Middrive

Middrive, or mid-drive, refers to a type of electric bicycle drivetrain where the motor is mounted near the crankset at the bottom bracket and drives the bicycle through the existing chain and gears. This placement positions the motor in the bike’s center, allowing it to leverage the bike’s gears to optimize torque and efficiency.

Most mid-drive systems use pedal-assist modes controlled by a torque or cadence sensor, with a battery powering the motor. The motor applies force to the crank, and power is transmitted through the chain to the rear wheel. This setup often requires compatible chainrings, derailleurs, and a robust frame to handle the torque.

Advantages of middrive include improved weight distribution, natural riding feel, and strong hill-climbing performance due to leveraging the bike’s gears. It often offers better efficiency on varied terrain and can provide smoother integration with the rider’s pedaling. Drawbacks can include higher stress on chain and drivetrain components, increased maintenance, and potentially higher cost. Some systems also add complexity and may transfer more vibration to the frame.

In the market, mid-drive systems are common on mountain and trekking e-bikes. Prominent examples include Bosch Performance Line, Shimano STEPS, Brose, Yamaha PWSeries, and Bafang mid-drive units. Compared with hub-drive motors, middrives emphasize drivetrain integration and gear-based efficiency, while hub motors typically offer simpler maintenance and lower gear load.