Can't change gear on cassette (won't go up or down)

[Maz]

Hi

Specialized Allez Elite 2008.

Today riding home, I was not able to change the gear on the rear cassette. Moving the Tiagra levers/paddles on the shifter made no difference. Can't move up gear, can't move down gear. It is stuck on the 2nd highest gear on the cassette.

Oddly, the gear cable it tight. If it were broken, I imagine it would be loose. Any ideas what the problem is?

Thanks

 

[gbb]

First thing I'd do is disconnect the cable at the RD and while pulling the cable end, shift the gears....have you got cable movement ?
While the cable is off, preferably remove the chain and see if the RD is swinging freely..
That should identify if it's a shifter or mech problem, then work from there. Cables may want inspecting as well.

 

[Tin Pot]

First thing I'd do is disconnect the cable at the RD and while pulling the cable end, shift the gears....have you got cable movement ?
While the cable is off, preferably remove the chain and see if the RD is swinging freely..
That should identify if it's a shifter or mech problem, then work from there. Cables may want inspecting as well.

You can check the rear derailleur (RD) is moving okay without disconnecting the cables, just manipulate it while turning the cranks/pedals.

If there is exposed cable in the cable routing you can also pull that out to see if the mech responds to the cable, without disconnecting it.

But if as you say it's not moving up or down, I'm thinking both these tests will change the gears okay, and it's the shifter that needs looking at.

 

[mickle]

Shifter's shaggered by the sounds of it.

 

[Tim Hall]

Cable jammed/rusted in the outer will give those symptoms too, although the onset is usually gradual.

 

[Maz]

I had noticed that over time, it was taking several (5 or 6) taps of the paddles to move the gear up 1/down 1 on the rear derailer.
Maybe this extra info sheds more light on the problem.

 

[andrew_s]

Sounds like new cable time to me - either a rusty/gunged up outer, or the inner starting to break inside the shifter, with loose strands jamming things up.

 

[Maz]

Thanks, I will investigate it further and report back.

 

[Maz]

Update:
I flipped the bike upside down, turned the crank by hand and, with the other hand, manually pushed the RD through the range of gears (admittedly, I couldn't push it on to the largest cog/lowest gear, but that is a separate issue). The chain moved across as expected.

Plucking/twanging the rear gear cable, there is tension in it. It is not loose. I only changed the cable about 6 months ago, so it should be in good shape.

The RD (Sora) is also only about 6 months old.

The shifters are the originals. Bike has had daily use, from new, in all weathers.

I can see the cable & its nipple inside the shifter [see pic, but it's not very clear]

Tapping either of the paddles will not move the gear indicator needle on the display.

Does the above narrow down where the problem is? Thanks

 

[Ajax Bay]

As has been said, the symptoms from that testing suggests the RD is fine and that the shifter (STI) is not functioning correctly, may be a cable interference issue, or it may be beyond repair. Before deciding on STI replacement, I'd do two things:
1) Apply the STI brake lever and give all the innards a good squirt of WD40/GT85 (from every direction), manipulate both the lever and paddle; let it stand for an hour and then do it again. Most STIs do get gunked up inside and this one is 9 years old (I'm assuming, and I have had these 9sp Tiagra STIs (last about 10000km for me).
2) Replace the cable but at the first stage just through the STI, and applying some tension to the wire, operate the lever paddle and see if it then pulls and releases cable.
3) In any case you'd be well advised to replace both cables, both inner and outer. Might be worth looking at the brake cables and replace them too; again both inner and outer.

 

[accountantpete]

As above - probably the mechanism has jammed.

Usually something breaks and jams the mechanism - normally fatal. Occasionally the cable can stretch and the nipple at the end of the cable cause an obstruction.

I'd remove the cable and see if it clicks through - if it does then re-introduce the cable and, as Ajax says, pull on the cable and see if it still clicks through with pressure applied.

 

[confusedcyclist]

I have had similar issue, turned out the cable had frayed inside the STI lever and jammed everything up. Remove the cable and check it's intact. Snip just above the RD clamp and pull it carefully from the mechanism. You don't want to yank too hard and leave reminants behind. Fit new cable. If it's still not working follow the advice above about squirting the STI with penetrating lube, failing that get a used but good condition replacement on eBay. Be sure to replace outer cables also.

 

[Maz]

Update

I tried applying wd40 to the internals of the shifter, but to no effect.

I have now disconnected the rear gear cable from the RD.

Question: Should the outer cable that feeds into the shifter be able to pull away from the shifter?

It seems to be stuck in solid. It should pull away easily, right?

 

[Tim Hall]

Yes, the outer should move if the cable is disconnected. Make sure the outer isn't jamming on a guide before you try to move it.

 

[Maz]

Update
I had to force the outer away from the shifter by pulling it with some pliers.
It appears the spiral wire casing of the cable outer had lodged itself into the shifter body...

The nipple-end of the cable was intact but bent...

With the cable now removed, tapping the paddles moves the gear indicator needle as expected.

I re-introduced the cable (albeit bent) and held it by hand under tension, tapping the paddles through the full range of gears. The cable was pulled through, which is a good sign.

I think that all I need to do now is fit a new cable and outer.

Fingers' crossed it will be OK. I will let you know!