The Isle of Man TT (Tourist Trophy) races are an annual motorcycle racing event that has been held on the Isle of Man in May and June most years since its inaugural race in 1907. The two-week event is sanctioned by the Auto-Cycle Union, which also organises the event. The Manx government owns the rights to and promotes the event.
The Isle of Man TT is a series of time-trial format races, run on public roads closed for racing. The event consists of one week of practice and qualifying sessions, followed by one week of racing. The closed public roads form the Snaefell Mountain Course, a 37.73-mile (60.72 km) route containing 219 turns that traverses through a mix of urban and rural areas. The event currently features 5 different classes of road racing, each competing in two races over the course of the racing week. Since the inaugural Isle of Man TT in 1907, the event has been held mostly every year since, with seasons being cancelled only due to war or disease outbreak. The TT has become part of the local culture and economy of the Isle of Man with more than 40,000 visitors annually travelling to the island for the event.
Motor racing began on the Isle of Man in 1904 with the Gordon Bennett Eliminating Trial, restricted to touring automobiles. The Motor Car Act 1903 placed a speed restriction of 20 mph (32 km/h) on all automobiles in the UK, effectively restricting road racing activities. Julian Orde, Secretary of the Automobile Car Club of Britain and Ireland approached the authorities on the Isle of Man for the permission to race automobiles on the island's public roads. The Manx government agreed, and passed the Highways (Light Locomotive) Act. This gave permission for the 1904 Gordon Bennett Eliminating Trial to take place on the Isle of Man around the 52.15-mile (83.93 km) Highroads Course. The first year of the trial was won by Clifford Earl (Napier) in 7 hours 26.5 minutes, driving five laps of the Highroads Course for a total of 255.5 mi or 411.2 km. The following year, the Gordon Bennett Trial was held on 30 May 1905, and was again won by Clifford Earl driving a Napier automobile, completing six laps in 6 hours and 6 minutes. In September 1905, the first Isle of Man Tourist Trophy Race for automobiles, now known as the RAC Tourist Trophy was held. This race was won by John Napier (Arrol-Johnston) in 6 hours and 9 minutes at an average speed of 33.90 mph (54.56 km/h).
In 1905, it was decided to run an eliminating trial for motorcycles the day after the Gordon Bennett Eliminating Trial. This was to qualify a team to represent Great Britain in the International Motor-Cycle Cup Race held in Austria. The inability of the motorcycles to climb the steep Mountain Section of the course forced the organisers to use a smaller 25-mile (40 km) section of the Gordon Bennett Trial course that included less elevation. This ran from Douglas south to Castletown and then north to Ballacraine along the primary A3 road, returning to the start at the Quarterbridge in Douglas via Crosby and Glen Vine along the current Snaefell Mountain Course in the reverse direction. The 1905 International Motor-Cycle Cup Race consisted of five laps, and was won by J.S. Campbell (Ariel) despite a fire during a pit stop. Campbell completed the 125 mi (201 km) race distance in 4 hours, 9 minutes and 36 seconds at an average race speed of 30.04 mph (48.34 km/h).
The 1906 International Motor-Cycle Cup race was plagued by accusations of cheating and fraudulence. Frustrated by the experience, the Secretary of the Auto-Cycle Club, Freddie Straight, brothers Charlie Collier and Harry Collier of Matchless Motorcycles, and the Marquis de Mouzilly St. Mars (president of the FICM) had a conversation on the train journey home that led to a suggestion of a race the following year for road touring motorcycles based on the automobile races held on the Isle of Man.
At the Annual Auto Cycle Club dinner party on 17 January 1907, the editor of Motorcycle Magazine formally proposed this new race for motorcycles on the Isle of Man. This new race, named the Auto-Cycle Tourist Trophy, was to take inspiration from the earlier motorcycle trial race that was held in 1905, running on a shorter course with less elevation than the mountain course used by automobiles. This shorter course, named the St. John’s Short Course formed a 15.85 mile triangular shape, and the race was set at 10 laps for a 158.5 mi (255 km) overall distance. Based on the touring oriented style racing at the time, two classes were established for the Auto Cycle Tourist Trophy based on number of cylinders and fuel economy. The first was a single cylinder class, with a fuel economy limit of 90 miles per gallon of fuel, and the second was a two cylinder class, with fuel economy limit of 75 miles per gallon of fuel throughout the race. The machines competing were mandated to be touring motorcycles equipped with saddles, pedals, mudguards, exhaust silencers, and a toolkit.
The first Isle of Man TT race was held on Tuesday 28 May 1907. Charles Collier won the single cylinder class riding a Matchless machine at an average speed of 38.22 mph. Rem Fowler won the two cylinder class riding a Peugeot engined Norton at an average speed of 36.22 mph. Of the 25 race entrants, only 12 finished the race. Auto-Cycle Tourist Trophy Races continued for the next four years on the St John's Short Course. For the 1908 race, the fuel consumption was raised to 100 mpg for single-cylinder machines and 80 mpg for twin-cylinder machines and the use of pedals was banned. The 1908 race was won by Jack Marshall on a Triumph motorcycle at an average speed of 40.49 mph (65.16 km/h). In 1909, the fuel consumption regulations were abandoned along with the use of exhaust silencers. The single-cylinder machines were limited to a capacity of 500cc and the twins to a 750cc engine capacity. Due to the concern over increasing lap-speed, the 1910 event saw the capacity of the twin-cylinder machines reduced to 670cc. By 1910, the last year of the short course, the average speed had risen to 55.15 mph, achieved by Charlie Collier riding on a Matchless motorcycle.
Due to the ever increasing speeds and technical innovations seen in previous years competitions, the 1911 TT was moved to the much longer and challenging Snaefell Mountain Course. At the time this course was 37.40 miles (60.19 km) long, with its layout differing slightly from the current mountain course. Similar to the short course of the previous years, much of the mountain course consisted of unpaved dusty tracks with loose rutted surfaces that created many obstacles for the riders to overcome. The two classes were changed and renamed as the Senior and Junior classes. The Senior class permitted single cylinder machines with engines displacing up to 500cc and two cylinder machines with engines up to 500cc. The Junior class permitted 300cc single cylinder and 340cc two cylinder motorcycles. Each class was run in their own separate race, instead of together as in previous years. The Senior race was five laps and the Junior race was four laps. The steep gradients of the mountain course made the single gear machines of the past years obsolete, requiring manufacturers to develop some type of transmission to be competitive. American built Indian motorcycles proved to be well suited to the mountain course and won the top three positions in the Senior TT race. Oliver Godfrey won the Senior class with an average speed of 47.63 mph. The 1911 TT recorded the first fatality at the motorcycle race with Victor Surridge dying from a crash during practice.
The Isle of Man TT continued in a similar format for the next three years. The 1912 race was boycotted due to protests from some Isle of Man residents regarding the safety of the event. Despite this the TT continued, albeit with a much reduced entry list. Additionally the classes were tweaked for 1912 with both single and two cylinder motorcycles being held to the same engine displacement, 500cc for the Senior, and 350cc for the Junior. The 1913 race saw a large rebound in the number of entrants compared to the previous year. The race format was changed, now with two races per class. A six lap Junior race was split up into two races, a two lap event, and a four lap event. The seven lap Senior race was split up, starting with a three lap event, with another 4 lap race being run concurrently with the 4 lap Junior race. The 1914 race was the last to be held before the outbreak of World War I, motorcycle racing would not return to the Isle of Man until 1920.