The latest motorcycle book I've read is 'On Motorcycles, the Best of Backmarker' by Mark Gardiner.  Mark has been writing his 'Backmarker' column for many years.  At one time it was in Motorcyclist Magazine, then in Road Racer X until that folded, and currently online at  http://www.motorcycle-usa.com and at his personal blog  http://backmarker-bikewriter.blogspot.com/.  This book is a collection of what he considers his best columns.  There are 76 'columns' which average less than 6 pages each.  This means that it's a book that one can pick up, read a bit, and put it down without having to worry about losing continuity.  However, I found that I pretty much plowed straight through it because I found it that compelling.
I've know Mark for a while and have had great respect for him after reading his book 'Riding Man'.  This is the story of him quitting his job and selling virtually everything he owned to move to the Isle of Man, learn the circuit and race there.  I didn't know, until I read it in 'Best of Backmarker' that he was suffering from debilitating rheumatoid  at the time.
While he covers a lot of racing topics, the book is not primarily about racing.  Mark is a real investigative journalist.  When he's  intrigued  by a topic, he does the footwork to get to the bottom of it.  Perhaps the best example of this is the lead column in the book: 'Searching for Spadino'.  Spadino was the nickname of the motorcyclist who rode his bike repeatedly into  the Mont Blanc tunnel while it was blocked and burning from a tanker truck accident, saving many people, then succumbing to the fire.  Mark wondered what kind of person would do this.  So, he went to Italy and France and interviewed as many people as he could who knew Spadino.  The result is a terrifically moving portrait.
Or the Hollister 'riot' that was the inspiration for the film 'The Wild Ones'.  Mark went to Hollister more than once to interview people who were there and remembered.  A picture emerges that is nothing like the movie.
Mark organized an expedition with Patrick Bodden and Bob Hansen to go to Paris and check out a bike claimed to be the CR750 Honda that Dick Mann won the '70 Daytona 200.  Bodden is a Honda race bike expert and Hansen hired Mann and ran the team.
While Gardiner's main interest is probably road racing, his columns run the gamut including the 5-5-5 tour (cross country ride on bikes costing less than $500, less than 500cc and pre-1975), the Cannonball run (cross country ride on pre 1916 bikes), Bonneville speed week, and Black Bike Week in Daytona, and the Catalina GP.
There are profiles of several characters including Rob North (frame builder), Udo Gietl (tuner and team manager), Anthony Gobert (road racer), Big Sid Biberman (Vincent expert), and Mike Goodwin (serving a life sentence for murdering Mickey Thompson and his wife, but did he?)
And, much, much more.  Fascinating stuff and highly readable.  Available at : http://thebestofbackmarker.blogspot.com/