Bradley Wiggins admits he hasn't yet been able to find his top form at this year's Tour de France.

Wiggins, unlike last year when he was fourth behind Alberto Contador, has been one of a number of top riders who have struggled to stay with the elite front group at this year's race and it was a similar story on Sunday as the route hit the Pyrenees.

The 30-year-old Londoner, three times an Olympic champion on the track, conceded four minutes 59 seconds to Christophe Riblon, who won the 184.5-kilometre 14th stage from Revel to Ax-3-Domaines.

Wiggins now lies 18th overall, 11mins 30secs behind yellow jersey incumbent Andy Schleck.

But with six days of racing remaining, Wiggins stressed that he will battle on, saying: "I just haven't got it as I did last year. I don't know why - form is a funny old thing. I'm just trying my hardest, battling on rather than giving up.

"It's disappointing but that's the reality. There's no point kidding yourself that it's going to happen. All you can do is keep pushing on. I think I have a duty to the team and to the race itself. The support out there is fantastic, I'd hate to give up.

"I'll just keep pushing on every day and do my best and see what that is in Paris. Then I'll come back next year and try again."

Looking at his preparation for this year's race, Wiggins said everything had appeared to go to plan, adding: "It's the first year I've really tackled it full on like this but I'd recovered well from the Giro d'Italia and did some good stuff in training. That suggested I was pointing in right direction, but it's obviously another thing doing it in racing, day in, day out. It's another thing altogether. And you can't account for what other people are doing.

"But I'm not giving up on anything at this stage. It's a funny old race at the moment, the second part of the GC, and tomorrow I might have a good day."