(Spoiler alert - I reveal a lot about the book below)
I just finished reading this book. A friend challenged me to finish this book and explain it.
As I got through the first third of the book, I found that it was alternating between the author's narrative of his motorcycle trip with his son and friends, his struggling recollection of a person that he referred to as Phaedrus, and his chautauquas - his musings on philosophy. As his memories of Phaedrus become clearer, the chautauquas start overlapping his recollection that Phaedrus is actually the younger version of himself, who was so frustrated by his inability to reconcile philosophical dilemmas that he drove himself insane.
I had to suspend my attempts to make sense of his philosophizing, because doing so would require me to spend a lot of time reading and pondering, and I wasn't about to make that commitment given that I might still not understand what he was talking about. At the core of his philosophical division were the realms of classic vs. romantic understanding of life, reflected through the maintenance of the motorcycles that they were traveling with (hence the title).
At the end, he rediscovers his insanity and is about to go off the deep end again, when a dream about his relationship with his son shocks him back into reality and he's able to connect with his son.
Upon finishing the book, there was mild satisfaction that he seems to connect with his son. But through the book, I not only didn't feel like rooting for the main character, I actually thought he was a pompous douchebag.
I don't know if he had decided to embrace a more romantic notion of fatherhood. But to see someone convert from an asshole to less of an asshole wasn't terribly satisfying to read.
I don't feel like I am any better for reading this book.