Climbing Resistance
The gradients on roads are first defined:
The gradient p is the quotient of vertical and horizontal projections of the road, this corresponds to the tangents of the upgrade angle αst. The upgrade is either indicated as p in % or as p=tan αst (indication as a percentage is common in traffic signs)
 
Remark: tan 45°=1 νp=100%
Gradient measurement:
Vertical projection with a level device
Measurement of the length of road
In this way αst can be calculated
With small αst: sin αst ≈ tan αst = p 
αst < 30° ν error < 5%