How can I print a 1 cm overhang with minimal supports?
Three ideas


If either side of the red ring can have a chamfer to meet the cylinder, add the chamfer and print with the chamfer side down.
If both sides of the red ring must be perpendicular to the axis of
the cylinder, can you print the cylinder lying on its side?  You
might get good enough print quality, especially if printing with
thinner layers toward the top.
If that is unsatisfactory, try explicitly adding an inner support
ring as part of the model. Don't depend on the slicer to do what
you want, do it yourself.  You would then be bridging to make the
red disk, but that can work surprisingly well with a good cooling
fan and printer.


In all three cases, consider the slot holes you have in the red ring.  For case 3 you may need to add a support around those holes as well.  In case 2, they would want to be pointed vertically.  In case 1, the chamfer would be modified to have holes of cavities matching the slot holes.