This question is from a comment I got on my Calories Burned in Running vs Cycling post.
Question: If you double the speed you cycle will you burn more than twice the calories since air resistance increases exponentially with speed?
Answer: According to Dr. Edward Coyle of The University of Texas in Austin who did a study to determined the average values of oxygen consumption by cyclists at difference speeds, your position that if you “double the speed you cycle at, you will burn MORE than twice the calories” is incorrect. Here are the numbers Dr. Coyle’s tests came up with.
mph | calories/mile
Here they are in metric.
km/h | calories/km
You can see from these numbers that while at 10mph you burn 26 calories per mile but you don’t burn 54 calories per mile at 20mph but only 38 .
In metric at 16kmph you burn 16 calories per kilometer but at 32kmph you don’t burn 32 calories but only 24 calories per kilometer.
My typical average speed is 25kmph (15.5mph) so I am burning 19 calories per kilometer (31 calories per mile). Yesterday I managed to do 12.4km in 25:01 which is an average speed of 20kmph (18.6mph) which is close to my max.
While air resistance is an issue according to Dr. Coyle’s the effect is not doubled when you double your speed from 10mph to 20mph (16kmph to 32kmph).
When it comes to bicycle we are not dealing with the same speeds we are dealing with when it comes to cars. Wind resistance increases exponentially in higher speeds but not in lower speeds.
Biking on a non-professional level we are dealing with speeds below 30mph (48kmph) which are covered in Dr. Coyle’s numbers.
In cat 4 races, riders maintain an average speed of 18mph to 20mph (29kmph/32kmph), in cat 3 riders 24mph to 28mph (39kmph/45kmph), and in the US or EU pro circuit riders maintain 30mph to 35mph (48kmph/56kmph).
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