Seventeen years after Sir Bradley Wiggins won his first medal at a major championship, at the 1998 Commonwealth Games, he is entering the final stage of his own personal tour.

In the Tour of Yorkshire, which begins today, Wiggins will race for the first time as a member of Team Wiggins, the team he formed last year to be a vehicle for his quest for a fifth and final Olympic gold medal, in the team pursuit, in Rio next year.

Today begins the final chapter of an illustrious career but the fact that Wiggins is continuing at all is intriguing in that it poses a question that has attached itself to the late stages of many great sporting careers. What more does he have to achieve?

He was, along with Sir Chris Hoy and Victoria Pendleton, a founding member of the golden generation of British cycling, a group who helped transform a minority sport into a mainstream, mass-participation colossus. Both Hoy and Pendleton retired in the aftermath of London but Wiggins vowed to continue.

It seemed a curious choice. Wiggins was in his 30s, admittedly not particularly old for a cyclist but not young either, and he had lived the life of an elite athlete for over 15 years - a lifestyle that is limiting in the extreme. Wiggins is an interesting, at times spiky character, and there were aspects of being a well-known and successful sporting figure that he clearly disliked. The most notable of these was dealing with the media, a requirement which he has often met with thinly-veiled disdain.

During the 2012 Tour, he became increasingly angered by the obligatory doping-related questions routinely directed at the wearer of the yellow jersey, which eventually led to him writing a riposte to the allegations that were being slung in his direction, as well as at the sport as a whole.

While the cynicism regarding doping is far less obvious in track cycling than it is in road cycling, Wiggins knows he will remain the primary focus of media attention for the British Cycling team for the next year or so. So why is he continuing? He is already the equal-most-decorated British Olympian of all time in terms of number of medals and it seems unlikely that one more would propel his legacy into another stratosphere.

Perhaps Wiggins feels like he still has something to prove. In an interview with Cycling Weekly, Shane Sutton, Wiggins' long-time mentor and the man who will oversee his return to the track, believes that his remarkable palmares does not get the credit it deserves. "People don't appreciate Bradley Wiggins for what he's achieved," said Sutton. "Can Mo Farah win the 100m through to the marathon? No chance. This guy's won everything, from the track through to time trials, from the Madison, team and individual pursuits through to the Tour de France.

"He's not just the greatest cyclist Great Britain has ever produced, he's probably the greatest athlete Great Britain has ever produced."

We could argue with that assertion all day but to suggest Wiggins is underrated by the public is erroneous; he was named BBC Sports Personality of the Year in 2012, the year the Olympic Games were held in London. That was an unambiguous endorsement of public affection and respect that proves there is at least a certain acknowledgement of the scale of his achievement.

Yet there is something that continues to drive the only man to have won Olympic track gold and the Tour de France on to further success. Considerable parallels can be drawn with Katherine Grainger. The Scottish rower fulfilled her lifelong goal of winning Olympic gold in 2012 yet she chose not to hang up her oars despite the logical, rational choice appearing to be retirement.

It is almost certainly the insatiable desire to succeed that was necessary for them to become champions which prohibits these individuals from making the final, definitive decision on ending their careers. Great champions like Sir Chris Hoy and Rebecca Adlington are among those who feel they stepped back at the right time, but it is a choice that can backfire, and sometimes spectacularly.

There are innumerable examples of athletes who have allowed glorious careers to drag on for too long, running the risk of sullying their reputation. Tiger Woods is wrestling with this conundrum right now as he sits outside the top 100 and another major victory looks ever more doubtful. Lleyton Hewitt, Mike Tyson and Michael Jordan have known how he feels. Retirement is the most difficult choice for any athlete to make and delaying it often seems not only the most favourable option but the easier option.

Wiggins may not damage his reputation by riding on to Rio but whatever he achieves in the next 16 months, it is unlikely to overshadow his previous achievements, even if his career does culminate in a fifth Olympic gold medal. His decision illustrates just how hard it is for athletes, even great ones, to give it all up.