After riding on amateur teams Team Winfix and Team AKUD Arnolds Sicherheit, in 2005 he became a professional rider for Team CSC after a recommendation from Dennis Kraft, signing on for a 2-year contract.
In his first year as a pro, he won the 7th stage of the UCI ProTour race Tour de Suisse and had the leader's jersey in Four Days of Dunkirk.

In late 2005 he agreed to a contract with rival UCI ProTour T-Mobile Team, starting from 2006.
This got Team CSC owner Bjarne Riis to release Gerdemann from his contract at the end of 2005.

On Saturday 14 July 2007 he secured his biggest victory in his career, the seventh stage of the Tour de France from Bourg-en-Bresse to Le Grand-Bornand.
The stage win gave him the yellow jersey as leader of the general classification, as well as the white jersey as leader of the young rider classification.
He was also awarded the combativity award for this stage.

In March 2008 he sustained injuries from a crash in the Tirreno–Adriatico and was unable to race in the 2008 Tour de France or the Beijing summer Olympics.
He came back from his injuries to win the Deutschland Tour in August 2008.

Gerdemann also won the Tour of Luxembourg in 2011 and 2015.
After riding on amateur teams Team Winfix and Team AKUD Arnolds Sicherheit, in 2005 he became a professional rider for Team CSC after a recommendation from Dennis Kraft, signing on for a 2-year contract. In his first year as a pro, he won the 7th stage of the UCI ProTour race Tour de Suisse and had the leader's jersey in Four Days of Dunkirk.
In late 2005 he agreed to a contract with rival UCI ProTour T-Mobile Team, starting from 2006. This got Team CSC owner Bjarne Riis to release Gerdemann from his contract at the end of 2005.
On Saturday 14 July 2007 he secured his biggest victory in his career, the seventh stage of the Tour de France from Bourg-en-Bresse to Le Grand-Bornand. The stage win gave him the yellow jersey as leader of the general classification, as well as the white jersey as leader of the young rider classification. He was also awarded the combativity award for this stage.
In March 2008 he sustained injuries from a crash in the Tirreno–Adriatico and was unable to race in the 2008 Tour de France or the Beijing summer Olympics. He came back from his injuries to win the Deutschland Tour in August 2008.
Gerdemann also won the Tour of Luxembourg in 2011 and 2015.
Linus Gerdemann