In high-school teaching of mechanics, we deal, among other things, with the nature of static and
kinetic friction, forces that are proportional to the normal force. Under the influence of
frictional forces, a body moves down a rough sloped decline at a fixed rate of acceleration that is
independent of its mass. This situation does not apply to cases where the frictional force is
dependent upon velocity, such as bodies which are moving through a streaming fluid (such as
raindrops falling to the ground). In this case the body moves with a continuously decreasing
acceleration, eventually reaching a terminal velocity when the frictional and gravitational forces
balance out. This velocity constraint is determined by the dependence of the frictional force on
velocity and geometric parameters that determine the strength of the frictional force. We show here
that a similar situation takes place when bicycles descend an incline with a fixed slope. We also
investigated the dependence of t…