Date of this Version
Procedia Engineering 72 ( 2014 )
Modern bicycle disk-brake systems often induce vibration and noise in bike components such as brake rotors, wheels, and even bike frames. When the vibration or noise are excessive, brake performance can be perceived as unsatisfactory. Previous research incorporating bike frame structural dynamics and brake friction modeling has shown that stick-slip friction is likely the cause of much of this vibration and noise. Bicycle design parameters such as brake friction behavior and bike component structural properties are central in producing and/or sustaining these vibrations. The predicted dynamics of these models has correlated reasonably well with the testing of braking systems. This research extends the modelling of previous efforts to improve correspondence with brake noise/vibration testing and gain further understanding into the contributors and possible cures of this unwanted vibration. Specifically, the extended model incorporates torsional wheel dynamics (including rotor/hub, rim, and tire inertias, and spoke, rotor, and tire stiffnesses) into previous models. This new model allows the dynamics of the bike frame and wheel to couple through braking application. To support and validate the modelling, motion/vibration measurements are recorded during noisy braking with a non-contact laser vibrometer in the laboratory and with an accelerometer in field tests. Vibration measurements are studied along with model predictions toward the goal of connecting unwanted noise/vibration with specific design parameters of the bicycle brake-frame-wheel system.