https://www.xshifter.com/ ?
have been considering this for my sscx if i want to convert to gears - bit spendy but no cables, no messing with levers, can use any rear derailleur...
dunno... i thought it looked fairly legit? seems pretty well developed if you look at the youtube vids of it. i mean it's pretty ugly looking, but aside from that it could be a good solution for adding gears easily. the inventor used to work for sram...
https://www.xshifter.com/ ?
have been considering this for my sscx if i want to convert to gears - bit spendy but no cables, no messing with levers, can use any rear derailleur...