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Putting together new bike and then brake line got frayed (just one piece) going pretty far back and cannot thread it now. Can I cut the one frayed piece or does that ruin the brake line functionality?

Thank you

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    Sometimes you can wrap it back. Otherwise I’d get a new cable, they are like 1€ for the cheaper types. On the front brake the reduced strength might pose a safety risk. – Michael Mar 20 at 13:55
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    Note if you're going to try to rewrap that strand it helps (a) to use electrical tape to tape the cable together every few cm so if the strand gets away from you it doesn't uncoil and (b) to try to slightly untwist the rest of the strands in the section you're working on so the loose strand fits in firmly. It's a lot of work for a cheap part, though, and I'd only do if it's a choice between fixing it and not riding (i.e. it's not possible to get a timely replacement). – DavidW Mar 20 at 15:34
  • Did the strand come loose or did you cut the inner with pliers ? – Criggie Mar 21 at 0:02
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If it's only one strand then you can safely cut it off. The problem is that this leaves a jagged end that will hang when you try to thread it, so some very careful work is required to get the cut end bent tightly back against the remaining cable. Often this is more trouble than it's worth.

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I'm going to disagree with Criggie's answer here.

It looks to me like the cable itself has come unraveled and the outer housing is fine. I would not recommend cutting that brake cable or trying to rewrap the loose thread. Simply throw it away. Failure of that cable would be catastrophic. Brake cables are really cheap. It's not worth the risk to try to save it.

The only way that I would use that cable is if there was enough excess to cut the entire thing an inch or two above the frayed line and still be long enough to attach to the brakes.

You should, however, be able to keep the outer housing. Just pull the brake cable out and insert a brand new one.

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    In my experience, unraveled/broken stands don't cause catastrophic failure. Instead moving the handle becomes slowly harder and harder as the cable unravels into/inside the sheath and gets kinked, giving plenty of warning. But: if one ignores that warning then at least the better sheaths with inner plastic lining can get so scratched that they need to be replaced together with the new cable. – cbeleites unhappy with SX Mar 20 at 22:01
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    Yeah - turns out its for the front brake, which must be as good as possible because its the most effective brake. – Criggie Mar 21 at 0:01
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Probably yes.

If its the outer housing that has come loose, the main risk is cutting the outer too short. Depends on how much slack there is - an outer cable has to have enough slack for the fork/bars to turn without binding, and also enough slack so the calipers can pull without binding (this last bit is more of an issue on rear rim brakes)

You will need to cut the outer housing only - so pull the inner cable completely back first.

Ideally use a cable cutter tool would be used to cleanly cut the outer. A small rotary tool like a dremel works. Pliers or bolt cutters do not work well because they tend to crush the housing. There's an existing Q&A on this at What is the proper way to cut brake cable housing?

You will also need to check if there is a ferrule that needs to be saved.


If you mean the inner cable has lost a strand and that it has come unwound, well that could go either way.

The best fix is to carefully re-lay the loose strand back into its groove. Once its laid flat, drop some superglue on the cut end to restrain the strands for now. You can also solder the end.

If the strand is really messed up and just won't lay flat, it is possible to undo one single strand and cut off, but the cut end never lies flat so it will snag any outer cable.

I have unwound one strand enough that the cut end was in the open air, and then I used solder to stop it coming loose in the future. BUT this was on a rear derailleur cable and I would not recommend this for a brake inner cable.

You need to make a judgement call. Personally, buy a new brake inner cable for a few dollars and do over. You can save that damaged one for the front brake by cutting off the bad section. Aside, this is why I often do the rear brake and rear derailleur before doing the fronts, to let me reuse a shortened cable if needed.


Based on photo, I'd definitely try and "relay" the strand into the fluke. Use finger and thumb to wind it back in place - and secure with superglue as you go.

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  • If this doesn't make sense, please add a couple of photographs showing your unwound housing, and where it goes on this bike. Don't be tempted to go without the brake - this is fixable. – Criggie Mar 20 at 11:47
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    Thank you! This is the front break. I don’t think it is saveable in terms of rearranging, so I will the cutting the one piece and if that doesn’t work replace. Many many thanks!! – Casey Mar 20 at 11:56
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I'm not exactly sure what you are trying to do. So I'll answer all three possibilities:

  • If you plan to shorten the brake cable up to the point where all strands are good, shortening the housing correspondingly: Make sure that you retain enough length and go for it. Note that the brake cable/housing needs to handle any angle of the handle bar that is achievable. If you can still turn your handlebar freely after you've shortened the cable/housing, you are good.

  • If you plan to cut only the one unwound strand mid-cable: Don't do this. The open end of that cut strand will be somewhere within the housing when you ride and operate your brakes, and you will move it under quite significant forces. It is very likely that the open end of this strand will start unwinding again, and this time right in the middle of the housing. Once enough of the strand is unwound, it will stop the cable from gliding through the housing, leading to a failing brake.

  • If you plan to continue unwinding that one strand, up to the very end of the cable, and then removing it entirely from the cable by cutting it right at the end of the cable: I believe this should be safe. There are enough strands in your brake cable to keep it safe. And because all remaining strands are good and well-wound from one end to the other, you won't get problems with unwinding mid-cable. Nevertheless, control of your brake may suffer slightly because there is now more wiggle room for the cable within the housing. So, I would still prefer installing a fresh cable.

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