The official Sachs website is not very informative. Traditional saddles are made of leather stretched over a metal frame, hammock style. This type of saddle requires care and careful breaking in , but when this is done the classic leather saddle moulds itself to fit the particular anatomical shape of its rider. There is a more extensive article on Leather Saddles on this site. Most cyclists have never experienced the comfort of a well broken-in leather saddle, because most modern bicycles come with plastic saddles which require no break in or other maintenance.
Plastic saddles are also lighter and cheaper than leather ones.
S.A.E. Society of Automotive Engineers, a quasi-official trade association which establishes standards for materials and parts used in the automotive industry. This body has jusisdiction over screw threads and wrench sizes based on the inch system, so inch-based fasteners are sometimes referred to as S.A.E. sizes. A conventional bicycle, with wheels of similar size and chain drive. When the modern style of bicycle was replacing the high wheeler , in the late 1880's, the new style was mainly noted for its greater safety compared to the older design. The two breakthroughs that allowed the safety bicycle to obsolete the high wheeler were Dunlop's pneumatic tire and the chain drive .