There used to be a number of "alternative" wikipedias made by people
   who didn't agree with the editing and administrative decisions of
   Wikipedia.  It's hard to find them now.  The one I visited I found via
   its link from a wikipedia article that was removed.
   I do not observe leftist bias in wikipedia myself, it more looks like
   general mainstream bias of the powerful and formally educated.
   Far-left information is also removed and replaced with citations to
   published propaganda.  You can defeat individual situations if you make
   them your crusade in its system.