EDIT: Dropped it off at my local bike shop and the mechanic had the following to say about it:
Bottom bracket very low quality, also worn bearings. Due to open frame type was a lot of dirt inside that could make noise. Excentric bottom socket was removed, cleaned and greased. New bottom bracket installed. Tightening bolts on frame were also corroded. Those were replaced and greased.
Original Post below:
I did read some of the other questions regarding clicking sounds when pedalling. However my bike is a bit different to the bikes from the other questions so I hope this question is fine.
Cube Travel EXC 2021 with 8-speed Alfine hub gear and Gates' belt drive
It started making a clicking noise (see video below) when I pedal hard (uphill) ever since I moved to a more hilly location. I've only had the bicycle for 9 months but because I am not in the same country anymore as when I bought it I can't make use of warranty.
It has a round bit (what is the name for that kind of system?) for adjusting the tension of the belt by turning it. It's held in place by two bolts that come with the instruction to only tension it up to 8Nm. I use a torque wrench to make sure I don't tighten it too much and make sure to tighten it evenly (is there a best practise?). I have attached pictures below.
Every time I loosen the bolts, adjust the round bit and therefore the tension of the belt (make sure it has the correct tension) the clicking noise goes away for a few days and then comes back.
Therefore it must have something to do with that round bit but I am not familiar with that system so I hit a dead end.
Video and pictures:
The clicking noise video can be found here (youtube video).