Chris Froome keeps yellow as Geraint Thomas and Richie Porte head home

Geraint Thomas and Richie Porte crashed out of the Tour de France on a chaotic, incident-strewn day which saw Chris Froome extend his lead in the yellow jersey as Rigoberto Uran won stage nine.

The 181.5 kilometre stage from Nantua to Chambery had it all: a succession of crashes, Fabio Aru attacking the yellow jersey when Froome had a mechanical problem, and Uran beating Warren Barguil in a photo finish despite losing the use of most of his gears in the finale.

Amid all of that, several contenders shipped time after seven categorised climbs – three of them hors categorie – and 4,700 metres of ascent.

When the dust settled, Froome’s lead in yellow increased from 12 seconds to 18 – now over Astana’s Aru rather than his Sky team-mate Thomas – after he finished third in a sprint between the general classification hopefuls to take the final bonus seconds.

Thomas suffered a broken collarbone in a crash on the damp descent of the Col de la Biche, the first hors categorie climb of the day, while there was clear concern for Porte after a frightening high-speed crash on the way down the Mont du Chat.

The Australian was travelling at 72.5km/h when he ran onto the grass on the inside of a corner, hit the deck and then slid across the road into an embankment, collecting Irishman Dan Martin of Quick-Step Floors as he went.

BMC later said Porte had suffered a fractured collarbone and pelvis.

“Normally a fractured clavicle (collarbone) and pelvis would require four to six weeks’ recovery, providing there are no complications,” team doctor Max Testa said in a statement.

BMC sports director Fabio Baldato said the 32-year-old had remained conscious throughout.

“What was important, he was always conscious, he knew what happened,” he said. “He was asking for his helmet, his glasses.”

The crashes were not the only cause of drama.

Froome suffered a mechanical problem on the way up the Mont du Chat, the last of three hors categorie climbs on the day, and as the three-time Tour winner was calling for the team car Aru attacked in a clear breach of cycling’s protocol.

Froome’s other rivals followed the Italian, seemingly in order to remonstrate with him and tell him to wait.

“I wasn’t aware of Fabio attacking,” Froome said. “I only found out at the finish. At the time I was too busy looking for my team car to get a spare bike. From what I understand it looked like Richie (Porte) had said to my other rivals, ‘Listen guys, this is not the moment to attack when the leader of the race has got a mechanical’.

“I want to say thank to you Richie and thank you to the rest of the group for not taking advantage.”

Froome appeared to ride into Aru after he had caught back up, but insisted it was not a barge in retaliation for the attack.

“I just had a bit of a wobble on a switchback,” he said. “It wasn’t a swipe at Aru or anything like that.”

After being caught in Porte’s crash, Martin fell again on the way to the foot of the mountain, and the Quick-Step Floors rider made his feelings clear about a stage design with such a strong emphasis on high-speed descending.

“Richie lost it on one corner – it was so slippery, I guess the organisers got what they wanted,” he said. “It was so slippery under the trees. I was very, very lucky to get away as lightly as I did.”

After picking himself up, Martin finished in a group including Movistar’s Nairo Quintana and Orica-Scott’s Simon Yates, one minute and 15 seconds behind the leaders.

Martin dropped from fourth to sixth overall, one minute 44 seconds down, 18 seconds ahead of Bury-born Yates who retains the white jersey as the best young rider.

Frenchman Romain Bardet is up to third, with Uran fourth after his stage win.

But Quintana’s ambitious Giro-Tour double bid appears to be extracting a heavy price – he is now two minutes 13 seconds down in eighth while two-time Tour winner Alberto Contador slipped all the way to 12th after shipping four minutes.

Thomas’ crash was his fourth of a race he led for four days after winning the opening time trial, something which already feels a long time ago.

“I can’t really think about that at the moment,” Thomas said. “I’m just thinking of the devastation of leaving the Tour and another Grand Tour. I crashed at the Giro (d’Italia) on stage nine, and it’s stage nine again here. I was lying second overall on both days as well. It’s just so disappointing.”