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Catastrofic brake cable failure

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Catastrofic brake cable failure

Old 06-28-08, 05:29 AM
  #1  
The Van
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Catastrofic brake cable failure

So I wasn't really sure where to post this since I was commuting from work riding my single speed when this happened..... so it spans a few different forums.

Was riding along at maybe 18mph on a busy downtown street when a car coming the opposite way tried to make a right hand turn (UK roads) across traffic into a side street. I pulled hard on both brakes and hear a "pop-ping" and my rear brake goes dead. Pulled on the front brake... "pop-ping", now no brakes at all. Lucky the car saw me at the last minute and I was able to swerve around it. Pulled a Fred Flintstone stop at the next traffice light and looked over the brakes. At first I figured I had stripped out both of the crimp connections at the brake calliper, but both of them were fine. Looked at the brake levers and found that both of the brake wires had catastrofically failed inside the levers.

Got home and took a closer look. The stopper at the end of the brake line didn't strip, but each wire had actually completely failed. Only thing I can figure is that I hadn't adjusted the brakes in a long time, so to get full stopping power you had to pull them down pretty far. This may have cause the wire to rub against an edge inside the lever and eventually fatigue the wires.

Still kinda crazy that both wires should fail at the same time. Maybe someone at my work had it out for me and cut the brake lines

Guess I will be checking my brake wires on a more regular basis in the future....



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Old 06-28-08, 06:28 AM
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Brake cable failure is relatively rare if they are replaced with any reasonable frequency and having BOTH fail has got to be VERY unusual. I'm happy you came through it ok.

What make were the cables? Shimano and Campy cables are particularly good and worth the extra cost.
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Old 06-28-08, 08:05 AM
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Not sure about the make of cables, they came stock on my IRO Jamie Roy. The bike is only about two years old, but I use the bike every day for city commuting so am on the brakes a lot.
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Old 06-28-08, 09:12 AM
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This a good example of not inspecting and adjusting your equipment. Sure it is only a bike but you are sharing
the roads with cars and little things like this can cause you a crash. You could have used the old school foot
on the back tire trick to stop. The best time is after you rest after a ride and using the sun or a bright light
(I like those led hat lights) clean the frame with a rag and inspect your welds, wear points, chain for kinks
or loose plates, and grab your brake levers and really squeeze the piss out of them like you were in a panic
stop situation and that will hopefully point out any frayed spot or even a too loose cable pinch bolt which will
cause a no brake situation.
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Old 06-28-08, 12:27 PM
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If I remember correctly, Shimano brake cables a few years back had a recall for the exact same problem. I could be wrong though.

Here, found it:
http://www.nashbar.com/recall.cfm
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Old 06-28-08, 03:14 PM
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Originally Posted by HillRider View Post
.. and having BOTH fail has got to be VERY unusual. I'm happy you came through it ok. ...
+1. Do you have any enemies or ex-spouses ?

I've been riding and working on my bike for 20+ years. I never work on both brakes at the same time. I'll do one, get a couple of rides in then do the other - trying to minimize the chance of both failing due to workmanship issues.
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Old 06-28-08, 03:23 PM
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Did they fail right at the edges of the swaged on end?

This is why MTB brakes use the barrel end in a sort of fork recess. When greased or equipped with a plastic slip cover the barrel end can turn in the lever's recess and help avoid a lot of the flexing that would otherwise occur right where it passes from the swaged on end.

But these style of bar end brakes don't do it that way. Instead they use the road bike ball end which sits solidly in the opening. And it doesn't take much to realize that without the ability to pivot that the cable is going to flex right at that end on a regular basis. Obviously this works for a while but it would be worth doing new cables on a regular basis. Like once a year.

Any idea how long you had used the same cables?
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Old 06-28-08, 05:19 PM
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Originally Posted by z415 View Post
If I remember correctly, Shimano brake cables a few years back had a recall for the exact same problem. I could be wrong though.

Here, found it:
http://www.nashbar.com/recall.cfm
That the recall was for failure of the cable end fitting. That's not what happened here.
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Old 06-28-08, 05:28 PM
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I'm not so sure this isn't a cable end issue as well. Remember that when the levers are fully back the end of the swaged part is pretty darn close to where the end is showing in the housing. And without the end to hold the cable the broken end will tend to spring back like this one is.

Did you manage to keep one or both of the ends? That'll tell you where the wear is located for sure.

I'm also basing this on the fact that so many of the strands are all the same length in the picture. If the failure was due to a progressive wearing of the cable dragging over the metal of the lever you'd see a major wear groove around the opening where the strands are peeking out in the first picture. Also the varioius strands would have brokent at different places and would show signs of wear in the third picture. Instead all I see is a lot of similar length cleanly broken strands that obviously all flexed and fatigued at the same point.

