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I broke my rear derailleur cable right at the shifter. These are Shimano Ultegra STI shifters from a 2008 Giant TCR C2 (I think they're Shimano 6600). I'm assuming that the cable head and frayed wire are stuck inside the shifter, but I can't see how to access them.

I have seen various online videos, such as How To Replace Shift Cables In STI Shifters/Brifters (Combined Brake/Shifters). However, I can see right through the shifter and don't see the end bit. I first shift into the easiest (biggest) ring. The shifter then only shifts 4 clicks into smaller rings, but I would expect 9 clicks (since this is a 10-speed shifter).

Does anyone have any ideas, based off the following images? I see a few screws that I could try to remove, but am wary about disassembling the shifter. Broken Shimano STI 6600 shifter cable

  • With this style often there is a small hole about halfway around the cylinder where the cable was fed in. Usually, for this type, the cable has a fairly tiny knob on the end that fits into the hole. Usually, in this situation, you can figure out how to extract the broken cable end and clear the hole for a new cable. – Daniel R Hicks Apr 28 at 20:36
  • The reason that it's not shifting is that in order to shift down the STI needs the pull of the derailleur, so try to get hold of the cable and pull while shifting down the rings. Or try to push from the outside of the STI on the lower right picture. – hannes101 Apr 28 at 21:44
  • @hannes101 - thanks for the info about needing the pull of the derailleur. Unfortunately I don't see any piece of the cable That I can hold on to. I'm not sure what you mean by the alternative, "push from the outside of the STI" – maurera Apr 28 at 22:17
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    Figure out the cost of a replacement shifter before you start disassembling - it may be cheap enough to buy a used one. – Criggie Apr 29 at 1:17
  • Unscrew the screw at the side and open the plastic cover, it should give you better access. Don’t worry, it’s easy to reassemble. – Michael Apr 29 at 11:20
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This is fixable, but may be any level of difficulty. It depends on how the strands of cable have moved and whether the cable head is caught.

Given its your rear shifter, its on the Right side of the bars, and there's a port for the cable outer to seat in on the left side. When you shift down (to an easier gear/bigger rear cog), the whole brake lever rotates, and holding the lever there will show the access hole on the right/outboard side.

Moving only the upshift lever (the smaller one behind the brake lever) won't show the hole.

Your next task is to hold the lever across, and try to make the cable head fall out the right hand side access hole, by hook or by crook. The head may not fit through the hole sideways, it may have to come through flat-face first.

Some ideas to help manipulate it...

  • More Light! You need to see, so use at least two bright lights. I have a pair of 200W desk lamps over my bench, which helps avoid shadows.
  • A thin and stiff wire in the left side port to push the head from underneath
  • A tiny magnet - depends if the head is steel, or if the cable has enough steel to react to a magnet.
  • A tiny sharp pick to help manipulate whatever you can see through the holes.
  • Slack off the clamping bolt to rotate the lever hood, get gravity on your side
  • Undo the stem to let the bars rotate, again for gravity
  • Untape the bars, get the whole shifter body off the bars for easier access.

You might try flushing the mech with light degreaser, in case theres a blop of grease holding it down. However this might have the opposite effect


If that doesn't work, you're probably up for disassembly. Since Shimano shifters are not intended to be serviceable, this can ruin the shifter if done wrong. There's no shame taking the part to a good LBS bike shop for repair.

Have a read of https://bicycles.stackexchange.com/a/35662/19705 where I did a similar recovery on my 7 speed RSX shifter.

There was a useful video at


Gear cables should be replaced whenever shifting starts feeling "a bit weird" or every 10,000 km of road riding, or 5000 km of off-road. It would have been impossible to see this cable fraying in place during inspection though. You should probably replace the left-side cable too, and check the brake cables as well.

Sadly 6600 and 6700 and 5700 shifters were known for munching through cables quite quickly. If it were my bike, I'd replace the shift cables annually whether they need it or not. Cables are cheap.

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    Newer versions still munch cables, but Shimano have put a removable cover on that makes this removing the head, easier – Swifty Apr 29 at 11:25
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    @Criggie - thanks for this fantastic detailed response. Based on your description, I may just take this to a bike shop. I'm just trying to understand your second paragraph "When you shift up, the whole brake lever rotates". "Shift up" means shift to a harder gear / smaller ring on the casette, right? On the right shifter I do this by just pressing the small black lever. Pressing the whole brake lever downshifts (goes to an easier gear). Could you just clarify this point? Thanks again! – maurera Apr 29 at 18:34
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    @maurera yep good point and you're right - I wrote that late and was thinking of the cassette/block - pushing the chain upward to a bigger gear is shifting down. Corrected now. – Criggie Apr 29 at 20:44
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    I ended up taking it to a bike shop. They spent over 30 minutes working on it and had all sorts of thin poking / hook tools. I don't think I would have managed – maurera May 7 at 22:17
  • @maurera Awesome news - thank you for the followup. There is absolutely no shame in using your bike shop for jobs. – Criggie May 7 at 22:38

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