When I hold front brake on there a bit of movement on bars/forks. Topcap and stem are tight. Do I need new headset of something else.
Alpine 160
Fox talas
fsa CHISEL HEADSET.

Loosen the stem and tighten the top cap until there’s no movement but the bearings turn smoothly, re-tighten the stem.

If the bearings don’t run smooth the headset could be worn out or you over tightened it.

C

Take the stem off and inspect the bearings for play/roughness.

If they feel smooth then make sure that your stem is not the problem, is there a spacer underneath it? If not then it might not be preloading the upper bearing properly.

loosen stem bolts – increase pre-load on the bearings by tightening the topcap bolt – refasten stem and loosen slightly the topcap bolt again

tightening the topcap while the stem is tight should have no effect and once the stem is on tightly, you can release the pressure on the star nut slightly

if there’s still a problem then you could look to either the suspension (if the bushings are worn) or check the bearings in the headset

others may have a more educated opinion on what to do next but those would be my first steps

Check the headset is tight enough – if not tighten.

Or – sometimes the steerer can be too long to pull everything together and tighten properly – instead it sits flush with the top of the stem (there needs to be a 2mm ish gap) – also sometimes the star nut is not far enough down the tube and hits the top cap before pulling tight causing the same issue.

Adding another spacer above the stem will tighten everything properly and show if either of the above are the problem – If so then cut steerer or push star nut further down to fix.

If not your bearings need replacing.

Also….check that your crown race is fitting tightly on the base of the steerer and isnt loose. If you can rotate it, that could be your problem.