Howdy,
IIRC the Simplex derailleur known as "The Criterium" featured an aluminum allow pulley cage and pulleys with ball bearings. This was the black silver mode found on yer PX-10e, Gitane Tour de France, and (greatest of all French bikes) apple/lime green Meral. The Simplex Prestige featured a stamped steel cage and pulleys with bushings. Apparently this stamped steel wasn't as rigid as the aluminum cage.
There was also a plastic bodied LJ rear model from the mid seventies. It came with plastic retro-friction levels.
Question: Is there any way to fix a Simplex Competition front derailleur (the plastic parallelogram model found on you 1976-78 Px-10e and PX-10le type bikes), the plastic body of which has cracked neatly at the hinge?
Regards,
John "Has the repainted Meral up and running but with a LJ 5500 rear derailleur and I don't which metal metal LJ in front, but darn bike drew lots of compliments until people realized it weighs about 26lbs+ with fenders but it is a 62cm frame with huge cool tires, so cut it some slack, OK?" Taglia
Chicago, dark and 50s