Rolling Resistance by Surface: Tarmac, Gravel, Trail
At lower speeds and uphill, rolling resistance shares the stage. On gravel it is often the biggest brake of all.
Crr reference values
The rolling-resistance coefficient depends on tyre, pressure, surface and speed. Rough starting points for predictions:
- smooth tarmac, fast slick: 0.0035 to 0.0045
- normal tarmac: 0.0045 to 0.0060
- firm gravel: 0.0080 to 0.0110
- loose gravel: 0.0120 to 0.0180
- trail, soft ground: 0.0200 and up
What that means in seconds
Moving from tarmac to firm gravel often doubles rolling resistance. On a flat 2 km segment at 35 km/h that easily costs 10 to 20 seconds — which is why farm-track segments depend so heavily on tyres and surface condition.
Condition changes
After rain, gravel first gets faster (bound together) and then slower (soft). After a track is graded it stays noticeably slower for days. If your best time came from a good surface day, it is harder to beat than the weather data suggests.
Tyre pressure
Too much pressure raises resistance on rough ground through vibration losses. On gravel, lower pressures with wider tyres are almost always faster — on smooth tarmac the opposite holds.
In short
On gravel the surface is the dominant uncertainty — give predictions more tolerance there.
Frequently asked questions
How do I measure Crr on my local track?
Roll-down tests in still air with known mass, or comparing two runs with a power meter on the same track.
Why are my gravel predictions worse?
Because surface condition varies a lot. Your own segment history matters even more there than the physics model.