I have been riding for a few weeks now with a Garmin Edge 500 HRM getting to know it. I am ready to start getting more involved with using it as a training tool and figured my max HR using the 220-age = max HR, in my case is 168bpm (52 year old). I do a short ride where I ride a 4 mile flat stretch at about 145bpm before hitting a short steep hill I like to push it on usually going up and down it 4-5 times before returning home. I noticed after uploading the data that I hit a max HR of 187bpm. Am I to assume that this reading is my max HR and not the 220-age 168bpm?