Cavendish claimed the world champion's prestigious rainbow jersey by winning last year's race over a much more favourable course in Copenhagen, but is realistic about his hopes this time around.
Cavendish told Belgian newspaper Het Nieuwsblad: "The chances of retaking my world title are non-existent. Ten times around the Cauberg is just too much for me. We have to be realistic.
"I can't win, but I'm here out of respect for the jersey and because I'll be wearing race number one. I always enjoy racing in the colours of the national team.
"The Tour means a lot to my career, but as world champion you wear the most beautiful jersey ever for a year. The rainbow stripes have something magical. All great champions have worn them."
The Great Britain team are expected to focus on trying to push recent Tour of Britain winner Jonathan Tiernan-Locke into medal contention.
Tiernan-Locke is better suited to the course, but still inexperienced over the 267km distance.