Brake Force And Motorcycle Stability - Yamaha 2003 FJR1300 Service Manual

ANTI-LOCK BRAKE SYSTEM (FJR1300A)
È
Brake force
Side force
É
Slippery road surface
Slip ratio (%)
Less slippery
road surface
Controlling zone
Slip ratio (%)
• Slip ratio:
When the brakes are applied, slipping
occurs between the tires and the road sur-
face. This causes a difference between the
wheel speed and the chassis speed.
Slip ratio is the value that shows the rate of
wheel slippage and is defined by the follow-
ing formula.
Chassis speed – Wheel speed
Slip ratio =
Chassis speed
0%: There is no slip between the wheel
and the road surface. The chassis speed is
equal to the wheel speed.
100%: The wheel speed is "0", but the
chassis is moving (i.e., wheel lock).
EAS00874

Brake force and motorcycle stability

When the brake pressure is increased, wheel
speed is reduced. Slip occurs between the tire
and the road surface and brake force is gener-
ated. The limit of this brake force is determined
by the friction force between the tire and the
road surface and is closely related to wheel
slippage. Wheel slippage is represented by the
slip ratio.
Therefore, side force is also closely related to
wheel slippage. See figure È. If the brakes are
applied while keeping the proper slip ratio, it is
possible to obtain the maximum brake force
without losing much side force.
ABS allows full use of the tire capabilities even
on slippery road surfaces or less slippery road
surfaces. See figure É.
– 60 –
CHAS
× 100 (%)