A Compact and Lightweight Centre-Mounted Drive Unit

In pursuit of even greater usability, a compact and lightweight centre-mounted drive unit employing a brushless DC motor using rare-earth magnets was developed. The new direct-to-chain assist arrangement brought higher efficiency and lower loss and enabled a smooth but powerful ride feel. The adoption of a new torque sensor not only reduced resistance felt at the pedals but also provided a light pedalling feel akin to a conventional bicycle when not receiving a power assist. Locating the drive unit near the pedals also aided in balancing the bicycle’s weight, making it easier to move around.