Zero ratio: Hmm, I'd have to examine the hub.

This sounds like back in the day, a variable ratio zoom telescope, never had 1X as the low, it had to be like 1.25X or 1.5X, because evidently trying to magnify a 1X was a problem, at least that's the reason given to me. Nowadays, I'll see "1-5X" and others starting at 1, all the time. Something must have changed in the designs.

The NuVinci CVT hub with angled surfaces on the balls, it could go from reduction to overdrive and right in the middle was... wait, that's not zero, that's one, so direct drive.

I'll be curious to see a true 0X, without simply disengaging the transmission, also known as Neutral.