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Updated 23/05/07 RAOM0507 Apollo Bicycle Company Pty. Ltd. ABN: 60 001 914 469
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Derailleur Systems
The front and rear derailleurs, the shift controls, and the derailleur control cables
collectively are known as the derailleur system. For smooth gear changes all the
components of the derailleur system must operate properly. Several different types
of derailleur systems are available; the “friction” type system, the “index” system (e.g. SIS)
and the fully integrated system (e.g. STI). The basic operating principles are the same
for all of the different systems. With a standard “friction” derailleur system, the rider should
feel each gear shift into position. With an “index” system changing gears is very easy and
precise; each different gear position is linked to a positive click mechanism in the shifter.
The shifting levers may be positioned above or below the handlebar, or in both locations
(dual levers), or the shifting mechanism may even be incorporated into the hand-grip.
The fully integrated system is an upgrade of the index derailleur system. Braking and
changing gears can occur simultaneously as the shift lever and brake lever mechanisms
form an integrated unit with the derailleur system. For further information relating to
your derailleur system refer to the separate, specific manual supplied with your bicycle,
otherwise consult your professional bicycle mechanic.
Inspection
Review the overall functioning of the derailleur system at least monthly. Begin by testing
the rear derailleur. Check that it moves the chain easily and speedily from one cog to the
next, with no rubbing after shifting. Ensure the chain does not fall from the inner or outer
freewheel cogs when the rear derailleur is activated. In the case of bicycles fitted with
SIS derailleur systems, each notched position in the shifter must equate to a new gear
position. Check that the front derailleur shifts the chain smoothly and without hesitation
between each chainring. Ensure that the chain does not rub on the front derailleur when
it moves onto a new chain ring, and that it never falls off the chainring. In SIS derailleur
systems, each click or stop in the shifter should equate exactly to a new gear position
when the front SIS is activated.
It is also important to check the derailleur control cables for any signs of rust, fraying,
kinks, broken strands, and any damage to the cable housing. Replace as necessary to
ensure accurate shifting performance.