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Discussion Starter · #1 ·
Hi guys,

I have had two stainless steel shifter cables snap about 1" from the end cap within six months. This is not such a massive problem, except that each time it takes me hours to extract the 1" bit of exploded cable from inside the STI (you'll know if you've tried - no stiff cable to "push" against...) So I fear if it continues to happen it could cause my STI's to be binned if I can't extract the cable (on a side note, any tips for easy cable-end extraction in this situation?)

I am running 10 speed Ultegra 6600 STI's with Shimano stainless cable and housing. Tension is coming from a 2006 Dura Ace deraileur...

Its almost as if the cable is being wrapped around too-sharp-an-angle somewhere inside the STI, which is putting tangential forces on the cable?

Any help would be much appreciated, this has got me stumped!

Cheers
 

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GoingDHfast said:
Hi guys,

I have had two stainless steel shifter cables snap about 1" from the end cap within six months. This is not such a massive problem, except that each time it takes me hours to extract the 1" bit of exploded cable from inside the STI (you'll know if you've tried - no stiff cable to "push" against...) So I fear if it continues to happen it could cause my STI's to be binned if I can't extract the cable (on a side note, any tips for easy cable-end extraction in this situation?)

I am running 10 speed Ultegra 6600 STI's with Shimano stainless cable and housing. Tension is coming from a 2006 Dura Ace deraileur...

Its almost as if the cable is being wrapped around too-sharp-an-angle somewhere inside the STI, which is putting tangential forces on the cable?

Any help would be much appreciated, this has got me stumped!

Cheers
I have the same problem. I’ve no experience with other brands of shifters, but this seems to be a Shimano 10sp issue.
The flame that burns twice as brightly burns for half as long. Neat line, even if it doesn’t make you feel any better.
I can predict that my rear shifter cable will start to produce imprecise shifts after 3,000 miles. Inspecting the cable end in the shifter reveals a few strands of the cable starting to break.

Get a handle on how many miles you can ride before you get cable fraying. Change it then to preclude cable failure mid-ride.
 

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Perhaps try a teflon coated cable

or something other than stainless? Not sure that there is anything else, any chance of warranty on the shifter? It really should not be cutting a cable.
 

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Carbon Fiber = Explode!
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Cable routing can be an issue, got any sharp angles or too long of housing? Or too short of housing?

All of these are problems.
 

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Sharp edges

GoingDHfast said:
I have had two stainless steel shifter cables snap about 1" from the end cap within six months.

Its almost as if the cable is being wrapped around too-sharp-an-angle somewhere inside the STI, which is putting tangential forces on the cable?
Your analysis would be my guess as well. If the cable fails where it enters the casing, then you want to look at the casing end or ferrule. When you say "end cap" can we assume you mean the "button" on the end of the cable? If the failures occur before the cable enters the casing, then take a magnifying glass and bright light and see if you can spot the sharp edge that might be damaging the cable. Your failure rate is way outside the norm, so there must be some specific cause beyond "normal wear and tear."
 

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Something I used to be guilty of, when I was done riding I would finish the night in the big-big combo. That puts maximum tension on the derailleur cables for hours on end, needlessly wearing them out.

What I do is when I place my Ciocc on its stand I run small-6th, and once it is in 6th gear, click the STI into 9th so there is no tension on that cable.

Thank God I went 9-speed. :thumbsup:
 

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Cleaves hit the nail on the head I think - route those cables at the wrong length or angle and your toast...

Solution - go to SRAM or Campy - they shifters can be rebuilt if there is an issue, unlike the STIs. I had the same problem with my 6600s and finally just threw my cash to SRAM - thrilled with the changeover.
 

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Uh, no

j-dogg said:
Something I used to be guilty of, when I was done riding I would finish the night in the big-big combo. That puts maximum tension on the derailleur cables for hours on end, needlessly wearing them out.
This is nonsense. Compared to the strength of a steel cable, the force of a derailleur spring is nothing. Cables wear out from friction, bending, corrosion, sharp edges, etc. but NOT from the tension of a derailleur spring.
 

