I hope the photo below provides enough detail of interest. The chain going through the derailleur does not cause problems in folding and unfolding. On rare occasions it gets mangled in unfolding but getting it on track is not much of a deal.
Yes, my interest in lower gears is in the context of riding Brompton in mountainous areas. 3 rear cogs and 3 front rings will have to wait - my next priority is to convert T-bag into a backpack
Thanks, that helps and I like how the derailleur cage seems somewhat protected from bumps by the right pedal.
FWIW, here's one simply backpack mod that I've been using... just need a longer shoulder strap.
