(Adds details, quotes, byline) By Neil Robinson LONDON, Dec 28 (Reuters) - Britain's most decorated cyclist Bradley Wiggins announced his retirement on Wednesday after a stellar career during which he won most of the sport's biggest prizes. The wise-cracking Londoner with a Mod haircut played a major part in growing cycling's popularity in his homeland, becoming the first Briton to win the Tour de France in 2012 and collecting a British record eight Olympic medals, including gold in the time trial at the 2012 London Games. "2016 is the end of the road for this chapter, onwards and upwards, 'feet on the ground, head in the clouds' kids from Kilburn don't win Olympic Golds and Tour de Frances'! They do now," the 36-year-old Wiggins said on Twitter. More...