Patent ID: 12012169

Abstract:
A foldable rotary arm structure and device for a bicycle. The foldable rotary arm structure includes a rotary wheel and a rotary arm. The rotary wheel is coaxial with a transverse tube or surrounds the transverse tube. The rotary arm is in steering connection with the rotary wheel or a supporting base, such that the rotary arm is attached to the transverse tube when folded, thereby reducing the space of the transverse tube occupied in a radial direction. A flywheel for use in a balancing device of a bicycle or a motor-assisted bicycle or an amusement device is provided. In the rotary arm, individual batteries or multistage batteries are arranged in a single layer in the radial direction and are stacked in multiple stages in the axial direction. When the rotary arm is unfolded and rotated, the angular momentum is increased or the torque is balanced.