Abstract: An auxiliary device of a monocycle has an auxiliary body connected to a monocycle. The main fork of the monocycle has a main sleeve. A detachable auxiliary body is connected to the main sleeve. Thereby, the auxiliary body can be installed to or detachable from the monocycle. The auxiliary body is mainly formed by a front head and a frame tube. The front head has a handle frame, a sub-wheel body and a sub-fork. The frame tube is connected to the monocycle. A front end of the monocycle is installed with a sub-sleeve which is formed at an upper end of the sub-fork so as to be formed as a monocycle with an auxiliary wheel.

Abstract: An auxiliary device of a monocycle has an auxiliary body connected to a monocycle. The main fork of the monocycle has a main sleeve. A detachable auxiliary body is connected to the main sleeve. Thereby, the auxiliary body can be installed to or detachable from the monocycle. The auxiliary body is mainly formed by a front head and a frame tube. The front head has a handle frame, a sub-wheel body and a sub-fork. The frame tube is connected to the monocycle. A front end of the monocycle is installed with a sub-sleeve which is formed at an upper end of the subfork so as to be formed as a monocycle with an auxiliary wheel.

Abstract: A mini bicycle in which the chain stays are respectively pivoted to a bracket at the seat tube to support the pedal-driven chain transmission mechanism. The seat tube extends across a rear part of the upper tube and connected to the rear end of the lower tube to hold the saddle stem, enabling the saddle stem to be vertically adjustably locked at the desired elevation. The springing is coupled between downwardly extended rear lugs of the upper tube and the chain stays, and the handlebar assembly is vertically adjustably coupled to the head tube and locked at the desired elevation.