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Shimano Positron/PPS

Details
Short Name:	Shimano Positron	Year Introduced:	1975
Speed Range:	6sp	Indexed Component:	Rear Derailleur
General Information
Shimano's Positron systems were an early attempt at an indexed shifting system. Unlike their later attempts, the Positron system was targeted at entry level bicycles, not road racing 10 speeds. The name Positron was given to a couple of different indexed shifting setups from the mid 1970's through the mid 1980's. Some used a single heavy duty cable to push/pull the rear derailleur, another used a pair of cables to cause the derailleur movement.

Shifting System Component Variations
Name	Category	Gearing	Year Introduced
Positron	Shifters	5sp	1975
Notes:
Positron	Rear Derailleurs	5sp	1975
Notes:

Component List
Generally in Indexed systems, either the shifting or the derailleur component contains the indexing logic. Here is a list of components currently on VeloBase.com which utilize the Shimano Positron/PPS shifting mechanism.
Component Name		Model	Group	Compatibility
Shifters
	Shimano LB-500, Positron	LB-500	Positron	Positron
	Shimano LB-700, Positron	LB-700	Positron	Positron
	Shimano LE-420, Positron 10-S Console	LE-420	Positron	Positron
	Shimano Positron		Positron	Positron
Rear Derailleurs
	Shimano DG-100, Positron	DG-100	Positron	Positron
	Shimano DG-200 Positron II, Positron	DG-200	Positron	Positron
	Shimano DG-300, Positron 400	DG-300	Positron	Positron
	Shimano Positron		Positron	Positron
	Shimano RD-P500 Positron	RD-P500	Positron	Positron