Dick Francis used to be a top horse racing jockey, and started writing mystery novels after he retired from racing. This novel was written in 1965, and is especially interesting because the main character rides a Norton parallel twin and does the ton (100 mph). Here is one review:
“I have read all the Dick Francis books and I have 3 favorites. This one, Enquiry, and Bolt. I have read this book at least 8 times and I think it is awesome! It is so perfectly written.”
from http://www.amazon.com/Kicks-Dick-Francis/dp/0515123862
.
.