The Ducati ST series of sport-touring motorcycles debuted in 1997, with the Ducati ST2 as the first member of the family. Besides the ST2, the range comprised the ST3, ST3S, ST4, and ST4S models with similar appearances but different engines.
In late 2001, the Italian motorcycle manufacturer added the Ducati ST4S to the range, which became available in 2002. The ST4S was based on the standard ST4 and featured an improved suspension system and a slightly larger engine.
In the appearance department, the Ducati ST4S was similar to the standard model, packing a full fairing, a single headlight, a windscreen, a one-piece dual seat with a passenger grab handle, a dual exhaust system, and five-spoke lightweight alloy wheels.
Compared to the ST4 model, the ST4S was fitted with a larger 996cc four-stroke liquid-cooled V-twin engine with a different fuel injection system, boasting 117 hp at 8,750 rpm and 98 Nm (72 lb-ft) torque at 7,000 rpm.
The engine worked in tandem with a six-speed manual transmission, a hydraulically controlled wet multi-plate clutch, and a final chain drive, pushing the bike to 249 kph (155 mph).
In the suspension department, the ST4S was fitted with an improved suspension system comprising a 43 mm fully adjustable upside-down TiN-coated Showa fork on the front and a fully adjustable Ohlins shock absorber with progressive linkage on the rear.