[Electric Bicycle Assistant Sensor]: The speed sensor detects some forward pedal rotation or a certain rotational speed and activates the motor to power your ride [Electric Bicycle Assistant Sensor]: The speed sensor detects some forward pedal rotation or a certain rotational speed and activates the motor to power your ride [Dual Magnetic Loop]: Speed sensor emplothe dual-magnetic loop - Hall elastic angle difference to detect the dynamic torque, which is converted to DC signal and sent to the controller [Application]: Suitable for almost all electric bicycles available in the market with compact size, light weight, long durability, anti-shock, anti-corrosion and dustproof Color: black size: Disc Diameter 65mm/2.56" Rim Diameter: Approx. 35mm/1.37" Cable Length: Approx. 1.1m / 43.3 inches Delivery Quantity: 1 Piece