This is not the place for a detailed bible-length essay on the long and fascinating history of Shimano. But here is a brief, scrappy, derailleur focused, bullet point, summary:

• Shimano Iron Works was established in 1921 by Shozaburo Shimano in Sakae, near Osaka.
• Shozaburo Shimano’s first product was the ‘3.3.3.’ single freewheel.
• In 1951 the company changed its name to Shimano Industrial Co.
• In 1956 Shimano produced its first derailleur, also called the ‘3.3.3.’. It was a pull-chain model loosely based on the Simplex Tour de France design, with one sprung pivot and one unsprung pivot.
• However, Shimano’s real interest at this time lay in hub gears. It ceased production of derailleurs in 1958, when it launched its three speed hub gear (inevitably called the ‘3.3.3.’), which was immensely successful.
• The 3.3.3. hub gear was particularly significant because it established two things. The first was that Shimano was more than a freewheel and derailleur company. Shimano has often been more ambitious than its competitors in terms of the scope of its product range. The second was that Shimano was not afraid of undertaking complex and sophisticated engineering projects in-house. Shimano long had a policy of employing an army of design engineers that it can mobilise for such projects.
• Shimano re-entered the world of derailleurs in 1965 with its first parallelogram derailleur, loosely based on the Campagnolo Sportman. At first this was called the Shimano 3.3.3.(!) but it was later renamed the Shimano Archery.
• In 1967 Shimano introduced the Skylark derailleur. This had two sprung pivots and was derivative of the Simplex Prestige. However Shimano avoided the temptation to make it out of plastic - opting for tried-and-true pressed steel. The Skylark and its derivatives, the Lark, the Eagle and, eventually, the 1980s Tourney, went on to dominate the low-end market for derailleurs for the next 3 decades.
• Shimano called its design with two sprung pivots the ‘servo pantograph’. They touted it as the equivalent of SunTour’s slant parallelogram. In truth, it was good but not quite that good.
• For 1971 Shimano released the Crane, a silky, forged, aluminium beauty that combined the ‘servo pantograph’ with a dropped parallelogram. It was a statement of intent, perhaps not as special as a SunTour Cyclone but technically superior to anything that those complacent Europeans had to offer.
• Also in 1971, Schwinn, the most powerful bicycle brand in the USA, imported some ‘Schwinn’ models from Japan that were fitted with derailleurs also branded as ‘Schwinn’ but manufactured by Shimano. It was an important breakthrough for a Japanese component manufacturer.
• For 1973 Shimano decided to get real about the racing market and the prestige that this could bring. To this end they put together a top-end groupset including the Crane derailleur. They named this groupset ‘Dura-Ace’. Then they sponsored the European Flandria racing team and Freddy Maetens came second in the World Road Race Championships riding a Crane derailleur. The first derailleur that was physically branded ‘Dura-Ace’ - the 7100 - appeared In 1977.
• 1975 saw the launch of the Positron system. This was one of many indexed derailleur systems at the time - none of which worked particularly well. But Positron was distinguished by three unique attributes. Firstly Shimano was fully committed to it, investing serious engineering, marketing and, crucially, reputational resources from the outset. Secondly Shimano immediately understood that any successful indexing system would entail redesigning all the elements; derailleur, lever, freewheel, chain and even the cable. Thirdly, and typically for Shimano, they were in it for the long haul. Shimano was selling systems branded ‘Positron’ well into the 1990s.
• in 1978 Shimano released the 600 EX groupset with its strange arabesque detailing. This was a largely unsung, but extremely important, event because it was the first truly successful mass-market mid-range groupset. The high-end had been dominated by the Campagnolo Nuovo Record groupset for years, but in the mid-range component choice was seen as a Smörgåsbord of mixing and matching. 600 EX started to change that - bringing the ‘integrated’ approach of Positron to components you both could afford and actually wanted to use. And besides, a derailleur emblazoned with arabesque swirls only looks right when combined with a chainset also bedecked in levantine curves.
• For 1980 Shimano went all-in-bat-shit-crazy and sprung their Dura-Ace AX, aerodynamic groupset on an unsuspecting world. This broke every established convention in engineering design, product styling and consumer marketing and sent shockwaves through the industry. If the truth be told, it did not function spectacularly well, and customers were surprisingly disinterested, but it established Shimano as the leading innovator in the cycling world. A position that it, arguably, holds to this day.
