Shimano Altus ST-CT 90 Derailers

Question
I have an old mountain bike I bought years ago. I brought it out of the garage today to find neither of my shifters work. The levers don't have any tension on them and they won't shift gears. Is this an at home adjustment? Or is it part replacement time?
Thanks,

Charley

Answer
Charley,

As far as I can tell from the symptoms, the problem may be a little at home adjustment and a little replacement.  When you leave a bike unused for a period of time, even if inside, corrosion can get to the cables and the pivot points of the components and seize them up.

If you feel comfortable working on your bike, you can test to see if the problem is the cables.  For the rear derailler, shift the shifter to the smallest rear cog.  Push the derailleur inwards and see what happens to the cable.  Does it just sag at the rear or does it slide through the housing up to the lever?  If it doesn't slide smoothly and easily, you should think about replacing your cables and housings.  This can be difficult without a proper bike cable cutter, so you should consider having a bike shop do it.  

If the derailleur itself doesn't move easily, you can try gently forcing it. Once free, try a drop of oil at each of the parallelogram's pivot points.  Again, if it doesn't return to smooth action, think about replacing it.

The final possibility is that the return spring doesn't move the derailleur back towards the small cog when you let go of it.  That one is easy: Replace the derailleur.  

You can perform a similar test on the front derailleur cables and housings by first releasing tension by shifting to the small ring and then attempting to move the derailleur to see if the cable is sliding smoothly.  

I am not aware of your level of comfort with working on bikes.  Thus, I would say that you should take it to the bike shop if the cables don't slide.  If you have some skill with bikes (they aren't terribly complicated, after all) then you can:
1.  Buy a derailleur cable/housing set ($25)
2.  Disconnect the cables, pull them out
3.  Remove the housings
4.  Cut new housings to same sizes as removed housings
5.  Slide new housings in
6.  Run new cables through the housings from the shifters
7.  Attach cable to the derailleurs and adjust so the shifter shifts the entire range between the large and small gears.
8.  Cut off excess cable.

I hope this helps.  I can answer further questions if you like.

Graeme