Charles, I wish I understood the problems you cite with Duopars! I've used one for about three year on an on-topic Trek, with an off-topic 7-speed freewheel and an off-topic x-speed chain, and it has given me zero problems whatsoever.
Ann Arbor, MI USA
> The Cyclone GT and the Luxe VGT are both very good single-spring touring
\r?\n> derailleurs..I've put many miles on both.
\r?\n> But....the best one I've ever used in terms of predictablity,
\r?\n> reliability, and shifting to rival perfectly-adjusted Ergo, is the Huret
\r?\n> Duopar. We've had one on our Taylor tandem for years, through many
\r?\n> miles...I even used it with an 8-speed cassette for awhile...it didn't
\r?\n> like the narrow cog spacing, but it did work. Use it with a proper 5 or
\r?\n> 6-speed on-topic freewheel, and the Duopar is unbeatable... smooth and
\r?\n> precise every time, especially with Simplex retrofriction shifter
\r?\n> just make sure, as has been noted by others, that you don't try to back
\r?\n> up unless the derailleur is perfectly aligned with a given rear-cog, or
\r?\n> the chain will wrap right around the derailleur cage, or the cage will
\r?\n> try to wrap itself around the freewheel.
\r?\n> The problem is easy enough to avoid, with a little care.
\r?\n> I'd never used a Duopar until 3 years ago, when we got our tandem, and I
\r?\n> have to say I've been mighty impressed with it. It'll shift to 32 and
\r?\n> 34 tooth cogs as smooth as silk. We have the titanium version, I
\r?\n> assume the steel version works as well.
\r?\n> Charles Andrews
\r?\n> Los Angeles