Originally Posted by
HTupolev
The thing about road 1x is that it's impractical to start with 2T jumps if you want tight spacing, and if you start with 1T jumps, it's impossible to avoid annoying ratio jump discontinuities even if you are totally non-limited by cog count.
You could solve the problem by doubling the sizes of all the sprockets, but that's impractical with a half-inch-pitch chain. You could switch to itsy-bitsy chain pitch, but then the costs would shoot way up and sprocket life would be reduced.
With the capabilities of modern derailleurs, the flexibility of modern chains, and with e-shifting and synchro-shift becoming a thing, personally I'd like to see a modern take on half-step.
50-46
11-13-15-18-21-25-29-34-40-46-54
But, some people might still say that you lose the smooth shift pattern at the outer edges if you want to avoid cross-chaining.
SO.
Wild solution: Switch the chainrings around. Put the big ring on the inside and the little ring on the outside!
46-50
11-13-15-18-21-25-29-34-40-46-54
Even, reasonable-chainline shifting all the way from 46-11 (~110GI) to 50-54 (~24GI). 20 gears with step sizes of around 8%.
Half-step was popular in the '60s and some of us were still using it in the early '70s. It makes a lot of sense from the rear derailleur's point of view since it gives you more gear range with less chain slack for the rear derailleur to take up. For example, 52-42 with a 13-21 on the back is 18t, which gives you the same range as 52-48 with 13-24, 15t.
On the other hand, it requires two shifts to get the single-step gear change that keeps you from getting dropped, and when going hard front derailleurs balked at dropping the chain to a ring that was only three or four teeth smaller.