The Wayback Machine – Simplex JUY 543

Simplex JUY 543:


This is one of the rarest and most sought after derailleurs ever made. There are few people out there who have been able to experience the incredible precision that has made many people state that the JUY 543 was a far superior derailleur to Campagnolo’s earlier parallogram designs that eventually rendered it obsolete… even the legendary NR can take a back seat to the 543 as it’s performance pales in comparison. Having used both I can only agree that the Simplex JUY 543 is a superior derailleur that seems to function as if it was indexed, and this stems from it’s patented alignment system that means you almost never miss a shift. It is quite honestly, one of the most remarkable friction derailleurs ever made and may have inspired some designers to look into developing indexed systems. French bicycles have always been immensely popular in Japan and there is a good chance that the designers who worked for Suntour (they developed the first indexed system) and Shimano may have had some experience with the Simplex JUY 543. The build quality is very good and it is very well sealed against the elements, it uses an oil bath system to ensure that even in the most grievous of weather, the derailleur will continue to function smoothly and the coil spring that moves the cage will not seize. It is an interesting design in that it can be set to run with a 3, 4, or 5 speed freewheel which was more common in the early 1950’s and production continued until 1957 where it was fitted to a good number of higher end French bicycles and used as a racing gear. Like other road derailleurs it seems to have a practical cog limit of 28 teeth which pushed the unit to it’s limit. Like the Campagnolo NR, it is much better when it is paired with a freewheel that does not exceed 25 teeth. In practice shifting does feel like it is indeed indexed as you can feel the derailleur align itself and the shift lever transmits this feedback well, downshifting requires a little more effort while the upshifts are like warm butter on glass. I run mine with a 4 speed block which is the originally equipped freewheel for my 1957 Peugeot… the front shifter is a Simplex rod type that is not quite as precise but also not as suicidal as people make them out to be. It was an expensive piece of kit in it’s day and now they often sell for amounts in excess of $1500.00 when they are new in the box.