• In stark contrast to the razzmatazz of the ‘AX’ circus, the period 1981 to 1984 saw the launch of a succession of relatively low-key models that established Shimano’s vice-like grip on the market for mountain bike derailleurs. First came the 1981 New 600 EX. This was rather conventional, excellently engineered, cleanly styled in a very modern way and completely devoid of indulgent fripperies. It was the first Shimano derailleur that I preferred to its SunTour contemporaries. For serious touring cyclist the New 600 EX was developed into the Deore groupset, with superior seals at the pivots and the Centeron mechanism. Touring cyclists were mildly interested in Deore, but, more importantly, it was adored by the new tsunami of mountain bikers flooding into the market. It was strong, simple and reliable unlike SunTour’s offerings at the time. The Deore derailleur was then developed into the Deore XT (M700) at first by adding a ‘deer head’ logo and later by making a few small changes. By this point mountain bikes dominated the market for high end bikes and the groupset of choice for the discerning mountain biker was Deore XT. Shimano had the world in its hands.
• And so we arrive at 1984, and the era-defining launch of Dura-Ace SIS. The first indexing system that really worked on the multiple sprockets found on a modern bike. Many commentators identify this as the moment that Shimano established world domination - but I think that, while SIS was undeniably important, Shimano had already decimated its competitors before SIS had trickled down to its mass market groupsets. For me, SIS was the icing on a pre-existing cake.
• There is then something of a pause in the Shimano derailleur story. But it’s a busy pause, filled with a multitude of incremental improvements. The most notable development might be the introduction of XTR, the more deluxe version of the all-conquering, but unfashionably common, Deore XT.
• in 1997 Shimano released the XTR (M951) derailleur featuring ‘Rapid Rise’ technology - which was marketing speak for the derailleur being low-normal. This undoubtedly gave an elegantly smooth, sophisticatedly quiet, gear change - but I hated it. For me, all that elegance and sophistication only manifested when both the nicely cleaned transmission and the perfectly adjusted cables were perfectly lubricated. When Sloppy Joe Public’s unmaintained bike had spent a winter in a damp garage the situation was a little different. But I know rational people who love Rapid Rise and Grant Petersen at Rivendell Bicycle Works has created a cult around it. Shimano were uncharacteristically indecisive and continue to supply top-normal derailleurs as an option.
• But then in 2001 Shimano kind-of launched, kind-of just demonstrated, the Nexave C901 Di2 electronic derailleur. There were two possible reactions; stunned silence or unbridled mockery of its unfamiliar complexity, excessive weight and rotund form. But, just as the low-end 1975 Positron prefigured the ultra-high-end 1984 Dura-Ace SIS, so the humble Nexave eventually led to the Tour de France winning Dura-Ace Di2…
• 2009 saw the true arrival of the modern electronic era with the launch of that very Dura-Ace Di2 7970.

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

• In the 1950s Shimano seemed to have stamped at least some of their derailleurs with two numbers separated by a dot. A typical example would be '32.1'. This is a traditional Japanese date format. The first number is the year of the then Emperor's reign. The second number is the month of that year. The 32nd year of the Emperor Hirohito's reign was 1957. So '32.1' is January 1957. The code was often stamped on the back of the main arm of the derailleur.
• Possibly in the early 1960s Shimano adopted a new scheme, involving two capital letters. This time a typical example might be 'KH'. Here the first letter indicates the year - 'K' is 1965, 'L' is 1966, 'M' is 1967 etc. The original 'A' in this scheme would have been 1955 - it is slightly unclear what the significance of this is, perhaps 1955 was the start of Shimano's push to increase their product range from simply freewheels. The second letter indicates the month, - 'A' is January, 'B' is February, 'C' is March etc.. So 'KH' is August 1965. The code was often stamped on the b-knuckle. Note that in this scheme January 1976 would be 'VA'.
• Then, at some point, possibly in the early 1970s, Shimano continued with two capital letters, but rebased the year sequence so that, for example, 'A' was 1976, 'B' was 1977, 'C' was 1978 etc. The second letter continued to indicate the month as before. So now January 1976 was 'AA'.