it.
That 55-mile figure assumes easy, efficient riding. Your real-world number drops when you climb hard, push through soft sand or mud, carry a load, or lean on the throttle. On steep, technical days, plan your route around a shorter distance and you won't get caught out miles from the car.
If range is a genuine concern, Biktrix offers an optional 910Wh range extender that roughly doubles your capacity for long backcountry days.
You'll see a few battery numbers floating around this bike. The built-in pack is 1,040Wh, which is what we base range on. Some listings advertise a combined 1,924Wh, but that figure only applies once you add the optional 910Wh extender, so budget for the second battery separately.
Ride & components
This is a fat bike through and through, riding on 24x4 Kenda Krusade tires that float over sand, gravel, and loose dirt far better than a skinny tire could. The 24-inch wheels are a bit smaller than the usual 26-inch fat setup, which lowers the frame and makes the step-thru easy to swing a leg over.
Stopping comes from IIIPro E500 quad-piston with big 203mm rotors. On a heavy bike that can carry a lot and pick up speed downhill, that's the braking you want, and it's a big reason the build quality here rates so well.
Shifting is handled by a Shimano Alivio 9-speed drivetrain, a reliable everyday setup with enough gear range to make the most of the mid-drive on climbs. As a bike it has a and assists up to 20 mph, so you can ride without pedaling if you want. At about 88.5 pounds with the battery it's a substantial machine, which is par for a fat-tire mid-drive carrying a battery this size.
Price & value
At $3,046, this sits firmly in premium territory, and that's the expected cost of admission for a genuine Bafang Ultra mid-drive, a battery this big, and this level of braking. You're paying for capability, not a badge.
For what you get, the value is strong. Against the dozen rivals we scored it with, it delivers a lot of climbing power and battery per dollar, which is a big part of why it lands where it does overall.
Biktrix lists the load capacity two ways: a badge that says 330 lb and a detailed spec that says 380 lb. Even the lower figure leaves plenty of headroom for most riders plus gear, so treat 330 lb as the safe number to plan around.
Who it's for
The steep-country climber
If you actually ride mountains, with long fire-road grinds, loose steep pitches, and real elevation, this is where the 160 Nm earns its keep. It'll pull you and a loaded pack up grades that would leave a lesser motor gasping.
The easy-on, easy-off hauler
If swinging a leg over a tall top tube is a pain, whether from a bad knee, a shorter inseam, or climbing aboard with cargo already strapped down, the low step-thru makes getting on simple. Its 380 lb covers a heavier rider plus panniers or a trailer without you doing the math.
The throttle-only cruiser chasing speed
If you love the idea of thumbing a and riding without pedaling, it does that up to 20 mph. Just know that riding on the throttle, especially on climbs, pulls your range down faster, and 20 mph is as fast as the assist will take you.
The pavement-mostly rider
If most of your miles are flat bike paths and smooth city streets, this much motor and torque is far more than you'll ever tap into, and a simpler commuter would save you real money. The Bafang Ultra earns its price on rough terrain, not on errands around town.
Frequently asked
Does the Biktrix Juggernaut Ultra Duo Pro Step-Thru have a throttle?
Yes. It has a , so you can ride without pedaling up to 20 mph, which is also what makes it a e-bike.
Can you ride the Biktrix Juggernaut Ultra Duo Pro Step-Thru without pedaling?
Yes, the throttle moves you along without pedaling up to 20 mph. Leaning on it, especially on climbs, drains the battery faster than riding on .
How far does the Biktrix Juggernaut Ultra Duo Pro Step-Thru go on a charge?
Biktrix estimates up to 55 miles from the . Hard climbing, soft terrain, or heavy throttle use will bring that down, and an optional 910Wh range extender adds more capacity for long days.
How fast does the Biktrix Juggernaut Ultra Duo Pro Step-Thru go?
The motor assists up to 20 mph. Even with on tap, it's capped there as a Class 2 bike.
How much does the Biktrix Juggernaut Ultra Duo Pro Step-Thru weigh?
About 88.5 pounds with the battery installed, which is normal for a fat-tire mid-drive carrying a 1,040Wh pack.
How much weight can the Biktrix Juggernaut Ultra Duo Pro Step-Thru carry?
It's rated up to 380 lb for rider and cargo combined, though one badge lists 330 lb. Either way, there's real headroom for a heavier rider plus gear.
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