I looked at some of Team Sky's data - some of the numbers are fascinating. Most of the guys on the team seemed to do a 3 hour race and their average heart rates were between 120 and 130bpm, but still maxed out around 175 to 180. And their average power seemed relatively low, but I guess it's because a lot of them weigh like 135lbs.
I assume there are books on pro's and their training, but I wonder if they actually don't do much training because they ride in such long races that they rack up the miles that way. Sort of similar how basketball players don't have many structured practices as they play so much throughout the year.