LONDON • Cyclist Chris Froome - fresh from wrapping up a Tour de France and Vuelta a Espana double - believes winning all three Grand Tours in the same year is possible, but will require a massive effort.

Froome, 32, completed victory in the Vuelta on Sunday to become only the third man to achieve a Tour-Vuelta double in the same year and the first since Bernard Hinault in 1978.

The first rider who achieved the feat was Frenchman Jacques Anquetil in 1963.

No rider has ever pulled off a Giro-Tour-Vuelta treble .

"I wouldn't say it's impossible," the British rider, a four-time Tour de France champion, told BBC Radio Four on Monday.

"Nothing's impossible, but certainly it would take some doing."

He was more circumspect about surpassing Belgian Eddy Merckx's record of 11 Grand Tour victories.

"A completely different era," added Froome, who finished second in the Vuelta three times (2011, 2014 and 2016) before finally securing the red jersey.

"Eddy Merckx's time of racing, he was able to win every single race on the calendar. The sport has transformed since his time."

Froome's double triumph came after a tough period for Team Sky.

Bradley Wiggins, Froome's former team-mate, was revealed to have obtained permission to use a powerful corticosteroid before the 2011 and 2012 Tours - the latter of which he won - and the 2013 Giro.

Wiggins and team principal Dave Brailsford said the rider's use of the drug, which was sanctioned by cycling authorities, was necessary for medical reasons.

Sky, who have denied any wrongdoing, are also under investigation by UK Anti-Doping over a package that was sent to Wiggins during the 2011 Criterium du Dauphine.

When asked if his support for Brailsford was unequivocal, Froome replied: "Certainly."

AGENCE FRANCE-PRESSE