Abstract: A learning-aid bicycle includes a main body, a connecting member, and a pedal set. In practice, the connecting member may be detached from the connecting portion of the main body, so that the pedal set is detached from the main body. Thus, the learner, such as the child, may be seated on the main body, with his two feet stepped on the ground, so as to ride and move the bicycle by his two feet, so that the learner may learn how to operate, maneuver, manipulate and balance the bicycle, without having to step on the cranks of the pedal set to ride and move the bicycle, thereby preventing the learner from falling down from the bicycle, and thereby protecting the learner's safety.

Abstract: A learning-aid bicycle includes a main body, a connecting member, and a pedal set. In practice, the connecting member may be detached from the connecting portion of the main body, so that the pedal set is detached from the main body. Thus, the learner, such as the child, may be seated on the main body, with his two feet stepped on the ground, so as to ride and move the bicycle by his two feet, so that the learner may learn how to operate, maneuver, manipulate and balance the bicycle, without having to step on the cranks of the pedal set to ride and move the bicycle, thereby preventing the learner from failing down from the bicycle, and thereby protecting the learner's safety.

Abstract: A joint having a metal or plastic core and a metal or plastic outer shell. The core has two studs extending in a direction of an axis of rotation and arranged vertically at 180° from each other. The outer shell consists of two half shells, each having a reinforcing segment. A bore with a bore base is provided on each reinforcing segment. Two cup-shaped elastomeric pads are located between the core and the outer shell and are insulated from one another. The elastomeric pads surround the studs which penetrate the bore in the reinforcing segments. A ratio of the stud diameter to the pad thickness is specified.