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Tom Simpson (UK) - Simpson was a leading British cyclist in the 1950s and '60s who tragically died on Mount Ventoux during the 13th stage of the Tour de France at just 29 years old in 1967.

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Tom Simpson (UK) - Postmortem examinations revealed that he had ingested amphetamines and alcohol, a mixture which proved fatal when combined with the high temperatures that day and sheer exhaustion.

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Jacques Anquetil (FRA) - Throughout his career in the 1950s and '60s (during which time he won the Tour de France five times), the French cyclist openly said he thought the use of performance-enhancing drugs was fine.

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Jacques Anquetil (FRA) - Though his own drug use was never publicly proven, his open attitude towards it was a key reason for why he was dropped from major teams in later years, and died in relative obscurity from the cycling world.

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Eddy Merckx (BEL) - The Belgian rider won the Tour de France five times, winning a total of 34 stages in the race over his career—the most won by any Tour de France competitor ever.

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Eddy Merckx (BEL) - Merckx tested positive for doping three times throughout his cycling career, though never during the Tour de France.

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Joop Zoetemelk (HOL) - The Dutch cyclist got caught for blood doping in 1977, 1978, 1979, and 1983. On his winning of the Tour de France in 1980, however, he was apparently clean.

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Joop Zoetemelk (HOL) - Zoetemelk (pictured left) claimed that his blood doping incidences came from anemia treatment he was prescribed after he suffered a serious crash in 1974, says Cyclingnews.com.

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Felice Gimondi (ITA) - Gimondi (pictured third from left, speaking into a microphone) tested positive for doping twice in his career.

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Felice Gimondi (ITA) - This occurred once at the 1968 Giro d'Italia and once during the 1975 Tour de France, after the fifteenth stage.

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Bernard Thévenet (FRA) - Thévenet won the Tour de France twice, in 1975 and 1977.

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Bernard Thévenet (FRA) - Even though he never failed drug tests during his career, he later admitted to having taken the steroid cortisone during his two Tour victories.

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Laurent Fignon (FRA) - Fignon was the Tour de France champion in 1983 and 1984.

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Laurent Fignon (FRA) - Though he was never implicated in doping during the Tour de France, he did test positive for amphetamines in other races, once in 1987 and once in 1989.

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Marco Pantani (ITA) - Known as "Il Pirata" ("The Pirate") for his aggressive racing style and the hooped earrings he often wore, Pantani came under a lot of media fire for doping from 1999 onwards.

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Marco Pantani (ITA) - He struggled to clear his reputation and cope under the heavy criticism. In 2004 he was found dead in a hotel, having succumbed to cocaine poisoning.

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Bjarne Riis (DEN) - Winner of the Tour de France 1996, the Danish cyclist admitted to having doped with EPO from 1993 to 1998.

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Bjarne Riis (DEN) - He was stricken from the record books but later written back in, in 2008. Riis still works as a team manager in professional cycling today.

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Jan Ullrich (GER) - The German rider suffered a career decline after he was suspended from racing in the 2006 Tour de France.

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Jan Ullrich (GER) - In 2007, almost ten years after he won the Tour de France, Ullrich announced his retirement from professional cycling. 

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Lance Armstrong (USA) - But perhaps no cyclist is more famous for doping than the American Lance Armstrong (center).

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Lance Armstrong (USA) - His seven consecutive wins at the Tour de France (1999, 2000, 2001, 2002, 2003, 2004, and 2005) were all voided after he was found to have serially taken performance-enhancing drugs throughout much of his career.

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Lance Armstrong (USA) - After successive investigations and denials, Armstrong finally openly confessed to having doped during an interview with Oprah Winfrey in 2013.

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Floyd Landis (USA) - Amid Armstrong's doping accusations, another American rider was caught in the fire, Floyd Landis.

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Floyd Landis (USA) - Landis won the Tour de France in 2006, but was stripped of the win a week later when a test done during stage 17 of the race (the results were delayed) proved he had doped. He retired from professional cycling in 2011.

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Denis Menchov (RUS) -

Menchov announced his retirement in May 2013, citing knee problems. But in 2014, it was revealed that the International Cycling Union had suspended the Russian cyclist in March of 2013 because he was found to have abnormal blood values.

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Denis Menchov (RUS) - He was subsequently stripped of his results from the Tour de France of 2009 (51st), 2010 (2nd), and 2012 (15th). He has not returned to professional cycling since.

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Bernhard Kohl (AUT) - Kohl came in third overall in the Tour de France in 2008, and also won the famous red polka dot shirt for coming in first in the Mountains Classification that same year.

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Bernhard Kohl (AUT) - However, he was stripped of both these titles after it was discovered that he had taken EPO during the race. He admitted to the charges and retired from the sport in 2009.

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Alberto Contador (ESP) - Contador's name was tarnished by a couple of doping allegations, including the Operación Puerto case in 2006.

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Alberto Contador (ESP) - During the Tour de France in 2010 it was discovered that Contador's urine sample contained traces of clenbuterol and he was stripped of his winning yellow shirt that year, as well as of his 5th position overall in 2011.

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