Late 40s / Early 50s René Herse tip find

Back to the derailleur restoration project, I had some round aluminium bar stock which would have made an ideal shim material. I started by drawing round it onto some paper and then transposing the shapes of the worn derailleur and the pivot. I planned to bore into the end with a 19mm cutter (same diameter as the pivot), part it off and finish it by hand. The idea being I was going use the paper template to work out where the bore needed to go, then do the rest by hand with a file.

But I had a lab clear out a few weeks ago and without thinking threw out the bit of material I wanted to use 🤬

The reason I haven’t just bought another secondhand derailleur is these early Cyclo derailleurs seem to go for a lot of money for what they are. However, I spotted a very filthy similar model on eBay which I think might use the same arm. I put in a low but not-too-cheeky offer and it’s on its way. So, fingers crossed 1) it fits; and fingers crossed 2) it’s not too worn.
 
Filthy Cyclo has arrived:

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It is indeed filthy and a bit gummed up. I haven’t got the original with me so I can’t do a direct comparison, but this looks like an all-steel version of the one that was on the bike. So it’s got a steel arm, steel nuts and a steel lower jockey wheel instead of an alloy guide pulley. Still a bit of a fingers crossed job, but it’s looking hopeful.

Side by side pics for comparison:

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So if I get this right, an AL and Steel version was on the market at the same time? Compatible fittings and possibly cross compatible gubbins?
Potentially yes to all of that. We know that early on English riders weren’t keen on alloy components because they could be fragile compared to steel counterparts. The steel Cyclo could either have been a cheaper model or it could have been the same thing but destined for the UK market?

There’s probably a perfectly reasonable explanation but I haven’t looked into it yet 😂
 
The good news is the derailleur cleaned up nicely and under the grime it’s in really good mechanical condition:

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The bad news is that it’s a completely different size! Digging around the internet, it looks like there were English and French versions of these early Cyclo derailleurs. The English ones were steel and I don’t think they were used much because most roadmen rode fixed wheel. The French ones appeared on the higher-end French touring bikes like mine and were lightweight alloy. However, they are also quite a bit smaller than the steel English ones. The arms are the same length, but the mounting points and mechanism are larger diameter on the steel version. You can see this if I put the two next to each other:

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You’d kind of think it would be the other way around, with the alloy one being beefed up to account for the additional flex and lower strength of the alloy.

So that’s a shame, because the arms aren’t a direct swap and the mount on the steel derailleur is too big for the Rene Herse so I can’t just use the whole thing. Now I have to decide whether I sleeve down the steel arm (which will be quite straightforward) or if I commit some time to making a shim for the original alloy arm. What will make either of these jobs a lot easier is it looks like I actually threw my bit of material into my spares box before I did that scrap metal clear-out:

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I’ve got plenty there to have a few goes, so if it doesn’t go right first time all is not lost.
 
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