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Juggernaut Ultra Duo 3 Step-Over

Sale price $2,799.00 Regular price$4,699.00
Save $1,900

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

Still Interested in the Juggernaut Ultra Duo Step-Over? Check out the Juggernaut Ultra Duo Step-Over 2 below!

Juggernaut Ultra Duo 2 Step-Over
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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.

Performance. Fully Loaded.

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 Renegade coil spring fork provides 100mm of travel with pre-load and lockout adjustability


From climbing hills to holding maximum speed on the flats, the SRAM NX 11-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 100 miles.

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

150mm 36h

seat post

Aluminum 28.6mm


Rst renegade coil spring w/100mm travel, lockout & preload

front axle

15mm qr-thru axle

seat post clamp



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

rear hub

190mm 36h


Bafang m620 ultra

shifter rear

Sram 11 speed trigger shifter

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

Sram nx 11 speed


Black 24", 26", 27.5" 36h




11 speed sram 11-42t cassette

tire sizes

24x4", 26x4", 27.5x3"


Integrated headlight, taillight


Kmc e11s


650mm wide mtb w/30mm rise, 31.8mm clamp

assist type

Torque + cadence

crank set

44t 170mm arms


90mm adjustable

assist levels


bottom bracket

Bafang isis


Slide-on comfort grips


Thumb throttle


Biktrix dual piston hydraulic w/ 180mm rotors


Biktrix spring supported comfy cruiser


Front and rear metal fenders, rear rack, kickstand

brake levers

Biktrix w/ adjustable reach and motorcutoffs

rear suspension

N/a (l | 19" so)/none (l | 19" st)/none (m | 17" so)/none (m | 17" st)

Size & Fittings

1 Effective Top Tube Length 590mm 23.2in
2 Seat Tube Length (Classic Bike Size) 470mm 18.5in
3 Reach 440mm 17.3in
4 Stack 660mm 26in
5 Chainstay Length 510mm 20.1in
6 Standover Height 730mm 28.7in
7 Head Angle 70° -
8 Seat Angle 73° -
9 Head Tube Length 180 mm 7.1 in
10 Fork Length 540mm 21.3in
11 Front Center 730mm 28.7in
12 BB (Bottom Bracket) Drop 60mm 2.4in
13 Fork Offset 40mm 1.6in
14 Wheelbase 1230mm 48.4in
15 Total Length 2000mm 78.7in
16 Max Seat Height 1050mm 41.3in
17 Min Seat Height 880mm 34.6in
18 Handlebar Height 1140mm 44.9in
19 Weight (Without Battery) 35kg 77.2lb
1 Effective Top Tube Length 540mm 21.3in
2 Seat Tube Length (Classic Bike Size) 460mm 18.1in
3 Reach 500mm 19.7in
4 Stack 540mm 21.3in
5 Chainstay Length 520mm 20.5in
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 540mm 21.3in
11 Front Center 730mm 28.7in
12 BB (Bottom Bracket) Drop 50mm 2in
13 Fork Offset 40mm 1.6in
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 1100mm 43.3in
19 Weight (Without Battery) 35kg 77.2lb
1 Effective Top Tube Length 590mm 23.2in
2 Seat Tube Length (Classic Bike Size) 420mm 16.5in
3 Reach 440mm 17.3in
4 Stack 660mm 26in
5 Chainstay Length 500mm 19.7in
6 Standover Height 690mm 27.2in
7 Head Angle 70° -
8 Seat Angle 73° -
9 Head Tube Length 180 mm 7.1 in
10 Fork Length 540mm 21.3in
11 Front Center 720mm 28.3in
12 BB (Bottom Bracket) Drop 60mm 2.4in
13 Fork Offset 40mm 1.6in
14 Wheelbase 1230mm 48.4in
15 Total Length 2000mm 78.7in
16 Max Seat Height 1000mm 39.4in
17 Min Seat Height 830mm 32.7in
18 Handlebar Height 1120mm 44.1in
19 Weight (Without Battery) 34kg 75lb
1 Effective Top Tube Length 580mm 22.8in
2 Seat Tube Length (Classic Bike Size) 420mm 16.5in
3 Reach 580mm 22.8in
4 Stack 490mm 19.3in
5 Chainstay Length 480mm 18.9in
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 540mm 21.3in
11 Front Center 710mm 28in
12 BB (Bottom Bracket) Drop 40mm 1.6in
13 Fork Offset 40mm 1.6in
14 Wheelbase 1240mm 48.8in
15 Total Length 1960mm 77.2in
16 Max Seat Height 1000mm 39.4in
17 Min Seat Height 830mm 32.7in
18 Handlebar Height 1160mm 45.7in
19 Weight (Without Battery) 34kg 75lb

