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Shimano derailleurs

Positron1

Shimano Positron Preselect (PPS):

The first indexed gearing system to appear on a significant number of bikes – the first version in 1975 used two pull cables, the second in 1976 (this one) used a semi-rigid push-pull cable. The parallelogram is not spring-loaded, and is held in position by a spring-loaded ball on a notched arm.
The problem was that Shimano thought that indexing would only be for non-enthusiasts, so it was introduced as a cheap derailleur – the weight and build quality didn’t do it any favours, and it was dropped in 1982. Continue reading “Shimano derailleurs”

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Suntour Derailleurs

Superbe Tech:

Probably Suntour’s most innovative and beautiful derailleur – and the company’s first glorious failure. The 1983 Tech has a completely enclosed linkage instead of the open parallelogram other mechs use. The cable routing was clever too – straight along the chainstay with no loops of cable.
That clever linkage would be the downfall, though – it wore and broke very quickly, and was very difficult to fix – so the Tech only lasted for a year.

Superbe Tech
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Ovo tandem

Ovo tandem, originally uploaded by Ben Cooper.

The Ovo tandem is ingenious – it splits and the seats come off in seconds, so it packs into a few rather small bags. Still rides very well, though. Trying to decide if I can afford to be a dealer for this 😉