After having narrowly missed selection for the 1992 Italian Olympic pursuit team, Collinelli gradually improved his individual performance. After four Italian titles, he he won a silver medal at the 1995 World Championships, making him a medal candidate for Atlanta. At the Stone Mountain Velodrome, Collinelli impressed, breaking the World Record twice in the preliminary rounds. The second mark was never recognized as such, because Collinelli did not want to lose time by taking a doping test. Wet weather prevented another record in the final, but Collinelli took home the gold. He never won the world title in the individual event, but succeeded with the team in 1996. In 1998, he also won a silver medal in the Madison. Collinelli was set to return to the Olympics in 2000, but tested positive at the Italian Championships prior to the Games, and was banned for 10 months.
Italy