G B Altenburger gear
Author Peter UnderwoodThe Altenburger gear was first produced in Germany, the home-country of Karl Altenburger after WWII after he had purchased the patent from the original designers.
It was sold in the UK as the GB Altenburger.
The top 'bar' mounting for the pivots is clamped to the chainstay and the gear change is via a horizontal parallelogram. Jockey pulleys are attached to the spring-loaded parallelogram and a cable moves them from side to side with an adjustable stop the limit the 'throw'. The adjustable outer cable-stop can be seen in the images below (click on image for enlarged version). In the centre image the hole can be seen for the inner-cable clamp bolt which is missing.
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 GB Altenburger gear with double
lever
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