Sara Carrigan, an Olympic road champion in 2004, has announced her retirement from professional cycling, Cycling Australia reported on Wednesday.

The 28-year-old Carrigan represented Australia at eight world championships, two Commonwealth Games and two Olympic Games. Four years ago in Athens she won gold in the road race.

Carrigan was twice Australian champion in the road time trial and won a clutch of victories in international races around the world.

"I am excited about my new adventures but it is sad and emotional for me to let go and say goodbye to what has been half my life," Carrigan said. "I'd like to thank everyone for their support, they have helped make me who I am today.

"I'm in it to be the best, and if I feel I don't have that kind of focus or commitment to win and conquer all, it is the right time for me to walk away.”

Carrigan will now turn to completing her bachelor's degree in business; she is majoring in property and development at Griffith University.