Professional biker Alberto Contador has been suspended for testing positive for Clenbuterol. Traces of the bronchodilator were found in urine he provided during the Tour de France in July.

So far, Contador is denying the use of any banned substances, but most people aren’t buying it.

Clenbuterol is a sympathomimetic amine used by people who have breathing disorders. It is commonly used by people with asthma to help them breath easier. Clenbuterol is not a steroid, like some people believe. However, it is a performance enhancing drug since it helps oxygen transport throughout the body more efficiently.

The 27-year-old Alberto Contador Velasco is a road bicycle racers for UCI ProTeam Astana of Spain. He is known for winning the 2007 Tour de France while a member of the Discovery Channel team.