Four steps towards a bike friendly slope:
1. Try to avoid differences in height as much as possible. Every rise means extra effort for cyclists, leading to less frequent use of bicycles. Overcoming a difference in height of 5 meters, for instance, requires that a cyclist expend as much energy as is required when cycling half a kilometre on level terrain. Rises can be negotiated through the use of either a bike ramp or a tunnel. For tunnels, smaller differences in height usually suffice. The differences in height can also be tackled by slightly raising or lowering the road itself.
2. Determine the desired length of the slope using the CROW-recommendations or Roos’s formula. Use a value greater than 10 when extra comfort is necessary, for instance in urban areas, areas with many elderly people, or windy areas.
3. Determine if the desired length of the slope will fit in the available space. If not return to step 1 and start anew.
4. Work out the detailed design of the slope. The onset of the slope may be steeper than the aftermath. Consider introducing a plateau when the height difference exceeds 5 metres.
The Fietsberaad website gives a spreadsheet that one can use to calculate both the average grade (step 2) as well as the slope profile (step 4).