Jupiter Defiant Review | An Out of This World Folding Bike?

In our Range Test, our goal was to find out how far a single battery charge could fuel the Defiant’s 750W motor. We tested the bike by riding on our local network of shared-use paths until its battery was drained, once using PAS 5 and again using PAS 1. Our test riders traveled 20.4 and 52.2 miles, respectively, showing a realistic minimum and maximum range for the bike.

Jupiter advertises 20-40 miles of range from the Defiant’s 48V, 499-Wh battery. Our test results show these estimates to be realistic, with some potential to exceed the high end under the right conditions.

Compared to similar folding e-bikes we’ve tested, however, the Defiant’s results are somewhat low; a group of comparable models averaged 30.7 and 63.5 miles in their tests.

There are two obvious reasons why Jupiter’s folding e-bike fell below the averages.

First, the bike’s 499-Wh battery is smaller than average next to the 667-Wh average among similar models in our comparison group. To put it simply, less capacity typically means less range.

Second, the Defiant’s motor (which is similar in power to most of its competitors) is paired with a cadence sensor, while many bikes in our comparison group were equipped with more efficient torque sensors. Instead of variable output that fluctuates in response to the rider’s pedaling, the Defiant’s motor output is steady and constant as long as the bike’s cranks are turning.

It’s worth noting that we performed our testing in the bike’s default Class 2 settings where pedal assist is limited to 20 mph. Users who choose to raise the bike’s maximum speed above that limit should expect a single battery charge to yield fewer miles.

Still, we expect the Defiant’s range to be serviceable for most riders. Many that we interact with take relatively short rides of around 10 miles, meaning that a single charge should last for a couple of rides. Those comfortable with riding below the bike’s maximum speed and saving the highest power levels for hills should be able to get more from a single charge.

When the battery does need refueled, the included 2-amp charger can power up the Defiant’s 10.4 amp-hour battery in around 5 hours.

As I hinted at in the introduction to this review, the Jupiter Defiant proved to be a heck of a hill climber! We tested the bike using the method explained above, and recorded a throttle result of 1:51 at 16.3 mph and a PAS 5 (pedal) time of 1:42 at 17.8 mph.

Both results were faster than average; similar folding e-bikes we’ve tested averaged 1:56 using their throttles and 1:54 in their highest pedal assist settings. In comparison, the Defiant’s throttle test was marginally faster, while its pedal result was significantly quicker than most of its competitors.

The Defiant’s 750W nominal motor can produce up to 1130W of peak power and 80 Nm of torque. The motor’s peak output in watts is below the average peak of 1210W when compared to similar bikes we’ve tested, while its torque output falls in line with the average of 79 Nm. The Defiant’s low weight (59 lbs, compared to the average of 72 lbs) was enough to make up for the difference in power—and then some.

My personal experience coincides well with our test results and analysis; at our secondary test location, called Pilot Hill, the Defiant throttled quickly up the slope. When pedaling, I had to apply only minimal effort to reach the top, resulting in a quick climbing experience that was faster and nearly as easy as my throttle trip.

I encountered one area of the Defiant with room for improvement when testing the bike at Pilot Hill—the powerful motor surged above the bike’s 20 mph speed limit both when throttling and pedaling to the top. While I appreciated the boost in climbing power, I’d prefer that it kept to its programmed limit for the sake of safety and legality.

Aside from that point of critique, the Defiant’s ability to conquer hills makes it well-suited for heavier riders and those who live in areas with drastic changes in topography. The bike’s low weight and powerful motor proved a winning combination that should allow riders to throttle effortlessly or pedal casually over most hills.

After taking the Jupiter Defiant through three test runs using the process explained above, we calculated its average stopping distance to be 24’ 8”. While still within the zone we consider to be safe, this test score is significantly longer than average when compared with a group of similar models, including many of the best folding e-bikes we’ve tested.

In contrast with most of its competition, the Defiant is equipped with mechanical disc brakes with 160mm front and rear rotors. Many similar models we’ve tested relied on hydraulic disc brake systems with larger 180mm rotors, which were more effective at dissipating heat, provided better overall stopping power, and required less grip strength to apply.

I found the Defiant’s longer-than-average stopping distance to be noticeable during my time on the bike, though I encountered only one instance where this quality of the bike could have been problematic. Even in that instance, a hard grab on the brake levers was enough to bring the bike to a stop safely.

Still, considering the Defiant’s price point between $1,500 and $2,000, we suggest that Jupiter upgrade to a hydraulic disc brake system in the future. The increased stopping power and easier application of the brakes would add value to the bike while also making it safer and more user-friendly.

