Unlike other major British imperial thread standards (British Standard Whitworth and British Standard Fine) the thread runs at a 60 degrees rather than a 55 degrees angle.
In the bicycle industry it is still found on virtually all bottom bracket threads and the wheel axles of low-end models manufactured in China, which are derived from pre-WWII British roadsters.
[citation needed] BS 811: 1950 provides specifications for British standard cycle threads.
British Bicycle standards for other parts which are not strictly BSC but come in similar fine threads include: The thread was defined to meet a requirement for a thread form for bicycles and motorcycles, originally specified by the Cycle Engineering Institute.
Before being adopted as a British Standard it was known as the CEI thread.