Flux Primo: Electric Dirt Breakthrough? or Engineering Risk?
- Paul Roberts
- Sep 15
- 5 min read
Just when we thought we’d seen it all in e-dirt bikes, Flux Moto is making a game-changing promise. The Primo isn’t just another battery and motor slapped into a dirt chassis — it’s a deliberate exercise in engineering choices most manufacturers might avoid.
Equipped with a 14,500 rpm featherweight motor, a two-stage straight-cut transmission, and a virtual clutch lever for precise rider control — not to mention fully adjustable ride maps via their app — the promise is sharper handling, more nuanced control, and a riding experience unlike anything else on the market. The downside? More complexity, more electronics, and more systems that have to work perfectly to deliver on that promise.
Not heard of Flux? Don’t worry, we cover that below, but first, let’s get stuck into the technical setup.
High-RPM Motor — Small Size, Sharp Edge
Flux has built a motor that runs fast—really fast. We’re talking 14,500 rpm at the motor shaft, in a lightweight 7.7 kg water-cooled package designed to deliver 85 hp peak and around 200 Nm at the output shaft (~750 Nm at the wheel after the two-stage reduction). The motor is a high-voltage (~450 V) design, optimized for efficiency, with a small rotor diameter and high pole count to keep it compact without sacrificing torque density.
The key engineering choice here is prioritising high-RPM operation over low-end grunt. Most electric dirt bikes rely on larger, lower-RPM motors that produce torque more directly, but add significant weight and bulk. Flux’s approach allows the motor to stay light and compact, which lowers the centre of gravity and improves chassis balance — a critical factor for handling in tight technical terrain.
On the trail, this should translate to quicker response on throttle changes, cornering that feels dynamic, and more headroom for aggressive acceleration. But it’s not without trade-offs. High-RPM motors generate more heat at high load, so cooling is crucial. In response, Flux has integrated water cooling for both the motor and inverter. Bearings, windings, and the reduction system are also under higher stress than in conventional setups, so component fatigue is also a factor they're working with.
In short, Flux has made a calculated bet: shrink the motor, push the RPM, and rely on careful engineering and control to gain the performance edge, rather than adding raw weight and brute torque. What's clear is that Flux isn't shy of a challenge.
Two-Stage Transmission + Straight-cut Gears — Precision Over Simplicity
Here’s where the Primo diverges sharply from many rivals: it uses two-stage reduction gearing — motor → intermediate shaft → chain/sprocket → rear wheel. The gears are straight-cut, using an F1-style tooth profile to reduce losses and keep things efficient.
In practice, this lets the motor stay in its high-RPM sweet spot while still delivering usable torque at the wheel. Trade-offs include added gearbox complexity, some noise from straight-cut gears (known as straight-cut whine), and more parts to maintain. But if the engineering holds up, this could feel like a real step up rather than a marginal improvement.
Virtual Clutch Lever & Regen Finesse
No mechanical clutch here — instead, Flux provides a digital (virtual) clutch lever that also doubles as a regen-braking control. Want to creep out of mud, feather torque, or avoid wheel spin at low speeds? That lever is your fine control. Let go or modulate, and the software takes over.
This is a big deal for riders who miss the nuance of a clutch in steep or challenging terrain. It promises more control without the weight, maintenance, or complexity of a wet clutch. Of course, its effectiveness depends heavily on algorithms and calibration. Wet, muddy, or extreme temperatures are where digital systems really get tested, but if the mapping is right, it could redefine e-dirt handling.
Ride-by-Wire, Firmware & App Customisation — Software as Part of the Bike
The upside? Post-release updates and full customisation for whatever terrain you throw at it — UK mud, US dunes, Indian heat. The downside? You’re tied to Flux’s update pipeline, and a buggy firmware tweak could leave you stranded or running hot. Purists who love mechanical simplicity might scoff — but if you crave adaptability and precision on demand, this is the tech playground you’ve been waiting for.
Other Specs
Known / reasonably confirmed:
85 hp (63 kW) peak
14,500 rpm max
≈ 7.7 kg (17lb) motor
Water cooling for motor + inverter
Two-stage straight-cut reduction
Virtual clutch / regen lever
App / ride map customisation & vehicle control unit with multiple sensors
~200 Nm at output shaft (~750 Nm at wheel)
Swappable/removable battery pack (7.92 kWh, high voltage ~450 V)
Premium suspension hardware (KYB forks and Öhlins shocks)
Brembo brakes
Early reservation pricing ~ €12,500 (£10,800) ($14,700)
Less certain:
Real-world range under trail abuse & full-power use
Weight when production version has all parts (bodywork, cooling, protection, etc.)
Long-term durability under dust, water, and high vibration
Final firmware feel — how smooth and predictable the maps are, especially with the virtual clutch lever
How battery swapping will work globally (availability, replacement cost, logistics)
Flux's Background
Flux Performance (company name) is a Slovenian start-up founded in 2021 by Marko Ukota, a former Slovenian and Italian national supermoto champion, alongside aerospace engineer Jure Tomažič. Their mission: to develop high-performance electric off-road motorcycles that push the boundaries of what's possible in the e-moto space.
Ukota, with over 15 years of racing experience, co-led an electric supermoto project in 2009. However, the limitations of battery technology at the time hindered its success. Eleven years later, as an engineer, he reunited with his team to create Flux Performance, aiming to overcome those earlier challenges and bring innovative electric motorcycles to market.
In a significant move to bolster their expertise, Flux appointed César Ferreira as Chief Technology Officer in June 2025. Ferreira's appointment underscores Flux's commitment to advancing electric motorcycle technology and solidifying its position in the industry.
Why The Primo Matters
Although not yet available, the Primo’s ambition lies in cramming several tricky, high-risk elements into one package — not something you see every day. Most manufacturers play it safe with two, maybe three; Flux is rolling the dice with all four.
The payoff? Sharper performance, finer rider control, and a ride feel most bikes can only dream of. The downside? More moving parts, more electronics, and more things to go sideways. For riders, it’ll come down to real-world reliability, firmware smarts, battery life, and how long you’re stuck tinkering before hitting the trails. Spending hours fiddling instead of riding — that’s a real kick in the teeth. But if Flux nails it, the Primo could rewrite the rulebook for e-dirt. Watch out, Stark — the competition just got serious.
Ride safe, folks.
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