Shifter stuck

[devaneym]

I have a grip type shifter and I am stuck in high gear (7 speed bike). The shifter actually turns on the handlebars if I apply enough pressure when i try to turn it.

[nfmisso]

(09-23-2011, 12:03 PM)devaneym Wrote:  I have a grip type shifter and I am stuck in high gear (7 speed bike). The shifter actually turns on the handlebars if I apply enough pressure when i try to turn it.

Is it the derailleur, cable or the shifter that is stuck?

Disconnect the cable from the derailleur; can you move the derailleur over it's full range of motion? It will always spring back to top gear.

Can you pull the housing(s) off the cable? Or is the cable stuck to the housing?

Most likely, it is a cable issue, not a shifter issue.

[devaneym]

please excuse my ignorance about this subject but when you ask about whether cable is stuck to housing do you mean the section of cable that is inside the shifter and whether i can free the cable from the shifter housing?

The cable for the shifter does not appear to be kinked in any way.
If i can free the cable from the shifter will the derailleur move if i pull on the end of the cable that was freed from the shifter housing?

If i free the cable from the derailleur and am able to move the derailleur in or out and it returns to it's starting point does that mean the derailleur is functioning properly?

[nfmisso]

Do the following:
1. disconnect the cable from the derailleur at the derailleur. The derailleur should go to the highest (smallest) cog due to internal spring force. You should be able to push it by hand to the lowest (largest) cog while rotating the pedals to keep the chain moving. Easiest done on a bike stand or upside down.

2. pull the cable housing(s) of the cable, so that there is just a wire coming out of the shifter. The housing(s) should come of easily. Most common issue is lack of lubrication/protection for the wire/housing and they rust together.

3. With just the wire coming out of the shifter; you should be able shift easily and the wire will move in and out of the shifter - keep a light constant tension on the cable while you shift using your fingers to hold the wire.

Most likely you will find no problem with the derailleur.

Most likely your cable rusted on the inside - get a new cable; I get mine from Wal-mart, pull the wire out of the housing, drip a tiny amount of oil into the housing, and put the wire back in. That is enough to coat the inside of the housing and the wire to prevent rusting.

If the shifter does not work; get a new one. They are around $10 from Amazon. If your rear derailleur is NOT a SRAM, you want either a SRAM MRX or a Shimano shifter. If your derailleur is a SRAM you need a SRAM shifter (not MRX). Or you could change to a trigger shifter if you want to try that, such as a SRAM TRX (not for SRAM derailleurs).

[devaneym]

(09-23-2011, 04:33 PM)nfmisso Wrote:  Do the following:
1. disconnect the cable from the derailleur at the derailleur. The derailleur should go to the highest (smallest) cog due to internal spring force. You should be able to push it by hand to the lowest (largest) cog while rotating the pedals to keep the chain moving. Easiest done on a bike stand or upside down.

2. pull the cable housing(s) of the cable, so that there is just a wire coming out of the shifter. The housing(s) should come of easily. Most common issue is lack of lubrication/protection for the wire/housing and they rust together.

3. With just the wire coming out of the shifter; you should be able shift easily and the wire will move in and out of the shifter - keep a light constant tension on the cable while you shift using your fingers to hold the wire.

Most likely you will find no problem with the derailleur.

Most likely your cable rusted on the inside - get a new cable; I get mine from Wal-mart, pull the wire out of the housing, drip a tiny amount of oil into the housing, and put the wire back in. That is enough to coat the inside of the housing and the wire to prevent rusting.

If the shifter does not work; get a new one. They are around $10 from Amazon. If your rear derailleur is NOT a SRAM, you want either a SRAM MRX or a Shimano shifter. If your derailleur is a SRAM you need a SRAM shifter (not MRX). Or you could change to a trigger shifter if you want to try that, such as a SRAM TRX (not for SRAM derailleurs).

Thanks for your help

[trevgbb]

you say the shifter turns on the bar!!
this is because the clamp screw is loose, it is not always easy to see this, but look up from below at the shifter body and you will see a small allen screw, about 4mm. across flats and m6 thread, if I remember right, tighten this and all should be ok. if not, you will need to examine for other faults.
this is the tech doc for shimano revo-shift, the clamp screw is item 5.
http://techdocs.shimano.com/media/techdocs/content/cycle/EV/bikecomponents/SB/EV-SB-C055-2122_v1_m56577569830609034.pdf
other makes will be similar.