Shimano Positron 1550mm vaihdelanka

Shimano Positron promotes the use of shifting systems to enhance vicycle value

In the early 1970s, shifting required riders to move the shift lever by feel, making derailleurs challenging for general users. The perception that shifting systems were only for sports bikes hindered their popularity for non-sporting bicycles. Focused on creating an easy-to-use shifting system, Shimano introduced POSITRON in 1974. This rear derailleur, equipped with an index system, allowed secure gear shifts without requiring precise lever adjustments. It was a significant benefit for general users unaccustomed to conventional derailleurs. Technologies for smooth and safe shifting in diverse riding environments emerged subsequently. This made shifting operations accessible even for children and dramatically lowering the barrier to shifting systems.

POSITRON I, featured on junior sports bikes in the late 1970s, initially regarded as a derailleur for children, gained industry-wide recognition for its durability in harsh climates like Europe. Consequently, POSITRON became popular not only among users but also dealers and completed bicycle manufacturers.

Continuing Evolution to Shimano Index System (SIS)

In the 1960s, Shimano prioritized developing shifting systems for comfortable and safe use by all bicycle enthusiasts to expand the adoption of sports bicycles. POSITRON, unveiled in 1974, introduced the Positron System. POSITRON II, announced in 1976, incorporated the Positive Pre-select System (PPS), allowing pre-shifts when the bicycle was stationary, facilitating smoother and safer starts on hills. Despite using a steel wire cable, which addressed issues like stretch and rust, POSITRON II faced challenges due to its high cost and inflexible cable routing.

To overcome these issues, POSITRON III, unveiled in 1978, reverted to a normal wire. This new shift lever-equipped index system, laid the groundwork for the later Shimano Index System (SIS). However, it fell short of delivering satisfactory performance at that time.

In 1982, the announcement of NEW POSITRON (PV 11) featured an index system on both the shift lever and rear derailleur. This, however, led to synchronization issues between the two systems and heavy lever operations. Addressing these concerns, NEW POSITRON (NP11), unveiled in 1983, introduced the double servo-pantograph mechanism in the rear derailleur, significantly enhancing shifting performance. The incorporation of a single index system into the shifting lever marked the inception of the later Shimano Index System (SIS).