Originally Posted by
Citoyen du Monde
The fact that Schwinn mounted everything on the right side does not make them tandem cranks. Tandem cranks according to TA foresaw left cranks fitted with chainrings and reverse pedal threading. Using standard cranks was an expediency that worked perfectly well as long as you were OK having two usable chainrings for the drive chain. On track tandems, it is commonplace to have both the drive and timing chains on the right.
The cranksets came from TA in boxes marked "Tandem". (Years ago I bought 6 sets)
In the boxes were;
2 standard left arms
1 short front and 1 long rear BB. I'd have to do some measuring, but I believe the rear BB was longer than the standard triple. If so it was probably also used to make the TA 26-36-46-56 quad shown in Paris in the early '70s.
1 standard right arm with 32-36-52 chainrings. The bolts connecting the middle and inner ring to the outer ring were longer than normal. This was because 2 sets of spacers were needed between the inner and middle ring so the two chains would clear.
1 standard right arm with the tandem specific "Etoile" adapter allowing a middle/inner ring to be mounted without an outer ring.
I would wager that, over all the years of production, these were the more common "TA Tandem" configuration, as opposed to the "Crossover" versions which became popular later.