Indexing problem

[rich p]

I fecking hate fixing bikes - I want to make that clear.

My rear changing has become increasingly sloppy lately. Sometimes I click and nothing happens, then I click again and it changes twice or maybe once. Sometimes it will change up fine but not down ( or vice versa).

I have had it on the stand and started from scratch but always end up with the same issue. The outers are newish, as is the cable and it seems to run smoothly through the outer. I removed the rear derailleur yesterday, took it apart and cleaned it but to no avail.

Any ideas what I should try next? Could the chain and cassette be worn out or maybe the shifter isn't releasing enough cable.

 

[Angelfishsolo]

Worn sprockets are easily identified by looking for shark toothing on the teeth. ie pointy rather than flat topped.

For the sake of a few seconds measure you chain. 12" for a road bike 6" for a MTB if the chain is n1/4" long than it needs changing.
Assuming all is ok there then for the cost of a new gear cable I would start there. This is one of many videos on how to do it.

 

[Dayvo]

I fecking hate fixing bikes - I want to make that clear.

Any ideas what I should try next?

Sounds like you need a new bike, mate!

Difficult to know without being able to see/visualise the bike.

Can you try and google a bike site looking for specific help? This, for example
View: http://www.youtube.com/watch?v=SjJfKO_tAo0&playnext=1&list=PLEC87665E2D8810D0

 

[rich p]

I've measured the chain and it is marginally 'stretched' by about 1/16" over 12 links. I know in theory how to set it up.

FWIW, this is what I am doing. I put it in the big ring and loosen off the rear cable and let the chain default onto the smallest sprocket. Then I pull the cable finger tight and clamp it. I click once which should move the chain onto the second smallest sprocket and if it doesn't, I use the barrel adjuster until it just does.

 

[RecordAceFromNew]

Sounds like you need a new bike, mate!

Difficult to know without being able to see/visualise the bike.

Not difficult - it will be a ss or fixie.

 

[Angelfishsolo]

I've measured the chain and it is marginally 'stretched' by about 1/16" over 12 links. I know in theory how to set it up.

FWIW, this is what I am doing. I put it in the big ring and loosen off the rear cable and let the chain default onto the smallest sprocket. Then I pull the cable finger tight and clamp it. I click once which should move the chain onto the second smallest sprocket and if it doesn't, I use the barrel adjuster until it just does.

Sounds ok. Try tensioning the cable manually instead of using the adjusters at this stage.

 

[Angelfishsolo]

Not difficult - it will be a ss or fixie.

 

[rich p]

Not difficult - it will be a ss or fixie.

You're not helping!

 

[RecordAceFromNew]

I've measured the chain and it is marginally 'stretched' by about 1/16" over 12 links. I know in theory how to set it up.

FWIW, this is what I am doing. I put it in the big ring and loosen off the rear cable and let the chain default onto the smallest sprocket. Then I pull the cable finger tight and clamp it. I click once which should move the chain onto the second smallest sprocket and if it doesn't, I use the barrel adjuster until it just does.

Before the ss/fixie arrive, you might want to follow Shimano's guide for setting indexing (it is in everyone of their rear mech installation instruction leaflet). Essentially, switch the gear onto the 2nd smallest sprocket first, then increase the cable tension (by turning the barrel adjuster anticlockwise) slowly until a slight push of the shifter towards a lower gear (i.e. towards the 3rd smallest sprocket) causes the chain to start catching (but not yet shifting) onto that sprocket. It usually works.

Angel's suggestion re junking old (if they are old) and getting new outers/cables is a good one. They don't need to be expensive to transform shifting.

 

[gwhite]

Before doing anything else I would check that the gear-hanger is not bent. From the rear of the bike ensure that the cage and pulley is exactly vertical below the sprocket chosen. Going on to adjust or replace is a waste of time if this is out of alignment.

 

[Angelfishsolo]

Before doing anything else I would check that the gear-hanger is not bent. From the rear of the bike ensure that the cage and pulley is exactly vertical below the sprocket chosen. Going on to adjust or replace is a waste of time if this is out of alignment.

A very good point indeed

 

[rich p]

I've tried an different wheel from my wife's bike - same problem occurs

I've now tried a different derailleur - same prob

It takes sometimes 3 clicks to change to a lower gear in the middle range of the block which, given that the cable and outers are only a few months old, seems to suggest it may be the shifter. There's an expensive way of finding out but I may try the shifter off her bike first when she's not looking.

 

[Angelfishsolo]

I've tried an different wheel from my wife's bike - same problem occurs

I've now tried a different derailleur - same prob

It takes sometimes 3 clicks to change to a lower gear in the middle range of the block which, given that the cable and outers are only a few months old, seems to suggest it may be the shifter. There's an expensive way of finding out but I may try the shifter off her bike first when she's not looking.

I would say that the cable is at fault TBH.

 

[rich p]

I would say that the cable is at fault TBH.

Okay, I'll try that first!

 

[Dayvo]

Okay, I'll try that first!

C'mon Rich, the suspense of this Sunday's drama is killing us! What happened?