Abstract: A tricycle includes a frame, a chair, a handle, a front wheel, two pedals, two wheel-supporting units, two rear wheels and a connector. The frame includes a longitudinal tube, a fork connected to the longitudinal tube, and a transverse tube connected to the longitudinal tube. The chair is supported on the longitudinal tube. The handle is pivotally supported on the longitudinal tube in front of the chair. The front wheel is connected to the fork. The pedals are connected to the front wheel. Each of the wheel-supporting units includes a threaded shaft inserted through the transverse tube and engaged with a nut and an axle inserted through a corresponding one of the rear wheels. The threaded shaft comprises an axis that does not intersect the axle. The connector connects the handle to one of the wheel-supporting units.

Abstract: A tricycle includes a frame, a front fork connected to the frame, two rear forks each comprising a shank connected to the frame and two prongs extending from the shank, a front wheel rotationally connected to the front fork, two rear wheels each rotationally connected to the prongs of a corresponding one of the rear forks, and a steering mechanism connected to a selected one of the rear forks. There is a distance between an axis of the shank of each of the rear forks and a vertical line in which a center of the corresponding rear wheel rests when the rear wheels are laid on the ground.

Abstract: An apparatus is provided for rotating a wheel. The apparatus includes a hub, at least one two-way bearing fit in a hub, a shaft inserted through the two-way bearing, a first disc secured to the shaft, a first one-way bearing provided between the first disc and the hub for allowing only the forward spinning of the hub on the shaft, a second disc rotationally provided on the shaft, a second one-way bearing provided between the second disc and the hub for allowing only the rearward spinning of the hub on the shaft and a clutch provided between the second disc and the shaft.