Ultegra 6700 10 Speed inconsistent shifting.

rayman1

My chain is not shifting properly on the cassette. When moving up or down the cassette, usually once the chain will not move when I press the shifter. It makes a clicking noise as if it is trying to move. It moves when I press it a second time. After another few moves it will make a double move to make up for the missed move. I put on a new cassette and chain to no avail. Also the cable is relatively new as it snapped a few months ago and was replaced by my lbs.
Left it into my lbs and they thought they had adjusted the gears but it is no better. My lbs say that the only thing left that could be causing the problem is the shifter and recommend it be replaced. The shifter is clicking when pressed and sounds like it is working. The bike is 4 years old with about 23,000km done. Do shifters wear out???
Anyone have a similar problem. Any advice welcome.

cython

Shifters can wear out, but not sure personally what mileage the norm to expect from them is, to be honest. One thing that occurs to me though is you say the cable is new as it snapped - did the shop replace both inner and outers, or just the snapped inner? If the latter than there could be "drag" from an old outer that is contributing to this - checking it by replacing both now if just the inner was done before would definitely be cheaper than testing a replacement of the shifter!

not sane

Really sounds like a cable issue even though you said it had been replaced. If the shifter still clicks don't think its that. Sometimes even if an inner cable is replaced the problem can still be with the outer cable. 4 years is a long time not replace both inner and outer cables.

Dinging

Had the exact same problem and never really go to the bottom of it.

Changed cable, seemed to work for a while then issue returned.

I then change cable housing, had no impact.

Then changed the chain, is was suspected as worn but this had no impact the shifting was still not working at it should.

As the bike was under warranty the shifters were replaced, you guessed it the issue returned.

The cassette was new, spacing was checked and it was given the OK by the bike shop.

I gave up. I need to tune the rear derailuer and it lasts about a week. Talking to a bike mechanic he reckons that between the tension in the cable and the pressure on the shifter is causing the problem on some bikes. Might just need to look at the way the cable is running from the shifter and the rear housing, some oil in the cable housing and the shifter. It could be trial and error and you may not get it 100%.

outfox

The 6700 series wasn't the best Shimano groupset, it must be admitted. I have a sticking shifter, most likely an issue with a spring (or something) in the shifter. For the cost of replacing a shifter, it's nearly easier to pay for an entire new 105 5800 11 spd groupset. The 5800 is superb.

Luxman

I have found that once indexed on a stand correctly there can be still minor adjustments needed when the rubber hits the road (literally). I have a similar problem on the same group set and changed cables etc but my suspicions lie with the rear derailleur now as I think the bike fell over on that side once while I was washing it. I have a 5800 replacement but haven't gotten round to replacing it

Type 17

1. Check the cable, as mentioned - if you adjust the cable tension/indexing so it goes up the cassette well, but it won't descend well, then it's the cable.

2. Check the rear derailleur - if a lot of the 23k km were in harsh (wet) conditions, then the four pivots of the parallelogram of the derailleur can be worn, leading to misalignment which varies in different gears, meaning that indexing works at one end of the cassette but not the other.

3. Harsh conditions can also lead to heavy wear on the pulleys - if they can be wiggled sideways around their axis, then they'll be flopping to the side during changing, rather than being tight and drawing the chain across.

Solutions: 1. new cable or 2 & 3. new derailleur

rayman1

Thanks a million for all the very informative replies.