Hi I am looking for a title of a book about a man who takes a bicycle
trip while his wife is having an extramarital affair.  I have no idea
when this book came out or who published or wrote it.  I hope you can
help me.

Hello.

Your book sounds a lot like "Bicycling for Life" by Arthur Niehoff.
The book was published in 2000.

Here is a description of the book by reviewer Polly Bird:

"The book is readable and entertaining but at the same time the reader
is drawn into the mind of the main character Walter (the author) as he
copes with marital break up and the mental stress it causes. The main
story takes us on cycling trips familiar and strange and introduces us
to a variety of characters he meets on his travels. These sections are
set pieces of action and incidents. Interspersed with this
straightforward narrative are sections where Walter thinks about his
life and how he is coping with the strains of his broken
relationship."
Source: NEW HOPE INTERNATIONAL REVIEW ON-LINE
http://www.nhi.clara.net/bs0005.htm

I can't confirm that the wife in the novel is having an affair, but
it's a strong possibility given that the man's marital problems seem
to be a main focus of the book. The Library of Congress lists the
subjects of the book as:
Cycling--Fiction.
Divorced men--Fiction.
See http://catalog.loc.gov/cgi-bin/Pwebrecon.cgi?DB=local&PAGE=First

Here's a listing for the book from Amazon.com:
http://www.amazon.com/exec/obidos/ASIN/158820751X/ref=pd_ecc_rvi_1/002-9865455-2848045
search terms: bicycling, cycling, marital, relationship

I hope this helps.