“Weighing only 2.3kg, this ultra-compact drive integrates a groundbreaking magnetic gear transmission instead of traditional gears, promising higher efficiency, lower noise, and greater durability,” explains Zhi Pan, the director of Star Union, a firm with over 40 years of e-bike components manufacturing experience. “The MGM is being hailed as one of the most advanced coaxial mid-drive solutions on the market, reflecting our strong R&D focus and future-forward approach to e-bike technology.”
Compact mid-drive packs with 80Nm of torque
Despite its small footprint (roughly 9 × 12cm casing), the new MGM motor boasts a peak torque of 80Nm – a notable jump from the previous 75Nm generation. Importantly, this gain comes without any size or weight penalty, maintaining the same diminutive form that already rivaled premium European mid-motor systems. “The result is a power unit that can match or exceed the performance of larger competitors, while remaining half a kilogram lighter than many,” adds Pan.
Seamless and clean integration
“The compactness of the MGM should please e-bike makers,” notes Pan. “The motor’s compact volume allows it to integrate seamlessly into the frame with minimal visual impact. Bikes equipped with the MGM can thus maintain sleek, high-end aesthetics, hiding the drive neatly for an elegant look. This can be especially valuable for premium city e-bikes, road e-bikes or full-suspension e-MTBs that demand both performance and discreet styling.” In short, the MGM delivers big torque in a tiny package, giving designers more freedom to create refined, lightweight electric bicycles.
“Beyond just numbers, the reduced bulk of the MGM means better ground clearance and more placement options on different frame styles,” continues Pan. “It mounts coaxially at the bottom bracket, preserving a central, low center of gravity for balanced handling. With less volume to accommodate, manufacturers can reinforce the frame’s lines and pursue cleaner integrations, whether it’s a graceful city commuter or a rugged trail bike. The overall impression is a premium, integrated e-bike rather than one dominated by a bulky motor – a clear selling point in high-end segments where design elegance matters.”
Frictionless magnetic gear technology
At the heart of the MGM is its magnetic gear transmission – a novel drivetrain technology that does away with conventional gearbox cogs. Unlike a standard mid-drive that uses planetary or harmonic gears to reduce motor speed, the MGM employs a frictionless magnetic coupling to transmit torque. In simple terms, it uses powerful permanent magnets to achieve the reduction ratio, with no direct contact between moving parts. This design yields multiple benefits for performance and longevity:
- Higher efficiency: The MGM technically reaches about 90% energy efficiency, significantly above the ~80–85% typical in geared mid-motors. “Virtually no energy is wasted as heat from friction, meaning more of the battery power translates into wheel torque,” comments Pan. “Riders can expect better range and sustained output.”
- Near-silent operation: With no gear teeth grinding, the motor operates with remarkably low acoustic noise. The magnetic design dramatically cuts drive noise, making for a quieter and more pleasant riding experience. “Test riders have reported an almost imperceptible hum, which not only improves comfort but also lets cyclists enjoy their surroundings without the buzz of a motor,” adds Pan. “This stealthy operation stands in contrast to many traditional mid-drives that emit a noticeable whir under load.”
- Minimal wear & maintenance: The contact-free transmission means there are no gears to wear out or lubricate. “This results in excellent durability and very low maintenance needs over the motor’s service life,” explains Pan. “The frictionless system greatly extends longevity. There are fewer points of mechanical stress, and the magnetic coupling can ‘slip’ harmlessly if overloaded, avoiding damage. Of course, the MGM motor doesn't slip, because we understand the torque limits of magnetic gears and can control the current accordingly. For e-bike fleets or demanding riders, this reliability is a major advantage, reducing downtime and service costs.”
Test results
Test data indicates that the MGM motor delivers a peak power of approximately 580W, with output characteristics optimized for real-world e-bike conditions. It can sustain 80Nm of peak torque for extended periods and provides stable continuous torque during prolonged climbs.
Pan explains: “This ensures the MGM performs effectively in both low-speed scenarios, such as starting on steep inclines, and high-speed cruising, where the low resistance of the magnetic drive enhances efficiency. These performance attributes position the MGM as a premium solution for various e-bike applications, from elegant city bikes to performance-focused mountain bikes. Industry observers even suggest that this magnetic mid-drive motor could represent a watershed moment in e-bike drive design, marking it as a groundbreaking innovation in the electric bicycle sector.”
Eurobike 2025 and future outlook
European manufacturers and bike brands will get their first hands-on look at the MGM system at Eurobike 2025 in Frankfurt. For the first time in Europe, Star Union is offering demo rides of the MGM-equipped e-bikes on the show’s Demo Area, allowing industry professionals to experience its smooth and silent power delivery up close. Early prototypes of the MGM have already been trialed by partners of the company in Asia, and the feedback has been resoundingly positive. “We showcased it at Eurobike [2024] and the responses were excellent,” shares Pan. “Several major bike brands expressed strong interest in the technology.” Following successful pilot production, the company expects to kick off volume manufacturing by Q4 2025.
Bike Europe readers attending Eurobike can find Star Union at Hall 8.0, stand I18. There, the company’s team will showcase the MGM system’s features and answer technical questions.
This article is sponsored by Star Union.
