This was a complex build! One of my Duplex tandem recumbent tricycles, with hand crank power for the stoker, Rohloff gearing, and electric assist from a Pendix drive. S&S couplings let it split in half for transport. The mid-drive system has a freewheel so the stoker can stop pedalling, and there’s a tensioner to keep the chain on when folding the hand crank arm forwards to get on and off.
