Denmark's Mads Pedersen sprung a huge surprise when he emerged from a rain-drenched Yorkshire road race with cycling's world title on Sunday.

As the race was shortened from 284.5km to 261km due to wet weather, over six hours and 27 minutes of exhausting racing in hostile conditions that took a huge toll on the field, the 23-year-old unleashed an astonishing late burst.

He left a devastated Italian Matteo Trentin and Swiss rider Stefan Kung trailing in the silver and bronze positions.

"That's an unbelievable day, I didn't expect this morning," said the Leopard-Trek team rider, who enjoyed great success at under-23 level.

"After six and a half hours on the bike like that, everyone is on the limit and anything can happen," he added.

"It was just survive, survive, and survive. Then hope for the best in the sprint," said Pedersen, who was far from favorite to beat Italian 30-year-old Trentin, usually a crack in the sprints.

"When I saw the finish line, I thought, 'anything can happen'," he said.

The race was shortened Sunday morning as relentless overnight rain took its toll on the narrow roads through the Yorkshire dales, flooding an iconic hilly section of the route that featured in the 2014 Tour de France which was cut out altogether.

In the brutal conditions, only 46 of the 182 starters crossed the finish line.

The rain also turned the Harrogate fan park into a quagmire and grounded the television helicopters.