Due to their high specific strength and the possibility of creating a load-adapted property profile, composite materials are ideally suited for the design of high-speed flywheel rotors. The rotors are exposed to extreme loading conditions by high centrifugal forces, partially superposed by elevated temperatures due to an integrated electrical machine, bearings or air friction. A sophisticated fail-safe design of composite flywheel rotors has been applied here, which allows the rotor to fail catastrophically. To withstand the manifold burst behavior safely the exact loading of the containment must be known within a simultaneous engineering approach of rotor and containment. Therefore, adapted rotor rigs and devices for measuring the burst effects in the axial, radial and circumferential direction have been designed and successfully tested. Experimental failure studies on the fiber composite flywheel rims prove the manifold burst behavior and containment interactions. Extreme axial shock waves due to the composite fragment movement have been measured experimentally, which are principally not known for isotropic rotor failure.