I guess having chain on left side would be better for left footers, because most of strenght then would go to freewheel when pedalkicking and not to BB. Thus would save some energy. I guess it would be possible if use fixed hub, with threads on both sides, chain would suite. Most problems would be with cranks and freewheel (it would go in opposite direction). Is it possible just put BB otherwise into frame, thus longest end would be on left side and i could put on right sided crank on that left side of bb. Still remains problem with freewheel...