Phantom shifting

[chesterbull]

I've had a search of the forum and cant find anything specific on this, so my problem is...

Shifting around the small cogs of my cassette. Sometimes the gear changes with no manual intervention. I have a new rear wheel, cassette, chain and chainrings. The problem also occurred with the old cassette, chain and chainring on the same wheel. Its SRAM Red shifting. Could the shift be delayed in someway by a the shifter (unlikely I think) or something in the cabling? The cable is 4 years old and I can see a small kink forwards of the bottom bracket. Could I just be using the shifter incorrectly (if so, why is the ghost shift later?). The other option then is the rear mech, could that be causing it?

My next stage is a new gear cable, unless anyone has any other ideas. Any thoughts?

[NUKe]

cables as you say but check the cable guides underneath the BB. cable innners and outers need checking or just replacing. check how the cable is attached to the rear mech.
Are the jockey wheels in good condition

Check the spring is still good in the rear mech,

[chesterbull]

Thanks - I've done some of the cable stuff you mention, but have not thought about the jockey wheels before. There is a couple of mm side to side play in each one, which in my ignorance I thought was normal. On reflection, this could be it.

[CJ]

What "cable stuff" though?

Cables get cruddy, especially after four years, and the crud resides in the casings, from where it's nigh impossible to remove - rather than the cable, which is easily cleaned. So get a new cable if you like, but certainly get new casings, which sadly, on a road bike, means re-taping the handlebars.

[[XAP]Bob]

Does crud tend to be at the top or bottom of the outers? Is there milage in an outer outer, which is there just to allow a new outer yo be installed under existing tape?

[CJ]

Does crud tend to be at the top or bottom of the outers? Is there milage in an outer outer, which is there just to allow a new outer yo be installed under existing tape?

Top or bottom?? It's inside, nuff said!

But yes, a casing sleeve would be a nice idea - if it could be provided without unduly increasing total bulk or a uncomfortably large ridge in the handgrip. Some handlebar tape installations use a plastic section to smooth the resulting ridge. With some thought and development, such a section could possibly also provide this functionality. A crucial feature would be the transition from sleeve to lever body. Here the casing has to execute a sharp curve up into the body and anything less than a completely uninterrupted transition will, I think, cause the casing to jam and not be budged beyond this point simply by pushing on it. And I think it'll be hard to avoid leaving a small gap at that point.

EDIT: Just understood what you probably mean by bottom. Yes, that last bit of casing by the rear mech is the prime suspect. Renewing that is easy and might sensibly be done much more frequently than the rest, like every one to three years rather than every five or ten.

[NUKe]

Surely the answer is good quality rim tape, which you can take off and re-apply, If you don't want to replace the whole thing. I have re-applied bar tape several times. you only need to take it off back to the hood. the bit of tape at the end to stick can be repalced with insualtiing tape. Even if the tape has faded you can realine it.

[Norman H]

I ran the outer casings for both brakes and bar end shifters in 8mm OD nylon hydraulic tubing before covering with Grab-on foam grips. I used double grooved bars and the gear casings are routed all the way under the grips to exit by the stem. The Idea was to make them easily replaceable but since I’ve not needed to replace them yet, the jury is still out.

With the foam grips I don’t find it uncomfortable but with bar tape you may need extra padding.

[Brucey]

I have always thought that these;

http://www.sjscycles.co.uk/shimano-dura-ace-ultegra-outer-cable-guide-per-pair-y-86b-22000-prod20270/

would work as guides that would allow the outer to be changed, if they were but fitted to the bars in the right way.

I used these for many years beneath the upper section of bar tape, to connect to aero brake levers; however, as normally installed the hidden part of the cable outer couldn't be changed.

I also used joiners so that the visible cable housing could be changed whilst leaving the stuff beneath the bar tape alone. The cable housing usually outlasted the bar tape anyway.

cheers

[willcee]

Hi, afaik campagnolo who use good quality cables imo, recommend total cable change every 2 years, so as others have said a cable change would be a start, the next thing that i would check is the dérailleur hanger and the pivots on the dérailleur , for play, and before that actually ensuring that the cassette is tight on the freehub. all these cause ghost shifting ime.. will