Biktrix Juggernaut Classic Duo ST Review | Burly & Bespoke

To evaluate the Juggernaut’s range, we used the process explained in the graphic above. We achieved the above results using Eco mode and a maximum speed of 20 mph; users riding in Sport mode and/or with Class 3 speeds will likely reduce the bike’s range.

Additionally, our test bike was equipped with the standard single (and honestly, massive) 52V, 910-watt-hour (Wh) battery. As mentioned previously, buyers can upgrade the Juggernaut’s battery capacity by adding a second external power supply (either 884 Wh or 1,092 Wh) to extend the bike’s range.

The Classic Duo ST’s results were above average when compared to other fat-tire e-bikes we tested. At the time of writing, the average minimum and maximum for this category are 32.4 and 57.7 miles. We attribute the bike’s excellent performance primarily to its high-capacity battery; most of the others we compared it to had smaller power packs.

Most of the bikes used for comparison had rear hub motors, which are typically less efficient than mid-drives. In this case, however, it’s likely that the Juggernaut was similarly efficient to a hub drive because of its cadence sensor. Instead of varying its motor output based on rider effort, the Classic Duo’s drive unit was steady and consistent in its power.

Still, it proved surprisingly efficient. Based on the bike’s motor and battery specs, we expected its PAS 5 test would endure for roughly an hour and 15 minutes, yielding approximately 22 miles of range. Its real-world results gave us an additional 14 miles and 45 minutes on the bike.

Our testing took between two hours and 6.5 hours, so we would expect most riders to fall between these numbers (unless riding at higher speeds, in extremely hilly areas, or when carrying a significant amount of cargo), depending on which pedal assist setting they use.

The standard battery’s range potential is functional for a variety of uses, including commuting or leisure riding on paved paths, multi-use trails, and beyond. With the optional secondary 884 Wh battery, we estimate that the bike could reach between 71 and 134 miles—and even further with the larger upgrade option.

Finally, we were pleased to note that the bike ships with a fast 3-amp charger, which can refill the battery in under 6 hours.

The Juggernaut Classic Duo ST performed well in our Hill Test, which is explained in the graphic above. Its results were relatively average for the fat tire category; with averages of 1:21 on throttle power and 1:14 in the pedal test, the Juggernaut differed by only a second in both portions of the test.

These results are deceptive, however, as all but one of the bikes used for comparison had rear hub motors. E-bikes with mid-drives are often slower than those with hub motors, so in truth, the Juggernaut’s results were better than expected. It had a few key advantages that likely contributed to its success.

First, the bike’s 52V electrical system delivers power from the battery to the motor faster than more common 48V motors and batteries. With quicker access to power, the Classic Duo’s motor can do more work, making the job of the rider easier.

Second, the Juggernaut’s motor is more powerful than average with its substantial peak wattage and torque output. Based on previous testing, peak wattage seems to be a greater factor in the throttle test, while torque influences the pedal test to a higher degree.

Third, as mentioned previously, the bike’s motor output is constant thanks to its cadence sensor. As long as the pedals turn, its motor generates maximum power when climbing hills.

In our experience, e-bikes with mid-drives and throttles are fairly uncommon, but they have a distinct advantage over bikes with hub motors. With the drive unit placed at the bottom bracket, e-bikes like the Juggernaut can take advantage of the drivetrain’s gearing ratios for improved efficiency. We found 4th gear to be a good starting point.

To demonstrate the small differences between Eco and Sport modes, we tested the bike using both power levels in two locations. First, at our main test location, Hell Hole, and also at a secondary environment nearer to our office, called Pilot Hill.

Both modes were almost equally effective, with similar power levels shown by their results. When comparing pedal test results from Hell Hole, Sport mode proved roughly five seconds and one mph faster. At Pilot Hill, I measured a difference of six seconds and 1.2 mph. With the throttle, there was only one second of difference in both cases.

Our results show that the Juggernaut Classic Duo ST can handle extreme hills with relative easy. Riders have the option to throttle or pedal, though when pedaling, only light effort is required due to the bike’s mid-drive/cadence sensor combo.

The standard version of the Juggernaut Classic Duo is equipped with Tektro HD-E350 hydraulic disc brakes with 2-piston calipers and 180mm rotors. Using the process explained above, we determined its average stopping distance to be 24’5”.

I thought the brakes felt fine while I was riding the bike, but this test score is longer than we had hoped to see. For comparison, the average for the fat tire category at the time of writing is 22’6”, making the Classic Duo nearly two feet beyond the average.

