The KTT was developed from the Velocette KSS road motorcycle by Percy and Eugene Goodman, sons of Velocette founder Johannes Gutgemann. The starting point was the Velocette Model K, an overhead-camshaft single that the Goodmans recognised had the potential to be competitive at the Isle of Man TT — the most prestigious road race in the world at the time. After approximately twelve months of development, a racing version of the Model K secured Velocette their first TT victory in 1926 with Alec Bennett winning and Gus Kuhn and Fred Povey finishing within the top nine, earning the factory the team prize as well.
The production racing KTT — designated as such because the TT suffix indicated a machine intended for competition — first appeared in 1929. The earliest cars were retroactively classified as Mark I examples, establishing the Mark numbering system that would track subsequent development through the model's life.
In 1928, during the development programme that preceded production, Veloce introduced the first positive-stop foot gear change on any motorcycle. Previous foot-operated gear selectors had been adaptations of hand-lever mechanisms and required the rider to make a deliberate up-and-down movement for each shift without a defined end position. The Velocette mechanism allowed gear changes both up and down with a single directional movement, with the lever automatically returning to its neutral position after each shift. The improvement was immediately recognised as significant in a racing context and was rapidly adopted across the industry, eventually becoming the universal standard for motorcycles worldwide.
The KTT's second landmark contribution came with the Mark VIII of 1938, which was the first production motorcycle to feature a swingarm rear fork with enclosed suspension units. The system was developed by Veloce engineer Harold Willis, who drew inspiration from the oleo pneumatic suspension legs used on light aircraft — he contacted the Oleo company directly for a custom pair of air-sprung units. Although the air-based medium was later replaced industry-wide by coil-spring and oil damper arrangements, the swingarm configuration itself was adopted universally and remains the standard for motorcycle rear suspension.
The KTT was produced in a continuous Mark series throughout its life, with each designation reflecting meaningful engineering changes. The Mark V of 1935 introduced a new full-cradle frame, replacing the open-bottom frame in which the engine functioned as a structural member. Only approximately six Mark VI KTTs were built in 1936, reserved for selected riders; this variant introduced a cast aluminium cylinder head, the first KTT to use the material. Production paused in 1936 for all practical purposes.
The Mark VII of 1937 reflected input from Stanley Woods, who was contracted to ride for the Veloce racing team. His feedback prompted a repositioning of the engine approximately 1.5 inches forward in the frame to improve handling, along with a redesigned aluminium cylinder head and barrel of larger proportions to improve cooling. Power increased substantially, and although only 37 Mark VII examples were built, they are considered among the most technically accomplished and aesthetically refined of the series.
The Mark VIII of 1938 followed with the swingarm rear suspension development described above. Production of the Mark VIII continued until 1949. In total, approximately 1,000 KTTs were produced across all variants between 1929 and 1950.
The Velocette KTT accumulated an extensive competition record across its production life, winning repeatedly in international events and providing competitive privateer machinery for a generation of riders. Its position in motorcycle history rests equally on racing success and technical innovation — few individual models can claim to have introduced two separate mechanical arrangements that became permanent industry standards. The KTT is preserved in major motorcycle collections and remains actively raced in appropriate historic competition classes.