Too right, you don't want your heart rate monitor to add a layer of stress precisely when you're riding out to get rid of stress. That's why mine got moved off the handlebars into my pocket, and the average reported respiration rate for the ride immediately fell a couple of percent.
That bracket from about 84% to around 90% is not a good one to be in, as it produces lactic acid. You either want to be below, building endurance, or above, building sprinting strength right up near your max. If you're going to exercise consistently above 80% either deliberately or by accident but often, at our age you want to consult a physician once in a while and tell him what you're doing.
I ride with mine, and also with a trained nurse among my pedal pals, so I could ask them, but in fact I never go above 80% for more than a few seconds at a time, just spikes, no consistent high effort. It helps that we're all recreational riders, not old roadies, with all the roadie attitudes about keeping up speed; we trundle along, talking, at the speed of the slowest. Today I caught an unplanned ride, alone, just before dinner, 8 1/4km in 30m on very hilly countryside, 5 big hills in that distance, and my highest spike was 70% with an average at 60%, a fairly typical ride, except normally I'm slower because I dawdle and look at the countryside and wait for the pedal pals to catch up at the top of the hills.
