DISRAELI DOCUMENTS

UK Patent 1896 # 1,570

UK Patent 1896 1,570 - Gradient main image

Edmund Hodgkinsons first ‘Gradient’ derailleur design (possibly THE first design of a derailleur as we know it) was this Heath Robinson contraption. The patent describes a two speed system with a sliding ‘cassette’ of cogs and a straight chainline - much like the later TriVelox. The mind-bending bit is the chain lifting mechanism which lifts the chain off one cog, then the cogs slide sideways, then the chain lifter drops the chain onto the newly aligned other cog. The patent describes two possible configurations, one where the chain lifter is operated by the rider using a lever, and the other where the chain lifter is operated by back-pedalling.


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