Rear Mech Indexing - Adjustment Sensitivity

[andytheflyer]

Hi,

A couple of weeks ago I changed the 2 yo 2500 mile Shimano Tiagra gearset (HG50) chain, jockey wheels and cassette (9 spd) on my Defy 2.5 with identical parts - but the jockey wheels are Tacxx - and they are for Shimano 9 spd. I also changed the rear mech cable (complete) for a Clarke Professional (Teflon lined). The old chain was shot. Chainwheels etc are fine.

No problem - all went together Ok and I followed the standard practice in adjusting the cable tension to get the indexing to work properly. Easy-peasy.

Now for the problem - on the old (original) setup I almost never had to adjust the cable tension, today I had to do it 3 times in 40 miles. I did think at one point that the cable was slipping through the clamp on the mech - but the pinch bolt's about as tight as I'd want to make it.

So, not sure whats's going on. I can ride for maybe 1/2 an hour with no problem, silky smooth changes, total silence, then for no apparent reason the chain changes down (next larger sprocket) and then back again - flip-flopping between 2 cogs for maybe a minute - but if I increase the cable tension maybe 1/4 turn that cures it - but that's the wrong way surely? The chain and cassette are spotless, no tight links and I used a new 9spd Powerlink when I fitted the new chain.

So, I'm confused. I know new cables stretch, but this seems much more than I'd expect.

Watching a couple of vids in Youtube I got the impression that a couple of turns of the adjuster would be needed to get the chain to change cogs - mine's far more sensitive than that - 1/4 turn is all it needs. So out on a ride if the chains jumps between cogs it only needs a very small tension adjustment. But surely not every hour?

I'd dearly love to get back to a nice smooth ride - not a smooth ride for 1/2 an hour followed by a minute of total and clattery chaos!

Anybody got any bright ideas?

Thanks

Andy

 

[BigTone0777]

Did you change the outer cable as well as the inner wire cable? Sorry if this sounds obvious but if you did change the outer is it linear stranded for indexed gears and not spiral wound like on brake cable outer?

 

[andytheflyer]

Did you change the outer cable as well as the inner wire cable? Sorry if this sounds obvious but if you did change the outer is it linear stranded for indexed gears and not spiral wound like on brake cable outer?

Hi, yes I changed the whole cable, inner, outer, ferrules....

 

[swee'pea99]

Did you change the outer cable as well as the inner wire cable? Sorry if this sounds obvious but if you did change the outer is it linear stranded for indexed gears and not spiral wound like on brake cable outer?

There's a special kind of cable housing for indexed gears?

 

[gwhite]

That doesn't sound like cables or an indexing problem. I'd check that the Gear Hanger is hanging plumb before I do anything else. If bent, it does cause the rear gears to behave in an erratic way.

 

[potsy]

Only other thing I can think of is that the jockey wheels are having an affect, I did the same and changed them on my Tiagra rear mech to the ones you have bought. The indexing is fine but on certain cogs there is a definite noise difference that I didn't use to get.
The Shimano ones have a 'float' to help the chain stay on the correct cog, but the Tacx ones are fixed.
Did you pu the correct spacer on them? There are different sizes depending on what speed chain/cassette youare runing.

My problems started with a frehub that was very loose, and there was loads of playin it, no amount of adjustment would cure it so I opted for a new wheel

 

[HLaB]

When you changed the outers Andy did you put them to the exact same length as previously on the bike that's now on my turbo when it was still on the road I had to make the rear derailleur loop fractionally bigger than what was there when I bought it it then changed sweet as a daisy :-)