Cd or Coefficient of drag represents the “Slipperiness” of the Bike and Rider and is a dimensionless number that relates an objects drag force to its area and speed, it ranges upwards from 0. (An object with a drag coefficient of 0 does not exist on earth).
Teardrops or wing shapes have some of the lowest drag coefficients.
Typical drag coefficients are as follows:
| Shape | Cd |
| Wing or Teardrop | 0.005 |
| Ball | 0.5 |
| Person stood upright | 1.0 |
| Flat plate face-on to airflow | 1.17 |
| Brick | 2.0 |
| Cyclist (Tops) | 1.15 |
| Cyclist (Hoods) | 1.0 |
| Cyclist (Drops) | 0.88 |
| Cyclist (Aero Bars) | 0.70 |