If you don't have a power meter on a bike then it's possibe to estimate how much power you produced say on a particular
climb using the power calculator on the website. N.B. this tool uses mathematical models which, eventhough are exact,
rely on input parameters which are approximated. For example a tall cyclist will have greater wind resistance than
a shorter one. The derived results from the calculator have not been verified by an SRM or similar power meter. The tool
is useful for showing comparisons as opposed to giving absolute results.
The following example uses the calculator to work out the power produced when climbing the Windy Gap, Farnanes,
Co.Cork.
The input parameters are:
a) Rider weight including clothing, helmet, shoes items in back pocket etc is 69kg
b) Bike weight including filled bottles, pump, saddle bag, computer is 9kg
c) Duration = 5mins 17secs = (17/60+5) = 5.28mins = 5.28/60 = 0.088 hrs
d) Distance is 1.43miles = 2.3km
e) Height difference between top and bottom of climb is 105m.
f) Avg. speed on climb is 2.3km/0.088hrs = 26.1kph (16.2mph)
g) Gradient is 105/2300 = 4.56%
i) No headwind.
k) Hands on the hoods.
l) Clinchers
1. On www.bikecalculator.com. click on the calculator graphic shown below and then click on SPEED from
Power, Metric units. The calculator allows you to enter two different sets of data for comparison purposes.
2. Enter the data from the input parameters given above until the calculator looks like that shown below. Enter
386 in the Power box and ignore Temperature, Elevation and Trans efficiency. Do not enter values in Velocity, Time, Calories
and Weight loss. Click on Calculate to get the derived Velocity, Time and Calories.
3. In the example above I put the same values into Set B except for Bicycle weight which I set to the UCI limit of 6.8kg.
The difference in climbing times (assuming the same power) between a bike that weighs 9kg and one that weighs 6.8kg is
0.08mins which is 5 secs. If you enter different values in the Power box you get corresponding velocities and times.
If you set power to 200W for Set A then it takes 8.69mins to climb the hill. If you weigh 80kg and you want to cycle the hill
in 5.29mins then you would need to generate 428W.
