Yesterday's Il Lombardia marked the end of David Zabriskie's long and successful career as a professional bike rider. The American preferred a low-key exit from the sport and is at peace with his decision to end his career as an athlete.

It came as a surprise to many when rumours started to circulate on Twitter that Il Lombardia could be the final race of David Zabriskie's career. While his Garmin-Sharp team had said proper farewell to Christian Vande Velde by issuing a press release ahead of his final race at the world team time trial championships, few had any clue that Zabriskie was about to park his bike in the garage.

Nonetheless, Zabriskie has indeed chosen to bring his successful career to an end and when he pinned off his number to abandon yesterday's race, it marked the start of his time as an ex-professional. The American made the decision some time ago and chose to have a low-key exit from the sport.

"The time for me to stop has come. I'm at peace with that," he told Cyclingnews prior to the race. "I unfortunately had a bad season with the injuries and hardly raced at all. That gave me a lot of time away from the sport this year and that helped me reach my decision to not pursue it anymore."

"My body feels it's the right moment too. My left leg is all crappy. I still feel the effects of the car hitting me in 2003."

Zabriskie turned professional in 1999 with the 7-UP/Colorado Cyclist Team and joined the US Postal team in 2001. He won a stage of the 2004 Vuelta a Espana from a fantastic solo attack and continued his career at Team CSC where he beat Lance Armstrong in the 2005 Tour de France stage 1 time trial and wore the yellow jersey until crashing in the team time trial a few days later. He left Team CSC to join his current Garmin squad where he finished 2nd in the Tour of California three times.

Throughout his career, Zabriskie has been known as one of the best time triallists in the peloton with TT stage wins in both the Tour and the Giro. He finished 3rd in the 2008 world championships and he has won his nation championships in the discipline a massive 5 times.

His career has been tainted by his doping confession that was part of the process that led to the fall of Lance Armstrong. Following the 2010 Tour of California, he admitted to having been doped from 2003 to 2006 when the fall of his close friend Floyd Landis prompted him to stop his use of banned substances. He served a 6-month ban over the winter and returned to competitive action in March.

His final season wasn't one to remember. He crashed during the warm-up to the Tour of California time trial and hardly raced all season. He returned to competition in the Tour of Utah and raced all three major North American autumn stage races when he also lined up at the USA Pro Challenge and the Tour of Alberta. He was back in European action at the world team time trial championships before abandoning his final two races, Milan-Turin and Il Lombardia.

Zabriskie is the third big-name rider who announced his retirement last week. Juan Antonio Flecha and Marco Pinotti will put an end to their careers in the Tour of Beijing and the GP des Nations respectively.