Rear Shifting Problems

[nmfeb70]

Hi all, I have just replaced my 7 speed rear shifter plus cable and housing. I have three front chainrings (I don't use the smallest), so I set up the indexing from the middle front chainring and everything worked fine. However, when I switched to the largest front chainring, I couldn't switch to the smallest rear cog (highest gear). I loosened the cable tension to no avail and even when I released the cable from the derailleur completely it still wouldn't shift to the small cog. Rear mech is Shimano Altus, eighteen months old and very used. Any suggestions? Thanks.

 

[Globalti]

So the spring isn't quite managing to pull the chain down to the smallest cog?

Have you tried loosening the outer limit screw a tiny bit? Did you change the outer cable as well as the inner? These need changing every six months to maintain performance.

 

[C R]

Hi all, I have just replaced my 7 speed rear shifter plus cable and housing. I have three front chainrings (I don't use the smallest), so I set up the indexing from the middle front chainring and everything worked fine. However, when I switched to the largest front chainring, I couldn't switch to the smallest rear cog (highest gear). I loosened the cable tension to no avail and even when I released the cable from the derailleur completely it still wouldn't shift to the small cog. Rear mech is Shimano Altus, eighteen months old and very used. Any suggestions? Thanks.

Have you checked the high limit screw?

 

[MrGrumpy]

Watching with bated breath! Similar shifting issues since fitting a new chain and cassette. However no amount of playing about with limit screws or tension stops the chain throwing into the jockey wheels. Suspect it’s them at fault !

 

[Globalti]

What do you mean by throwing into the jockey wheels?

 

[MrGrumpy]

The chain runs into the jockey wheels , between the cage and the wheels

 

[Globalti]

Can you post a photo of the jockey wheels taken side-on? It sounds as if they may be worn.

 

[Cymro74]

Just a thought, but could you need a longer derailleur cage if chain is hitting jockey wheels. This sorted a similar problem for me.

 

[Ajax Bay]

OP: With the chain on the large chainring, and with the cable unclamped, unscrew the 'H' screw a full turn or more. If the cage won't at least line up with the smallest sprocket then maybe the RD is ****ed. Generous spraying of every pivot point might free it up sufficiently. Pictures of the RD and sprockets from the rear and from the side might help.

 

[nmfeb70]

So the spring isn't quite managing to pull the chain down to the smallest cog?

Have you tried loosening the outer limit screw a tiny bit? Did you change the outer cable as well as the inner? These need changing every six months to maintain performance.

Yes, I replaced outer & inner cables. Never thought of adjusting the limit screws because everything works fine on the front middle chainring? I'll try that anyway.

 

[Globalti]

If everything works fine on the middle ring it should be ok on the big. Let's have a pic of the jockey wheels.

 

[MrGrumpy]

Can you post a photo of the jockey wheels taken side-on? It sounds as if they may be worn.

I think they might be to be honest. New derailleur was ordered . Just seems odd never had that before.

 

[Darius_Jedburgh]

Just a thought, but could you need a longer derailleur cage if chain is hitting jockey wheels. This sorted a similar problem for me.

A mech extender would be a lot cheaper.

 

[nmfeb70]

If everything works fine on the middle ring it should be ok on the big. Let's have a pic of the jockey wheels.

Will post a pic tomorrow.

 

[Globalti]

Unless it's so worn as to be sloppy a derailleur will go on working for years.