The real plan was to go to the cabane on Monts Chevreuils for lunch as part of a round trip. Only the first part of that worked out, after leaving the cabane I caught a bit barbed wire in my rear derailleur and tore it off. That’s actually the second time this week and it was a replacement derailleur the store had just fitted.
The first derailleur was a Shimano Deore MTB RD-M6000-GS that was an original part. That’s supposed to be a medium length but it’s a lot longer than, for example, Zee derailleur. The second was a Shimano Deore XT RD-M786 which was a long, that’s not really ideal although I don’t think it made this failure more likely. I’ve since been able to buy two more RD-M6000-GS units which means I’ve bought four derailleurs in the space of a week! Right now, two of them are in the post and a third is on the bike.
In the original failure, the damage was so severe that I had to remove the remains of the derailleur and single-speed the bike by shortening the chain. And the store didn’t have that either so they took a short chain and added links. None of this ideal so I’ve now bought spare chains and a cassette to go with the spare derailleurs. It’s pretty obvious that while there are still some units around there are serious shortages of parts.
I’d swap all that for a Zee set but the cassette isn’t very wide so I’m not going to do that. The Zee derailleur is a lot shorter and so it’s less exposed. I’m guessing that Shimano will extend the Zee cassettes sometime and it’s likely that’s going to be after I use my spare parts.
RD-M6000-GS 
Shimano Deore XT RD-M786
