<p>“When you are riding your 70 miles and burning 3900 calories, how many calories per hour are you buring, or how many mph per hour are you biking? What is your rpm?”</p>
<p>dstark, the answers to your questions can vary dependent on the mixture of flats and hills on the ride and who I am riding with. There are formulas out there that base the caloric calculation on weight, time and pace. I have a Garmin cycling GPS/bike computer on one of my bikes and I programmed it with my body weight. It measures heart rate, wattage, distance, speed, cadence, riding time and % grade of the road but frankly, I’m not sure exactly how it factors in all of those measures to come up with the calories burned. I was using that bike on the ride in question that I posted about and took the calories from the Garmin.</p>
<p>Depending on who I am riding with, my speed on the flats can range from a sustained 18-24 mph with periods higher at times. I try to keep my cadence on flats at between 92-105. On hills, depending on how steep and long the hill and how beat up I am, my speed can range from 10-20 mph and my cadence from the high 60’s to low 90’s. There’s a world of difference for me between a half mile 18-20% grade that I might ride at 10-12 mph and a 1 1/2 mile 5% grade that I might ride at 16-20 mph. In general, my average speeds on my rides range from upper 15’s to low 19’s.</p>
<p>On the ride I posted about, there were a load of challenging hills including steep long climbs and rollers for about half the ride. I was riding with some slower riders so our average pace was low 15’s. According to the Garmin, I burned an average of 840+ calories an hour. </p>
<p>I think, however, that the most important metrics in determining calories burned on a bike are body weight, speed and duration. It’s all about the amount of work being done. Body weight is a constant. The variables are speed and duration. If distance and route are held as constants, I don’t think that you burn off more calories doing a 20 mile ride in an hour than if you do it in 2 hours. You have still moved the same weight over the same distance under the same conditions. The intensity i.e. speed (other than differences in the training effect) just impacts on the efficiency of time utilization. Throw in hills and you change the conditions, requiring more energy consumption to move the same distance, but other than that, a ride is a ride over a given distance and will burn the same calories regardless of speed, I think, all other things being equal.</p>
<p>P.S. Just found an interesting link discussing how various Garmin devices calculate calories burned. <a href=“http://www.dcrainmaker.com/2010/11/how-calorie-measurement-works-on-garmin.html[/url]”>http://www.dcrainmaker.com/2010/11/how-calorie-measurement-works-on-garmin.html</a></p>