Image 1 of 3 A thoughtful Bradley Wiggins (Team Sky) (Image credit: Fotoreporter Sirotti) Image 2 of 3 Bradley Wiggins (Team Sky) kept in touch until the final few moments (Image credit: Bettini Photo) Image 3 of 3 Tour de France 2012: Wiggins triumphs in the final time trial to become the first British winner of the Tour de France (Image credit: View over Abinger Hammer cricket ground as the peloton ride by fans in the Surrey countryside sitting in their local watering hole)

As Chris Froome and his Team Sky teammates continue their final preparation for the Tour de France at training camp in the Alps, doubts about Bradley Wiggins's future at the team have emerged, with reports that he is refusing to ride the Vuelta Espana and a suggestion that he may never again lead Team Sky in a Grand Tour.

Writing in Times and the Australian newspapers, chief sports reporter Owen Slot suggested that Wiggins' career has 'fallen off a cliff' after the heady heights of his 2012 Tour de France victory and his gold medal in the time trial at the London Olympics.

The papers claim that Froome has been offered a contract extension beyond 2014, with Team Sky logically keen to build the next phase of the British team around the Tour de France favourite.

Wiggins also has a contract for 2014 but will be 34 next April and is unlikely to continue racing much longer. He has not been selected for Team Sky's Tour de France squad due to a knee injury that forced him to miss the Tour de Suisse.

Slot highlights the difference in character and performance between Wiggins and Froome, writing: "Froome is a very manageable athlete, whereas Wiggins has been deciding this year which training camps he will or will not attend. Froome is also more consistent; Wiggins has up years and down years. And Froome's performances are flat lining at a very high level."

No Vuelta Espana

The British newspaper reports that Wiggins is currently training in Mallorca after intense treatment on his knee but that he has made it clear to Team Sky that he does not want to ride the very mountainous Vuelta Espana. Instead he could ride the Tour of Poland and the Eneco Tour as preparation for the world championships in Florence.

Speculating long term, with Richie Porte apparently set to lead Team Sky at the Giro d'Italia in 2014, the Times goes as far as suggesting that Wiggins may never again lead Team Sky in a Grand Tour.

"It becomes reasonable to ask if Wiggins will lead a Sky team in a Grand Tour again. Will the Tour de France winner even ride again in that race? And have we seen the best of him?"

Team Sky has remained tight-lipped on Wiggins' conditions and his goals for the rest of the season, with only British Cycling head coach Shane Sutton publicly urging Wiggins to bounce back and find new goals.

