New DJI bike: New ROTWILD R.EX...

With the new ROTWILD R.EX ULTRA, the German bike manufacturer is launching its first eMTB with a DJI motor. At its core is the Avinox M1 drive unit, which delivers 105 Nm of torque and draws its power from the removable 864 Wh battery. Combined with 160/150 mm of travel (front/rear) and a mullet setup, the bike is designed to shine as a sporty trail machine. But how does it actually perform on the trail?

Six months. That’s all ROTWILD needed to turn an idea into a finished eMTB. The result is the R.EX ULTRA,the first production bike to feature the DJI Avinox M1 motor and a specially developed, removable 864 Wh battery. This combination has never been seen before. With 160/150 mm of travel (front/rear) and a mullet wheel configuration, the bike is clearly aimed at ambitious trail riders. The 23.32 kg weight in size L is a promising figure. The € 12,490 price tag for the ULTRA spec we tested, however, is a serious chunk of money. So, does the ROTWILD R.EX 900 ULTRA live up to its price? And how does it ride on the trail?

The ROTWILD R.EX ULTRA in detail

The ROTWILD R.EX ULTRA features a full carbon frame with an aluminium rocker link. Visually, it scores with clean, well-balanced proportions, where the top tube and seat stays align in a single flowing line, ensuring a noticeably slim downtube. Our pre-production test bike still had a yellow logo on the down tube, which will be toned down for the production version, along with the grey stripes.

One striking detail is the elevated swingarm at the rear, which ROTWILD call the “Elevated Box Design,” first introduced on the R.EXC ULTRA. This element doesn’t just shape the bike’s silhouette – it’s a key part of the mid-high-pivot rear suspension design. The raised and more forward main pivot is designed to combine the strengths of a traditional four-bar linkage with those of a high-pivot layout. The goal is a responsive, sensitive suspension feel with efficient pedalling performance, without the usual drawbacks like drastic chainstay length changes under compression or excessive anti-rise values.

The generously sized chainstay protector also doubles as a chain guide. On our test bike, it was still made of plastic and made quite a bit of noise on the trail. The production version is expected to significantly reduce chain slap and noise while also protecting the frame. The cable routing is well thought-out, with all lines either running directly to their destination or neatly tucked into the frame behind the head tube through bolted cable ports. A practical touch: there’s a tool mount under the top tube with space for a multitool, spare tube or CO2 cartridge.

The spec of the ROTWILD R.EX ULTRA

At the heart of the ROTWILD R.EX ULTRA is the DJI Avinox M1 motor, delivering 105 Nm of torque, with short bursts of up to 120 Nm in Boost mode. Thanks to the latest software update, the full 1,000 watts of peak power are now available continuously in Turbo mode. The motor draws its power from an 864 Wh battery, which was developed in-house by ROTWILD. Weighing around 3,600 g, the battery uses 21700 cells and is based on existing tech from ROTWILD’s portfolio.

To ensure compatibility with the DJI Avinox motor system in the R.EX ULTRA, the battery’s cell voltage was specially adapted. A quick-release button on the side of the downtube allows the battery to be removed with ease. A nice touch: the battery cover is attached directly to the battery itself, which gives the bike a clean, integrated look– though the large release button stands out visually.

Charging is done via ROTWILD’s own 7-amp charger. Unlike DJI’s 12A fast charger, this one doesn’t support quick charging. According to ROTWILD, there simply wasn’t enough time before the bike’s release to develop a fast charger in-house. The charge port is located in the motor area and protected by a magnetic cover. However, the cover is fully removable, which also makes it easy to misplace. The motor system is controlled via DJI’s familiar handlebar remotes, while an integrated touchscreen in the toptube displays all ride data and also features a practical USB-C charging port.

For the suspension, ROTWILD reached into FOX’s premium line-up. Up front, the new FOX 36 FLOAT Factory fork with GRIP X cartridge generates 160 mm of travel, while at the rear, a FOX FLOAT X Factory controls 150 mm of travel. Both components offer a wide range of adjustments and deliver a strong performance on the trail. However, the fork makes a slight slurping sound on rebound – a known issue with this damper.

Shifting is taken care of by an electronical SRAM XO Eagle AXS Transmission drivetrain, which delivers crisp, reliable gear changes even under load. Braking power comes from SRAM’s MAVEN Silver four-piston brakes, with 200 mm rotors front and rear, providing powerful, reliable deceleration. The new EightPins NGS 3.0 dropper post has 210 mm of travel, ensuring plenty of freedom of movement. It’s directly mounted to the frame without a traditional seat clamp, which means that it’s not possible to fit alternative seatposts to the R.EX ULTRA.

The R.EX ULTRA. rolls on a Crankbrothers Synthesis Enduro carbon wheelset in a mullet configuration – 29-inch up front, 27.5-inch at the rear. It comes fitted with Schwalbe Albert tires in the Trail casing and soft rubber compound at both ends. Riders who frequently tackle rough or wet trails may want to upgrade to a Magic Mary up front in the Ultra Soft compound for added grip and control.

