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 are not on their bikes got stuck at the finish line, literally wedged under scaffolding, unable to move. The timing couldn’t have been much 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, 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 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.

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

And this was merely Day One. Riders have another 20 stages and 1,982 more miles to survive to the finish in Paris.

Keeping his head and riding his luck amid the chaos, German Marcel Kittel of the Argos-Shimano team sprinted for the victory, claiming the first yellow jersey.

“It feels like I have gold on my shoulders,” he said.

He might have had Teflon on them during the stage, though.

The crash that caught his rivals also took down a number of general-classification contenders, including Spaniard Alberto Contador of the Saxo Bank-Tinkoff team and Tacoma-born Tejay van Garderen of BMC Racing.