Don't know what this "cap" looking thing is called. But it was loose and was causing the stem to rock slightly forwards and backwards causing a "clonk" sound when riding on bumpy surfaces.
I turned it clockwise until it cannot move downwards anymore and the stem is now steady and no longer rocks. To experiment, I turned it anticlockwise so it went all the way upwards. That also stops the rocking.
Question is, which way, up or down, is the correct adjustment for this "cap"? I'm thinking downwards is the correct way as it shields and "grabs" the moving stem.
Thanks!
by Duck_999