Join Date: Sep 2009
Location: SoCal (So. O.C.)
Bikes: Zinn road bike, Rockhopper MTB
They are accurate in the same sense that "Ideal Height and Weight" charts are accurate.
They are guidelines and generalizations that don't take into account individual variations, like age, bone/frame size, individual metabolism, etc.
One way that they are useful is to notice the differences in kcals burned at one speed vs another or for a ride of one length vs another. It can help you decide whether you want to burn X number of kcals by riding harder for a shorter duration or spinning easier for a longer duration.
BTW, your BP & HR look good!