I spent so much time adjusting the rear derailleur and never got it right, at the end I gave up and took the to local mechanic who quickly adjusted it and pointed out that the cassette needed to be replaced. I thought the old cassette was good enough for lots more kilometers, but the lowest gears were wear out making the chain skipping under load.

The derailleur part was probably the trickiest to get right and made me really hate them once I learned how they function. I hope this 100-old technology gets replaced with something more durable and easier to maintain.