According to your method, my max HR should be 192 but it has registered at the highest 197 according to my HR monitor while on rides. I'm with Julibird on this one. The method you used is just to give you a guideline.

I, too, have been trying to keep my heart rate at Zone 2 and it is INCREDIBLY slow, I would be better off walking. I have high heart rate averages like you and I'm hoping that as I get fitter and more conditioned, those will lower. I can't seem to stop getting my workouts out of Zone 4.