Doping is the dark side of mega cycling events such as the Tour de France. One particularly perfidious method, and one that is becoming more and more common in competitive cycling, is that of minimally invasive technical doping systems, as they are known: in other words, hidden auxiliary motors. The current variant is an extremely quiet electromagnetic drive that can be used to “dope” the rim of the rear wheel with strategically placed magnets. This is about the same technology as used in the German maglev Transrapid – the transverse flux motor. Other recent sophisticated methods of deception are based on energy storage and re-release by mechanical means, or on pneumatic storage for drive support.

New field of application for industrial testing systems

The Fraunhofer Institute for Nondestructive Testing IZFP has a wide range of monitoring and inspection systems at its disposal. Originally developed for quality and safety control of technical systems in industrial production, some of these technologies could also be put to good use in the fight against doping by uncovering forbidden manipulations that are otherwise hard to find.

Finding hidden motors – acoustically, thermographically, and magnetically

One option involves analyzing the acoustic emissions from bicycles. These emissions could be recorded while the racers drive past gauging stations, which are equipped with sensitive microphone arrays and appropriate signal processing. Here, the acoustic signature analysis can filter out ultra-fine irregularities and compare them with the profile of “clean” bicycles. Thermographic inspections with infrared cameras, meanwhile, can detect minimal thermal changes of approximately 0.05 °C – the type of change that could be caused by the attachment of hidden electric motors or batteries. Magnetic probes can be used to detect the smallest magnetic fields, generated even by an electric motor when it is switched off. A simple multi-step inspection strategy counteracting electric motor doping is based on the assessment of signals from thermographic cameras and magnetic field probes. In a next step, wheels showing conspicuous features can be finally characterized using additional nondestructive inspection methods where a look into the interior of the component will clarify the situation beyond doubt. With the modern digital X-ray techniques developed by Fraunhofer IZFP, hidden auxiliary motors can be mapped clearly in the previously inaccessible interior of the wheels. This could allow manipulations to be uncovered and excluded with certainty. After all, every fan of competitive cycling has a right to expect that the cyclist on the winner’s podium has gotten there strictly through his or her own efforts.