AbstractBicycles are an important means of transport — over 20 million are manufactured worldwide each year, and, because their source of motive energy is human, their energy conversion, as measured by their resistance to motion, is critical. The bearings used in bicycles are rolling bearings, but are normally of different materials and construction quality to the roller bearings used in other applications.The present paper is intended to provide an indication of the phenomena influencing the resistance to motion and loss of energy of these bearings, and is based on a rolling bearing test stand designed by the author. A mathematical model derived from experimental observation is presented, and the theoretical results compared with experimental result