For my birthday and as an award for reaching a weight goal I got a Garmin FR70 Heart Rate Monitor. I wanted one for two main reasons. I commute to and from work at least 3 days a week. I wanted to verify the intensity of my ride and the calories burned.
The way to work is a downhill ride but I ride as fast as safety and my ability allow me. I was concerned I was coasting too much. It turns out I generally stay in 70-80% of my target heart range for the to work trip. On the trip back, I had no concerns that I was work hard but I was concerned I might be working too hard. Although I one hill I get close to my calculated maximum heart rate, for most of the ride I stay 75-85% of my THR.
I was more surprised on the total calories burned. The Garmin FR70 uses a very good correlation for calorie burn (see http://www.dcrainmaker.com/2010/11/how-cal
orie-measurement-works-on-garmin.html #2) using sex, age, weight, height, current activity level, and lifetime activity level. Before using a HRM, I had determined my calories burned through SP, Livestrong, and Endomondo. The HRM has been calculating 20% more for the same routes and time I had been doing before a total of about 250 more calories per a day that I bike commute.
My only previous with HRM was with the grips on cardio machines. I never understood the criticism of of those because when I would do a manual measurement they always seemed spot on. With my new HRM, I have realized that the cardio machine HRM have very slow responses. On machines, it always took 3-5 minutes to get to my target heart rate. I now know its easily possible to do so under a minute with moderate effort.
I did a fair amount of research on SP on HRM. I found a good amount of info but I wanted to add my experience for those who are considering buying. The HRM I bought is $130 and does not have GPS but I should be able to use a smart phone with it to get that ability. Another reason why I wanted a HRM is that in a few months I may not be able to commute by bike anymore due to a change in jobs. I wanted to be sure whatever I replace it with that I am getting the same result.