I would like to say that I'm not at my first build, almost 10 bikes (road, MTB, chinese, branded, Dengfu, Cannondale, OPEN Cycle, etc...)
To resume, I cut the fork steerer under the top of the stem and when I put the expander there is more or less 3mm free, to the top of the stem, so enought to compress the headset.
There is no spacer installed under the stem.
![](https://nsm09.casimages.com/img/2021/08/13//21081308060820397117528119.jpg)
For me this flex is coming from the stem
Apart from that, a photo of the bike under construction (size 56cm, color blue chameleon)
![](https://nsm09.casimages.com/img/2021/08/13//21081308060920397117528121.jpg)
And a little hack on the seat post (gain 28gr)
![](https://nsm09.casimages.com/img/2021/08/13//21081308060920397117528120.jpg)