I think this will naturally differ by country. In the U.S., we’ve taken designated to mean more or less “designed for” or “intended for” in many contexts. It’s a more holistic standard than in some other countries. If we had to strictly map bicycle=* to standard MUTCD signs, we would do something like what’s documented on the wiki:
no |
yes |
designated |
|---|---|---|
 |
 |
 |
However, this only works in theory. 
is relatively rare and only posted on dedicated trails or sidepaths, never in a situation where bikes share the road with traffic or where a pedestrian mall has plenty of room for all non-motorized traffic. 
isn’t just an access sign; it can also indicate lcn=yes, or that the street is a bike boulevard. In practice, permission for non-motorized vehicles isn’t consistently signposted, and few off-road signs adhere to any standard to begin with.