A brief history of SunTour might go like this:

• According to Frank Berto's legendary article 'Sunset for SunTour'...."The Maeda Iron Works Company was founded by Shikanosuke Maeda in 1912 in Kawati-Nagano. Maeda made freewheels and sprockets for bicycles and agricultural machinery. Maeda was owned by the Maeda and Kawai families. A few months later, Maeda moved to Sakai... In 1931, Mr. Taizo Kumagai married Shikanosuke Maeda's daughter and changed his name to Taizo Maeda. During World War II, the Maeda Iron Works merged with eleven other small factories. The new company was called Toa Seiki Kosakusho. Taizo Maeda was elected President. The merged company was taken over by the Japan's military government in 1943 and became a subsidiary of the Kure Military Factory and produced ammunition. On July 10, 1945, a major B-29 raid on Osaka burned out the Maeda factory. The factory was rebuilt after VJ Day and by 1946, 58 employees were producing freewheels at prewar volumes. Twenty-five year-old Junzo Kawai joined Maeda Iron Works in 1946. He moved ahead rapidly and became President when Taizo Maeda passed away in 1975."
• From a very early point Maeda Ironworks adopted ‘8.8.8.’ as a logo. It is widely considered that, to Japanese eyes unfamiliar with the Roman alphabet, ‘8.8.8.' looked very similar to ‘B.S.A.’. BSA was, at the time, revered in the bicycle world for the quality of its engineering.
• Possibly in 1955 Maeda Iron Works partnered with a company called Iwai Seisakusho to produce a derailleur set. Maeda contributed the multiple freewheel, which was branded '8.8.8.', and Iwai contributed the derailleur and lever which were branded 'SunTour'. It is possible that, at this point, the SunTour brand actually belonged to Iwai. This first SunTour derailleur was a sliding-rod pull-chain design, as was typical at the time, but it had a long main arm and a long pulley cage. This made it a distinctly touring model suitable for a wide ratio freewheel. This was relatively unusual.
• In 1958 Iwai Seisakusho went bankrupt and Maeda Iron Works took over the manufacturing of the derailleur and also took over the SunTour brand.
• Possibly in 1963 SunTour formed a relationship with Huret. Initially this may have involved importing the Huret Svelto) derailleur into Japan. Then it may have evolved to assembling the Svelto from parts made in France and finally into manufacturing the Svelto entirely in Japan.
• Also in 1963 SunTour launched their first original design of a parallelogram derailleur, called the Skitter. This was quite a complex, sophisticated and, probably, expensive design, a little reminiscent of the Huret Allvit.
• 1964 was a landmark year in derailleur history. SunTour released the Grand-Prix (also, sometimes, called the Gran-Prix). This featured a dropped, slant parallelogram - a simple design that allowed the guide pulley to naturally track the profile of the freewheel, maintaining an even chain gap. This basic geometry is still preferred for many derailleurs today.
• While the SunTour Grand-Prix was ground breaking, it was also slightly eccentric. It was low-normal and also cunningly used a single, hard working, spring for both the parallelogram and the pulley cage. But in 1965 SunTour launched the Competition. This was similar to the Grand-Prix, but was top-normal and used separate springs for the parallelogram and the pulley cage. The fundamental design of the modern derailleur was now complete.
• SunTour was now on a hot streak. In 1968 the first of the legendary SunTour V series appeared. This took the basic form of the Competition and rendered it in aluminium. First the knuckles and pulley cage plates were aluminium. Then, from the 1973 V Luxe models, aluminium parallelogram plates were added to the recipe.
• The key models in the V series were the long pulley cage GT variants. These could handle a 34 toothed sprocket and also a total difference of 34 teeth. Not only could they handle these numbers, they did so with considerable style and aplomb. New cyclists were streaming into the bike market, fueling the ‘Ten Speed Boom’, and they wanted easy gears for climbing hills. The V series provided a solution that was all of affordable, bomb proof and sophisticated.
• While it was churning out V GT Luxes, SunTour found the time to make a respectable foray into racing equipment with the Cyclone and Superbe groupsets. The Cyclone derailleurs, in particular, were tiny jewels that worked well and weighed next to nothing. But racing was never really their thing.
• During the 1960s and 1970s SunTour repeatedly toyed with indexed derailleur systems. Examples included the 1966 Competition Twin, the 1975 Maruishi PC electronic system, the 1975 Bridgestone Synchro Memory Shift and, in 1978, SunTour’s own Mighty Click. All these included interesting and well engineered ideas - but none were totally convincing. And, as with racing, SunTour was not totally committed. There was a sense that they weee not too bothered, they were too busy selling ship loads of excellent V GTs, V GT Luxes and Vx GTs.
• And then came the mountain bike, sweeping through the cycle industry like a tsunami. SunTour was perfectly placed - the V GT Luxe had been the derailleur of choice of the wild-haired Marin County freaks battering down Mt Tam. At the start of the mountain bike boom SunTour had around 60% of the world derailleur market, and its share of the long cage derailleur market was even higher.
• But SunTour decided to go all-in and develop the most sophisticated wide-ratio derailleurs the world had ever seen - the MounTech and Superbe Tech series. Both were triple pivot designs that gave an excellently tiny chain gap even over the widest freewheels. The Superbe Tech even had a mud-proof sealed parallelogram. But both were also heavy, expensive and, crucially, unreliable. The very opposite of everything SunTour was famous for. Shimano, in contrast, kept it simple, even dull, offering the Deore XT (M700) - and cleaned up.
• The second punch in Shimano’s mid 1980s combo was the launch of SIS - indexing the worked. This took time.

As with Shimano, a useful addition to any history of SunTour is a brief discussion of the date codes that they stamped on their components. The story of these date codes may go like this:

• In the 1950s and 1960s SunTour appears not to have stamped their derailleurs with any kind of date code.
• Possibly in the 1971 SunTour adopted a date code, involving two capital letters. A typical example might be 'OB'. Here the first letter indicates the year - 'N' is 1971, 'O' is 1972, 'P' is 1973 etc. The original 'A' in this scheme would have been 1958 - it is slightly unclear what the significance of this is, perhaps 1958 was the point at which SunTour took derailleur production in-house. The second letter indicates the month, - 'A' is January, 'B' is February, 'C' is March etc.. So 'OB' is February 1972. The code was often stamped on the rear parallelogram plate.
• I have a slight suspicion about some of these date codes. My suspicion is that these codes may indicate when the rear parallelogram plate was manufactured. I guess that SunTour, in some circumstances, may have made a pile of rear parallelogram plates and only assembled them into the complete derailleur at some slightly later date.