I've only been using a heart rate monitor since May -- and I've only tried to up the intensity of my rides since being cleared (or is it pushed?) by my cardiologist and the execericise physiologist to up the intensity...

But, August 7 my highest heart rate during an 82 minute ride was 154 (my calculated max is 157 and the cardiologist said his stress test showed it is 161). The average for the whole 82 minute ride was 131 -- but that doesn't include the last 17 minutes on a down hill where it dropped well below the 120's.

I haven'figured out how to get my IPHone software to break the ride into pieces so I could answer your question.