MELBOURNE - Two-time Tour de France winner Chris Froome has said he warned authorities about possible mechanical doping in cycling and wants them to intensify bike checks to catch offenders. After decades of struggling to combat illegal drug use, cycling's image suffered a fresh blow when stewards at the world cyclo-cross championships found an electric motor in Belgian teenager Femke Van den Driessche's bike. Den Driessche has maintained her innocence since the discovery but Briton Froome said he had heard whispers about mechanical doping before and shared them with the International Cycling Union (UCI). "It's a concern that I've had, something I've brought up with the UCI and advised that the UCI implements controls and measure to start checking bikes more regularly."