Creaking bottom bracket only when standing on the pedals

I would replace rather than repair at that price.

Clean it properly first, half of these problems are just dirt.

There is a good guide on this in the Articles section.

Sounds like the bearings. They are cheap and easy to swap.

Solved it last month with a new cable. Night and day.

Make sure the wheel is seated fully in the dropouts.

Marking this one to follow, same issue here.

Check the simple things first: tension, limit screws, and that everything is tight.

Had exactly this. It turned out to be the cheapest part in the whole system.

Bring it on Thursday and we will have a look together.