Fox Factory, best known for its suspension forks and shocks, may be eyeing a much bigger role in the e-bike drivetrain market. A patent application published by the USPTO (No. 19/037,562, filed in January 2025) describes a mid-drive motor unit that pairs two electric motors with a strain-wave gearbox to form an electronic continuously variable transmission — an eCVT.
The timing is notable. At Eurobike 2026, integrated stepless transmissions emerged as one of the hottest topics in the mid-motor segment, with Avinox and Gobao both showing eCVT-based systems. Unlike motor-gearbox units with fixed gears, such as Pinion’s MGU, an eCVT promises lower weight, seamless ratio changes with no perceptible gear steps, and smooth shifting under full load.
Fox’s approach stands out through its use of a strain-wave (harmonic drive) gearbox, a technology already familiar from TQ’s HPR motors. But where TQ uses a fixed reduction, Fox makes it variable: one electric motor drives the outer ring gear, altering the effective ratio electronically, while a second motor works with the rider’s cadence to control the wave generator. Together they determine the torque and speed delivered to the chainring, with a theoretical reduction of up to 100:1.
Whether Fox is actually developing a production motor remains unknown — a patent filing is no guarantee of a finished product. Still, a major suspension player exploring drive units underlines how quickly the eCVT race is heating up, with clear implications for future SUV e-bikes and e-MTBs.
Source: eMTB-News.de