Leading Manufacturer of Advanced Mid-Drive Motors for Electric Bicycles

As a professional motor manufacturer, Qianjiang Motor offers over 80 motor models, including the Mid-Drive Motor series and boasts an in-house R&D team capable of transforming conceptual designs into prototypes and supporting mass customization.

Vehicles equipped with mid-drive motors benefit from balanced weight distribution and excellent handling; the use of a transmission to amplify torque ensures strong climbing performance. Additionally, the lightweight wheel assembly reduces unsprung mass, enhancing braking safety, while the concentration of wear-prone components simplifies maintenance. 

What is a Mid-Drive Motor?

The motor unit of a mid-drive system is mounted at the bicycle frame's bottom bracket (the axis of the pedals). Instead of driving the wheel directly from within the hub, it propels the rear wheel via a chain or belt connected to the chainring. These motors come in two main types—those with reduction gears and brushless direct-drive models—though the mainstream design utilizes an internal multi-stage planetary gear reduction system.

Working principle: Motor output torque → torque amplification via reduction mechanism → combination with human pedaling force → chainring → chain → rear wheel cassette/freewheel → wheel propulsion.

Product Structure

1. Motor Unit: High-speed BLDC inner-rotor motor combined with a multi-stage planetary gear reduction set; the reduction ratio is significantly higher than that of hub-based geared motors.

2. Torque/Speed Sensor: A core component that captures pedaling force and cadence; the controller adjusts power output based on the pedaling effort.

3. Integrated Hollow Spindle: The crank passes through the center of the motor, allowing human pedaling power and motor power to converge at the bottom bracket and jointly drive the chainring.

4. One-Way Clutch Mechanism: Disengages the motor load when pedaling stops, ensuring coasting without drag resistance.

5. Housing, heat dissipation structure, Hall sensor assembly, and sealing system; high-end models feature oil-bath lubrication and liquid cooling.

Product Specifications

Which Vehicles Are Suitable for Mid-Drive Motors?

1. High-end e-mountain bikes, long-distance touring e-bikes, and off-road mountain e-bikes

2. High-power off-road electric motorcycles and electric trials bikes

3. Consumer vehicles designed for a premium riding experience, frequent hill climbing, and long-distance riding 

Why Choose Qianjiang Motor?

With over a decade of experience in R&D and mass production, Qianjiang Motor has developed more than 80 motor models. We collaborate with top-tier institutions—such as Tsinghua University and Harbin Institute of Technology—to deliver solutions and provide motors tailored to the specific requirements of various industries.

We offer services ranging from conceptual design to the production of 3D prototypes and small-batch trial runs. Following successful sample validation, we proceed to mass production in strict accordance with ISO 9001 standards, ensuring full process traceability. We offer factory-direct pricing and invite you to contact us to discuss your customization needs.

FAQ

Q: What customization options are available?

A: Qianjiang Motor possesses comprehensive R&D and manufacturing capabilities, supporting in-depth customization:

Electrical parameters: Operating voltage (24V / 36V / 48V / 60V / 72V, etc.), rated power, rated speed, and torque.

Mechanical structure: Wheel size (ranging from 6 to 12 inches, etc.), axle length, dropout width, mounting hole configuration, and tire compatibility (solid or pneumatic).

System integration: Compatible with matching sine-wave controllers, throttles, and battery systems.

Q: What is the difference between a mid-drive motor and a geared hub motor?

Q: What is the noise level of the mid-drive motor?

A: During normal operation, the noise level is below 60 decibels; the use of precision gears and high-quality bearings ensures minimal vibration and quiet operation. If abnormal noise occurs, check for gear wear, bearing condition, or installation alignment.