Giacomo Agostini 1967 he battled Hailwood in one of the most dramatic seasons in Grand Prix history. Each rider had 5 victories before the championship was decided in Agostini's favor at the last race of the season. Agostini dropped a bombshell on the Grand Prix world when he announced he would never again race at the Isle of Man TT, after the death of his close friend, Gilberto Parlotti during the 1972 TT. He considered the 37 mile circuit unsafe for world championship competition. At the time, the TT was the most prestigious race on the motorcycling calendar. Other top riders joined
Kenny Roberts the 1983 season would be his final year in Grand Prix competition. Yamaha team manager Giacomo Agostini had been unable to agree on a contract with rider Graeme Crosby, so AMA Superbike champion Eddie Lawson was brought in as Roberts' new teammate. The 1983 battle for the championship between Roberts and Honda's Spencer would be considered one of the greatest seasons in motorcycle Grand Prix history, along with the 1967 500 cc duel between Mike Hailwood and Giacomo Agostini. Roberts began the season with his YZR500 having problems with overheating and rear suspension, while Spencer started strongly, winning the first