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i agree w/ kerry, there's probably a sharp edge in the shifter, just past where the cable end is held. if you can't find that offending spot, take a look at the cable every month or so, undo the housing from one of the braze-ons and push it out of the shifter, once it starts to stay bent, get ready to replace. there aren't any tricks that will work every time for getting the end out...it's different every time.
 

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Just for information: here's one picture from an Ultegra 6603 shifter take-apart series posted by RBR member martinrjensen on another website. (Hope he doesn't mind me posting it here.) My arrow shows the cable end hole. As you can see, there are a couple of ways the cable can get frayed quickly if the end barrel isn't seated perfectly into its recess. There's a smooth cable groove starting beyond the "U" opening, so I don't think there are any more sharp edges behind that "U." Shimano makes a note of proper end barrel seating in their shifter service instructions.
 

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Discussion Starter · #11 ·
wim said:
Just for information: here's one picture from an Ultegra 6603 shifter take-apart series posted by RBR member martinrjensen on another website. (Hope he doesn't mind me posting it here.) My arrow shows the cable end hole. As you can see, there are a couple of ways the cable can get frayed quickly if the end barrel isn't seated perfectly into its recess. There's a smooth cable groove starting beyond the "U" opening, so I don't think there are any more sharp edges behind that "U." Shimano makes a note of proper end barrel seating in their shifter service instructions.
Thanks for all the advice guys. I do always try to store my bike without tension on the deraileurs so that can be ruled out twice.

Yes, when I talk about end-cap I mean "button".

This picture is very useful, thanks WIM and martinrjensen. I never took much notice of end-barrel seating because I presume that once I am sure it is seated properly it will not come out... Is there a chance the button could become un-seated, maybe due to the STI ratchet system not following through after the cable?

Changing to teflon cables is an option, I wonder how Teflon handles tangential forces compared to stainless? From now on I will unhook the outers and check the button's position and cable condition every 1000k's.

Considering I spent nearly 30% of my bikes budget on these STI's it is very disapointing to have this happen, and to learn that they are not repairable. I will definitely be converting to SRAM or Campy soon.

If you can't open it, you dont really own it!
 

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I'd have a hard time believing it's an STI defect.

Are you sure you're using derailleur (not brake) housing and that the end is properly finished and with the plastic end cap fully seated?

I'd redo the housing end and try again.
 

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GoingDHfast said:
I never took much notice of end-barrel seating because I presume that once I am sure it is seated properly it will not come out... Is there a chance the button could become un-seated, maybe due to the STI ratchet system not following through after the cable?
The button unseating is something that occured to me as well. With too much cable slack in the full-relaxed shifter position, I could imagine it happening. The cable could then saw across the sharp lower edge of the "U"-slot every time slack is taken out on the initial shift. Just a theory of mine, not proven.

I don't think Teflon coating gives additional strength to the cable. IMO, it's basically a marketing gimmick to make people think 'lubrication' and 'corrosion protection.' The coating wears off quickly at the friction points. So after a few months, it's gone in the very places where you'd want it.

Lower center of page, see box on cable seating: http://techdocs.shimano.com/media/t...001/SI_6K20A_001_En_v1_m56577569830616322.pdf
 

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You're teetering upon opening the big SVsC/S mess

I would call it user install error. Something is not seating properly in the head housing area. And that rebuildable stuff is alot of hype. By the time it takes to wear out that part, the model lineup has changed so much, it is worth it to upgrade. Based upon my experience, I am still have available to me for use Shimano RSX 7 spd STI, Ultegra 9 spd that is first generation and DA 10 spd. None are even close to jumpin' the shark.
 

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I've been in this twenty years and this is a known issue. Burrs or what ever.

We are liking the new 7900 cable set from Shimano, as well as trying out a Campy Ergo Cable in the shifter.

I'll let you know!

"T"
 

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Shimano 10 speed STI levers all put a bend in the cable around 10mm from the end button. That bend is likely to fray and eventually snap the cable after a lot of use. I have recommended new derailleur cables and housing at least once a year for most avid riders for years- it is even more important to do with 10 spd STI levers(pre-7900 and 6700). New cables regularly gives better shifting anyway, so change them more often and all will work better.:)
 

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It was a problem with early Shimano 10 speed shifters (that they knew about). They made a running change to smooth out the spool that wrapped the cable.
 
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