UKC

After some advice please..

I changed the gear cables and everything was working fine on the stand and the road but after a few outings the rear gear still changes but in certain cogs it just stays and then after a while will change without warning.

Is this the indexing or just need to tighten the cable again? Or possibly the cassette/chain rings?

Not changed anything in a while but it was only doing a 3 mile trip to work three days a week but now is doing an 18 mile one three days and the changing was getting slower so thought I better get some new cables in at least!

any help would be appreciated.

Lynsey.

In reply to Lynsety:

new cables stretch after a bit of use so you'll need to re-adjust.

In reply to Lynsety:

did you change the inners and outers or inners only?

are there any obvious kinks in the cable run?

is the top jockey wheel in the rear gear changer clean and free to wobble / float a bit side to side?

In reply to Lynsety:

Cable stretches after the first use, and needs to be re-indexed. prob just needs a half turn on the derailleur or shifter barrel adjuster.

In reply to Lynsety:
The delayed changing suggests it is more likely to be a shifter problem - is this with thumbshifters on flat/straight handlebars (MTB style) or road/ dropped handlebars with STI shifters?
The grease inside the shifters tends to congeal a bit over time and can cause stickiness in the ratchet mechanism - can often be alleviated by liberal spraying of WD-40 into the shifter mechanism (or if really bad it may need a dismantle and clean - be careful of small springs pinging out).
(It shouldn't be 'cable stretch', the cables may 'bed-in' a little after fitting and brief use - as others have said - this would be solved with a little turn of the adjuster).

In reply to Lynsety:

Did you change the cable outer at the rear derailleur? If not, you wasted your efforts; the outer is stressed at that curve and wears sooner than the inner especially when gritty water penetrates. A new outer will transform the shifting and you'll be amazed at how bad it had become without you noticing.

Hi everyone, inner and outer cables both changed. Jockey wheels cleaned and fine with a bit of 'wobble'

Will try adjusting the cable and see what happens...

Well I tried adjusting the cable tension but can't say it improved it.

I can see with some of the cassette rings, it sort of sits half on, half off and then slips one way or the other. Can it be a worn cassette?

In reply to Lynsety:

How many miles have you done on the cassette ? You should be able to do 5000 + miles if you change your chain every few thousand miles. If you don't clean the chain regularly, or don't change it often enough, you will accelerate wear of the cassette.

Is it a ten speed set up ? Mine is and I find it very sensitive to incorrect adjustment. Once it is bob on, it will work perfectly. But another half a turn of the adjuster and it skips and jumps. To be honest, they are a bit of a faff to set up properly. Persevere!

In reply to Lynsety:

Do you mean the round bits that hold the two side plates of the chain links apart are not nestling down into the valley between the teeth on the sprockets but are riding up? If that is the case it sounds like a very worn chain and almost certainly a worn cassette. If you mean the side plates seem to sit on top of the teeth then having replaced the cables indicates the problem could be - in no particular order:

• Incorrect cable routing at the pinch bolt on the rear dérailleur.
• Incorrect cable routing under the bottom bracket.
• A section of outer cable may be too short leading to too tight a bend at the handlebars or on the last section before the dérailleur.
• Something wrong with your shifters.
• Worn pivots on the rear dérailleur’s parallelogram.

I would probably start by giving the rear dérailleur cage a firm wiggle in every direction to see if it is sloppy. Any problem will be made worse if the distance between the top jockey wheel and the sprockets is too big.

An 8 speed. Bought in 2008 and last had cassette replaced etc in 2010. I have no idea how many miles its done to be honest!

Not sure it'll have done 5000 though. Mainly used as a commuting bike. Not been very well looked after...I'm getting better though

This is a new chain fitted with new inner and outer gear cables. Sorry should have said about the new chain.

It goes to change up but the outer part of the chain seems to sit on top of the teeth so the chain doesn't sit over the teeth properly if that makes sense!

Its a KMC chain on a shimano cassette if that makes a difference?

So can see now that it pretty much skips one gear cog on the cassette so only ever goes from 8 to 2 or 1 to 7 on the shifters depending on how taught the cable is!

Shifter problem then? Anyone had this before?

In reply to Lynsety:

If the chain doesn't sit properly on either the cassette of the chain rings, it suggests a very worn chain. How long since you changed it ? Around 2-3000 miles causes enough wear in the rollers in each chain link to warrant changing it. If you've not changed anything since 2010 and used it a reasonable amount, then everything might be a bit worn out. Which is probably not the answer you were looking for.

Put the chain on onto the largest chain ring at the front (on the pedal axle). Take hold of the chain at the very front of the chain ring and pull it forwards. If you can pull it just clear of the teeth on the chain ring, the chain has worn too mutch (i.e stretched) and needs replacing. That should correspond to about 2 or 3 % stretch in chain length (which is what received wisdom says is quite enough for a chain).

If you put a new chain on and you have gear changing problems, the chain rings or the rear cassette may need replacing.

Its a new chain.

Managed to fix it. The shifter cable wasn't sat in the holder properly so popped it in and then tightened the cable and seems to be changing properly! Yippee.

Thanks for all your advice

In reply to Lynsety:




It's the best feeling, you learn about maintaining bikes without really realising it, until eventually you can sort out most things.

In reply to Timmd:

Plus saves you cash!