This sketch belongs to Leonardo's Codex Atlanticus, but it was not drawn by Leonardo. Who was its author? Was it perhaps a pupil, who drew on the back of a sheet belonging to his master a two-wheeled vehicle, with pedals and a chain transmission? Or is the drawing a recent forgery? The case of "Leonardo's bicycle" came up in the 1970s, when the restoration of the Codex Atlanticus was completed. Experts have not yet reached an agreement on the drawing's age. The prevailing opinion, however, is a strong skepticism about its authenticity.