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Two small contact patches

A motorcycle stands on two contact patches, each about the size of a credit card. All braking, accelerating and cornering must pass through them. The pressure on the road is roughly the air pressure in the tyres, so wrong tyre pressure changes both the size of the patch and the grip. Cold and new tyres also grip less.

p = \dfrac{F}{A}

the pressure on the road

Symbols

$F$	weight of bike and rider	N
$A$	the two contact patches together	m²

Example

Bike and rider weigh 300 kg ( $F \approx 2940$ N). Each patch is about 46 cm².

$p = \dfrac{2940}{2 \cdot 0.0046} \approx 320\,000$ Pa $= 3.2$ bar.

Check tyre pressure when the tyres are cold, and adjust it when carrying a passenger or heavy load.

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Part of Motorcycle licence (A1, A2, A): Grip, road surface and weather.