Originally Posted by
Doc Sharptail
That's quite a tandem! Thought I was looking at a modern 650b drop bar conversion at first. Rear d/r on it too! Front chain appears to be running without a retaining idler.
-D.S.
I think (it appears) the front bottom bracket is inside an eccentric for front chain tensioning, just not perfectly adjusted. Notice the spindle is off-center, and the two bottom bolts to lock the eccentric in place.