Schlumpf being way expensive, and Hammerschmidt needing ISCG mounting tabs at the BB, anyone ever use or think about installing one of these?:
This is the 2sp Metropolis to which I referred previously, 1:1 and 1:1.6 ratios -- 28T chainring standard; equivalent of 45t chainring in overdrive. I'm seeing it online for $299.00 retail, as low as $225 ebay.
Unlike auto or back-pedal shifting, this does complicate matters a bit with handlebar mounted shifter and cable/housing setup.