In April 2017, Thomas became the first British rider to win the Tour of the Alps (formerly known as the Giro del Trentino). Thomas won the third stage of the race, taking the leader's fuchsia jersey as a result, and ultimately won by seven seconds ahead of Thibaut Pinot (FDJ). Thomas began the Giro d'Italia strongly, finishing third on stage 4 to Mount Etna to sit second overall for the rest of the first week. However, on stage 9, as the peloton approached the final climb of the day to Blockhaus, Wilco Kelderman of Team Sunweb collided with a police motorcycle which had been parked at the side of the road. This caused him to swerve to his right into the Sky riders, who were in a line in the peloton, and resulted in Thomas and the majority of his teammates being brought down. Thomas reported his shoulder popped out during the crash, but he remounted to complete the stage, dropping to 17th in the standings, five minutes and 14 seconds behind Nairo Quintana. After a rest day, Thomas recovered to finish second to Tom Dumoulin on stage 10, a individual time trial, to move back up to 11th overall. However, after losing further time on the next two stages, Thomas withdrew from the race with a worsening knee injury.