Competitive cycling already has a checkered history of its riders using performance-enhancing drugs to cheat, but it's long been rumored that some professional bike athletes are also engaging in so-called "mechanical doping" by secretly adding motors to their bikes, allowing them to conserve energy during grueling races. Now we have proof. The world's governing body for competitive cycling, the Union Cycliste Internationale, confirmed this week that it found an concealed motor inside the frame of a bicycle belonging to 19-year-old cyclocross athlete Femke Van den Driessche, shortly after the conclusion of the sport's world championships in Belgium.

Van den Driessche had been one of the favorites for the race, but was forced to withdraw, citing a mechanical problem. The motor in her bike was reportedly spotted during a pit stop equipment check — according to journalist Martin Vangramberen, electrical cables were observed protruding from inside the frame when the bike's saddle was removed, leading to the motor itself hidden inside the crankshaft. Such checks were introduced by the UCI after professional cyclist Fabian Cancellara was accused of using a motor in his bike in 2010, and use a scanner and a camera to probe the bike's exterior and interior. Peter van den Abeele, the UCI's head of off-road cycling, said that the governing body has also been trialing a new method of detecting illegal modifications recently.

Random checks were introduced in 2010 after "mechanical doping" was first rumored

Both Van den Driessche and her father denied all knowledge of the motor, telling Belgian TV channel Sporza that the offending bike wasn't her's, but a friend's. "This friend went around the course Saturday before dropping off the bike in the truck," the athlete said. "A mechanic, thinking it was my bike, cleaned it and prepared it for my race." Her father said that the bike had been inadvertantly brought to the pit, but that "it was never the intention that she would ride it."

But the UCI appears unconvinced. "It's absolutely clear that there was technological fraud," UCI president Brian Cookson said during a press conference soon after the bike was seized. "There was a concealed motor. I don't think there are any secrets about that." If found guilty of deliberately deceiving the governing body, Van den Driessche faces a fine of up to 200,000 Swiss francs (about $196,000) and a six-month suspension from the sport as standard, but is likely to face a lengthier ban, possibly barring her from ever competing in cyclocross again.