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Juggernaut Ultra Duo 4 Step-Thru

Sale price $2,749.00 Regular price$4,499.00
Save $1,750 New

🚨 Get a FREE Range Extender Battery (worth $499) by adding it to your cart and applying the code EXTRA at checkout. Offer for a limited time only.

Our signature mix of comfort and control with the powerhouse Ultra motor

Pearl White
Range Extender Battery

Add an additional battery to extend your bikes range and give you that boost!

**This option adds an extra battery that mounts on top of the frame that doubles the range of the stock battery.
Motor Power

Program your motor to meet local eBike regulations or opt for unlimited speed and power suitable for off-road use only.


Suspension seatposts offer great riding comfort as they absorb many of the imperfections on the road/trail.

***Adding a suspension seatpost to your eBike will increase the minimum seatpost height by 100mm/4" to 150mm/6"

Illuminate your path to adventure with an upgraded eBike headlight, delivering superior visibility and style for night-time riding.

**The price is discounted from the regular price of $300

Enhance your safety and control on every ride by upgrading your eBike brakes.

***Tektro and Magura upgrades come with a brake rotor upgrade from 160mm to 203mm
Rear Hub

Upgrade your eBike's rear hub for a smoother, more efficient ride, unlocking enhanced performance and reliability with every pedal.

Biktrix A-Bars

The swept-back design provides an upright riding position with multiple comfortable hand positions so you can enjoy further and more frequent rides!


Secure your investment by opting for an extended warranty through the BiktrixCare+ plan.

Shipping: Leaves within 6-7 business days
Sale price $2,749.00 Regular price$4,499.00
Lifetime Support
14 Days Return
Custom Built
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Miles Range


Torque For Extreme Hills

52V 17Ah

Strong, Reliable Battery

The Duo Series. Ebikes For Everyone.

The Juggernaut Duo Series is all about flexibility. Hub-drive or mid-drive, step-over or step-thru, single battery or dual battery, entry-level or high-end. No matter your needs, there's probably a Duo for you.

Watch this video to see how The 3 Duo models stack up.

Welcome To The Big Leagues.

The Ultra Duo sits at the top of the Duo range, so naturally, it boasts one of the most powerful motor systems available today. The Bafang Ultra M620 mid-drive motor is loaded with 1500W of peak power and 160Nm of torque. Pair that with the 11-speed drivetrain and you'll be nearly unstoppable.

Ultra Power. Greater Features.

Mid-Drive Motor

The Bafang Ultra M620 mid-drive motor features 1000 watts of power and 160Nm of torque. Span cities, climb hills and explore all the places you want to go with ease.

LCD Display

The LCD display shows all kinds of important information about your ride including speed, battery life, odometer, pedal assist level and more.

Thumb Throttle & Control Pad

With just a push of the thumb, you can access all of the power the motor has to offer. No need to pedal, just sit back and enjoy the ride.

Suspension Fork

The RST Guide spring suspension fork provides 75mm of travel with pre-load and lockout adjustability.


From climbing hills top holding maximum speed on flats, the Shimano Alivio 9 Speed drivetrain has you covered.

Hydraulic Disk Brakes

When it’s so easy to go fast, you need strong stopping power. These hydraulic disc brakes will quickly and reliably bring you to a halt.

Integrated Front Light

This bright LED light is powered by the bike's battery and can be turned on/off with a button on the handlebar control pad.

Optional Range Extender

Multiple range-extender battery options can expand your eBike’s range all the way to 160 kilometres.

Rack & Fenders

These fenders will keep you and your bike clean. Need to carry some gear? Strap on the rear rack and make your way!

Technical Specifications


6061 aluminum

front hub

135mm 36h

seat post



Rst guide w/75mm travel, lockout & preload

front axle

5mm qr

seat post clamp



Threadless 1-1/2" 1-1/8" tapered

rear hub

190mm 36h


1000w bafang ultra m620

shifter rear

Shimano alivio 9 speed trigger

rear axle

5mm qr

battery sizes

Total capacity of 52v 36.5ah 1898wh: 52v 17.5ah 910wh (internal battery) + up to 52v 19ah 988wh (external range extender battery)

rear derailleur

Shimano alivio 9 speed


26" black with round cutouts / 27.5" black solid




9 speed 11-34t cassette

tire sizes

26x4", 27.5x3"


