Can't tighten rear derailleur cable enough ...

[Jimmy Doug]

... and so I can't get into first gear, and nor can I re-index my gears. It's a bicycle I've recently bought second hand: a classy machine from the early 90s with a Shimano 600 groupset (there's a post about it here). The STI shifters didn't work initially, but a good squirt of WB40 sorted that out. But now I can't get into first gear and in some gears the chain jumps around slightly. The barrel adjuster doesn't seem to do anything, neither does the little lever on the down tube. The only way I managed to get the lower gears working at all was by pulling hard on the cable with a pair of pliars until I got enough tension there. But I can't pull it any more! I've also tried adjusting the limit screws, but as the derailleur goes out to within only a few millimetres from the spokes I'm wary of adjusting this any more. What else can I do? Could it be related to the fact that the cable doesn't seem to fit snugly into the barrel adjuster? I did try fitting a ferrule onto the end of the cable housing, but it seemed to make it worse as the ferrule is slightly bigger than the orifice of the barrel adjuster (I don't know the technical term!). Here are a couple of photos if it helps (the cable is slightly damaged because I had to pull it really hard to get any of the lower gears working!) :

Notice how the cable housing seems too small for the barrel adjuster. A ferrule makes it slightly too big. Is there perhaps a piece missing?

There's this adjuster on the down tube. It tightens the cable a small amount, but it's now as far as it will go:

If anyone has any ideas, I'd really appreciate your help with this. It's driving me nuts!

 

[User33236]

Are you sure you are trying a gear cable ferrule and not a brake cable one? The former has a slightly smaller diameter.

 

[Jimmy Doug]

Are you sure you are trying a gear cable ferrule and not a brake cable one? The former has a slightly smaller diameter.

Yes, I'm sure. I changed gear and brake cables at the same time so it was easy to see which was which.

 

[User33236]

Can you measure the inner diameter of the adjuster? There certainly looks enough space to fit a ferrule or similar there.

 

[CopperCyclist]

It's difficult to tell from the picture. I had an identical issue on a SRAM Apex derailleur, and it took me ages to notice that the derailleur needed the cable to sit in a small groove on it to work correctly. I was setting the cable outside this groove when the bike was on the smallest cog. As the bike changed down gears, the cable got trapped against the side of the groove rather than running within it, causing it to not manage to pull the chain into the last gear.

It was a simple mistake that took me ages to spot!

 

[Smokin Joe]

It's difficult to tell from the picture. I had an identical issue on a SRAM Apex derailleur, and it took me ages to notice that the derailleur needed the cable to sit in a small groove on it to work correctly. I was setting the cable outside this groove when the bike was on the smallest cog. As the bike changed down gears, the cable got trapped against the side of the groove rather than running within it, causing it to not manage to pull the chain into the last gear.

It was a simple mistake that took me ages to spot!

Similar to this.

The cable looks to me to be on the wrong side of the clamp bolt from what I can see in that photo. It should run wheelside of the bolt otherwise it will never index properly. And you MUST use ferrules on gear cables.

 

[boydj]

The cable looks to be going into the mech at a fairly tight angle. It's possible that the last piece of outer is too short and your are getting a bit of friction in there. A ferrule will help to ensure the outer cable is properly seated. The inner looks a bit rough too, which won't help, especially if there's a broken strand inside the outer.

 

[T.M.H.N.E.T]

Cable looks short + no ferrule..

 

[Mugshot]

In the pics you originally posted there does appear to be some additional ferrules and bits, have you replaced everything that was there on the old set up?

 

[Jimmy Doug]

Thanks for your input, guys. I've just had a look at it again and the cable snapped! I was able to get it back into position, but with only about two mms of slack!

The cable looks to me to be on the wrong side of the clamp bolt from what I can see in that photo.

No, the cable appears to be clamped in the right place. The groove is on the inner side.

The cable looks to be going into the mech at a fairly tight angle.

Well, it's even tighter now! I'll buy more cable tomorrow and try again!

no ferrule..

Indeedy - I've managed to find a ferrule from an old cable (slightly different design) and it fits like a glove. Hasn't changed anything, though, but ....

Obviously, I need to change the cable. I'll cut it longer this time.
However, I can't help but feel there's a problem with the barrel adjuster. I can only turn it by using a pair of pliars - and nothing, absolutely nothing happens. When I undid the cable I noticed that the barrel adjuster didn't seem to screw at all. You can pull it out of the hole - there's the screw itself, a washer and a spring - but when you put it back in you can screw, and screw, and screw till your sick but nothing happens - I mean you can still pull it out with your hand. Surely that's not normal?

 

[fossyant]

Cable looks like it needs replacemen. The adjuster screw should be somewhere in the middle so you have adjustment on the fly. You need to fit a new cable and outer (will havethe ferrule also).

I have the same mech on my Ribble.

 

[Jimmy Doug]

In the pics you originally posted there does appear to be some additional ferrules and bits, have you replaced everything that was there on the old set up?

I replaced everything brand new - except for that old ferrule I've found.

 

[Jimmy Doug]

Cable looks like it needs replacemen. The adjuster screw should be somewhere in the middle so you have adjustment on the fly. You need to fit a new cable and outer (will havethe ferrule also).

I have the same mech on my Ribble.

It might be interesting to compare barrel adjusters. I really feel there's a problem with mine.

 

[shouldbeinbed]

However, I can't help but feel there's a problem with the barrel adjuster. I can only turn it by using a pair of pliars - and nothing, absolutely nothing happens. When I undid the cable I noticed that the barrel adjuster didn't seem to screw at all. You can pull it out of the hole - there's the screw itself, a washer and a spring - but when you put it back in you can screw, and screw, and screw till your sick but nothing happens - I mean you can still pull it out with your hand. Surely that's not normal?

Sounds like the thread for the barrel adjustor in the derailleur has worn or become badly crossed, if you are sure the cable run is right then this could be your problem, you could try to re tap it but a new derailleur is a few quid nowadays.

Never cut your cable until you've got your gear indexed properly then cut it to leave a couple of inches free

 

[Jimmy Doug]

Sounds like the thread for the barrel adjustor in the derailleur has worn or become badly crossed,

It doesn't feel like that to me. It's more like the barrel adjuster is too small for the hole. When you release the cable from it, it pops out - which can't be right.

Never cut your cable until you've got your gear indexed properly then cut it to leave a couple of inches free

A good tip. I usually cut the cable to the approximate size I want so that it doesn't get in the spokes, then index the gears.