CHRIS Froome strengthened his grip on the yellow jersey in the most bizarre circumstances after stage 12 of the Tour de France ended in chaos on the slopes of Mont Ventoux yesterday.

Froome was reduced to running up the mountain on foot after his bike was broken when he, Richie Porte and Bauke Mollema collided with a television bike on the crowded road a little over a kilometre before the finish line.

He ran as fast as his cycling shoes would carry him before taking a bike from the neutral service car, but struggled to gain traction on the ill-fitting machine and had to swap it again when his team car finally made it through.

Froome lost around a minute and a half on the road and slipped to sixth on the provisional general classification, 53 seconds behind Bury's Adam Yates, before the race jury intervened.

They ruled Porte and Froome should receive the same time as Mollema after the Dutchman got back on his bike and stayed clear of the chasing rivals.

"Ventoux is full of surprises," said Froome. "With about 1.2km to go, the motorbike slammed on its brakes – the road was blocked in front – the three of us just ran into the motorbike and another motorbike ploughed into me, breaking my frame. I just started running. I knew the (team) car was stuck and was five minutes behind.

"I think it was a fair decision, and I want to thank the jury and the organisation. It was the right decision."

Froome now leads by 47 seconds from Yates, with Mollema third at 56 seconds behind and Quintana fourth, one minute and one second back. Etixx-QuickStep's Irishman Dan Martin, who started the day third, struggled on the climb and dropped to ninth, one minute and 56 seconds back.

The 23-year-old Yates was in line for yellow before the race jury's decision, but endorsed the ruling.

"I don't want to take the jersey like that," the Orica-BikeExchange rider said. "I'd rather take it with my legs and not a crash in a bad situation.

"Everyone saw it, I don't think anyone would want to take it that way. If I was in the same situation in the yellow jersey, I'd want the same outcome."

Yates benefited from a similar decision on stage seven to Lac de Payolle when the flamme rouge banner collapsed on to him – another incident caused by a spectator – but he was given back the lost time.

Froome began the day 28 seconds clear of Yates and was looking to extend that advantage when he attacked alongside former team-mate Porte, now of BMC, late on a stage which was won from the breakaway by Lotto-Soudal's Thomas De Gendt.

The pair were joined by Trek-Segafredo's Mollema and were comfortably ahead of a group including Yates and Movistar's Nairo Quintana before calamity struck and there was the bizarre sight of the yellow jersey running up a mountain.

"Perhaps next year Chris will do the Paris Marathon," said Team Sky principal Sir Dave Brailsford.

Froome was fined for punching a fan who got too close during stage eight, but this incident will revive the debate over riders' safety when huge crowds gather on the mountainside.

"It was pretty dangerous (with the fans) but the fans make the sport," Yates said. "There are not many sports where the fans can get so close, but it is what it is."

Yates, meanwhile, maintained his lead in the race for the white jersey – for the best young rider in the Tour – finishing the day where he started, 1mins 42secs in front of South African Louis Meintjes.