Knocking noise from headset/stem

[NotAGolf]

I've started noticing a bit of a knocking noise on my bike coming from the headset/stem area. It happens when I break hard, or when I pull hard on the bars (e.g. when switching from a seated to standing position and giving it the beans).

I've had something similar before on a previous bike. When I held the front brake on and rocked the bike back and forward I could hear a knocking and feel movement, and resolved it by tightening the stem cap. This time I don't hear the knocking or feel any movement when doing the same action.

I've not tightened any bolts around the headset/stem/bar area recently, so I don't think it's because I've overtightened them (unless it's taken 6+ months to cause a problem). I've checked all bolts and there's nothing loose. Any ideas what it might be?

 

[NotAGolf]

Is it just a one-off knock or does it repeat rapidly as force is applied?

Maybe worn or broken bearings in the headset race, or you need to regrease headset bearings?

It's just a one off noise. Is there any tell tale tests that can be done to help pinpoint the issue?

If not, how do I determine which parts I need? The bike is a Vitus Vitesse Evo CRi Disc (Ultegra Di2 – 2019). Looking for at the spec I have from when I bought it, all I can see listed is:

- Frame: Carbon T700-HM UD
- Fork: UD Full Carbon Tapered
- Fork Material: Carbon
- Steerer: Tapered

 

[NotAGolf]

Thanks for the advice all. Sorry for not updating. I took the headset apart and it was full of cack. Bearings seemed ok, so cleaned everything, greased it up and put it back together again.

I've only been out for one ride as I had to wait for a replacement brake caliper due to me stripping a bolt ( ) , so I had to repair that too. Seems okay after one ride, but need a few more rides to be sure.

If nothing else, at least I've learnt how to strip a headset, replace a disc brake caliper and bleed brakes over the last week or two