A test rig for the accurate measurement of bicycle TYRES characteristics

In this paper, a new test rig for measuring the characteristics of bicycle tyres is presented. The test rig is designed to measure the parameters of a wide range of bicycle tyres, including race bicycles, mountain-bikes and city-bikes. The test rig consists of a frame that allows a single wheel to be cambered and steered. Electric motors can be added to produce longitudinal slip. The test rig is conceived to be employed either on a drum or on a flat surface. The friction on the drum or on the flat surface can be varied in a relatively easy way. The test rig can measure the vertical force, the lateral force, the self aligning torque, the moment around the longitudinal axis, and, after proper arrangement, the longitudinal force. The steering and camber axles of the test rig intersect at the centre of the contact patch. In this way, the vertical vibrations of the wheel cause a pure vertical motion of the centre of the contact patch i.e. without longitudinal velocity. The lateral force is measured by a Watt's linkage. The steering motion is allowed by pneumatic bearings, which guarantee a vanishing friction moment and thus an accurate measurement of the self-aligning moment. Some measured tyre characteristics are provided.