The 1978 Tour de France was the 65th edition of the Tour de France, one of cycling's Grand Tours. The Tour began in Leiden, the Netherlands, with a prologue individual time trial on 29 June, and Stage 12a occurred on 12 July with a flat stage from Tarbes. The race finished in Paris on 23 July.
The stage was neutralised after a protest, by the peloton, about split stages. The peloton rode slowly throughout the stage, and came to a stop 100 m (330 ft) before the finish line. The riders then dismounted their bikes, crossing the finish line on foot, and the stage was cancelled by the race commissaires.