Stephen Roche advises Bradley Wiggins to be open, frank and honest with those who question his credentials as the three-time Olympic champion prepares for his tilt at the Tour de France title.

Despite doing his utmost to prove his status as a clean rider, the spectre of doping looms large over cycling, with cynics already questioning Wiggins' remarkable run of victories never before achieved in the sport.

Wiggins enters the Tour, which begins on June 30, having won the Paris-Nice, Tour de Romandie and Criterium du Dauphine stage races this season.

The 32-year-old Londoner's, who finished fourth in the 2009 Tour, sense of humour and tendency for sarcasm has perhaps been misinterpreted.

Roche, the 1987 Tour champion, understands Wiggins' frustrations with being asked the questions, but insists answers are necessary.

"You're always under suspicion," Dubliner Roche said.

"It's only because of what's been happening in the last 15 years - and I understand that. It's important to answer questions, it's important not to avoid the questions."

"Bradley can answer those questions by riding his bike and inviting people to his training camp. That's great.

"But at the same time, someone will say 'we're not with him at night time, what's he doing then?' The only thing Bradley can do is keep his chin up and keep going forward."

While outsiders might suggest Wiggins has come from nowhere to contend in the Tour, Roche points out that the Team Sky leader first won an Olympic medal in the velodrome in Sydney 12 years ago.

Wiggins has long been a supreme talent on a bike and his meticulous preparation for the Tour in Tenerife and elsewhere now appears to be paying dividends.

Roche added: "Bradley Wiggins hasn't just come out and won Romandie, Paris-Nice and had all these great results.

"He's been knocking on the door for a long, long time, putting hours of training in for the last 15, 20 years.

"He was a trackie before he came on to the road and needed a period of adaptation to get on to the road.

"Don't just look at what he's doing now, look at where he's come from.

"He always was a hungry man as well. Add all those things up and you get what you get today."