I have taken the decision to make the Bike Aero Data calculator free for two reasons:
- I am a cycling and aero enthusiast. I only ever intended to offer this service as a sideline to my real job. I'd rather more people were able to take advantage of this type of tool. Sharing is caring, right? If you want to pay me for my time in helping you to calculate additional data points like your frontal area in different riding positions, then great, I will happily do so.
- At the end of the day, the relationship between power, aerodynamic position and your all important ride times is just physics (and a bit of maths). I'm a science and data nut, so I'm keen to promote this type of practical application in whichever way I can. I also really enjoyed the challenge of putting the page together!
So, how do you use the calculator?
Well, you will need some basic measurements like your weight and the weight of your bike. We also have to plug in a few coefficients like rolling resistance and drive train efficiency (don't worry there are default values you can use).
You will also need some sample ride data - distance, speed and power. You could use a race file, but any sample ride data in your chosen position will work. It's probably best to use a nice flat out and back course - I'd recommend a ride of a couple of miles to and from a roundabout (for easy turning) on a nice calm day. It's worth taking the time to collect some good data - as they always say with data "rubbish in, rubbish out". You will probably want to repeat your measurements in several different positions, so pick your course wisely.
Once you have the data, plug the numbers into the calculator and click 'calculate'. This will work out your CdA (and Cd if you have also been able to provide a measurement of your frontal area) as well as your performance potential. You can then change various variables to see how your potential might change at different weights, for different power values or in different riding conditions.
Entering your frontal area measurements would also allow you to determine your Cd value from the calculated CdA. This can be done from photographs using freely available computing tools (there are several sites which tell you how to do this), but it is a bit fiddly. If you want to pay me to do this I would be happy to hear from you!
I hope you enjoy using the calculator - I'd be pleased to receive your feedback.
Thanks for reading.