If you create a segment, you can change the segment from private to public. Please be aware that newly created virtual ride segments cannot be made public. At this time, Strava does not allow public segments to be made private, nor can you make a private segment public if there is a public duplicate segment.
From the menu under Dashboard, select My Segments.
Select the tab Created Segments. Select the private segment you wish to make public.
Find the Actions menu at the top right-hand corner, and select Make Public.