Ever come across a situation where the wheel is getting difficult to spin after tightening up the wheel nut? This usually occurs after changing the wheel adapter or the hub carrier. Adding spacers will only make things worse!
If this is a wheel adapter problem, it can be resolved easily by switching to one that is thicker. However, if it doesn’t work, chance is that the inner side (NOT the side facing the wheel adapter) of the hub carrier where the bearing sits is slightly thicker than usual (please refer to the photo below).
Solution ONE: If you have the proper dremel tool, dremel it to reduce the thickness by 0.5~0.8mm or so such that the bearing can fit “deeper” into it.
Solution TWO: You cannot make a ball bearing “thinner”. This is where a plastic bushing can come to the rescue. Use sand paper to sand one side of the plastic bushing. Keep sanding to make it thinner by 0.5~0.8mm and use it to replace the ball bearing (I mean the inner one, not the one facing the wheel adaptr). This will solve the problem once and for all.
UpgradePARTS.com has a ready made “thinner” plastic bushing file you can download and print.
https://upgradeparts.com/2020/07/12/10mm-outer-diameter-bushing-3mm-thickness-for-tt02-and-others/