Bicycle rear derailleur and transmission assembly of bicycle device

A bicycle rear derailleur, comprising:

• a base component;
• a movable component;
• a linkage assembly, pivotably connected to the base component and the movable component;
• a chain guide, pivotably disposed on the movable component;
• and
• a transmission assembly, disposed on the linkage assembly, wherein the transmission assembly comprises a driving source, a circuit board and a sensor, the driving source is configured to provide a power to the movable component to drive the movable component to move relative to the base component, the circuit board is electrically connected to the driving source, the circuit board has a through hole, and the sensor is at least partially located in the through hole of the circuit board,
• wherein the circuit board has a first surface and a second surface located opposite to each other, two opposite ends of the through hole penetrate through the first surface and the second surface, respectively, the sensor sticks out of the first surface, the sensor has a plurality of pins, and the plurality of pins are connected to the second surface of the circuit board,
• wherein the transmission assembly further comprises a plurality of transmission gears, a transmission shaft, and a sensing component, the driving source being connected to the transmission shaft via the plurality of transmission gears, the sensing component being fixed on one of the plurality of transmission gears, and the sensor measuring a rotation position of the one of the plurality of transmission gears via the sensing component, and
• wherein a distance between the sensing component and the sensor is smaller than a thickness of the sensor or a thickness of the sensing component.

A transmission assembly of a bicycle device, comprising:

• a driving source;
• a plurality of transmission gears, connected to each other and configured to be driven by the driving source;
• a magnet, disposed on one of the plurality of transmission gears and being rotatable;
• a circuit board, electrically connected to the driving source, wherein the circuit board has a first surface, a second surface and a through hole, the first surface is located opposite to the second surface, and the through hole penetrates through the first surface and the second surface;
• and
• a sensor, at least partially located in the through hole of the circuit board for measuring a rotation of the magnet;
• wherein the sensor sticks out of the first surface, the sensor has a plurality of pins, and the plurality of pins are connected to the second surface of the circuit board,
• wherein a distance between the magnet and the sensor is smaller than a thickness of the sensor or a thickness of the magnet.