Another recommendation here for "Chasing the Chimney Sweep" - have just finished reading it and thoroughly enjoyed it.
It's meanders back and forth between a journey through France, retracing the steps of the very first Tour - and factual/historical stuff about the 1903 Tour itself. I was absolutely gobsmacked when I read the conditions those first Tour riders had to endure. It's a brilliant read.

Hetty - thanks for the nudge about Josie Dew - I'm a massive fan of her books, so witty and fun to read - and I've just been on her site and see she has a new one out! Yay! And it covers New Zealand. Yay!