Hawkwind was a UK psychedelic heavy metal band. They formed in London in 1969 as Group X. They changed their name shortly to Hawkwind Zoo and subsequently Hawkwind. Although this was their only hit, their space-age rock albums sold consistently well throughout the '70s.
Hawkwind guitarist Dave Brock wrote the music to this track, and their frontman Bob Calvert composed the lyric. According to Mojo magazine September 2011, Calvert's lyric was inspired by an Alfred Jarry short story called How To Construct A Time Machine. However, rather than writing about a "cosmic space travel machine" he made it about his new silver racing bike.
That's bass player Ian "Lemmy" Kilmister singing lead on this track. Lemmy, who later formed Motörhead, wasn't the group's main singer - that was Bob Calvert, who joined the group for the Roadhawks album. Calvert's attempts to record the vocal weren't up to snuff, so Lemmy got the call.
"Lemmy had a high voice but it was just very much more powerful, he had a gruffness with it, so we decided to use his vocal," their manager Doug Smith explained. Calvert, who was hospitalized at the time for manic depression, didn't find out that his vocal had been replaced until later. When he did, he was not pleased.
Released as a single, the song was recorded live from the Roundtree in London on February 13, 1972. The live performance had vocals by Bob Calvert, but they were replaced by Lemmy's when the song was mixed and overdubbed at Morgan Studios.
This was by far the biggest hit for Hawkwind, reaching #3 UK and getting played on the TV show Top Of The Pops. Hearing Hawkwind on BBC radio was very strange for many of their fans, as the group was far off-center and notoriously anti-establishment.
When this song took off, the British music magazine NME put Lemmy on the cover with no sign of his bandmates. This gave the impression that he was the frontman and leader of the band, when really he rarely sang lead and had just joined the outfit.
A self-described "space rock" band from North Carolina named themselves Silver Machine after this song.