The race is on to create an ebike motor that provides the least quantity of weight and bulk as bodily potential, disappearing away into the bike the place it is barely seen or heard however is felt on each pedal stroke. The most recent contender is the Magnetic Gear Motor (MGM) from Chinese language ebike element provider Star Union. As its title implies, this electrical motor drive swaps out bodily gears in favor of a magnetic gear system that compacts the core whereas reducing friction. The drive is then capable of put out a critical punch from a tiny, incognito bundle.
Final week, we checked out how TQ’s latest electric bike drive is ready to minimize weight and bulk through the use of a Harmonic Pin Ring gearing system that locations two gears inside one another, slightly than laid out laterally as in a bigger ebike drive. Star Union makes use of an analogous gear-in-gear structure, albeit with out the necessity for mechanical energy transmission between bodily gear tooth.
Star Union isn’t the primary to explore the concept of magnetic gearing, but it surely does declare to be the primary to use it to an electrical bike drive. Its everlasting magnet-based gears transmit torque through a magnetic coupling that eliminates bodily contact. The contactless transmission, in flip, cuts friction down round nil, leading to an optimized energy transmission Star Union estimates at 90% most effectivity.
Star Union
“Nearly no vitality is wasted as warmth from friction, that means extra of the battery energy interprets into wheel torque,” summarizes Zhi Pan, Star Union director. “Riders can anticipate higher vary and sustained output.”
With that degree of effectivity and the cosy, concentric configuration of gears, Star Union is ready to guarantee potent efficiency from a really compact drive bundle. The MGM’s outer casing measures in at 4.7 x 4 x 3.5 in (12 x 10 x 9 cm), which is not fairly as grabbable as a 3.8-in-diameter (9.7-cm) softball, however the picture up high does present it becoming slightly comfortably within the hand.
Star Union
Extra importantly, the 5-lb (2.3-kg) MGM matches fairly neatly and inconspicuously within the bike’s backside bracket, enhancing floor clearance and delivering aesthetics which might be about as clear as any we have seen. It additionally offers bike producers extra flexibility in placement and total body design.
Past these huge benefits, the magnetic transmission system cuts out noise related to the bodily grinding of substances tooth and the accompanying put on and tear of mechanical transmission. As for the potential of magnetic decoupling and slippage, Star Union is assured it has designed the MGM e-drive to stop such issues.
“There are fewer factors of mechanical stress, and the magnetic coupling can ‘slip’ harmlessly if overloaded, avoiding harm,” explains Zhi Pan. “After all, the MGM motor would not slip as a result of we perceive the torque limits of magnetic gears and might management the present accordingly.”
The excellent news about main elements like this one is that the ebike business may have the possibility to completely vet Star Union’s claims earlier than integrating the drive into the precise bikes that shall be looking at shoppers by means of the home windows of native retailers. After exhibiting the Magnetic Gear Motor at Eurobike 2024, Star Union shall be providing hands-on demonstrations and check rides for the primary time at this yr’s Eurobike present later this month.
Star Union
The 2025 MGM produces a claimed 80 Nm (59 lb-ft) of peak torque, up from the 75 Nm (55 lb-ft) of final yr’s drive. Star Union says it was capable of bump the torque up with out including any weight or dimension to the bundle. The drive has a steady energy of 250 watts and has been examined to 580 watts of peak energy.
Star Union has developed a number of packages for highway and mountain bikes with 48-V batteries ranging between 160 and 480 Wh. It says it has been working with and speaking to a number of ebike OEMs in Asia and Europe on growth of MGM-powered merchandise and plans to start mass manufacturing of the mid-drive within the fourth quarter of this yr.
Supply: Star Union
