15 year old mountain bike question

jwroubaix said:

I decided to get my 15 year old Trek 930 out of storage. After a thorough cleaning it's in surprisingly good shape. The only problem I have is on the shifter for the rear gears. When I push the levers nothing happens. It doesn't look like there is a loose cable,maybe the shimano shifting unit is just bad. Is this a big deal to replace?

It is NOT difficult to replace a shifter/derailleur/cables/housing/whatever ... your wallet is the only limitation.

However, if the shifter is clicking-and-holding, then it should be shifting the rear derailleur if the cable is properly tensioned ...

So, the lube the cable ... if the end isn't frayed, take it out of the housing ... and inspect the housing while you are at it ...

SOMETIMES, some housing goes bad (the sheath around the core no longer holds the core securely) and needs to be replaced.

In the very unlikely case that the rear derailleur has seized, then its pivots need to be lubed with (household and/or penetrating) OIL, allowed to "rest" for a few days, and then manually worked until the parallelogram moves freely. ADD grease to a cleaned rear deralleur.