Stelbel (acronym for Stelio Belletti) is an Italian manufacturer of racing bicycles, founded in 1973 by Stelio Belletti.

After World War II, Stelio Belletti joined his father, Antenore, in his workshop in via Giovanni Antonio Amadeo, in the Ortica district of Milan. The mechanical workshop specialized in the construction of frames and other metal tubing structures. During the 1950s and 1960s, the Belletti Workshop collaborated significantly with important Aeronaticaul and motorcycle companies in Italy. It was one of the first companies in Italy to own and operate a TIG welding machine.

Stelio Belletti has always been a huge cycling fan and as a boy was part of local amateur cycling teams. Since the early 1970s, his experience as a welder fabricating motorcycle frames and aircraft fuselages pushed him to begin experimenting with the production of bicycle frames, combining steel tubing with TIG welding which at the time was a new technique in the bicycle industry. Encouraged by his father and by the results he had obtained, in the spring of 1973 he decided to found the Stelbel brand, allowing him to distinguish the production of racing bicycle frames from the other activities carried out in the family workshop. The frames were produced in Via Alessandro Manzoni, 1 in Lucino, a fraction of Rodano in the province of Milan.

Using the knowledge he had acquired as a mechanic, builder and welder, coupled with his experiences as a bicycle racer, Belletti began to work on the production of a frame model that would encompass all the technological advances he had witnessed in his time. The racing frame model he created was patented in 1975 and called the "Integrale" model. The title on the patent states: Bicycle frame designed for competition with at least a portion of the tubes directly joined through a welding process.

Source: Central Patent Office – Patent N. 166907

The patent description illustrates in detail how the steel tubing is joined to create a frame through a TIG welding process that uses a non-consumable tungsten electrode to produce the weld, which is protected during the welding process by an inert shielding gas (Argon).

In August 1975, the UCI World Road Championships were held in Mettet and Yvoir, Belgium. For the Championships, the Polish national cycling team was provided with Stelbel frames built specially for the event. It was the debut of Stelio Belletti's product in an international competition. Belletti made 6 frames (4 official frames plus 2 reserve frames) for the team time trial race and another six frames for the men's road race. The Polish team was made up by racers Tadeusz Mytnik, Mieczysław Nowicki, Ryszard Szurkowski and Stanisław Szozda who, racing on Stelbel frames, won the gold medal for the team time trial race.

Encouraged by the positive results of his frames, Stelio Belletti completely renounced all other commitments and began to focus solely on building racing bicycle frames. During the late 1970s, Stelbel frames continued to evolve, becoming increasingly refined and sophisticated, both in terms of technique and aesthetics. In particular, Belletti developed his concept of a fork crown produced in-house, which went on to become a hallmark of Stelbel frames. The development of the fork crown involved a distinctive production process and did not use any prefabricated components. The construction of the first Strada model dates back to 1979, and saw the end of the Integrale model.