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Customer Reviews

Based on 70 reviews
leonard Cervo
Ultra duo 3

Received e-bike, very easy to finish set up of bike. Already been on two rides

mark steiner
Wonderfully capable EBike

II am 66 years old. have had my UD3 for about 4 months now. In that short timeframe I have logged over 2500 miles on it. Riding It is so much fun that hasn't been hard to do. It is in charge and it gets noticed. I ride it on roads, trails and in the woods. This bike cannot be stopped, I and have yet to see another bike that can outperform it at any price. It will climb just about anything, as long as you can stay in the saddle! It is a big powerful bike that might take a little getting used to at first due to the sheer size and weight of it. But it is precisely the size, weight and power of this bike that make it such so exceptional and comfortable. You will ride with complete confidence in your newfound "partner" and it will not let you down. Get the extra battery (you will not want to get off this bike) and the Magura brake upgrade and it is even better! It has opened up a whole new world, conquering terrain a lesser bike could not dream of tackling It is worth every cent I paid for it. It is superb. As for the people who work for Biktrix, they are second to none.

Donald Martin
Juggernaut Ultra Duo 3

They say to save the box just in case. Well guess what, they never getting this thing back. It's mine now! I did a good amount of research beforehand and although I was a little skeptical because of the price and a couple of bad facebook reviews, I could not be happier with my decision to go with Biktrix. Customer service sent out a replacement front brake rotor that was damaged during shipping and I had it in my hands two days later. Canada to Louisiana in just two days! The bike rides like the wind and everything about it is high quality. I can comfortably recommend this bike and company with confidence. And yes, I'll be discarding the box.

mark steiner
The Freedom of a fat tire Ebike

I have owned the UD3 for several months now and riding season is just getting started. A fat tire Ebike is the way to go for anyone, because of its versatility. It can be a little difficult to load and unload due to its size and weight, but they make tilting bike racks that easily overcome that.

The bike is a joy to ride both on the road and on trails. But off-road it where it really shines. It is such a blast to ride. Provided you can stay on the bike, it will conquer any hill you can imagine.

i researched Ebikes heavily before deciding on this bike. I compared the components, specs and price to dozens of other Ebike manufacturers, as well as the reputation of the company's customer service. The process took a while but I made the right choice. Other big name bikes that have the EXACT same specs and components are selling bikes for twice what a Biktrix bike will cost you. Don't be fooled by those big names.

Also Biktrix customer service is phenomenal.

So glad I got this bike. But enough of the boring testimony from me, I gotta go for a ride!

Robert H.
Biketrix Juggernaut Ultra Duo 3 First impressions

The bike is really heavy. With the standard battery it weighs in at about 80#. The chocolate brown color is more purple than brown. I’ve had 3 people tell me they like the purple color, so it’s not just me. I don’t dislike it, but it’s not what I expected.
The bike came near fully assembled, so basically, I only needed to attach the handlebars, front fender & light, and the front wheel. The rear tire was flat and had a hole in the tube from shipping, so I took it to a local shop and had it repaired. Also had them put some sealant in it. Aside from that, everything worked fine.
The frame is larger than I expected. I’m 5’9” with 30” inseam and the stand over height is almost too tall. If you're shorter than me, you'll want the step through version, or a shorter frame.
The bike rides great & I love the way it shifts through the gears. First ride I went 14 miles in eco mode PAS 5 and the battery indicated I had 82% left. The motor is reasonably quiet and has a LOT of power! It will cruise comfortably 25-26 mph in high gear. (I don't normally ride that fast...just wanted to try it out. )
I did manage to get a bunch of thorns in both tires. The rear tire with sealant was ok, but I had to take the front to the shop for repair and add sealant. The tires have good tread, but the casing seems kind of thin. I was going to go ahead and replace them, but discovered the 27.5 x 3 tire is an oddball size, and no one in Tulsa stocks that size tube or tire. They're also not listed on Biketrix’s website as a replacement part.
The handlebar grips were not very comfortable, so I replaced them with a pair of silicone grips.
I’m at about 50 miles now, and so far very pleased with bike. I do plan to have Biketrix update the program so the throttle works as a variable speed rather than just off and on, however I find I don't actually use it very much.
Stay tuned…I will update this after I get a few more miles on it.

