A magnetic brake assembly for use with a wheel rim is described. The brake assembly includes a rotor secured to rotate with the rim and a stator secured to be rotationally stationary relative to the rotor. One of the rotor and stator has an electrically conductive body and the other of the rotor and stator has a magnetic array including a plurality of magnets configured to generate a magnetic flux. An actuator is connected to at least one of the electrically conductive body and magnetic array to selectively effect a brake mode and a non-brake mode. In the brake mode, the magnetic array induces eddy currents in the electrically conductive body to generate a magnetic braking force when the rim rotates above a threshold speed and in the non-brake mode, the induced eddy currents cause a negligible or no magnetic braking force as the rim rotates above the threshold speed.