Hi all again,
i still cant fix the issue.
I reinstalled crankset AND bb multiple times, using alot of grease and the correct torque. i also used spacers to eliminate play in the bb. Everything runs smovely and without any noise, when using the small chainring. But when using the big chainring and applying force the left pedal, there are these weird noises. I can rule out the chainring and pedals too, because i also reinstalled them and on the small chainring everything is perfect.
A lot of research let me come to the conclusion, that the BB does seem to not be able to handle the torque/torsion of the crank spindle when using left pedal with big power and using the big chainring.
Has anyone any experiences like this? What else can I try besides buying a new bearing?
I have something similar with my cheap Think Rider Alu Crank set (L165mm/D24mm) and power meter, normal pedaling is fine, but as soon you put a bit more power into it, you hear a chain rub on one spot of the chainring. I assume it's the cheap crank set in my case.
I had the same with a RIRO carbon crank set (L165/D29), which i had installed with a cheap ceramic BB. In this case it was the BB itself, it had to much play, even when pre-loaded correctly you could basically twist the axle in the BB shell. I have to make a picture of the spindle later today, because there is a specific wear pattern on the spindle (paint), which is 180° appeared on left and right of it.