Lewis is a difficult brand to understand. The derailleurs are relatively common for a minor brand of the 1930s or 1940s. But catalogues, adverts, reviews in magazines etc. are extremely rare. So people make up plausible stories for the brand - which may or may not be true.
Here is my version of the story of the Lewis racing models - which I think may be called 'Le Lewis Course'. Treat my story with a great deal of caution.
First off, these derailleurs share a number of key features:
- They are single pulley devices rather reminiscent of the Simplex Champion du Monde
- The operating mechanism is a rod sliding in a cylinder.
- It is a direct-pull device with no toggle chains to break.
- A Bowden cable is fed up the inside of a sliding rod. The cable nipple is on the very inside, close to the spokes of the rear wheel. The cable exits the outer side of the cylinder and enters the cable outer. The cable is clamped at the lever.
- Lewis derailleurs are generally well made and decently finished.
I believe that these derailleurs were manufactured between about 1937 and, perhaps, 1948. The war years may account for some of the lack of catalogues, adverts etc.. There were many versions, that may have been produced in a sequence something like the following:
- I think the story starts in 1937 with a model with a toothed guide pulley with a small rectangular pusher plate on its outside and a small chain trap on its inside. The cylinder was clamped to the steel main arm using a welded-on circular clamp. This version is described in an instruction leaflet as 'Le Lewis CM7'. It has been suggested to me that 'CM7' is a contraction of 'Course Modèle 7' and that the number 7 indicates the year 1937. This is very plausible - but backed by no solid evidence at all!
- Shortly after this, possibly around 1938?, the toothed guide pulley was replaced by a plain circular pulley and two extravagant chain pusher plates (similar to the Simplex Champion du Monde) were added either side of it.
- Then, possibly around 1940?, the main arm, cylinder and pulley cage plates were manufactured in aluminium. Due to the inability to weld aluminium, this generation had the cylinder bolted to the main arm using two large nuts.
- Then, maybe in 1941?, the cylinder was, once again, clamped to the main arm using a built-in circular clamp. The clamp was now cast as a single piece with the main arm.
- Very shortly after this, in 1942?, the pulley cage was modified to have two, rather stylish, cutouts in it.
- Finally, possibly some years later, in 1948?, the cast aluminium tunnel shaped cap on the outside of the cylinder was replaced by a simpler, cheaper dome shaped cap.
Throughout this sequence there may have been options offered to have various, otherwise identical, parts in either steel or aluminium.
This is an unused, steel-rich, example of what I have called the fifth (1942?) version of a Le Lewis Course. Some of its attributes are:
- The main arm holds the sliding cylinder mechanism in a clamp.
- The main mounting arm is polished aluminium.
- The cap on the outside of the cylinder is tunnel-shaped.
- The pulley cage is black steel and has two rather elegant cutouts.
- The pulley cage is kept in alignment by a peg in the cylinder that runs in a slot in the sliding rod.
- It has a black steel hanger plate.
- Derailleur brands: Lewis
- Country: France
- Date of introduction: 1942?
- Date of this example: unknown
- Model no.: unknown
- Weight: 214g including hanger plate
- Maximum cog: 24 teeth (this size of sprocket is pictured in my Lewis CM7 instructions)
- Total capacity: 8 teeth
- Pulley centre to centre: not relevant
- Index compatibility: friction
- Chain width: 3/32”
- Logic: low normal
- B pivot: none
- P pivot: sprung
- Materials: aluminium mounting arm and cylinder, steel pulley cage and sliding rod
Ref. 1861
