Shifting mechanism for the rear derailleur is sticky

[Nova8]

I am looking into buying a lightly used Cannondale R600 bike. The problem is the shifting mechanism for the rear derailleur is sticky and it seems to have a bit of a problem shifting. Would I have to buy a completely new part or is it something that could just be soaked?

[Joe_W]

It depends. Shifting problems can be causes by several things: worn or bent cables and housing, derailleur or shifter gummed up, broken parts. Usually it helps to

• replace worn cables and check the routing
• clean the shifters
• clean the derailleur
  

Some shifters and derailleurs can be taken apart for maintenance, check the manufacturer's homepage. Especially Shimano has very helpful explosive views.