Originally Posted by
Gene2308
Are these the old "thumb" shifters?
Nearly all shifting problems are related to the actual cables and cable housing coming out of the shifters....not the shifters themselves. Since they worked fine and have slowly stopped working due to nothing catastrophic, I would strongly suspect the cables/housing.
Replacing them is fairly inexpensive and is the single best thing you can do!
If you're handy read this:
http://www.sheldonbrown.com/cables.html
Completely false.
If the shifters are Shimano trigger shifters (which I am guessing they are), the lube that Shimano used on the ratchet pawls solidifies and keeps the pawl from engaging the toothed wheel. The result is a shifter trigger that moves but doesn't grab anything. If the "spray stuff on them" method doesn't work, there are only two options:
1) Replace the shifters. Best if you aren't mechanically inclined.
2) Disassemble the shifter, remove the small e-clip from the post where the pawl is mounted, remove the pawl and spring, clean the pawl and the post with brake cleaner, or a similar fast-drying solvent, lube the post and pawl, and reinstall. There are 2 of these pawls, usually. One is easy to get to, the other isn't. The one that isn't, spray with brake cleaner and work the pawl back and forth repeatedly with a small screwdriver until it moves freely. Spray it with lube (I use T9) and then reassemble the shifter.
Most bike shops see dozens of these every spring when people get their bikes out after being stored all winter.