When evaluating previous e-bikes, we have tested this brake system on a wide range of e-bikes of various styles and weights. At 73 lbs, the Classic Duo ST is on the lighter side for a fat tire bike, but it’s still relatively heavy in general. In our experience, the Tektro E350 system seems to work best on light-to-mid-weight e-bikes, so it struggled somewhat here.

Buyers can upgrade to a four-piston Magura MT5 system when purchasing the bike. Based on previous testing of this model, we expect it would perform better than the standard brakes. Regardless, we recommend that Biktrix upgrade the standard spec level with a more effective brake system, especially considering the higher speeds in Class 3 mode.

That aside, we appreciated the Juggernaut’s stable feel when braking. It could fishtail when braking hard, but not to an unusual or unsafe degree; the bike always felt under control.

Ride Quality is a broad subject with many smaller aspects, including comfort, sizing and fit, handling, motor engagement, and user interface. Together, these elements determine how a bike feels to ride and operate. We found many things to appreciate about the Juggernaut Classic Duo ST’s ride quality, but also a few significant areas with room for improvement.

The bike is offered in two sizes: a Medium for riders 5’4”+ and a Large for those 5’8”+. At 5’11”, I was pleasantly surprised at how comfortable the medium frame of our test bike was; with a relatively stretched and aggressive riding position, I would have guessed we had the larger model.

The bike’s contact points (saddle, grips, and pedals) were extremely comfortable. Our test bike was standard, aside from its color (a raspberry-like purple hue) and TranzX suspension seatpost. I am confident I would have liked the standard saddle without the upgraded seatpost, but I highly recommend one of the three suspension options for a smoother ride.

Handling is one of the primary areas we hope Biktrix will improve. We appreciated the Duo ST’s relatively nimble handling—a result of its 24” wheels—compared to many other fat bikes with larger 26” wheels. But the step-thru frame had a lot of flex when cornering, creating a loose feeling on faster turns that was not helped by its soft suspension fork.

It is possible that the standard RST Guide suspension fork on our test bike was a dud, but we recommend that Biktrix upgrade to a sturdier base model.

It’s also fair to point out these problems aren’t unique here – they are true of most fat tire e-bikes with step-thru frame. That’s why ST models are often best suited for paved areas instead of lots of off-roading or quick cornering.

Critique aside, we liked the motor’s quick engagement; it delivered power immediately without overrun. We also appreciated the near-effortless nature of the bike’s pedal experience, but we also recognize that many riders seeking a mid-drive will expect the more natural and adaptive feel of a torque sensor.

Fortunately, for those seeking such an experience, Biktrix offers a higher-end model of the Juggernaut with a 1,000W mid-drive and a torque sensor: the Juggernaut Ultra.

Less ideal is that shoppers will need to sift through a myriad of similar models to find the one they want; we counted 28 models with various frames, motor types, suspension options, etc. We appreciate customization options and variety, but we urge Biktrix to consolidate its catalog of options to be less confusing and more user-friendly.

We found the bike’s interface to be easy to use. You can adjust speed (or other) settings with a double press of the “i” button or switch between riding modes by holding the “+” button. The Juggernaut has one of my personal favorite control panels, with easy-to-press buttons and a very tactile feel.

The Juggernaut Classic Duo ST’s strengths are its comfort, easy pedaling, and powerful/aggressive feel, though it also has room for improvement.

We think the Juggernaut Classic Duo ST will likely appeal to younger riders seeking the thrills of high power and fast speeds or older riders wanting stability and an easy pedal experience with an accessible frame. Additionally, when outfitted with the right components, we expect it will make a rugged off-road adventure bike.

The Juggernaut performed well in most areas of our testing. It features intuitive speed profiles in both Class 2 and Class 3 modes. It had excellent range potential with a single battery and the option to increase battery capacity and mileage further. Finally, it made short work of hills thanks to its powerful motor and cadence sensor.

Personally, I enjoyed the bike’s comfortable, powerful feel, but there are a handful of areas we hope to see improvement in. The current setup is functional, but we’d also welcome a stiffer frame and upgrade the standard brakes and suspension fork. We also encourage rebalancing or consolidating the two riding modes.

Fortunately, some of these concerns can be alleviated with upgrades at purchase; the range of available customization options is tremendous! Biktrix offers models and options starting around $2k and extending beyond $8k (at the time of writing), so there’s likely a model to meet your needs and budget.

Happy Riding! In the comments section below, make sure to let us know if you have any questions or if you think we left anything out in this review of the Biktrix Juggernaut Classic Duo ST.