As it is, we recommend that users give themselves a generous amount of distance when braking, and we encourage new riders to practice with the mechanical brake system so as to understand its capabilities and limitations.

Ride quality encompasses many aspects of a bike, including its sizing and fit, comfort level, motor engagement, user interface, etc. The Jupiter Defiant’s ride quality was good overall, though these individual elements are worth exploring and explaining in more detail.

Though Jupiter does not advertise a recommended height range for the bike, our contact advised us that it is designed to fit riders from 5’ 0” to 6’ 2”. At 5’ 11”, this places me near the top end of its range, which makes sense based on its adjustability range.

The Defiant offers a moderate 8” of saddle height adjustment in its seatpost length and a generous 5.5” of handlebar height adjustment via its telescoping stem. I set the seatpost relatively high and the handlebars roughly in the middle of its height range to balance comfort and steering control—handling typically feels more sensitive with taller handlebars.

Thanks to the bike’s cadence sensor, maximizing leg extension isn’t necessary; even though I had a noticeable bend at the knee, I felt no strain since I kept only light pressure on the pedals.

I found the Defiant comfortable due to its dual-spring saddle, slightly curved, ergonomic handlebars, and rubber grips. The grips, while entry level, were supportive. The plush saddle was a standout for our entire team of testers, as it helped to smooth bumps and absorb vibrations while feeling soft and supportive.

With its aluminum frame and fork, the Defiant has no suspension, so the bike’s seat and 20×4” knobby tires are essential for ride comfort. In addition to the aforementioned saddle, the bike’s tires can be used with relatively low pressure to add cushioning and increase traction; I found the bike stable and well-suited for light off-roading.

The Defiant’s handling was both crisp and quick; its 20” wheels make it highly maneuverable while its rigid fork ensures a stable and predictable feel while cornering. Riders with relatively large feet may need to be mindful of their foot placement when pedaling; with US men’s size 12 shoes, I found my heel striking the bike’s kickstand or the cable guides on its chain stay if I wasn’t careful.

As referenced in previous sections, the motor is powerful and engages quickly. The Defiant’s five speeds, as dictated by its PAS, allow users of different experience and comfort levels to find a suitable pace, though personally, I wouldn’t mind seeing the same limits applied to the throttle for easier speed control.

Its operation is relatively simple, with an entry-level 7-speed drivetrain operated by an over-the-bar thumb shifter on the right handlebar next to a half-twist throttle, a basic black-and-white display, and a small button pad on the left handlebar. This quality makes the bike a solid choice for new riders seeking their first e-bike or riders who haven’t been on a bike in years.

In terms of features and accessories, the bike includes fenders and an integrated 4-LED headlight, though we also hoped to see an integrated tail light with brake light functionality. To expand the bike’s utility and comfort, it can also be equipped with a handful of optional accessories, including a cargo rack, a suspension seatpost, side mirrors, and more.

In terms of folding, the Defiant features a common design that includes a hinged frame, folding pedals, and a telescoping/collapsible stem. The central hinge on our test bike was somewhat stiff on arrival, but worked well after we added some lubricant. We found the folded dimensions Jupiter advertises to be generally accurate; our bike measured roughly 38.5”L x 21”W x 27”H.

All in all, the Defiant is generally comfortable, uncomplicated, and easy to use. While it has some areas with room for improvement, its overall ride quality is a solid foundation to build on.

Folding e-bikes offer their users freedom. For those in cramped living spaces, their collapsible frames can be stashed in inconspicuous nooks. They offer a portable ride to owners without trucks or the ability to carry a hitch rack. Additionally, they can provide a quality of life upgrade to RV enthusiasts who seek a compact, maneuverable way to get around campgrounds or new cities.

The Jupiter Defiant proved to be a fun, capable folding e-bike with a generally comfortable ride and easy operation. It scored well in most areas of our testing, with balanced and intuitive programming, respectable and practical range for its specs, and effective power for intimidating uphill climbs.

Our testing highlighted a few areas with room for improvement, with the Defiant’s brake system, speed limitations, and integrated lighting being those we consider most important. An upgrade to hydraulic brakes would likely elevate the bike’s stopping ability to more closely match that of its peers. Stricter programming limitations would prevent unexpected surges in speed. Finally, an integrated tail/brake light would improve safety and visibility.

Otherwise, we liked the bike’s overall simplicity, its crisp handling, and its comfortable ride. It performed well both on paved paths and dirt/gravel roads, giving riders the versatility to explore a variety of environments. Additionally, its relatively low weight and compact size makes it a practical choice for those seeking a powerful yet portable folding bike for travel or tight spaces.

Happy Riding! Make sure to let us know if you have any questions or if you think we left anything out in this review of the Jupiter Defiant down in our comments section.