Originally Posted by T-Mar

I don't buy into the theory that Shimano killed their AX series in favour of SIS. The circumstantial evidence suggests the big issue was lack of market acceptance.

First, if we look at 600AX, it was discontinued at the end of the 1983 model year, being replace by New 600EX for the 1984 model year. New 600EX wasn't upgraded to SIS until the 1986 model year, leaving a 2 year gap between 600AX and SIS at that level. The story is similar with Adamas AX. It was discontinued at the end of the 1983 model year and there wasn't any SIS at this level until two years later, with Light Action. Both these AX groups were discontinued for a more traditional group, without SIS being available.

Furthermore, if we look at model lines of bicycle manufacturers, we see two different situations but both support a lack of customer interest in AX. Miyata offered their Aero-Miyata with Dura-Ace in 1982 and 1983 but it's absent from the 1984 catalogue, when Dura-Ace AX was still available. If Dura-Ace AX was selling well, why would they prematurely eliminate the Aero-Miyata.?

Conversely, some brands, such as Velo Sport, continued to catalogue Dura-Ace AX models in 1985, after it had been discontinued at the end of the 1984 model year. This put it into direct competition with SIS equipped New Dura-Ace. The only reason to allow this would be if they had been saddled with lots of unsold inventory. The standard practice to liquidate leftover bicycles is to heavily discount them, so that they are more attractive to the shops. Normally, this would dispose of the stock. However, in Velo Sport's case, it didn't and the Dura-Ace AX models were catalogued again in 1985. This suggests to me that Dura-Ace AX was such a poor seller that LBS weren't interested in acquiring surplus AX bicycles, even at bargain prices.

Even Shimano themselves knew that the AX series would have limited appeal. They continued to offer the EX series at the Dura-Ace and 600 levels, concurrently with AX. The pros largely dismissed AX. Except for specialty ITT and TTT use, you rarely saw AX on pro team bicycles.

There's no doubt that Shimano was patiently waiting for the expiration of SunTour's slant parallelogram patent, to take their shifting performance to the next level. However, that was no reason to redesign an entire group. They could simply have introduced AX SIS, with a redesigned rear derailleur and shift levers, something along the lines of a anodized version of 600 Ultegra, That would have been aesthetically complementary. However, with the advent of New Dura-Ace, gone were several major innovations from AX, such as the Direction-6 hubset, Para-Pull brakeset, Dyna Drive crankset, Dyna Drive pedals and even the scalloped headset. These were the high profile technologies that the pro cyclists, consumers and shops deemed undesirable. Personally, I can appreciate the benefits associated with most of them and was disappointed to see most of them disappear, as I'm sure many other AX users did. However, we were an insignificant minority, from a market perspective.

So, while there is one tiny piece of circumstantial evidence supporting the SIS theory, when we take a look at the whole picture, there is far more evidence supporting AX's demise due to market failure.