Renthal was formed in 1969 by friends and motorcycle enthusiasts Andrew Renshaw and Henry Rosenthal, who are today the company's Technical and Commercial Director respectively. The company name is a portmanteau of the founders' names Renshaw and Rosenthal. The first handlebars were based upon a prototype that Rosenthal made for his trials bike from H14 aircraft aluminium that was World War II surplus material. The two founders made a tube bending machine to handle the aluminium and started small-scale production.
Making motorcycle handlebars was initially a part-time job while Andrew studied for a degree in mechanical engineering and Henry finished his business studies at a local university. Initially Renthal only produced handlebars for the trials market, but the two soon realized there was much more demand for this type of product in the motocross market. Full-time production began in 1975 in Stockport England, the very same place where the company resides today in northern England.
In 1990, Renthal opened its first US office and warehouse for sales/marketing with the help of a young American entrepreneur by the name of Jim Hale.
In October 2000, the Renthal factory in Stockport England was destroyed in a fire caused by a faulty aluminium particle extractor, which removes particles from the air during the machining process. A spark within this machine had caused it to catch fire and act as giant blowtorch straight through the roof of the factory. Before the machine could be shut down, the factory was destroyed. Plans were made to rebuilding the facility in the same location.
Renthal's 41,000 square feet (3,800 m2) factory houses machinery for manufacturing, quality control, R&D, and storage. This includes five Yamazaki two- and three-axis CNC turning centres, seven Kitamura machining centres, and one Kardex Shuttle 500NT automated vertical storage system. Custom specification machines include bar bending machines, a fatigue tester and drop test rig created to fatigue aluminium handlebars.
In 2004, Renthal began supplying the first aluminium 7/8" handlebars to be fitted as OEM equipment on a Japanese manufactured off-road motorcycle. For the 2004 model year, every Honda CR and CRF motocross bike came with the Renthal 971 "RC" bend handlebar. Soon after this, many of the other manufactures followed suit and began fitting Renthal handlebars as stock on their off-road models.