Spaniard Sastre believes that most riders are clean

Tour de France winner Carlos Sastre believes cycling is heading for "better times" after years of doping scandals.

Four riders tested positive for banned substances during the Tour, but Sastre is confident that cycling is making progress in its battle against cheats.

"There will always be cheats, but the vice is tightening each day," he said after his first Tour de France win.

"Certainly suspicions exist but we are getting closer and closer to better times. I am sure of that."

Kazakhstan's Dmitri Fofonov tested positive after stage 18 of the 2008 Tour, when it emerged he had taken heptaminol.

I am saying very forcefully that the majority of the riders are doing things honestly Tour de France winner Carlos Sastre

He joined Italy's Ricardo Ricco and Spanish duo Moises Duenas Nevado and Manuel Beltran in testing positive during the Tour.

But Sastre added: "I am saying very forcefully that the majority of the riders are doing things honestly.

"I know I am, and I know the sacrifices I have always had to make to be wearing this yellow jersey."

The race has been undermined by doping scandals in recent years and the 2007 Tour saw pre-race favourite Alexandre Vinokourov test positive and yellow jersey holder Michael Rasmussen withdrawn from the race after it emerged he had missed out-of-competition drugs tests.

Patrice Clerc, the president of Tour organiser Amaury Sport Organisation, said after the 2007 doping scandals: "Cycling is on the edge of the abyss."

Tougher rules were introduced and 2007 winner Alberto Contador was unable to defend his title this month because of his association with the Astana team, whom Vinokourov represented.

Meanwhile, Sastre said that he hoped his Tour victory would not impact on his desire to retain a low profile.

"I like to come to the fore on the bike and not in front of the cameras," said the 33-year-old.

"But my life is not going to be turned upside down because I have won the world's biggest race.

"I have always wanted to protect my family as much as possible. I have never liked to expose them.

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"This victory is the most amazing page of my life but I will exchange no victory in the world for the tranquillity of my family."

The CSC rider retained the lead he carried over from Saturday's decisive time trial and cantered to the finish among the peloton on Sunday to win by 58 seconds.

Australia's Cadel Evans, runner-up in 2007, took second place again, while Austria's Bernhard Kohl was third.