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| A - D E - H I - L M - P
Q - T U - Z |
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Racing Flags
Checkered Flag - First across wins: race over
Black Flag - Rider disqualified or problem with motorcycle
Green Flag - Race start signal, race in progress when all is “go”
Red Flag - Race stopped, sometimes to be restarted
White Flag - One lap left to race
Yellow Flag - Caution, do not pass if flag is waving
Yellow and Red Striped Flag - Caution, indicates debris, fluid or hazard
Rear Sets
Racing-style footrests fitted towards the rear of the machine to allow the
rider to adopt a racing crouch.
Rocker Arm
A centrally pivoted lever that transmits the motion of the camshaft to open
and close the valves.
RPM: Revolutions Per Minute
A term used to describe how fast a motor is spinning. Also known as “revs.” |
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Sipes
One of many small incisions on a tire’s surface for the purpose of
improving traction.
Slicks
Racetrack-only tires, so named because they have no tread at all, just a smooth
surface so that the maximum amount of rubber grips the asphalt.
Slipper Clutches
Specialized clutches developed for racing motorcycles to mitigate the effects
of engine braking when riders would decelerate as they entered corners. They are
designed to partially disengage or “slip” when the rear wheel tries to drive the
engine faster than it would normally. The engine braking forces in conventional
clutches will normally be transmitted back along the drive chain causing the rear
wheel to hop, chatter or lose traction. This is especially noted on larger displacement
four-stroke engines, which have greater engine braking than their two-stroke or
smaller displacement counterparts. Slipper clutches eliminate this extra loading
on the rear suspension giving riders a more predictable ride and minimize the risk
of over-revving the engine during downshifts. Slipper clutches can also prevent
a catastrophic rear wheel lockup in case of engine seizure or transmission failure.
Generally, the amount of force needed to disengage the clutch is adjustable to suit
the application.
Spine Frame
A motorcycle frame with a single main structural member from which the engine
is suspended. Also known as a backbone frame.
Step-Thru
Motorbike frame layout with a low structure between the seat and the steering
head often associated with scooters. On early machines it was commonly called an
open frame.
Stoppie
A motorcycle trick in which the rear wheel is lifted and the bike is ridden
for a short period on the front wheel. Front brake control during the stoppie is
essential.
Stroke
Measurement of length of piston travel in the bore, usually expressed in millimetres.
Subframe
Any auxiliary framework attached to the main body of a motorcycle frame. Typically,
this refers to the rear section of the frame which supports the seat, etc. The principal
purpose of using a subframe is to isolate vibration and harshness from the rest
of the frame.
Superbike
A high-performance sport bike with a big engine (generally 1000cc and larger)
Supercharger
An air compressor used to force more air into the combustion chambers of an
internal combustion engine which allows it to burn more fuel and results in more
power. (Also known as a Blower). When the blower is driven by exhaust gas instead
of an air compressor the device is called a turbocharger.
Supercross
Motorcycle racing sport incorporating high performance, off-road motorcycles
on artificially created dirt tracks that include obstacles and steep jumps. Professional
Supercross racing events are held within large sports stadiums.
Suspension
The system of components that reduce the impact of surface bumps and serves
to keep the wheels in better contact with the road or ground, thereby improving
control and traction. A typical motorcycle suspension includes a pair of fork tubes
for the front, as well as a swingarm with one or two shock absorbers for the rear
suspension.
Swingarm
The one- or two-sided arm (often made of aluminum or steel) that connects
the rear wheel to the frame and moves up and down with the rear suspension. A two-sided
swingarm could be described as a pivoted fork, as the wheel is supported at both
sides. |
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Tachometer
A gauge that measures how fast an engine is spinning. The measurement
is usually expressed in revolutions per minute
Telescopic Forks
Front suspension system on a motorcycle comprised of two fork tubes which
contain coil springs. The tubes “telescope” up and down to absorb road bumps. This
is the most common form of motorcycle fork commercially available.
Timing
Measurement of the exact instant when the valves open or close in an internal-combustion
engine, or when the spark occurs. It is normally expressed in degrees or millimetres
before TDC
Torque
A unit of measure describing the twisting force, or leverage, an engine can
exert on the rear wheel. Typically, an engine with a lot of torque will have the
potential to speed up faster at lower RPM’s.
Track Day
Organized events in which members of the public are allowed to ride motorcycles
around established racing circuits. Criteria for being eligible to participate is
usually the holding of a motorcycle licence and the payment of a fee.
Trail
The distance from the front axle’s vertical position on the ground, to the
spot in front of it created by drawing a straight line from the angle of the forks.
(Compare Rake). Trail is often cited as an important determinant of motorcycle handling
characteristics. |
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