▼ 1st step : install 0.5mm spacer (when using 11s cogs)

▼ 2nd step : install 1st cog and cog spacer (2.18mm for 11s, 2.35mm for 10s)

▼ 3rd step : install 2nd cog and machined 12T

▼ 4th step : fix sprocket using lock ring

▼ Final step : check, if not good go 1st step use more 0.5mm spacer.