Answer
Tour de France basically means "journey through France", so it can't really be held anywhere else.
There's another fairly well known competition that's called "Giro di Italia", which, guess what, is held in Italy. Plenty of bike races are named after where they're held.
Answer
Because it's an important sport event for French people. And it occurs in France because a Tour de France in Spain (for example) would not be the same!
"Tour de" basically means "tour of". So tour de France = tour of France.
Le tour de France
"Tour de France on TV" is "(le) Tour de France à la télévision" in French.
Tour de France Tour de France
Yes. He's done it!
Bicycles are raced in the Tour de France
bradley wiggins won the tour de france
Tour de France Féminin was created in 1984.
André Leducq, France, won the 1932 Tour de France
Rene Pottier won the 1906 Tour de France.
The Tour de France is not a sport - it is an event.
Maurice Gauring won the 1904 Tour de France.