8speed

8speed is a term used to describe drive systems that offer eight discrete forward gear ratios. The term is used across several domains, most notably automotive transmissions and bicycle drivetrains. In general, eight-speed systems are designed to balance torque across a wide range and to optimize engine or motor efficiency at varying speeds.

Automotive: The eight-speed automatic transmission, often labeled 8AT or simply eight-speed, uses eight gear ratios arranged in a hydraulic or electronic control system to deliver smooth shifts and improved highway economy. Since its introduction, eight-speed automatics have become common in contemporary passenger cars and light trucks, replacing older six- and seven-speed designs. Benefits include a wider optimal torque band, smoother acceleration, and better fuel economy at highway speeds. Tradeoffs can include higher production costs, increased complexity, and potential weight penalties; however, advances in materials and control software have mitigated these issues. Well-known examples include the ZF 8HP family, used by multiple automakers, as well as various eight-speed designs developed in-house by other brands.

Bicycle: In cycling, eight-speed drivetrains refer to rear cassettes with eight sprockets, paired with appropriate front chainrings and a compatible derailleur/shifter. Eight-speed systems were common on late 20th-century and early 2000s bikes and remain in use on budget and some mid-range models. They provide a moderate gear range at a lower cost and weight compared with more modern 9-, 10-, or 11-speed setups. Compatibility requires an eight-speed chain, shifter indexing, and rear derailleur designed for eight speeds.

Branding and other uses: Some products or services use the name 8speed as a brand or designation to emphasize eight-speed capability. In general, the term can appear in marketing or documentation without implying a specific standard.

See also: eight-speed transmission, bicycle gearing.