After about 8 months/5000km my alu road bike has developed an issue with the top bearing of the integrated headset, when sprinting, hard braking, or going over bumps it moves with a clicking sound/feel – no sensible amount of pre-load fixes it.

I’ve done a bodge fix which is to put a few wraps of PTFE tape around the bearing. Any tips for a better/more permanent repair?

The frame is a Brand X RD-01 and the headset is a Cane-creek IS41 28.6/30 (which still looks perfect and buttery smooth!)

I think I’m going to struggle to find a shop with an appropriate headset reamer here in Singapore plus would rather do a cheaper fix if I can.

Firstly, is the movement on the inner or outer bore – some headsets have split ring/collet that fits above the bearing and over the fork steerer. Have you also checked it’s the right size headset bearing? Some of them vary by as little as 0.5mm in OD.

Reamer? Reaming the won’t make any difference, it’ll make it worse if anything?
I’d say you’ve possibly got the wrong bearing in there. There’s loads of bearings that are very similar sizing, some just 0.2mm different.
If not I’m going with your frame is now scrap…..

I’d change the bearing first. They’re weird things. I had a knocking from a Pro 2 font hub, bearings felt perfect in spin mode, but putting new ones in completely sorted it. They can wear internally without obvious rotational roughness I guess.

I took another look today.
The top and bottom bearings are identical and 41mm.
Definitely no play in the bearings, the problem is quite certainly that the mate between the frame and top bearing taper is a bit iffy.
Reaming the frame would almost certainly sort it out (even the headset instructions recommend reaming the frame prior to installation), but the PTFE tape seems to work so I will just stick with that for now and see how I get on.