I just noticed that my rear rim has a dent in it and is slightly flat looking with the two nearest spokes very loose. Is this terminal or something that can be fixed?

Probabaly terminal from the description.

it’s not likely to go back to being perfectly round, if you’ve flattened it off that much. The question is, do you care? A couple of my wheels are permanently out of round but they still work perfectly well. And my old MTX31 was more dent than straight but they averaged out 😆

Personally I’d restore the tension and see what happens but you might prefer to go do a decent wheelbuilder.

Hmm I thought as much. I really need to be more careful on those cross drains. I’m amazed it didn’t pinch flat.

Yeah I’ll probably replace it but keep it as a spare as it’s rideable. The wheels not that old so it would be a shame to chuck it. It is/was a good wheel too build by a good wheel builder.

I’ll probably buy a wider wheel and put a bigger tyre on it for more rocky routes and avoid dumping my back wheel into cross drains again.

I flattened an on one reetard rim on my back wheel, it was too flat to get the spokes tight again, rode about on it for absolutely ages (at least a couple of years) and it didn’t die. Eventually replaced it with a new wheel just for peace of mind.