Tom Zirbel (born October 30, 1978) is an American former road bicycle racing cyclist, who rode professionally between 2006 and 2016 for the Bissell, Jamis–Sutter Home and Rally Cycling teams.

[2] Zirbel denied having taken the substance knowingly, but he nevertheless voluntarily accepted a two-year suspension, and immediately announced his retirement.

His suspension was reduced in March 2011 to 18 months, which had already been served, in recognition of assistance given to the United States Anti-Doping Agency (USADA).

[1] In an interview with cyclingnews.com in early 2016, Zirbel confirmed that the upcoming season would be his last as a professional cyclist before retiring.

[4] In September of that year, he set a new American national hour record in Aguascalientes, Mexico, completing 53.037 kilometres (32.956 miles) to break the 1997 record of 51.505 kilometres (32.004 miles) set by Norman Alvis.