Sounds like the UCI is testing bicycles for evidence of mechanical doping:
"The UCI said it used magnetic scanning tablets on 606 bikes before the start of stages, and put 114 bikes through its mobile X-ray lab after stages...In a press note Monday, the UCI outlined its testing protocol, saying that each day’s winner, as well as the GC leader, have their bikes X-rayed after each stage, along with other random controls throughout the race."
Tour de France: UCI says no infractions following 720 inspections for 'motor doping' | VeloNews.com
Still, the fact that they're introducing new tests for the Olympics suggests that there may be some insufficiency with the current testing protocol.