the Isle of Man TT is a road race , wikipedia describes it as such...
"The race is run in a time-trial format on public roads closed for racing by the provisions of an Act of Tynwald (the parliament of the Isle of Man). The first race was held on Tuesday 28 May 1907 and was called the International Auto-Cycle Tourist Trophy.[1] The event was organised by the Auto-Cycle Club over 10 laps of the St John's Short Course of 15 miles 1,470 yards for road-legal touring motor-cycles with exhaust silencers, saddles, pedals and mud-guards".

However, This video shows what it really is, only the coolest motorcycle racing event to ever be held on the planet earth!