How are the Challenge statistics calculated?

CO₂

Carbon emissions can be estimated from the distance travelled using average emission factors for modes of transport. The statistic for the amount of CO₂ saved by cycling on this website relates to cycle trips that have been logged for transport purposes only. The statistic relates to the total amount of CO₂ released by an average car, illustrating an estimation of the amount of CO₂ saved by cycling instead of driving. It is calculated as follows:

Total units travelled x kg CO₂ per unit = total kg CO2

This calculation is the total distance of trips logged for transport purposes times the amount of CO₂ released by an average car, which equals the total kilograms of CO₂ per mile.

For the purposes of this Challenge, Defra’s carbon conversion factor for an average car (fuel unknown) was used. This is 0.32641kg CO₂ per mile as provided in ‘Guidelines to Defra’s Greenhouse Gas Conversion Factors for Company Reporting’, June 2008. For a copy of this report please see here.

Fat

Cycling burns body fat and so cycling regularly can reduce our body fat percentage. There are 3,500 calories per pound of body fat. The statistic on this website for the total amount of fat burnt by participants relates to the total amount of energy expended for all cycle trips logged divided by the amount of calories per pound of fat.

Total energy expended = total pounds of fat expended
              3,500

Calories

A calorie is a measure of energy expenditure. The actual calories burned by a cyclist vary based on weight, age, body mass index, terrain, speed, wind etc. There are too many variables to accurately calculate calorie usage and so the statistic on this website is an approximation.

Dr. Edward Coyle of The University of Texas in Austin did a study to determine the average values of oxygen consumption by cyclists at different speeds. This information (based on an average-size adult of approximately 155 pounds) has been used to create a conversion factor table to estimate the approximate caloric equivalence between running and cycling:

A moderate cycling speed of 15 miles per hour has been assumed for our calculation of calorie expenditure with 31 calories burned per mile.

Distance (miles) x calories/mile = total calories Distance (miles) x 31 = total calories

If you would like to gain a more accurate calorie calculation that takes into account more variables, please see the following calorie calculator.

Energy

Energy can be measured in kilojoules and calories. One calorie has the same energy value as 4.184 kilojoules. The total energy burnt by participants cycling has been measured using the calorie calculation as above and converting this figure into kilojoules by multiplying the value by 4.184.