Once the cover is off, the fixing bolt on the Duopar Eco is pretty standard, at least the one on mine, which was purchased at a swap meet but unused. The bolt just screws in until it stops. The Ti Duopar is a bit more complex. The fixing bolt is split like an old style stem with another 'spreader' bolt that screws in from the wheel side of the dropout. That way the tightness or play may be fine tuned. There's a really fine mylar(?) washer that rides between the dropout and deraileur. You adjust the main fixing bolt to fine tune and tighten the inner expander from behind until it locks the threads into the dropout. A really small allen key is used for adjustment and I had one in the pile I'd collected through the years. I really couldn't tell you the size.
The cover over the bolt really isn't needed, but does dress up the derailleur. It's just a press fit and may be worked out with a fine bladed screw driver easily. I can usually pull them off by hand, just remember to pull it off along the axis of the bolt.
The Ecopar is really the lower price point derailleur. The ti version has nicer bolts all around and a barrel adjuster built in. I've got the Ecopar set up on my Barb's Jack Taylor ladies bike with an otherwise identical drivetrain to my bike. I wanted hers to have the steel derailleur since she's not used to friction shifting. It works well, but it clunks into gear a bit more noisily than the ti version on mine. Then again, as much as the Taylor gets ridden, it may be like new for some time.
The derailleurs work best with a light touch. Maybe I'm too used to the derailleur, but you can feel a nice shift through the shifter. It seems to feed back really nicely when it's grabbing the next gear. I've heard people claim that the Duopar is really frail and don't like them. I did bend mine once on a Bike Virginia when the chain got trapped up front. I was able to straighten the jockey cage by hand to finish the ride and then fine tuned it with an adjustable wrench when I got back to the wrenchforce repair guys at camp. The Ecopar should be much sturdier, but do minimize the limit screws on the spoke side of the freewheel to prevent overshifting.
Happy trails,
Dan Artley in Parkton, Maryland USA
From: Tom Hayes <hayesbikes(AT)gmail.com> Subject: [CR]Huret Duopar Eco rear derailleur To: "CLASSIC RENDEZVOUS" <classicrendezvous(AT)bikelist.org> Date: Friday, November 14, 2008, 3:04 PM
Checking the archives there is some discussion of this derailleur. One person mentions how it is attached to the rear hanger. But I cannot figure out how to unattach (is that a word?) a rear Duopar from the hanger. It has a cover where the head of the attaching bolt is, and this cover does not appear to be capable of being removed, though it could, but it looks as if I would have to break it to do so. On the backside of the bolt coming through the hanger, there is a hole in the center of the bolt. The message from the archives mentioned that it is removed by inserting a tool into this hole and unscrewing it. I have attempted to use every allen key size I have that fits into the hole but I cannot find one that will lock onto anything. Could someone please offer some advice for the proper (I have already thought of a lot of improper ways) removal of this derailleur? And if it is allen key, what size?
Thank you.
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Tom Hayes
Chagrin Falls, Ohio USA