Paul Lee wrote:
I am trying to restore an early 50's bicycle (built by Parisian constructeur Raymond Valance) to it's original equipment level (for the show at Larz this weekend) and am faced with setting up a "Le Spirax" rear derailleur. It is described in the Dancing Chain on page 150 and is further portrayed in the Data Book on pages 116 (internals) and 134, for those that have access to the books. This derailleur makes a pull chain model, like the Simplex, Huret and Cyclo, look positively normal and obvious to me now. Does anybody have any experience with this derailleur? It seems as though you have to wind up the fat spiral spring that, in turn, sends the pulley and cage towards the spokes, or the largest cog of the freewheel, and then some how tighten the cable, which seems to want to wrap around a pulley on the outside edge. The spiral spring seems to be responsible for both chain wrap and transcending the freewheel cogs, via the helical slot in the cage pivot tube. I don't see any pre-load stop screw. I suppose it is possible that I am missing parts too. <snip>
Although the appearance was rather different, in the early 60s I had to set up Simplex units which used a similar principle (not sure whether to call it anarchy or high entropy!) The good news is that you may not be missing parts, if you can get it to operate... The bad news is that it took a while to get set up so the spring was wound enough to give tension to the chain, and positioned right for moving the cage back and forth. The simplex at least had a series of notches for lodging the wire spring end. I remember no other details...
Harvey "I'm not that old" Sachs McLean VA