# Burning Calories

### How many calories do I burn per mile cycling?

When I was a runner, the rule of thumb was 100 calories per mile, and when I started cycling, it was 40 calories per mile. But that number does not make any sense given I could be riding a downhill or climbing the Alpe d’Huze or riding flats or sprinting. Using the Cycling Models developed later, we can estimate the calories burned under these various conditions.

### Do I use Joules or Watts?

Am I computing joules or watts? Calories are equivalent to 4.1858 Joules so we are interested in the total effort to ride a mile, rather not how many calories we burn per minute. The faster you ride a mile, the quicker you burn the calories. A person riding a mile in five minutes burns the same number of joules as a person riding it in three minutes.

### Riding Flats

Riding Flats means working against Rolling Resistance and Aerodynamic Drag. Let’s first compute the number of Joules when riding on an asphalt surface at a range of speeds upwards of 50 mph which correspond to the max of Elite Cyclists.

Note that for most realistic riding scenarios for recreational riders, the calorie burn is less than 10 per mile. In fact, 40 Calories per mile is only achieved at the outer limit of an Elite cyclist’s limits.

### Making Ascents

What are the comparable burn rates for an ascent? The total work is a combination of resistance forces and work against gravity. Work against gravity is computed by the CyclistCycle weight in Newtons multiplied by the elevation gain in meters. The chart provides the calories per mile to make a climb at a given slope measured by degrees. Note the one mile corresponds to the distance ridden so it is the Hypotenuse of the right angle.

In general, aerodynamic drag is usually not included because the ascent speeds are much lower, and with most climbs snaking back and forth, aerodynamic will alternate between drag and push.

Whereas riding flats have a physical limit of 40 calories per mile only achieved at 50 mph at the limit of Elite Cyclist sprinting, we see here an Alpe d’Huze climb of 8 degree slope, we would be  burning 50 calories per mile.

### Comparing Flats to Ascents for Calorie Burning

Not surprisingly, cycling ascents burn more calories than flats. 20 mph on flats burns approximately 7.5 calories per mile. An 8° slope ascent would burn approximately 50 calories, or 6.7 times as many..

Clearly, 40 calories per cycling mile is only achieved for challenging riding scenarios. On the flats, it would require an exceptional cyclist to be in that range. On ascents, however, moderate climbs are in that range and while it may take longer for a recreational cyclist to make an ascent, they will be burning in the 40 calorie and above range once the mile is complete.

### How Effective is Cycling for Weight Loss

When I worked these numbers out, I was surprised to see how few calories were being burned. I had expected moderate climbs to burn in the range of 100 – 125 calories rather than 40. And I did not expect that riding flats would be less than 10 rather than 40 calories.

By itself, cycling is not a big calorie burning engine. What I am cautioning against is misreading why cycling is good for your fitness. It is low impact, it gets you out and away from the refrigerator, and it can help keep your blood sugar levels in balance. The last is important because it can lower your appetite in general. It exacts a smaller toll on your joints which means it is something you can easily do into your Seventies unlike running.

Simply put, burning calories is hard work and in comparison to other sports, cycling is one  of the lower calorie burning ones. On the other hand, as part of a more comprehensive program, it can be an important component of a healthy living style.