Simplex Tour de France 34 derailleur

In the early 1930s there was no agreed way that racing derailleurs should look or even work. Cyclo and Chemineau had, pretty much, defined the the concept of the touring derailleur - but in the world of racing everything was up for grabs.

If you want evidence of this look no further than the Simplex Tour de France 34. It's a massive object, combining a 75mm sprung main arm with a 90mm sprung cage with the single pulley mounted at its end. That's 165mm of total throw, tipping the scales at a mere 400g, all for providing a total capacity of '8 to 10 teeth'. The chain is actually shifted by a substantial, but whimsically shaped, steel wing. It is actuated by Simplex's signature, top-normal, bell-crank mechanism, making its first appearance on a commercial product. Other Simplex features making their debut with this model include the 38mm diameter steel pulley wheel with its ball bearing race, and the steel loop chain guide at the pulley wheel.

This example looks magnificent, but is, in fact, quite a mess:

The bell crank has been replaced with an item from a late 1930s Simplex. The original bell-crank should be silver coloured and should accept a cable nipple, with the cable clamped at the gear lever. The bell crank should be held in place by a rivet, not a bolt and nut.
The cable adjuster at the bell crank, while charmingly dainty and undeniably useful, is probably not original.
The inner chain pusher plate on the pulley cage has broken off and a part of a pusher plate from a late 1930s Simplex has been welded on in its place. This seems to be an endemic problem with this model.

Overall it's constructed and finished to a high standard, using quality materials - but I wouldn't be that keen to actually use it.