Former name for the type of bicycle now in use, differing from the ‘Ordinary’ in the lower position of the saddle, whereby greater safety is afforded to the rider.
A better idea of the 'B.S.A.' Safety can be seen ... 32-inch driving wheel ... 20-inch steer
In 1876, the British engineer Henry J. Lawson proposed a new rear-drive machine he called the Safety Bicycle.
Thomas thought that this could be improved upon, and in 1868 invented the firsty 'safety' bicycle ever produced
The most famous of the rear-drive safeties introduced in 1885 was the Rover, produced in Coventry by John Kemp Starley.
...it not only prevailed as the universal bicycle style, it also triggered an unprecedented world-wide demand that culminated in the great boom.