BASTIA, Corsica >> Riders at the Tour de France know to expect the unexpected. But nothing could have prepared them for the mayhem that turned Saturday’s first stage of the 100th Tour into a demolition derby on two wheels.

Seemingly for the first time at the 110-year-old race, one of the big buses that carry the teams around France when they’re not on their bikes got stuck at the finish line, literally wedged under scaffolding, unable to move. The timing couldn’t have been worse: The blockage happened as the speeding peloton was racing for home, less than 12 miles out.

Fearing the worst — a possible collision between 198 riders and the bus — race organizers took the split-second decision to shorten the race. Word went out to riders over their radios and they adapted tactics accordingly, cranking up their speed another notch to be first to the new line, now 1.8 miles closer than originally planned.

Then, somewhat miraculously, the bus for the Orica Greenedge team wriggled free. So organizers reverted to Plan A. Again over the radios, word went out to by-now confused riders and teams that the race would finish as first intended — on a long straightaway alongside the shimmering turquoise Mediterranean, where an expectant crowd waited to cheer the first stage winner of the 100th Tour.

Then, bam! Two riders collided and one of them went down, setting off a chain of spills that scythed through the pack like a bowling ball.

And this was just Day One. The bad news for riders: They’ve still got another 20 stages and1,982 more miles to survive to the finish in Paris.

Keeping his head and riding his luck amid the chaos, Marcel Kittel sprinted for the win, claiming the first yellow jersey.

“It feels like I have gold on my shoulders,” said the German rider for the Argos-Shimano team.

The 22 teams know from experience that the first days of any Tour are always tough. Everyone is nervous, full of energy and jostling for position. Adding to the stress this year is the race start in Corsica. The island’s winding and often narrow roads that snake along idyllic coastlines and over jagged mountains are superbly telegenic but a worry for race favorites — the likes of Team Sky’s Chris Froome and two-time former champion Alberto Contador — because a fall or big loss of time here could ruin their Tour before it really begins.

Froome survived Day One more or less unscathed. Contador didn’t. The Spaniard, back at the Tour after a doping ban which also cost him his 2010 victory, crossed the line grimacing in pain, his left shoulder cut and bruised. He was tangled in the crash that threw about 20 riders to the tarmac. Contador said he’ll be sore for a few days, “but I still have enough time to recover.”

Even for the Tour, which has seen more than its fair share of dramas in 99 previous editions, Saturday’s calamitous chain of events was exceptional.

“We’ve never had to change the finish line before,” said Jean-Francois Pescheux, the event director who helps pick the route each year. “There’s never been a bus stuck before.”

The blockage at the line presented organizers with two solutions: cancel the stage entirely or shorten it, he said. They took the second option.

“We announced that in French, English, and Spanish on the Tour radio so that everybody was up-to-date,” he said. Then, “in the following three minutes, we were told that the finish line was cleared. At that point, we announced that the finish was back to the real, original finish line.”

Because of what Pescheux called “the little bout of panic and crashes” caused by this confusion, organizers subsequently decided to give everyone the same time as Kittel — 4 hours, 56 minutes, 52 seconds over the 132-mile trek from the port town of Porto Vecchio to Bastia in the north of the island.

That means no one was penalized by Saturday’s events.

“It’s clear there was a moment of panic, and that’s why we put everybody on equal footing,” said Pescheux.

“The lesson learned is that buses, that heavy vehicles, they should avoid going through the finish line,” he added.

“Everybody helped out, we deflated the tires of the bus so we could move it away as the peloton was fast approaching,” said Jean-Louis Pages, who manages the finish-line area.

Organizers fined the Orica Greenedge team the equivalent of $2,100. The team’s sporting director, Matt White, called the incident “really unfortunate.”

“We took for granted that there was enough clearance. We’ve had this bus since we started the team, and it’s the same bus we took to the Tour last year,” he said. “Our bus driver was told to move forward and became lodged under the finish gantry.”

Managers at other teams couldn’t agree who to blame or be angry with most.

Marc Madiot of French team FDJ.FR was forgiving of the bus driver but furious with race organizers for changing their mind about where to finish the stage.

But the sporting director for Contador’s Saxo-Tinkoff team, Philippe Mauduit, sided with the organizers.

“It’s not the Tour’s fault if there’s a guy who doesn’t know the height of his bus,” he said.

“What caused the problems was changing the finish,” said Mark Cavendish, the British sprinter who was counting on his great speed to win the stage but who instead was slowed by the crash. “It’s just carnage.”

His Omega Pharma-Quick Step teammate Tony Martin suffered concussion in the crash. Peter Sagan of Cannondale, another rider who was expecting to challenge for the win, finished with sticking plasters covering cuts on both legs and his left elbow. Other riders also suffered cuts and bruises. Froome’s teammate Geraint Thomas flipped over his handlebars and “really whacked the back of his pelvis,” said Dave Brailsford, the Team Sky manager.

“The goal for us is to get off this island in one piece, having lost no time,” he said. “It’s a much tougher ask than it may seem.”

“You don’t know what’s going to happen. But you know something is going to happen,” he added.

Perhaps as soon again as Sunday. The tricky second stage features four climbs along the 97-mile ride from Bastia to Ajaccio, crossing the island’s mountainous spine.

Before Saturday’s stage, French Sports Minister Valerie Fourneyron met with a delegation of riders unhappy that pre-race media coverage of the race dwelt heavily on doping in cycling.

That was partly the fault of Lance Armstrong. The disgraced former champion now stripped of his seven Tour wins caused a stir by telling Le Monde that he couldn’t have won the race without doping.

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AP Sports Writer Jerome Pugmire and Associated Press writer Jamey Keaten contributed to this report.