Thanks Chris for the info. I don't have the bike here with me so I can't measure the rear hub spacing. I had a tandem "expert" shop build the bike so I wouldn't have to figure this out by myself.

So, if the crank is intended for a single and if the rear hub is 140mm or 145mm, the cassette could be 5mm further outboard than the chainrings (right?).

If this is the case what is the right way to fix this? Tandem specific cranks?

Can you educate me on how chainline is measured?

Thanks again.