Camber thrust and
camber force are terms used to describe the force generated perpendicular to the direction of travel of a rolling
tire due to its
camber angle and finite
contact patch.
Camber thrust is generated when a point on the outer surface of a leaned and rotating tire, that would normally follow a path that is elliptical when projected onto the ground, is forced to follow a straight path while coming in contact with the ground, due to
friction. This deviation towards the direction of the lean causes a deformation in the tire tread and carcass that is transmitted to the vehicle as a force in the direction of the lean.
Camber thrust is approximately linearly proportional to camber angle for small angles,
On bikes
On
and
, camber thrust contributes to the centripetal force necessary to cause the vehicle to deviate from a straight path, along with
cornering force due to the
slip angle, can be the largest contributor,
and in some cases is the sole contributor.
Camber thrust contributes to the ability of bikes to negotiate a turn with the same radius as automobiles but with a smaller steering angle.
When a bike is steered and leaned in the same direction, the camber angle of the front tire is greater than that of the rear and so can generate more camber thrust, all else being equal.
On automobiles
On
, camber thrust may contribute to or subtract from the total centripetal force generated by the tire, depending on the camber angle. On a well-aligned vehicle, camber thrust from the tires on each side balances out.
On a surface rough enough for one front tire to momentarily lose traction, camber thrust from the other front tire can cause the vehicle to wander or feel skittish.
See also