Tyrell Hering

Juggernaut Ultra Duo 3 Step-Over

Richard Dickerson
Juggernaut Ultra Duo 3 Step-Over Review

For this review I will cover 3 things
The bike itself
The range extender
The pannier bags

The bike itself is great, although it's so heavy it feels like a tank.
I am a big guy and weigh approx 340lbs so I needed a bike that handles my weight. The Jugg Ultra duo 3 easily handles this. Once you are mounted it feels like a normal bike and handles well. I have to 4" fat tires, which are new to me, but make gravel roads a piece of cake. I do wish there was an option on the Biktrix shopping site that optionally includes something like tuff-liners to be added before the tubes are put in. Or maybe a tubeless option. As it is the tires are vunerable to flats.
Assisted peddling and a throttle are new to me, and boy it is awesome. You can feel the endorfins without being exhausted too. I like that. My biggest wish is for an option to have a bigger front crank. I find that when using the smallest gear and the high-end of my cadence the speed tops out about 20 mph. I would really like to go faster than 20 without having to peddle like crazy. I'm used to many gears from my other bikes. There isn't much I would change on the bike but this is definitely one of them.
I found I like a peddle assist of 3 being the most comfortable, spoiled already.
From my limited riding, I love the bike. It truly does open up the world to you.

The bike rack is a heavy thing, the bars seem thicker than another one I have on my recumbant, my old paniers (from a different bike) do not fit well due to the bar diameter. I did spend $100 on the offered panniers. I am sorry I bought them. The mounting depends on straps only and that is a big disappointment. You need top hooks over the bars and a lower hook for the bottom to make them solidly mounted. Hand tightened straps are never solid and will work loose. I don't like that. If I was smart I would have looked for other alternatives.

More options I wish for:
A mirror would be great.
A cell phone holder would be nice...maybe not viable due to so many variations.

Canecreek Thudbuster seat post
I spent another $150 on short-travel seat post. I really, really regret that. That is because the seat attachment assembly is a poor design. It's insane for one person to reassemble if it ever comes apart. New bikes always involve at least 100 seat adjustments to get dialed in to max comfort. Between height, tilt, forward or back rail adjustments, it takes a while to get right. Unfortunately, the assembly is finicky and the whole thing (my entire weight) depends on the robustness of a single bolt that is not big enough for the job. Plus you have to torque the crap out of it to keep it from rotating, there are no friction guards (teeth) to keep that from happening. So when going down the road at 20 or so and with a little uneven terrain, bounces will almost certainly rotate the seat tilt out of position. You can readjust in the field, but not well so your ride is compromised. (you can't really get the torque you need from a portable multi-hex tool). The normal seat post (thankfully was shipped with the bike) has a much better design. A bigger bolt and small gear teeth that mesh together to prevent tilting. Easier to slide forward or backward on the seat rails so you can position as good as can be had. So the Thudbuster is a bust for me.

Range Extender
For me, the range extender is essential. With my weight I need the extra juice for range. I don't know what my max range is but it's a lot less than 100 miles. It is a variable depending how much I use the throttle and peddle assist level. I would hope for 50 miles but I'm pretty sure it's closer to 40. That being said, I have no regrets using the throttle or higher assist. It's just way too much fun.

With the exceptions mentioned above, I have no regrets purchasing this bike and plan to put a great many miles on it.

Jeff Hennessee
Great bike

Really enjoying my first e-bike, the Juggernaut Ultra Duo 3. Very well built bike. Only have 15 miles on it but looking forward to putting many more on it. No complaints at this point.

Rick S
Great Bike - Quality and Power More Than Expected

Bike assembly was straight forward. Good customer support on a few newby questions. Exceeded expectations. Would definitely recommend