Professional road-race cycling has endured its share of ups and downs over the years.
We outline the major incidents that have marred the sport's recent history.
CYCLING'S SUSPICIOUS DEATHS
Tom Simpson, 29, died on Mont Ventoux (1967)
Denis Zanette, 32, died of heart attack (2003)
Jose Maria Jimenez, 32, died of heart attack (2003)
Marco Pantani, 34, died of unknown causes (2004)
Johan Sermon, 21, died of apparent heart failure (2004)
1967: Briton's Tommy Simpson collapses and dies on Mont Ventoux during the Tour de France. A post mortem finds levels of amphetamine in his blood.
1990: Former Tour de France rider Paul Kimmage publishes "Rough Ride", a book blowing the lid on drug-taking and corruption in cycling.
1998: Festina team masseur Willy Voet is stopped by police and his car found laden with performance-enhancing drugs at the start of the Tour de France.
Subsequent raids on 20 teams find endemic doping, with stimulants, anabolic steroids as well as used syringes.
Pantani was thrown off the 1999 Giro d'Italia for failing a drugs test
Three teams are expelled in what becomes known as the "Tour de Farce".
1999: Leader Marco Pantani is thrown out of the Giro' d'Italia after failing a blood test for haematocrit - an indicator, though not proof, of the use of performance-enhancing drugs.
After months of denials following the Festina affair, top French cyclist Richard Virenque eventually admits to having taken doping substances and is banned for six months.
2001: Insulin syringes are found in Pantani's hotel room during the Giro d'Italia. He receives a six-month ban.
The Fasso Bortolo team sack Daro Frigo after illegal drugs, including the blood substitute Hemassit, are found in his room.
May - Gilberto Simoni, the 2001 Giro winner, tests positive for cocaine, blaming the result on a visit to the dentist. Stefano Garzelli, winner in 2000, fails tests for the diuretic probencid.
July - Germany's Jan Ullrich, 1997 Tour winner, is banned for six months for recreational amphetamine use while recovering from a knee injury.
The wife of Tour de France third-place finisher Raimondas Rumsas is found with doping substances in her car.
Jimenez died of a heart attack, aged 32
Jan - Italian pro Denis Zanette, 32, dies of a heart attack while at the dentist.
May - Raimondas Rumsas tests positive for erythropoietin (EPO), a banned endurance-enhancing drug.
June - Marco Pantani checks into a health clinic for treatment for depression and drug addiction.
Dec - Spanish rider Jose Maria "Chaba" Jimenez, 32, dies of an apparent heart attack at a psychiatric hospital in Madrid. He had been suffering from depression.
Jan - French team Cofidis are placed under investigation after banned substances are found in the possession of a team assistant.
Cofidis cyclist Philippe Gaumont admits taking EPO, and says 90% of cyclists have taken banned drugs.
14 Feb - Pantani is found dead in a hotel in Rimini, Italy.
Hours later 21-year-old Belgian cyclist Johan Sermon is found dead from apparent heart failure in his sleep.