Friction Modeling of a Free-Spinning Bicycle Wheel

An experiment is conducted in which a free-standing bicycle wheel is given an initial angular speed and then allowed to slow down to rest. Measurements of the wheel speed, using a magnetic sensor, during the decay are compared to predictions from a model accounting for a combination of viscous and dry friction at the wheel bearing. The time history data indicate two dynamic regimes: (i) a higher speed phase corresponding to the first part of the motion for which a simple viscous friction model applies, and (ii) a slower speed phase corresponding to low speed to stop behavior for which a model involving both viscous and dry friction is proposed. A method is presented for finding the viscous and dry friction coefficients of the two phases.