At the beginning of Stephen King's career, the general view among publishers was such that an author was limited to a book every year at the utmost; any more, it was felt, was not acceptable to the public. King therefore wanted to write under another name in order to double his production. He convinced his publisher, Signet Books, to print these novels under a pseudonym.
King also stated in his introduction to The Bachman Books that Bachman was an attempt to make sense out of his career and try to answer the question of whether his success was due to talent or luck. He says he deliberately released the Bachman novels with as little marketing presence as possible and did his best to "load the dice against" Bachman. King concludes that he has yet to find an answer to the "talent versus luck" question, though the fact that the Bachman book Thinner sold 28,000 copies during its initial run--and then ten times as much when it was revealed that Bachman was in fact King--isn't encouraging.
The originally selected pseudonym was Gus Pillsbury (King's maternal grandfather); but at the last moment King changed it to "Richard Bachman", in tribute to crime author Donald E. Westlake's long-running pseudonym Richard Stark. The name Stark was used in King's novel The Dark Half, a novel about an author with a pseudonym.
The surname was in honor of Bachman-Turner Overdrive, a rock and roll band King was listening to at the time.