This Fichtel & Sachs 9/a is an example of the definitive German derailleur for a period from 1935 to about 1960. It is extremely strongly constructed in well finished steel. Every small component looks as though it has been machined to fine tolerances.
Despite all this love and attention, it is a single pulley, pull-chain design - meaning that capacity will be negligible and the gear change will be as precise as the long range weather forecast. This design was advanced in 1935 and obsolete by 1950.
You could just about get these derailleurs to work acceptably across three cogs mounted on a Torpedo three-speed hub-gear, but they were of no use for anything else. The hanger plate on this example, which fits inside the drop-out, indicates that this was exactly the intended purpose of this particular derailleur.
This example is covered in writing that I do not know how to fully interpret. The main arm is engraved: ‘Fichtel & Sachs A-G’ and ‘Schweinfurt a. M’ - all of which is understandable - but also ‘GS 9/a 54’ - which could indicate ‘Gang Schaltung (gear changer) model 9/a 1954’. The hanger plate is engraved ‘F & S 56’ and ‘356950’ and the hub of the pulley wheel is engraved ‘F & S 56’ - both of which could point to a date of 1956.
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