This, first, Altenburger design was a cleaned up version of the design covered in the patent that Altenburger bought from Cervino. Altenburger dispensed with the double cable mechanism, introducing a single cable working against a spring.

It is a rigid, well made, derailleur that mounts under the chainstay. The top sprocket stop is not adjustable - it is just a flange that stops the movement of the rod. The low sprocket stop is a small cylinder that clamps on the cable - you can see this in Altenburger's patent.

The way that the chain tension spring is hidden inside the tube, and pulled by a toggle chain (see photos), is devastatingly cunning but strangely unneccesary.

Finally, the patent shows an adjustable cable outer stop - which is not the case with this example.

• Derailleur brands: Altenburger
• Country: Germany
• Date of introduction: 1951?
• Date of this example: unknown
• Model no.: unknown
• Weight: 216g including fixing plate, but excluding frame fixing bolts
• Maximum cog: unknown
• Total capacity: unknown
• Pulley centre to centre: 41mm
• Index compatibility: friction
• Chain width: 1/8”?
• Logic: top normal
• B pivot: none
• P pivot: sprung
• Materials: steel