What is the meaning of out riding fences?

One of the jobs of a cowboy is to keep fences in good repair. So he gets on his horse with saddle-bags fulls of hammers and staples and goes riding around fixing the fences, usually barbed wired ones. So 'I have been outside riding my horse fixing the fences' gets contracted to 'Out riding fences." That is the literal meaning.

The figurative, or secondary, meaning of "riding fences" refers to a person who won't take sides or who equivocates on an issue or issues so as not to offend those on either side. Politicians do this a lot, as do "people pleasers." It speaks of deviousness or a weakness of character.

Another meaning comes to us from the rock group The Eagles in the lyrics to their song "Desperado," wherein the title character has been having a string of affairs and relationships, but can't seem to settle down with the right woman.