I too read "The Rider" and found it engrossing; it captured the racer's world and what goes on in his head.
"The Yellow Jersey" is good one, not my favorite but still available: http://www.amazon.com/Yellow-Jersey-Ralph-Hurne/dp/1558214526/ref=sr_1_1?s=books&ie=UTF8&qid=1356742987&sr=1-1&keywords=the+yellow+jersey
Two I really like, and often reread, are "Coppi Vivo" and "Gli Anni Ruggenti di Alfonsina Strada" (the only woman to ride the Giro with men, in 1924); they are very affecting but alas, only available in Italian.
My all-time favorite is "Dino Buzzati al Giro d'Italia di 1949" which was translated into English and published by VeloPress http://www.amazon.com/Giro-DItalia-Bartali-published-Paperback/dp/B0092534D4/ref=sr_1_2?s=books&ie=UTF8&qid=1356743193&sr=1-2&keywords=dino+buzzati+at+the+1949+giro+d%27italia.
It is currently out of print in both languages. I haven't read the English translation so I can't vouch for it.
Buzzati was an Italian novelist, short story writer, playwright, and journalist. In 1949 he was assigned by the newspaper Corriere della Sera to cover the Giro. Buzzati was not a sports writer and although he loved cycling, he had never seen a bicycle road race in his life! It was probably because of this that he was able to experience and write about the Giro in a a unique, original, and touching way, capturing not only its drama and epic majesty, but its humanity, poetry, magic, and romance: for example, he narrates a stage in Sicily from the point of view of a mafioso, a child in a wheelchair, a statue of the Madonna, an olive tree, and Mount Etna!
Here's an excerpt that I translated:
The Fable of the Bicycle Will Never Fade Away
And next year, the start will once again take place, and yet again the year after, from spring to spring...Until (but will we still be living?) reasonable people will say that it's absurd to continue; in those times bicycles will have become rare, almost comical junk, used by a few nostalgic maniacs, and voices will be raised, saying that it's time to put the Giro to rest.
No, don't give up, bicycle. At a cost of appearing ridiculous, set out once again on a fresh May morning, off along the ancient byways of Italy. We will travel for the most part by rocket train then; atomic energy will save us even a minimum effort; we will be very powerful and civilized. Pay us no mind, bicycle. Fly, with your little energies, among mountains and valleys, sweat, toil, and suffer. The woodcutter will still descend from his isolated mountain hut to cry "Evviva!," fishermen will come up from the beach, clerks will abandon their ledgers, the blacksmith will let his flame die out to come to celebrate you, the poets, the dreamers, the creatures humble and good will still line the roadsides, forgetting, to your merit, their troubles and hardships.
And maidens will cover you with flowers.