Integrated headlight, integrated taillight


Kmc e9s 124 links


700mm wide, 50mm rise w/31.8mm clamp

assist type

Torque + cadence

crank set

44t chainring w/ 170mm arms


Adjustable stem

assist levels


bottom bracket

Bafang isis


Slide-on comfort grips


Thumb throttle


Biktrix dual piston hydraulic w/180mm rotors


Wide spring supported comfort saddle


Front and rear fenders, kickstand, rear rack

brake levers

Biktrix adjustable w/ integrated brake cutoffs

Size & Fittings

1 Effective Top Tube Length 560mm 22in
2 Seat Tube Length (Classic Bike Size) 420mm 16.5in
3 Reach 520mm 20.5in
4 Stack 500mm 19.7in
5 Chainstay Length 480mm 18.9in
6 Standover Height 430mm 16.9in
7 Head Angle 68° -
8 Seat Angle 71° -
9 Head Tube Length 180 mm 7.1 in
10 Fork Length 530mm 20.9in
11 Front Center 710mm 28in
12 BB (Bottom Bracket) Drop 40mm 1.6in
13 Fork Offset 30mm 1.2in
14 Wheelbase 1240mm 48.8in
15 Total Length 2000mm 78.7in
16 Max Seat Height 1000mm 39.4in
17 Min Seat Height 830mm 32.7in
18 Handlebar Height 1100mm 43.3in
19 Weight (Without Battery) 33.5kg 73.9lb
1 Effective Top Tube Length 560mm 22in
2 Seat Tube Length (Classic Bike Size) 460mm 18.1in
3 Reach 560mm 22in
4 Stack 520mm 20.5in
5 Chainstay Length 520mm 20.5in
6 Standover Height 450mm 17.7in
7 Head Angle 68° -
8 Seat Angle 71° -
9 Head Tube Length 180 mm 7.1 in
10 Fork Length 530mm 20.9in
11 Front Center 730mm 28.7in
12 BB (Bottom Bracket) Drop 50mm 2in
13 Fork Offset 30mm 1.2in
14 Wheelbase 1240mm 48.8in
15 Total Length 2000mm 78.7in
16 Max Seat Height 1000mm 39.4in
17 Min Seat Height 880mm 34.6in
18 Handlebar Height 1160mm 45.7in
19 Weight (Without Battery) 34kg 75lb

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Customer Reviews

Based on 116 reviews
Eldon Konschuh
Eager to setup and ride

Looking forward to a great spring of riding.
Will update you once I have the opportunity to take the bike out of the box.

Charles Reed

It’s sitting pretty
Waiting for spring

Desiree Stephens
Amazing Bike

Love the power. Excellent brakes. It handles sand and rough paths like a dream! And handles city cruising like a sports car. Super powerful! Perfect amount of gears and shifts so smoothly! I have no negatives about this bike

Why did I wait???

I have had the bike about a week and it is everything I wanted it to be! Took it out this weekend twice and was able to ride some big hills around my house that I would never have tried before now. My husband has an older Ultra and is jealous of mine. I’m glad I went with the step through frame, because even though I’m not used to that style, it is so much easier on my 5’3” frame. I was worried about the size because I’m so short, but with the step through it isn’t even a problem. My biggest regret is not getting one two years ago.

Jon Allen
Solid Quality

I own four other e-bikes, and sprung for the Juggernaut Ultra Duo 4. I finally can say that I am happy with an e-bike. The Juggernaut Ultra Duo 4 is the perfect bike for my area. I live in Southwestern PA where we have rolling hills everywhere, and most of the are steep and hard to climb even with an e-bike.

It arrived rather fast, it was packaged well and was easy to assemble. There is really no assembly. Just mount the front wheel and handlebars, that is it. Takes about 30-40 minutes including unpacking. I did a once over to ensure everything was tightened, pumped up the tires and plugged in the batteries. They needed several hours to fully charge. There was a small issue the front brake rotor (disc) that was quilckly replaced by Biktrix. It arrived today and it took about 20 minutes to replace. Now I am ready.

We had a sunny warm day today, so I took it out for a 12 mile break in ride on some seriously steep and long hills. I am 60 years old, 6ft tall, 250 lbs, and partially disabled. These e-bikes give me a certain freedom like no other activity. The Juggernaut Ultra Duo 4 is a serious powerhouse and allows me to navigate any roads or prepared paths that we have around here. I was going up hills with over 26% grade like nothing. And the Dual battery configuration will allow me to do that all day long. My other e-bikes would not make the hills leaving me to walk them partially, and after the same 12 mile ride, the batteries were 50% depleted. The Juggernaut Ultra Duo 4 used only 6% I was amazed that I still had 94% after the ride.

The Juggernaut Ultra Duo 4 is solid and very high quality. It shifts smooth, rides smooth, is very comfortable and it looks great. I had one customization by adding the A-Handlebars for a more swept back ride that allows me to sit fully upright when riding. This is a terrific e-bike that finally fulfills my needs and wishes. I love it and I highly recommend it.

James Wolford
Juggernaut Ultra Duo 4 Step-Thru?

Lots of power. Easy to assemble . So far I haven't put many K on the bike.

Richard Meissner
Love the bike👍😊

Riding the bike with the mid drive is great. I was use to have a hub drive. I can tell I’m going to love this bike.

George Felegy
A lot of ebike

The bike is heavy and fast. It runs and rides like a small electric motorcycle which for me ( a motorcyclist for many years), it is perfect. For a novice ebike rider it may be too much bike to handle. Going from a lightweight regular bike to this might be overwhelming. The weight, wide 3” tires, and raw power is a handful, but an absolute blast if handled properly. I love it.

Quality built bikes and fantastic customer service

Bought the Ultra Duo 4. Its a hill climbing machine.
and the customer service is next to none.
5 star +.