When to Change Gear Cables?

[EasyPeez]

Recently I'm finding on my 'best' bike that the front derailleur is not quite moving across as far as it once did so that, when I'm on the 50t cog at the front and in the highest couple of gears (smallest cogs) on the back the chain is just lightly rubbing on the inside of the mech.

Similarly, on the rear it's showing reluctance to drop onto the 11t cog - I think this is a separate issue rather than being caused by the front derailleur rub, but I could be wrong.

Could these be signs that my cables are ready for changing?

I've tried adjusting cable tension with the barrel adjusters and starting from scratch with the indexing, but with no improvement. I'm proficient at indexing and the gears are otherwise changing just fine. I keep the bike, including the cables well cleaned and oiled.

The bike is coming up to 4yrs old and 11,000 miles, so the cables certainly don't owe me anything. I've never considered changing them before simply because everything has been in good working order.

I'd be interested to know how often others change their gear cables, if there are symptoms that cables are getting past their best to look out for, and if the slight issues I'm now having might qualify as such symptoms.

Also, if it is time for a change then I assume inners and outers ought to be done at the same time? And at 11,000 miles, does it make sense to change the rear derailleur at the same time? The jockey wheels and the mech itself all seem fine, but then I would have said the same about the cables until a couple of weeks ago...

Cheers,

Andy

 

[I like Skol]

Cable inners should last ages if they are decent stainless steel ones. I only change my inners if they get kinked, frayed, or a change of outers leaves them a bit short.
Outers are a different kettle of fish and can need changing annually or more frequently in some instances. I prefer full length outers as these are far more resistant to contamination and I have managed 3-4yrs of year round commuting on the same inner/outer set.

Inners are often killed at the cable clamp after swapping the outers a few times. Slick shifting can often be restored just by replacing the final length of outer at the rear mech and lubing the rest

 

[Globalti]

The outer cable where it curves round to the RD needs changing every 6 months if used on wet salty roads. I'm not surprised yours aren't performing. You ought to change them both, full length. You'll be amazed at what you've come to accept as normal bad performance.

The RD will be fine as the pivots last for years. Just change the jockey wheels.

 

[Svendo]

The gear cables can also fray in the lever where they get bent round as you change gear. One or two broken strands can cause annoying symptoms without preventing changing altogether. Shimano seems to be worse for this. Presumably it bends tighter than Campy or SRAM.
I did try to find out bending radius specs for Bowden cables and it varies but around 13x cable diameter is what I recall for a minimum radius, so that’ll be 15.6mm for a bike cable.

 

[pawl]

I had a problem with sticky gear changing at the rear mech. I lengthend the outer a bit as the angle looked a bit acute.Solved my problem.

 

[Smokin Joe]

As has been said by @Globalti, it is the rear loop which takes the biggest hammering. Changing this makes a huge difference.

 

[CycleCommute.CC]

Inners can be cheap as chips so worth changing. Easier than doing the outers too. Mine usually fray or even snap in the shifter before anything else though (yes, shimano).

Regarding the mech, have you checked the limit screws are OK?

 

[iluvmybike]

If you have those Shimano polymer coated ones they can delaminate very quickly - the coating scrapes off with movement inside the outer casing & lever mech and can really jam things up. Best ditch them and put in either the Optislick or good stainless versions

 

[EasyPeez]

Thanks for all the feedback.

The outer cable where it curves round to the RD needs changing every 6 months if used on wet salty roads. I'm not surprised yours aren't performing. You ought to change them both, full length. You'll be amazed at what you've come to accept as normal bad performance.

My best bike's been pretty molly-coddled for the last couple of years - ridden in nothing worse than a light shower. Previously to me acquiring my single speed it did go out in some real downpours occasionally, but never on salty roads. Still, at the age/mileage it's at, I'm well over your 6 month figure so will take your advice and change both. I wouldn't call anything about my gear performance apart from the reluctance to drop onto the smallest sprocket bad though - it's all nice and smooth and I keep it perfectly indexed. Very rare that I get a misshift or a delay in shifting.
I'm also a bit confused, if worn cables are the problem, about why it would be the smallest sprocket that's hard to engage - I would have expected it to be the largest rear sprocket (lowest gear), as that's the one that requires most cable tension.

Regarding the mech, have you checked the limit screws are OK?

Checked they are OK? As in tried adjusting them do you mean? I did wonder about that. Is that something I should try? I thought that as they were set up fine when I bought the bike and have never been altered since that they should probably be left as they are as there is no reason why they would move around if nobody has touched them. Is this wrong? Are they something that needs periodical tweaking?

If you have those Shimano polymer coated ones they can delaminate very quickly

I have Jagwire compressionless outers - not sure about the inners - I assumed also Jagwire but I don't think the bike specs specify

 

[CycleCommute.CC]

Best way to check limit screw is to disconnect the cable from the mech. The mech should then track the smallest cog. You are right that once set it shouldn't need adjustment, but things do move about with use, and 11k miles is a lot.

 

[I like Skol]

Inners can be cheap as chips so worth changing. Easier than doing the outers too. Mine usually fray or even snap in the shifter before anything else though (yes, shimano).

Regarding the mech, have you checked the limit screws are OK?

Absolutely no point changing the inners without doing the outers. The inners are just metal and can be cleaned up and lubed. The outers have a nylon type liner that gets worn, gets contaminated and loses the factory installed lubrication, the outers have by far the biggest effect on the cable/shifting performance.

You are right that once set it shouldn't need adjustment, but things do move about with use,

Once set it doesn't need adjustment, unless it takes a bang that moves things out of alignment. It shouldn't need adjusting just from normal use.​

 

[Ajax Bay]

Every year (10,000km) - inners and outers - for me. It's not easy to replace the outers without replacing the cable itself but @I like Skol has shown the way on that. The end has been cut and probably deformed by being clamped at the derailleur. One can reuse the rear cable by cutting it neatly so it's long enough to be a replacement front one, and just replace the rear with a new one.

if worn cables are the problem, about why it would be the smallest sprocket that's hard to engage - I would have expected it to be the largest rear sprocket (lowest gear), as that's the one that requires most cable tension.

No - the issue is that there is residual friction (caused by wear) between the inner and the outer and the cable is not 'letting' go enough to drop onto the smallest sprocket. The front cable does not normally have the same problem because the tensions are higher, FD arm movement is greater and the need for accurate indexing is less.

 

[Ming the Merciless]

Before an important event or when the shifting is less than crisp and efficient. I have full length otters now so cable changing is much rarer than before.

 

[DCBassman]

Thinking of going full length too, but with cables, not small mammals!

 

[Globalti]

When you cut your lengths of cable or get the shop to cut them for you, it's good to flat the ends of the outers with a grinding wheel so that they sit square and without deforming in the ferrules.