Motorcycle Cornering Speed Calculator
Calculate maximum cornering speed from turn radius, road friction, and lean angle.
Returns speed in mph and km/h with grip warnings for dry, wet, and gravel.
When a motorcycle corners, centripetal force must be balanced by the lateral grip of the tires. The maximum speed through a corner depends on the corner radius, road surface friction, and lean angle.
The formula: v = sqrt(r × g × mu × cos(lean) + r × g × sin(lean))
Simplified for a flat road: v = sqrt(r × g × mu)
Where:
- v = maximum speed (m/s)
- r = corner radius (meters)
- g = 9.81 m/s²
- mu = coefficient of friction (tire-to-road grip)
Friction coefficients (mu):
- Dry tarmac, sport tires: 0.9–1.1
- Dry tarmac, touring tires: 0.7–0.9
- Wet tarmac: 0.4–0.6
- Gravel/loose surface: 0.3–0.5
- Painted road markings: 0.3–0.5
Worked example:
- Corner radius: 50 m, dry road (mu = 0.85)
- v = sqrt(50 × 9.81 × 0.85) = sqrt(417) = 20.4 m/s = 73 km/h
Safety margin: Real-world riding always has unknowns — road camber, surface contamination, tire temperature, vehicle loading. Ride at 70–80% of the calculated maximum. Lean angle naturally increases as you approach the limit — the bike geometry handles this, but smooth throttle and no sudden inputs are essential.
Corner radius estimation: A tight hairpin is 5–15 m. A sweeping mountain bend is 50–200 m. A motorway on-ramp is 100–300 m.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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