The sprint stages in the Tour de France this year are quickly dwindling and, in the frantic finish to stage eight to Amiens, the desperation to win was writ large. While Dylan Groenewegen of the Netherlands took his second stage win in cathedral cities on consecutive days, there was chaos and recrimination in his wake.

Both Fernando Gaviria, the first yellow jersey in this year’s Tour, and rival André Greipel were relegated to the back of the lead group after a series of barges and butts, while Mark Cavendish, who placed eighth, accused longstanding rival Peter Sagan of “bashing” other riders out of the way.

“I followed Sagan, but following him is pretty sketchy,” Cavendish said of his sprint into Amiens. “He bashes everyone else out the way so you do get a clear run following him.”

The pair have history. Cavendish was forced to abandon last year’s Tour after bouncing off Sagan in the finish to stage four, an incident for which Sagan was thrown off the race, and led to him threatening to sue the UCI for loss of earnings.

“What can you do?” Cavendish said of Sagan. “At least it stops me having to think of excuses. I was in the perfect position. I was pretty happy. Coming around that corner with three [kilometres] to go, we knew it was pretty sketchy.”

Worse befell Dan Martin, winner of Thursday’s stage to Mûr-de-Bretagne, who hit the tarmac at speed inside the final 20km and was reduced to crawling on to his team bus on all fours at the finish.

“I’m ripped to pieces,” he said. “I landed on my bike. That’s why we thought there might be a fracture but it seems not. I bounce well.”

Dan Martin is left injured in a crash inside the final 20km. The Irishman did not suffer any broken bones but will find Sunday’s stage a major struggle. Photograph: Pool/Getty Images

Martin, who fractured two vertebrae in the Tour last year, then made his way to the medical facilities for x-rays. “It’s not as bad as I feared, and there’s nothing broken. I’ve got to try to ride over those cobblestones tomorrow. I’m going to be sore and my back is a bit of a mess.”

“Those” cobblestones are the dreaded pavé, narrow cobbled farm roads known as the “Hell of the North”, most usually associated with the spring classic Paris-Roubaix. Martin is one of several riders who are now steeling themselves for riding 21.7km of cobbles over 15 sections.

This will be no ordinary Tour stage, and with the peloton containing both specialists and novices on this treacherous terrain, large time gaps are expected. “You can’t control everything in bike racing but in those kinds of stages you can control a little bit less,” the Team Sky principal, Dave Brailsford, said. “There’s a lot more that can go wrong.”

Team Sky, like every other team in the race, is expected to deploy most of its team staff on each section of cobbles, with spare wheels in case of punctures or broken spokes. Like others, they have also thumbed their contact books to call in extra support.

“We’ll have half of Flanders working for us,” joked Brian Holm, sports director of the Belgian team Quickstep, which contains the greatest number of classics specialists.

The Tour’s defending champion, Chris Froome, often derided in the past for his lack of bike-handling skills, has also been working to up his game on the cobblestones.

“He has progressed in his movement on a bike,” Brailsford said. “Some riders have a natural affinity to the cobbles, some can learn that skill, while others are never at ease, but I’d say Chris has always been happy on gravel, dirt or cobbled roads. It’s a question of whether he can turn that to his advantage over others who don’t feel the same.

“All of the team have been up to the pavé and trained on it, and they found some rough tracks back in the south of France, where they can familiarise themselves with suspension. They will have the same suspension bikes that they used in Paris-Roubaix [this year].”

Sky, like others, are wary of a rider being stranded at the roadside without assistance, left behind by a mechanical mishap or crash.

“This stage massively increases the chance of losing the time on GC [general classification], which isn’t actually due to riding on the cobbles,” Brailsford said. “There’s enough of the pavé for long enough to make the difference between those who are comfortable or good on the pavé and those who never ride it. We’re expecting big time gaps.”