Tiagra Rear Derailleur Repeated Cable Fraying

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VinceLedge
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Tiagra Rear Derailleur Repeated Cable Fraying

Post by VinceLedge »

This is the second gear cable that has frayed on my partners bike in a year, there seems to be a much sharper angle as the cable leaves the adjuster compared to my 105 or Ultegra changers . Anyone else had this problem?
20220511_171229.jpg
peetee
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Re: Tiagra Rear Derailleur Repeated Cable Fraying

Post by peetee »

I have seen these mechs with elongated ferrules that travel down inside the cable adjuster and protect the inner at the exit point.
A ridiculous short-term solution to a problem that shouldn’t exist - if that’s what Shimano did it for, which I can certainly believe. :roll:
The older I get the more I’m inclined to act my shoe size, not my age.
VinceLedge
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Re: Tiagra Rear Derailleur Repeated Cable Fraying

Post by VinceLedge »

It does seem to be a design fault, are there ferrules available to fit, do you know?
colin54
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Re: Tiagra Rear Derailleur Repeated Cable Fraying

Post by colin54 »

One of these ? The one review specifically mentions fraying on the Tiagra derailleur.
https://www.sjscycles.co.uk/cables/shim ... -cap-each/
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Re: Tiagra Rear Derailleur Repeated Cable Fraying

Post by slowster »

1. I would dismantle and closely inspect for any irregularities:

- the end of the cable outer
- the cable bolt adjusting unit
- the corner surface of the derailleur against which the bare cable runs.

2. When setting up and indexing the derailleur, do you have minimal cable tension when the chain is on the smallest sprocket, i.e. when the cable exits at the most extreme angle? If the cable were first clamped with the limit screw completely backed off, the cable would be under more tension once the limit screw had been adjusted.

3. It looks like the damage would mostly occur when the chain is shifted between 1st and 2nd sprockets. However, few people spend much time riding in their top two gears, so does your partner spend a lot of time riding cross chained (middle/inner ring and 1st and 2nd sprockets)?
peetee wrote: 12 May 2022, 7:40am I have seen these mechs with elongated ferrules that travel down inside the cable adjuster and protect the inner at the exit point.
A ridiculous short-term solution to a problem that shouldn’t exist - if that’s what Shimano did it for, which I can certainly believe. :roll:
According to page 4 of the Shimano manual for that derailleur, the ferrule/cap with tongue should be fitted to the end of the cable at the cable stop on the chainstay, but some other derailleurs have a 'cover' with a tongue (page 12).

https://si.shimano.com/pdfs/dm/DM-RD0003-09-ENG.pdf
thirdcrank
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Re: Tiagra Rear Derailleur Repeated Cable Fraying

Post by thirdcrank »

colin54 wrote: 12 May 2022, 9:45am One of these ? The one review specifically mentions fraying on the Tiagra derailleur.
https://www.sjscycles.co.uk/cables/shim ... -cap-each/
That looks like just the job. To satisfy my curiosity, what led you to that? It makes me wonder why that's not fitted as standard - perhaps the manufacturers of gear cable inners are keeping it a secret to maintain sales of replacements. It looks as though you could have everything tip-top on the bike and have a duff cable after a few days touring
colin54
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Re: Tiagra Rear Derailleur Repeated Cable Fraying

Post by colin54 »

thirdcrank wrote: 12 May 2022, 10:43am
colin54 wrote: 12 May 2022, 9:45am One of these ? The one review specifically mentions fraying on the Tiagra derailleur.
https://www.sjscycles.co.uk/cables/shim ... -cap-each/
That looks like just the job. To satisfy my curiosity, what led you to that?
I just had a scout about in the cable section on the SJS site.
Like slowster mentions above, it might pay to make sure the cable's not going over a sharp edge on that casting on the derailleur, maybe ease it with a file if possible, the point about excess cable tension also seems well made to me.
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AndyK
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Re: Tiagra Rear Derailleur Repeated Cable Fraying

Post by AndyK »

thirdcrank wrote: 12 May 2022, 10:43am
colin54 wrote: 12 May 2022, 9:45am One of these ? The one review specifically mentions fraying on the Tiagra derailleur.
https://www.sjscycles.co.uk/cables/shim ... -cap-each/
That looks like just the job. To satisfy my curiosity, what led you to that? It makes me wonder why that's not fitted as standard - perhaps the manufacturers of gear cable inners are keeping it a secret to maintain sales of replacements. It looks as though you could have everything tip-top on the bike and have a duff cable after a few days touring
It kind of is fitted as standard - or rather, something that looks like the narrower half of that ferrule comes packaged with the "official" Shimano outer cable. The RD-R8000 (Ultegra) I was working on yesterday had one factory-fitted. Shimano quaintly describes it as a "cover with tongue".
screenshot-si.shimano.com-2022.05.12-11_20_35.png
And yes, it's an obvious bodge to compensate for a major design flaw.
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Mick F
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Re: Tiagra Rear Derailleur Repeated Cable Fraying

Post by Mick F »

I had a Tiagra on my Moulton when I first used it.
The top pivot wore out I swapped it for a Deore XT.

Never had a cable fray issue with the Tiagra despite ................... let me check on my records ...................

4,293miles on the Devon and Cornwall hills with millions/billions of gear-changes, all on the same cable.
Mick F. Cornwall
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Mick F
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Re: Tiagra Rear Derailleur Repeated Cable Fraying

Post by Mick F »

Zoomed in photo of the Tiagra showing the cable-line.
Rear Mech.jpeg
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Mick F
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Re: Tiagra Rear Derailleur Repeated Cable Fraying

Post by Mick F »

This is when brand new, so I don't understand how the cable line can be out of line unless the boss with the adjuster has been bent.
2016-03-03 08.59.01.jpg
Mick F. Cornwall
slowster
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Re: Tiagra Rear Derailleur Repeated Cable Fraying

Post by slowster »

Mick F wrote: 12 May 2022, 2:30pm This is when brand new, so I don't understand how the cable line can be out of line unless the boss with the adjuster has been bent.
I think yours is the RD4601-GS, i.e. the predecessor of the OP's model, which is RD4700-GS.

https://bike.shimano.com/en-EU/product/ ... -4600.html

https://bike.shimano.com/en-US/product/ ... 00-GS.html
AndyK
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Re: Tiagra Rear Derailleur Repeated Cable Fraying

Post by AndyK »

Mick F wrote: 12 May 2022, 2:30pm This is when brand new, so I don't understand how the cable line can be out of line unless the boss with the adjuster has been bent.
2016-03-03 08.59.01.jpg
Well, judging from the photos you have a 4600 series Tiagra mech (possibly RD-4601?) while the OP has the newer RD-4700. There are some small but significant design differences.
VinceLedge
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Re: Tiagra Rear Derailleur Repeated Cable Fraying

Post by VinceLedge »

colin54 wrote: 12 May 2022, 9:45am One of these ? The one review specifically mentions fraying on the Tiagra derailleur.
https://www.sjscycles.co.uk/cables/shim ... -cap-each/
That looks ideal, will get one of those!
Derailleur is undamaged, just poorly designed with an angled cable line!
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Mick F
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Re: Tiagra Rear Derailleur Repeated Cable Fraying

Post by Mick F »

So ........ mine was an earlier version.
Therefore a backward step by Mr Shimano.
Why a retrograde evolution rather than an improvement?

Seems daft to me.
Mick F. Cornwall
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