I have a doubt in which is concerning the right way to tag the situations in which you are allowed to ride your bike against the one way.
If there is a street (without lane or tracks) the correct way to tag it would be oneway:bicycle=no, cycleway=opposite or both together, oneway:bicycle=no and cycleway=opposite?
Of course using this approach you could never establish a new tag - the older tag (in this case cycleway=opposite) will always be used more frequently at first.
oneway:bicycle=no is usually considered “more logical” where there isn’t a separate marked cycleway (as would be the case with all the other cycleway=* tags), and it is obviously more consistent with other vehicle-specific exceptions like maxspeed:hgv=*.
If cycleway=opposite hadn’t been first, there wouldn’t be any reason to use it. But for historical reasons it is, afaik, still better supported by applications.
So it depends on your priorities. You could always use both, though.
Stefania - I was looking for an answer to a very similar question re: one way streets and tagging. Thanks for bringing it up, and thanks to Stephan and Tordanik for the great answers. I love how quickly Google indexes forum posts these days so you can find info like this almost in real time. The tag I’d use would be “awesome”. Happy mapping! - Jean.