CdA from photos
A photo from the front, one from the side, your height and weight. About a minute.
How to take the photos
- Sit on the bike in the position you want to measure, hands where they usually are. A trainer helps, or someone holds the bike.
- From the front: the camera at handlebar height, straight ahead, about 5 m away. Zoom in 2× rather than stepping closer.
- From the side: the same position, the camera at hip height, square to the bike.
- You and the whole bike in the frame, a plain background, nobody else in the picture.
Loading the image recognition, about 20 MB the first time…
1 Photo from the front
2 Photo from the side
3 You and your wheel
Printed on the tire. With the rim it sets the wheel's size, our ruler.
Your phone did not record its lens in the photo. A rough distance is enough; without it we assume 5 m.
Your CdA
m²
Drag to turn the model. The air paths show where the air meets you; they illustrate the result rather than simulate the flow.
Frontal area
Drag coefficient (Cd)
Power to air drag
The drag coefficient is an estimate from your position, so the true CdA is likely within the range above. Comparing two of your own positions is more exact.
Save to your bikit setup
With a bikit account this CdA goes into your setup, and ETA uses it for your ride times.
It opens in a new tab. Come back here afterwards: your result waits.