Shifting problems barely existed before the invention of indexed shifting. Now they're a regular annoyance for riders in all categories.
In my private war to eliminate 4-millimeter shift housing, inline cable adjusters have been a reliable ally. But the bike industry has finally figured out how to mess that up.
For years, 4mm housing used thick-walled ferrules that made the ends fit into the 5mm cable stops commonly in use. Because of this, it was easy to substitute 5mm housing to reduce friction in a system that was getting erratic.
Because mechanical indexed shifting relies on perfect cable tension, shifting systems included fine tuners in the form of barrel adjusters somewhere in the cable run for all rear -- and most front -- derailleurs. Lately, barrel adjusters have become a necessity for front shifting because the indexing requires higher tension than you can get just by pulling on the cable as hard as you can when you hook it up.
At the same time as shifting systems have evolved a need for super high tension, the trend to run all the cables inside the frame has led to systems that can only use 4mm housing, because the cable stops are holes built into the frame and do not accommodate -- or need -- a ferrule. However, with inline adjusters I could reduce the 4mm section to the bare minimum needed to enter the frame, and put 5mm from the shifter to the adjuster. With ferrules on the housing, 4mm could go in one end, and 5mm in the other. So the bike industry introduced 4mm adjusters that take naked housing with no ferrule. But they still made the 5mm adjusters as they did before. I could sub in a whole new adjuster.
Not anymore. The last 5mm adjusters I ordered in blissful confidence were sized for 5mm housing without ferrules.
Linear-wire shift housing has always needed a strong ferrule on each end to keep the stiff wires from poking through under the pressure of the shift cable tightening. We used to see ferrule failure a lot in the cheesy plastic ferrules on 4mm housing. The extruding wires would burrow into the shifter, making shifting maddeningly inconsistent, and sometimes even damaging the mechanism. That has gradually faded away as we see more metal 4mm ferrules and perhaps some reformulated plastic that is less prone to punch through. But that does not do away with the problem of drag from the skinny housing. The skinny housing is often applied over thicker cables with coatings that are supposed to make them slide better, but usually end up turning into lint in there.
The answer has always been 5mm housing and a 1.1mm stainless slick shift wire with no coatings of any kind. That's it. No secret formulas, no chemical agents, just the largest available housing with the skinniest available cable. And now you can't have it. As cassettes get more crowded and spacing between cogs gets smaller, smaller deviations make a noticeable difference. The bike industry once again makes riding less convenient and more expensive.