Scores of prisoners and their guards set off Thursday on a unique Tour de France cycling race for convicts, aimed at preparing them for life on the outside.

The prisoner cyclists have to stay in a pack and no “breakaways” are allowed during the 15 stages of the inaugural race that covers 2,300 kilometres (1,400 miles) from Villeneuve d’Ascq in northern France to Paris on June 18.

Twenty-three inmates and 57 staff went under the starter’s gun, of whom 18 — including just six prisoners — will complete the full course. A total of 196 inmates and 300 staff will take part throughout the event’s various stages.

As in the real Tour de France, which starts next month, the cyclists will be escorted by a “caravan” of technical support vehicles, medical teams, and gendarmes on motorbikes and in cars.

“The aim is to show that sport is a teaching tool,” said Jean-Paul Chapu, the director of a jail in the northern town of Loos who initiated the project.