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DERAILLEUR SYSTEMS
The derailleur system comprises the front and rear derailleurs, the shift controls, and the derailleur control cables, all of which
must function correctly for smooth gear shifting to occur. There are several different types of derailleur systems but all operate
using similar principles. Your new bicycle may be fitted with a standard “friction” type system where you will need to feel each gear
shift into position. It may be fitted with an “index” system (e.g. SIS) which links each different gear position to a positive click
mechanism in the shifter, and makes shifting very simple and precise. On some bikes the shifing levers may be above or below the
handlebar, have dual levers above and below the handlebar, or the shifting mechanism may even be incorporated into the hand
grip. A further development of SIS is the fully integrated system (e.g. STI) where the shift lever and brake lever mechanisms form
an integrated unit with the system allowing both gear shifting and braking to occur at the same time. More detailed information on
installation and lubrication of specific systems should be supplied with your bike, otherwise please refer to a specialist bicycle
mechanic.
Inspection
The operation of the derailleur system should be checked at least every
month. Check the operation of the rear derailleur first, then the front.
The rear derailleur should shift the chain cleanly from one cog to the
next without hesitation. On SIS equipped bicycles, each notched
position in the shifter must equate to a new gear position. After shifting,
the rear derailleur should not rub on the chain. The derailleur should
never cause the chain to fall off the inner or outer freewheel cogs.
The front derailleur should also shift the chain cleanly and without
hesitation between each chainring. If your bicycle is equipped with front
SIS, then each click or stop in the shifter should equate exactly to a new
gear position. When the chain has been positioned onto a new chain
ring, it should not rub on the front derailleur. The chain should not fall
off a chainring at any time.
Derailleur control cables are a critical component that must be well
maintained for accurate shifting performance. Check them for any sign
of rust, fraying, kinks, broken strands, and any damage to the cable
housing. If you find any problems, the cables may need replacing
before you next ride.
Pre-stretch the
derailleur cables to
remove slack
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