My wife, Susan, and I were very enthusiastic tandemists from ~1970 on into the indexing era. When it came out, the DuoPar was absolutely the lust object de jour in tandem circles, and remained so for quite a while. Blessings in abundance: Fine shifting, would wrap meters of chain without complaint, and all-round beat the CampGranola Grrann Terrista gear grinder and chain mangler.
But, it did have one peculiarity that caused many a bike to shrivel up in shame at the language uttered: If everything was not perrfecttllly aligned, backing the tandem up led to what even the physicists would recognize as entanglement.
You have to recall that tandems do get backed up. not just lifted. The typical tandem of the era (say a fine Jack Taylor or Bill Boston) probably weighed 40 lb or more (>18 kg, for those who compute rationally), and was about 95" from one end to the other. Hard to maneuver in college dorms at rallies, and in many of life's other challenges.
So, those of us on tight budgets got through the era with our $10 Suntour GTs, which had only the elegance of being utterly idiot-proof and very good shifters on their side. I do keep one or two DuoPars in the collection, sort of like the Campy (in both senses) 1pulley Sport: almost all the expense of the Gran Sport, and virtually none of the capability.
harvey sachs mcLean va +++++++++++++++++++++++++++++++++++ Sayeth Jan Heine:
I have used unmodified Duopars for years, on my camping (loaded touring) bike, on a tandem and on my city bike. Never had a problem with reliability, but then, I don't tend to pedal backwards violently. Never saw any use for that.
The biggest problem with the Duopar is that as an "early-shifting" derailleur, it will jump out of gear under hard acceleration as the bike flexes, especially if it isn't super-perfectly adjusted. See also the article "Riding with Classic Derailleurs, Part 1" in Bicycle Quarterly Vol. 4, No. 2.
This never is a problem on the camping bike on overland trips, but could be very annoying on the tandem, and even more so on the city bike when pulling a trailer and starting from a light.
Jan Heine
Editor
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