The 194 inmates, escorted by 124 prison guards and sports instructors, will set off from Lille and cycle about 2,400km (1,500 miles), ending up in Paris.
They will have to cycle in a pack, will not be ranked and, for obvious reasons, breakaway sprints will not be allowed.
Prison authorities say they hope the race will help the inmates learn values such as team work and self esteem.
The prisoners, all serving jail terms of between five and 10 years, will make stopovers in 17 different towns, each of which has a jail.
"It's a kind of escape for us, a chance to break away from the daily reality of prison," said a prisoner identified as Daniel at the project's launch in May.
"If we behave well, we might be able to get released earlier, on probation," he said.
Prison official Sylvie Marion said the project aims to help the prisoners "reintegrate into society by fostering values like effort, teamwork and self-esteem".
"We want to show them that with some training, you can achieve your goals and start a new life," Reuters quoted her as saying.
Source: BBC News/Europe