Classic Equipment: Huret Duopar

There was a time when if a touring cyclist wanted really wide-range gearing, there weren't a lot of derailleur choices, and there were a lot of compromises with the choices that were available. Simply adding a long pulley cage to a derailleur wasn't enough -- it might increase the chain wrap, but that didn't necessarily mean the derailleur would make the big jumps between gears.

Huret, of France, offered several touring derailleurs in the 1970s -- including a long-cage version of the Allvit, the Luxe Super Touring, and the superlight Jubilee Touring. The Luxe ST and the long-cage Jubilee really didn't work well on wide range freewheels (which kind of begs the question "what's the point"), and the 145-gram Jubilee was just too light for for the demands of touring. The Super Allvit had decent capacity, but it also had that cable-breaking tension the Allvit's were known for. More than that, for less than the price of the Allvit, a person could buy a SunTour VGT which had serious chain-wrapping capacity, worked better, and could handle at least a 34-tooth sprocket on the rear wheel. I've heard people say that with a little finagling in the setup, one could even stretch the capabilities a bit more, though it could result in less-crisp shifting out to the smaller cogs. Simplex offered some long-cage versions of their derailleurs, such as the SLJ 5000 GT, which was listed as being able to handle a 14 - 34 freewheel with an 18t difference in chainrings, though it wouldn't shift that wide of a range as quickly or reliably as the much cheaper SunTour. Shimano's dropped (but not slanted) parallelogram touring derailleurs, like the Titlist GS, were rated with some pretty impressive capacity, and shifted somewhere in-between the better French derailleurs and the cheap-but-effective SunTour.

The DuoPar's stamped construction had that
Erector /Meccano set aesthetic that Huret became
known for. Little plastic cosmetic covers were easily
 broken and lost (usually in that order). The extra
parallelogram moved the pulley cage up and down,
keeping a closer chain gap across wide-range freewheels.

In the interest of creating the best wide-range touring derailleur available, Huret came out with a completely new derailleur design in 1975 that used two independent parallelograms to move the pulley cage. The main parallelogram would move the cage laterally in and out, while a second unit would move the cage up and down to more closely track the steep profile of a wide-range freewheel. It was dubbed the Duopar -- as in "dual parallelogram."

Like many other Huret derailleurs, the Duopar sported stamped construction -- albeit stamped out of very expensive titanium. The main body bore a strong resemblance to their Challenger and Success models. Also, it had little plastic cosmetic covers that didn't really serve any functional purpose and could be easily broken off and lost. The exotic materials meant that the Duopar was priced out of reach for most people, so around 1981, a pressed steel version, called the Duopar Eco was released. The Duopar derailleurs were reported to be the best shifting touring units available -- capable of reliably shifting over 13 - 36 freewheels, and up to 27 tooth difference in chain wheels.

Three of Huret's touring derailleurs, with the official capacities listed.
Notice that the Super Allvit has nearly the same  listed capacity as the Duopar,
but it's a pretty safe bet it would struggle with shifting over such a wide-range
freewheel. The Jubilee with its long cage still wouldn't handle that wide of
a range, and was too delicate for any heavy-duty touring use.

For some people, the Duopar was the ultimate touring derailleur. In a 1978 Bike World article, Sheldon Brown described the "new" Duopar as a real improvement in wide-range applications. Probably nobody had more glowing reviews of the Duopar than Frank Berto, who was a technical editor for Bicycling magazine in the 1980s. Berto had built a derailleur testing rig on which he evaluated hundreds of derailleurs during his tenure at the magazine. In his careful objective analysis, the Duopar outperformed every other touring derailleur -- even unseating the previously top-ranked SunTour VGT. In his history of derailleur-equipped bicycles, The Dancing Chain, he writes, "I used Duopars on most of my bicycles. It was my reference for evaluating other touring derailleurs. SunTour's derailleurs came close, but they would not shift onto the small sprockets as positively as the Duopar."

The very un-SunTour-like Trimec.
Spotted on eBay.

The glowing reviews of the Duopar meant that SunTour and Shimano both set about trying to outperform it. SunTour's first attempt was a so-faithful-it-was-scary copy called the Trimec, around 1981 or 82. I saw one on eBay once, and it bore almost no resemblance to SunTour's signature design. SunTour's next attempt to Out-Duopar-the-Duopar was the MounTech of 1982 (which soon expanded to a whole series of "Tech" derailleurs) which combined their patented slant-parallelogram design with an extra parallelogram to move the pulley cage up and down. Being too complicated for its own good, too fragile, and non-rebuildable, the original MounTech would be seen as a serious blow to SunTour's reputation. Even after correcting a fatal flaw in the MounTech's design (a poorly-engineered jockey pulley that would self-destruct), the complex design of the MounTech made it too prone to being bent or twisted out of alignment.

Shimano also came up with a Duopar-inspired variation in 1984 -- the Deore XT Superplate. It had Shimano's familiar drop parallelogram design along with a second parallelogram for Duopar-like vertical pulley cage movement. While it didn't end up hurting Shimano's reputation, it failed to catch on. When SunTour's patent on the slanted parallelogram expired, Shimano came out with a new version of the Deore that did for mountain bikes what the DuraAce 7400 SIS did for road bikes. The complicated Superplate was dropped quietly.

Not everyone raved about the Duopar. While Frank Berto swore by it, others swore at it. In his fascinating derailleur-collection website Disraeli Gears, Michael Sweatman writes, "I hated the Huret Duopar in much the same way that I hated the earlier Huret Allvit. . . It was a fragile design made up of easily bent flimsy plates. But most of all it worked fantastically when new - but in British conditions at least, it then wore out almost immediately." Surprisingly, a lot of early mountain bikes used the Duopar,  mainly for its outrageous range. But it was a derailleur that, under the hard conditions of mountain biking, could end up hopelessly twisted and bent out of shape.

In the interest of disclosure, I've never used the Duopar. Too expensive and too complicated for my taste, especially when a SunTour would work well and had more than enough range for any riding I ever did. I had riding friends who used the Duopar, though. One saved up and dropped some serious money on one for his mountain bike (at a time when mountain bikes were still a pretty rare sight here in Ohio) despite my raised eyebrows. It suffered a tragic demise and was eventually replaced by a sturdy and reliable Deore XT (non-Superplate).

I've read that no derailleur, past or present, had the range and capacity of the Huret Duopar. Regardless, some loved it while others hated it. Used ones can be found at fairly decent prices nowadays in the vintage market, though I'd be hesitant to buy one used, considering the potential durability issues. Occasionally NOS examples come up on eBay with prices ranging from $150 - $250. Worth it? I guess it depends on whom you ask.