The Manxman only returned to racing in June at the Tour of Slovenia, having stopped racing after finishing Milan-San Remo in March and becoming ill.
After racing the British National Championships road race last week, he was selected for the Dimension Data Tour de France squad despite question marks over his fitness.
While Cavendish has retained his trademark confidence, saying he still believes he is the world's best sprinter, he says he has to be realistic about what he can expect from himself at this year's Tour.
“I truly believe that I am the best sprinter on the planet,” said Cavendish in an interview with the Times. “Without this illness, I would be going in looking to pass the [stage] record this year.
“The competitive fires are burning but I have to be realistic. It’s like, you know, Ducatis are going to be faster than Hondas. I’m not firing like a Ducati right now.”
Asked if he was planning on ducking out of the Tour after the opening week of racing, which sees at least three sprint opportunities, the 32-year-old said he wouldn't have come at all if that was the plan.
With 30 stage wins to his name, Cavendish is on the cusp of extending his legacy as cycling's greatest ever sprinter if he can get past Merckx's record of 34.
With nine potential sprint stages on offer through the entire Tour, it would certainly be a possible for a fully fit Cavendish, who says that he'll find it hard if he begins consistently losing at the 2017 Tour to rivals like Marcel Kittel (Quick-Step), André Greipel (Lotto-Soudal) and Peter Sagan (Bora-Hansgrohe).
Cavendish added that he had to weigh up whether he would be doing "more damage" by turning up undercooked at the Tour, saying "I could be setting up myself to fail."
“If I was planning on bailing after a week, I wouldn’t be going to the Tour at all,” Cavendish said. “The hardest thing for me is sprinting and losing.
“Not just because it’s damaging to my morale, the team’s morale, but it’s actually good for the other sprinters’ morale and once you are on a roll at the Tour, you build on that.
“I had to ask myself, ‘Would I do myself more damage not winning?’”
“As soon as we start on Saturday, a lot of journalists will forget I have been ill, that I’ve had glandular fever.”
“Half won’t have had it, half don’t like me anyway. A few people won’t even know.
"I could be doing myself more damage going and not winning than not going at all. I could be setting up myself to fail.”
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