Just last Sunday, I took the long cage Nuovo Record off my Heron and replaced it with a Duopar. Then I replaced the front (a Triomphe maybe?) with some sort of SunTour made specifically for half-step gearing. The new setup works really well. It's been nearly 20 years since I last used a Duopar. It has a wonderful liquid feeling to the shift and is very precise. It will handle horrible freewheels like the 14-16-19-24-34 my wife used to use. The down side to the Duopar is it's fragility. Don't back the bike up unless it's lined up perfectly with the cogs or it will bend. One I had a Duopar go into the spokes. That bent every part of the Duopar and tore the 980 front in half. The same thing happened with a Nuovo GranSport and the only thing that broke was the piece that holds the cage stop screw. I put on the corresponding part from a Nuovo Record and was back in business in a few minutes. My ultimate derailleur would be a Duopar built like a Nuovo Record. Some Duopars are all metal and some have a plastic outer parallelogram arm (The French and their plastic bike and car parts....) Early Duopars have a nut that goes on the mounting bolt on the inside of the dropout. You might have to respace the hub with one of these to move the freewheel away from nut. The later ones have a split mounting bolt with an internal jam screw instead of the nut. These work fine and are kind of cool.
Leonard Bulger Ann Arbor, MI
Thus spake the Monkeyman:
Anyway, what's the story with the Huret Duopar? I know there were three versions, alloy and titanium, all alloy, and alloy and steel. What are peoples opinions on these versions shifting, merits, and quality? Also what's the current market for these things these days?