Production chronology1911–1913
Sourced production or model lifecycle range used by the main catalog timeline.
curated ↗3 years
Aerodynamic-bodied twin-cylinder alternative to the angular single-cylinder A-series. Sources do not establish one dependable displacement for every BD1; later 1,055–1,100 cc figures primarily describe BD2 development and are not retroactively imposed.
Sourced production or model lifecycle range used by the main catalog timeline.
This record contains useful sourced evidence, but it does not yet meet the reference-ready standard. Still needed: attributed imagery. Fields we cannot source stay empty rather than guessed.