IV - THE MAIN PROBLEMS

Handling difficulties

Load distribution has a signif icant impact

on occurrence of vehicle handling dif f iculty

The presence of added or modif ied accessories

Topbox bags streamlining windshield handles seat

nonoriginal handlebar ends etc

The general condition

of the motorcycle

Uniformity of spoked wheels damaged wheels

Bearing wear

Fork Alignment seals oil etc

Steering column

Swingarm

Shock absorber

Damaged frame engine mounting

But the tyres are not always the cause

When the tyres are partly responsible for handling problems

Weaving KICKBACK Shimmy Vibration

LEVEL OF WEAR

Big ef fect Some ef fect Some ef fect Weak ef fect

INFLATION PRESSURE

Big ef fect Some ef fect Some ef fect No ef fect

STRUCTURE: BIAS/RADIAL

Big ef fect Some ef fect Some ef fect No ef fect

CENTERING OF TYRE ON RIM

Big ef fect Some ef fect Some ef fect Big ef fect

BALANCE OF WHEEL

AND TYRE ASSEMBLY

Weak ef fect No ef fect No ef fect Big ef fect

It is not always easy to determine the causes and origins of various handling problems. Handling problems may come from tyres

(type of tyre, incorrect pressure) and/or a change to the vehicle (accessory, load, etc.). Tyres are not always the cause.

Handling dif f iculties def ined

weaving kickback shimmy vibration

It is a wavering movement,

of variable extent occurring

on straight lines or bends,

usually starting at an

average speed of around

140 kph (90 mph).

It is a sharp sideways

movement at the front

(fork moves back and

forth), it is intermittent

and very fast, occurring

particularly whilst

accelerating. It is triggered

by an external source such

as a bump or join in the

road surface.

It is a sideways, continuous

oscillation of the fork at

low speed (<100 kph / 60

mph) usually whilst slowing

down.

It appears at the level of

the fork / wheel assembly

usually at speeds of around

90 to 130 kph (55 to 80

mph).

MICHELIN MOTORCYCLE AND SCOOTER 177

Technical data