Since forever*
Since the 1890s. Woods, Schrader and Sclaverand all date from that period.
The reason I linked to that wiki page is I wanted to find out when it was invented. It didn't have that info and I lost interest. You should update the wiki page and bask in eternal valvey glory.
@hippy started
London Fixed Gear and Single-Speed is a community of fixed gear and single-speed cyclists.
hippy
Since the 1890s. Woods, Schrader and Sclaverand all date from that period.