Originally Posted by
fietsbob
Techies with weak mechanics ? 1st videos, now audio.
Number One .. Why bypass of just taking it apart and looking at the condition of the parts ?
replace the cassette driver &/or maybe the axle and cones and bearing balls ..
Well, it's brand new. I wouldn't expect a catastrophic failure of the mentioned parts during the first 25km of its life

Anyway, i did take it apart on your advice and it looks good I guess. At least no broken parts fell out in the process. Put it back together and no difference.
That sound is only there when a cassette is mounted on the freehub and the wheel on the bike. Without the cassette, even when mounted on the bike and holding back the freehub it only makes the normal freehub sound. Any ideas?