Peter Sagan takes stage as Chris Froome squeezes lead out a little

Chris Froome extended his overall lead in the Tour de France with an opportunistic attack before organisers confirmed Thursday's stage to the famed Mont Ventoux has been shortened on safety grounds.

Howling crosswinds allowed Froome to take time out of his rivals on stage 11 from Carcassonne to Montpellier as he latched on to Peter Sagan’s stage-winning move 12km from the finish, coming home second to the world champion but crucially six seconds ahead of the chasing pack.

However, those same winds have forced organisers to move the finish of Thursday’s stage 12 from the summit of Mont Ventoux to Chalet Reynard midway up the climb, shortening the day by six kilometres.

Gusts were measured at more than 100kph on top of the mountain on Wednesday, with similar forecast for Thursday. Mont Ventoux is famed for its exposed summit, but the new finish will see the race end in the relative shelter of the forest.

Organisers said the decision to shorten the stage was taken now as the entire stage would need to be cancelled if nothing was done before Thursday morning and the conditions proved unsafe.

Froome won on Mont Ventoux on his way to overall victory in 2013, but thanked the organisers for putting riders’ safety first.

“Of course I was looking forward to doing Ventoux, it’s the most iconic climb, the most legendary climb in this year’s race,” he said after extending his overall lead to 28 seconds.

“At the end of the day, apparently there are really just gale force winds and it just wouldn’t be safe for the riders so thank you to the organisers for making the decision. It’s the right thing to do.”

A bunch sprint had been expected in Montpellier but instead there was the unusual sight of the points leaders’ green jersey and the race leaders’ yellow crossing the line first and second.

Crosswinds had caused splits in the peloton throughout the day, and although the riders were back together on the final approach to Montpellier, Sagan had one more trick up his sleeve.

The Tinkoff rider was clocked at 71kph as he burst clear of the pack with team-mate Maciej Bodnar, and Froome was first to respond before being joined by Geraint Thomas.

Together the quartet pulled more than 20 seconds ahead and that was enough to keep them clear to the finish.

“It is (special),” Sagan said after the sixth Tour stage win of his career and second this year. “It was something crazy that happened. I didn’t believe we could go and after Froomey and Geraint Thomas came with us, I said ‘We’re too strong, they’re never going to catch us’. They just pulled very hard and it happened. It’s unbelievable.

“Today everybody was like ‘it’s crazy wind, it’s crazy wind’. Crazy wind was the last 15km or 12km – I don’t know how much.”

With bonus seconds applied, Froome now leads the general classification by 28 seconds from 23-year-old Briton Adam Yates of Orica-BikeExchange, with Irishman Dan Martin of Etixx-QuickStep third, 31 seconds down.

Movistar’s Nairo Quintana, seen as Froome’s main rival for victory, is fourth, 35 seconds down.

Sagan's win strengthens his hold on the points leaders' green jersey after he took it from Mark Cavendish on Tuesday and, given the mountains to come, the Slovakian looks certain to win the category for a fifth straight year barring accident or illness.

Cavendish had been hoping for a shot at a fourth win of this Tour, but as Sagan and Froome were attacking ahead, the Manxman suffered a mechanical problem and was left to cross the line alone.

Cavendish is now left with a decision to make over whether or not to stay in the race for the final day’s sprint in Paris or withdraw early and focus on preparing to compete on the track in the Olympics.

Froome took yellow with a surprise downhill attack on stage eight into Bagneres-de-Luchon, and Wednesday’s attack shows he is in feisty mood.

“Obviously I took a few seconds on the downhill and then again on the finish here,” he said.

“Any opportunity I can see I’m going to take it.”