[1][2] Duggan turned professional in 2005 with TIAA–CREF (Slipstream Sports), which morphed into Garmin.

During his time with Liquigas–Cannondale, Duggan won the 2012 United States National Road Race Championships.

Born in Boulder, Colorado, Duggan skied competitively in high school, and became involved in cycling to maintain conditioning during the off season.

[3] In 2008, while racing at the Tour of Georgia, Timmy was involved in a high speed crash on a descent that resulted in a severe, life changing head injury (sub-arachnoid hemorrhage and subdural hematoma) and was forced to take nearly a year out of racing.

[4] However, the team was disbanded prior to the end of 2012, and Duggan was freed from his original contract.