Other spec options for the ROTWILD R.EX

Alongside the top-end ULTRA model we tested, ROTWILD also offer two additional builds for the R.EX 900. All versions come in the eye-catching “bloodfin red” paint finish and share the same carbon frame and DJI Avinox motor.

The R.EX PRO retails at € 9,990 and, according to the manufacturer, weighs 22.1 kg. Up front, it features a RockShox Lyrik Select+ fork with the Charger 3.1 damper, paired with a RockShox Super Deluxe Select+ shock at the rear. Shifting is taken care of by an electronic SRAM GX Eagle AXS Transmission drivetrain, while powerful SRAM MAVEN Bronze brakes do stopping duties. The bike rolls on a durable Crankbrothers Synthesis Enduro aluminium wheelset. (Image does not show the final spec.)

The € 8,990 ROTWILD R.EX CORE is the entry-level model, and tips the scales at 22.4 kg according to the manufacturer. It features a FOX 36 FLOAT Performance fork with a GRIP damper, while a FOX FLOAT X Performance shock handles the rough stuff at the rear. Braking is taken care of by MAGURA MT5 brakes, whilegear changes are managed by the reliable mechanical Shimano XT 8100 drivetrain. Like the PRO model, the CORE rolls on a Crankbrothers Synthesis Enduro aluminium wheelset.

All build variants come fitted with a tire setup consisting of Schwalbe Albert tyres in the Trail casing with a soft rubber compound at both ends. For riders tackling particularly rough terrain, upgrading to the Gravity casing on the rear adds extra pinch-flat protection, while an Ultra Soft compound up front boosts grip and control.

The geometry of the ROTWILD R.EX ULTRA

The ROTWILD R.EX 900 ULTRA is available in three sizes: M, L and XL. ROTWILD deliberately left out a size S. With a reach of 487 mm in size L, the bike sits firmly on the longer side of the spectrum, and in general, all sizes are quite stretched out – making things trickier for shorter riders. If you want to tweak the reach or head angle, you can do so easily thanks to the modular Acros headset system with adjustable reach cups. These allow for adjustments of ±5 mm in reach and ±0.5° in head angle.
At 439 mm, the chainstays are relatively short and paired with a slack 64° head angle and a steep 78° seat angle.

Fast and focused – the ROTWILD R.EX ULTRA on the trail

From the very first pedal strokes, the ROTWILD R.EX ULTRA makes you feel at ease from the get go. The pedalling position is comfortable, giving you a well-balanced, integrated feel on the bike – not too stretched out, not too upright either. The suspension setup leans on the firmer side. Still, it does a great job of soaking up smaller hits with sensitivity, while offering enough support to carry serious speed on the trail.

Uphill, the ROTWILD is plenty of fun. The steep seat angle puts you in a central, efficient position over the bottom bracket, and the DJI Avinox M1 motor offers strong support,even at low cadences,making it easy to power through technical sections and big steps. The rear suspension keeps traction high throughout. The front wheel remains planted on steep climbs, although when it gets really steep, you’ll need to actively shift your weight forward to keep it tracking. One small drawback: the Schwalbe Albert tires struggle for grip on loose and wet ground. If you often ride in steep terrain, it’s worth considering a more aggressive rubber compound.

When the trail points downhill, the intuitive handling makes it easy to ride actively. You can rip through tight berms and corners at pace, and the R.EX ULTRA’s agility really comes into its own, delivering a fun and lively ride. The suspension setup is on the firmer side but still smooths out smaller bumps effectively. Push things too hard, though, and you’ll start to find the bike’s limits. At high speeds through rock gardens, it can get a bit unsettled, and you may need to dial things back slightly. The R.EX ULTRA stays manageable, but it demands deliberate line choices and rider input in rough terrain.

Who should take a closer look at the ROTWILD R.EX ULTRA?

The ROTWILD R.EX ULTRA is right at home on varied trail loops– whether you’re tackling technical climbs, flowing descents or moderately rough terrain. It’s aimed at sporty e-mountainbikers looking for a lively, efficient climber with a solid, well-rounded spec. That said, if you blast through rock gardens at full throttle on a regular basis and value maximum composure above all else, you might want to look elsewhere. The bike is expected to be available from September or October.

Conclusions about the ROTWILD R.EX ULTRA

The ROTWILD R.EX ULTRA feels agile on the descents, quickly builds speed and climbs confidently thanks to the excellent traction. The big, removable battery and the powerful yet finely tuned DJI Avinox motor are standout features both on the trail and in everyday use. Sure, it lacks a bit of composure for full-on charging through really rough terrain, but if you’re okay with that – and have the budget to match – you’ll be getting a modern, versatile e-MTB that delivers in all the right places.

For more info, head to rotwild.com.

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Words: Benedikt Schmidt Photos: Peter Walker