A 250W electric motor (UK street-legal for a tricycle) fitted with a friction roller studded with 50 self-tapping screws is used to provide a good grip on the tyre, wet or dry. Power to the motor is controlled by a PWM controller attached by a gear cable to a handlebar lever to provide finely-controllable pedal-assist. The motor is mounted on a sprung, damped platform which in its rest position holds the friction roller away from the tyre, allowing the Trice XL to be pedalled normally. The platform is pulle
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