Radiator

Coolant is passed through the engine and through the radiator (normally at the front of the bike). This allows external air to pass over the radiator and thus cool the coolant which passes back through the engine to prevent overheating.

Rat bike

Bikes which are mechanically in good condition (usually) but look absolutely awful to many people

Rear sets

Describes the footpegs situated at the rear of the motorcycle

Redline

Describes the actual red line found on the RPM gauge to show the maximum revs allowed by the engine

Road rash

The effect of having a spill without wearing the appropriate gear

Roll on the throttle

Open up the throttle

Roundabout bash

Where people go to a roundabout to go round and round to destroy their chicken strips

RPM

Revolutions per minute

Rubber

Tyres

Rubber side down

i.e. not crash and keeping the tyres firmly on the road