Mutaped
The Mutaped is a three-speed bicycle transmission developed and built in the 1950s by the Biel company Sport AG as a bottom bracket shift .
Other sources, such as biennophones, assume marketing as early as the 1930s.
Unlike today's gearboxes, it is not switched via a Bowden cable , but by turning the crankshaft backwards; similar to the "Duomatic" hub gear from Fichtel & Sachs. The shift sequence is sequential and from third to first gear, ie 1-2-3-1-2-3 -...