poor shifting

[BianchiVirgin]

Cobblers!
The OP's symptoms are those of a gear cable and its outer which need changing. A worn (elongated) chain will not create the symptoms described in the OP - of course this doesn't mean the chain isn't elongated. But I note the OP has measured their chain and it's not.
An elongated chain will eventually 'slip' on the most used 'worn' sprockets under higher than normal power, eg up a gentle hill.

Not cobblers at all. An elongated chain, i.e. worn, can often give poor shifting as the chain does not mesh properly in the sprocket and therefore next sprocket when changing gear. I speak from experience and it can happen without the chain jumping. I expect it depends on chain/ cassette combination.

 

[Smokin Joe]

Not cobblers at all. An elongated chain, i.e. worn, can often give poor shifting as the chain does not mesh properly in the sprocket and therefore next sprocket when changing gear. I speak from experience and it can happen without the chain jumping. I expect it depends on chain/ cassette combination.

But it won't refuse to shift to the next sprocket. The chain will go where the mech takes it no matter how elongated it has become. It might jump when it gets there, but get there it will.

 

[Ajax Bay]

Not cobblers at all. An elongated chain, i.e. worn, can often give poor shifting as the chain does not mesh properly in the sprocket and therefore next sprocket when changing gear. I speak from experience and it can happen without the chain jumping. I expect it depends on chain/ cassette combination.

Anecdata. Your indexing was probably a bit off and your cognitive dissonance won you over: blame the chain. You'll be telling us that the chain ripped off your hanger, next. It was the chain, guv!
Which "chain/cassette combinations" did you experience this most? How many miles would you expect to get out of a chain/cassette combo?

 

[paxterg]

I normally change all my cables but this bike has internal gear and brake cables, just enough to put off this home mechanic!

 

[raggydoll]

I normally change all my cables but this bike has internal gear and brake cables, just enough to put off this home mechanic!

Internal as in the cables go through the frame?
I always thought they were just as easy to change but I have no experience of them.
All my cables are external.

 

[paxterg]

Yes they go through the frame. LBS has quoted me 25quid as it is quite time consuming

 

[raggydoll]

Yes they go through the frame. LBS has quoted me 25quid as it is quite time consuming

I didn't realise internal cables were hard to replace. I just figured you stick it in and wait till it comes out the other end.

Like I said, all mine are external so no experience of them.

 

[paxterg]

I think it gets more complicated when you replace the outers as well as the inners!

 

[raggydoll]

I didn't realise internal cable bikes had outer cables.

 

[paxterg]

Yes an outer runs down the down tube and the chain stay. My cable had one strand left, on the verge of snapping so I guess I was lucky enough...

 

[DRM]

I think it gets more complicated when you replace the outers as well as the inners!

It’s dead easy, poke new inner down old outer, remove outer, cut new outer to same length and push up new inner, it only becomes a problem if you pull the whole lot out in one go

 

[Tenacious Sloth]

Yes they go through the frame. LBS has quoted me 25quid as it is quite time consuming

I do all of my own cycle maintenance and there was a fair old initial outlay to buy the necessary tools.

I think £25 is a reasonable quote from your LBS for this job considering their overheads.

The frayed or snapped RH gear cable in the shifter seems to be the payoff for the convenience of having the cables exiting the rear of the shifter and running nice and tidily under the bar tape, instead of out the side of the shifter as they used to. The cable has to undergo a sharp direction change within the shifter and I’ve suffered frayed and broken cables several times in the past with 105 and Ultegra 11 speed.

Glad you’re all sorted.

 

[paxterg]

Yes I'm happy to have consistent shifting again. the mechanic did say he had to loosen the front cable to get the back one fitted, also the cable is fitted a wee bit tight and will need adjustment after some use. I will see tomorrow when i pick the bike up

 

[Tenacious Sloth]

Yes I'm happy to have consistent shifting again. the mechanic did say he had to loosen the front cable to get the back one fitted, also the cable is fitted a wee bit tight and will need adjustment after some use. I will see tomorrow when i pick the bike up

Hmmm… not sure what “loosen the front cable to get the back one fitted” means?

And by “the cable is fitted a wee bit tight and will need adjustment after some use” I’m hoping he means that you may have to make a small anti-clockwise adjustment on the rear derailleur cable barrel adjuster to allow for the outer cable ends ‘bedding in’ to the ports on the frame. This is sometimes necessary and not a problem

Some people incorrectly put this down to cable stretch, but is usually just the cable outers bedding in.

 

[paxterg]

I don't know either, the bike is a Canyon Aeroad. Maybe the cables are compact, i'll enquire more tomorrow. I always like to support my LBS although sometimes I do have to question their theories!!