1. There may or may not be mechanical shifting options (as rumoured for 105 next year) or else Di2 only
2. There may or may not be 2x, with who knows what cassette or chainwheel sizes
3. 1x might use the existing Microspline freehub bodies and 10-45/51 MTB cassettes or else???
There was a Q&A on bikerumor.com a in 2020 where Shimano got some input, but whether they'll listen to anyone other than racers remains to be seen; quite a few people wanted significantly lower gears for bikepacking (including me). Surprisingly, it seemed they responded to all the questions asked, though not necessarily helpfully:
https://bikerumor.com/aasq-71-shimano-g ... ents-gear/
It should be almost possible to make one's own GRX substitute now, with the only thing definitely missing now being a clutched 12 speed road rear derailleur. The 105 Di2 RD might well tolerate a cassette larger than 36T, given it seems quite a few have got the current ones to work with 42T (2x, rated 34T) or at least 46T (1x, rated 42T).
If there's a mechanical version and the cable pull remains the same maybe one could use a current GRX RD with the rumoured 105 mechanical shift levers, or else something might appear from China; there are 12 speed levers now from LTWOO and Sensah, and wide range road RDs from S-Ride - which might work together, or not...
If anyone knows anything at all from Shimano, please tell us!
