If you're talking about the timing rings on the left side of the tandem -- the ones that connect the captain & stoker -- yes, you can "flip them over" on their respective crank arms. However, since most timing rings are basically middle-size chain rings they are not always symmetric, i.e., the "inside" has ramps, pins or the mounting tabs are recessed so what we usually recommend is moving the front chainring to the back and the back one to the front which accomplishes the same thing as flipping them over.
If you're referring to the drive-side chainrings, now days these are almost uniformly asymmetrical with ramps and pins to aid shifting and thus they cannot be flipped over to double their lives.
Mark's Tip: Treat chains as consumable items and replace them more often and you'll find your chain rings and cassette cogs will last longer.
Last edited by TandemGeek; 01-30-05 at 09:45 PM.