ESPN Cycling

MENDRISIO, Switzerland -- Kristin Armstrong won the women's time trial at the road cycling world championships Wednesday, then confirmed she will retire after competing in this weekend's road race.

The reigning Olympic champion timed 35 minutes, 26.09 seconds over two laps of the 16.7-mile course, beating Noemi Cantele of Italy by 55 seconds. Linda Villumsen of Denmark trailed by 58 seconds to take the bronze medal.

"I can't think of any better way of saying goodbye to the sport," Armstrong said, cradling her gold medal with both hands as she spoke. "I had a little bit of motivation today. Now I hope another American can come out on top on Saturday."

The 36-year-old Armstrong dominated the 41-rider field to win her second time trial world title. The first came in 2006.

"It doesn't matter how many times you become world champion, it's always the best feeling in the world," Armstrong said. "I just wanted to focus on going as hard as I could possibly go."

Armstrong led at every time check and extended her lead the farther she went, recording an average speed of 28 mph. The effort on a hot day in the Swiss Alps left her slumped over her handlebars after crossing the finish line.

Armstrong said she will return to the U.S. to help young riders develop their careers. She recently launched a cycling academy in her home city of Boise, Idaho, and will work with a professional team based in California.

"I will be helping young riders come over to Europe," she said. "I want to give back to the sport and spend some time at home."

In the men's under-23 time trial Wednesday, Jack Bobridge of Australia captured the gold medal with a time of 40 minutes, 44.79 seconds on the 20.6-mile course, more than 18 seconds faster than Portugal's Nelson Oliveira.

Patrick Gretsch of Germany, last year's silver medalist, was more than 27 seconds back in third.

"It's absolutely fantastic," Bobridge said. "I couldn't ask for more. It's topped off an awesome year for myself."

International Cycling Union president Pat McQuaid said Wednesday that the governing body couldn't prevent Alejandro Valverde, the Spanish Vuelta winner, from lining up at the world championships before the Court of Arbitration for Sport rules on his appeal against a suspension.

"The rules say Valverde can start and we have to follow the rules," McQuaid told The Associated Press.

Sport's highest court soon will hear Valverde's appeal against a two-year ban on racing in Italy, imposed by the Italian Olympic committee in May.

If CAS rules against the 29-year-old rider, the UCI is expected to extend the ban worldwide and strip him of victories gained since the Italian sanction.

Britain's Mark Cavendish pulled out of the road race because of an illness. The winner of six stages at this year's Tour de France had been selected to ride in the race Sunday, but the British cycling federation said on Wednesday that he would not take part.

The 24-year-old sprinter had withdrawn from the Tour of Missouri earlier this month because of a lung infection.

The UCI announced that the Netherlands region of Limburg will host the road world championships in 2012. The 2010 road worlds will be held in Melbourne and Geelong, Australia, and in Copenhagen, Denmark, the year after.

Information from The Associated Press was used in this report.