It isn't the same as "The Devil Made Me Do It." In fact, Mark's earlier emails, and my response, got me to thinking that it was time to replace memory with data on how much chain could be taken up by a tandem's eccentric bottom bracket. . Sooo, I measured the eccentric throw on the first handy tandem. A (first year, 1988) Cannondale. It moves about 14.2 mm, which is easily enough to accomodate either even- or odd-numbered transfer cogs (14.2 > 12.7= 1/2" = difference in length around the two transfer cogs "seen" with a one-tooth change).
Feeling that I had just made a fool of myself with an incorrect assertion, I went out (to an unheated area) to the early 50s, fillet-brazed, chrome-moly, Schwinn Town & Country (remember, that's where this song and dance started?) and measured the throw of its eccentric. It is only 9 mm total. Thus, the first moral is simple: Measure before mouth. Even v. odd matters on some tandems, but not all. Second moral? Be careful not to get grease on the Spousal Unit's keyboard after mucking with the chains. That's the important one.
Harvey "humble and proud of it" Sachs mcLean va