There are some vintage components which I have never taken a liking to. Huret parallelogram rear derailleurs are one example. These rear gear changers were introduced in the 1960’s. The Huret rear derailleur line of this era ran the gamut from the lower end Alvit models to the very lightweight Jubilee models. In between are the Eco, Challenger, various Luxe models, Svelto, and the titanium version of the Challenger – the Success. In my experience, the lower end Alvit models can actually perform quite well, even though they are fairly heavy and unattractive.
This titanium model (one of many Huret models in my parts bin) is very visually attractive, but is essentially exactly the same as its Challenger counterpart, engineering-wise. One feature of both the Challenger and Success models is the ability to move the cage pivot to accommodate 24 or 28 teeth.
This is accomplished by screwing the cage pivot bolt into either the 24 or 28 tooth drillings on the parallelogram. That is all very well and good. Apparently, these derailleurs can accommodate a 31 tooth gear range, so they can be adapted to touring applications with the right set-up. Frank Berto’s book The Dancing Chain has a comprehensive discussion of these derailleurs, along with commentary regarding his own experience using them on his bikes. While noting their obvious shortcomings, Berto states that he has successfully used the Duopar models (which have TWO parallelograms), on his friction shifting touring bikes of this era.
Fortunately, the dropouts on the early 1980’s Meral Rando bicycle that I am currently working on are NOT Huret style dropouts. They are standard Shimano/Campy so can accommodate pretty much any kind of rear derailleur option. That set my mind at ease, in case something went wrong with my urge to disassemble the Huret Challenger which is original to the bike.
If you are into overhauling rear derailleurs, RJ the Bike Guy has a wonderful video showing the overhaul and reassembly of a Huret Challenger rear derailleur. As it turns out, the process of overhauling is very straightforward. The pulleys run on bushings which just need cleaning and lubrication. The body also needs to be cleaned, with the pivot points lubricated. The pivot spring on this derailleur was kind of kinked up, so we’ll see how well it performs once it has been cleaned, greased, and re-installed.
Now to the most challenging part of the overhaul process: installing the Huret derailleur into the dropout. This step would normally be something no mechanic would ever even discuss, except to recommend torque settings for the installation bolt. Not so with Huret rear derailleurs. There are all kinds of parts, including bolts, washers, clamps, and b-screw adjusters to be considered. I found myself really questioning my sanity as I attempted to mount my freshly overhauled derailleur to the dropout on the Meral. Fortunately, disraeligears.co.uk came to the rescue. As it turns out, the BLACK mounting bolt is very important – signifying the method which is necessary to secure the derailleur to a non-Huret drop-out. This also determines the line-up of the b-screw adjustment piece, which can be put into two different positions – see above. If you don’t have a headache by now, you are to be commended! I will circle back around once I have the Huret Challenger installed and tested.