So I still say it's a flex at the swaged ball end deal..... And in the words of the immortal Doug McKenzie "That's my story and I'm sticking to it, eh..."
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Old 06-28-08, 05:37 PM
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Over time the single strands of wire gradually break one at a time right next to the lug that the brake levers hold. This gradually makes them weaker and sooner or later that lug will pop right off, even without an unusually hard stop. I don't think most of my brake cables last 2 years without that happening. Since you were in a situation where you gave each an unusually hard pull, I think it is reasonable that it could be just normal wear and tear plus that unusual situation. I think that has a 99% better chance of explaining the situation than sabotage. There's probably no need to go out and buy a gun.
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Old 06-28-08, 05:47 PM
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That's why, about once a month, I do a full panic stop on my side street. IF it's going to fail, I want it to fail then, not when a car is in the immediate vicinity.
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Old 06-28-08, 06:00 PM
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I look at the photos of the cable break and really wonder if those cables have been cut deliberately. Only one strand isn't broken at the same level as the other ones, yet a normal failure would show much more ragged strands.

Looks intriguing to say the least.
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Old 06-28-08, 07:09 PM
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Originally Posted by BCRider View Post
...But these style of bar end brakes don't do it that way. Instead they use the road bike ball end which sits solidly in the opening. And it doesn't take much to realize that without the ability to pivot that the cable is going to flex right at that end on a regular basis......

Any idea how long you had used the same cables?
I agree, I think this is what happened. I've been riding this bike for about 2 years (same cables), but with a lot of heavy breaking due to riding mostly fast downtown rush hour traffic.
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Old 06-28-08, 07:12 PM
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Originally Posted by Michel Gagnon View Post
I look at the photos of the cable break and really wonder if those cables have been cut deliberately. Only one strand isn't broken at the same level as the other ones, yet a normal failure would show much more ragged strands.

Looks intriguing to say the least.

I wish my life was exciting enough that some one would actually want to kill me......
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Old 06-28-08, 07:21 PM
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Originally Posted by Michel Gagnon View Post
I look at the photos of the cable break and really wonder if those cables have been cut deliberately. Only one strand isn't broken at the same level as the other ones, yet a normal failure would show much more ragged strands.

Looks intriguing to say the least.
Yes, me too. The recall was specifically for North America. They look cut to me. Who hates you that much?
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Old 06-28-08, 10:33 PM
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Originally Posted by The Van View Post
I wish my life was exciting enough that some one would actually want to kill me......
ROFL
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Old 06-29-08, 07:26 AM
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Originally Posted by BCRider View Post
<snip>
I'm also basing this on the fact that so many of the strands are all the same length in the picture. If the failure was due to a progressive wearing of the cable dragging over the metal of the lever you'd see a major wear groove around the opening where the strands are peeking out in the first picture. Also the various strands would have broken at different places and would show signs of wear in the third picture. Instead all I see is a lot of similar length cleanly broken strands that obviously all flexed and fatigued at the same point.
+1
It looks like all the cable strands broke at the bottom of the cable end. Cables are meant to be flexed that way- if you look inside a conventional road brake lever, you'll see that the end is held by a pivoting dingus that keeps the cable from flexing.

IMO, those brake levers are improperly designed. I'd get rid of them.
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Old 06-29-08, 04:57 PM
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Those levers need to have a roller for the cable so it doesn't take a sharp bend where it exits. As the lever gets squeezed more and more, the cable gets bent more and more at the hole. Brake-cables don't take kindly to being bent 90-degrees.
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Old 06-29-08, 05:50 PM
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Originally Posted by Jeff Wills View Post
+1
It looks like all the cable strands broke at the bottom of the cable end. Cables are meant to be flexed that way- if you look inside a conventional road brake lever, you'll see that the end is held by a pivoting dingus that keeps the cable from flexing.

IMO, those brake levers are improperly designed. I'd get rid of them.


Originally Posted by DannoXYZ View Post
Those levers need to have a roller for the cable so it doesn't take a sharp bend where it exits.......
Exactly. Just as found inside of drop bars. Or the lever should have a mountain bike style of cable anchor to take the pivoting barrel shaped ends like a mountain bike lever does.

It looks to me like these are cyclocross top bar levers that have been adapted to use on the ends of the bullhorns. I know I've seen this suggested here and elsewhere before but now I'm not sure it's all that good an idea given what has happened here. As mentioned it's not a good way to support the cable and ball end.

Gotta go check the Cane Creek bullhorn levers that I just got recently......
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Old 06-29-08, 10:52 PM
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Actually, they are reverse brake levers, designed for this application. I don't think the angle can get that extreme either. I still think the cables were cut.
http://www.jensonusa.com/store/produ...ke+Levers.aspx
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Old 06-30-08, 02:26 AM
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how often should one replace cables for brake? even if they arent really to worn..just on a good measure basis. 1.99 cable is worth life imo.
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Old 06-30-08, 07:26 AM
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Originally Posted by HillRider View Post
That the recall was for failure of the cable end fitting. That's not what happened here.
The end failing is what I see as happening here. Looks like the cable pulled out of the end entirely. With the exception of the one stray cable, all the other ends are very even. I suspect that the one stray cable may have been the last soldier holding on before everything went south.

I'd suspect the brake lever. The movement of that lever is very different from the type of lever you find on just about any other brake. I'd suspect that you can develop more leverage on the cable with it than with a road or mountain bike lever.
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Old 12-01-10, 07:44 PM
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Thanks for leaving this post up - I just switched over to bar end brakes on bullhorn handle bars and will keep a close eye out for this kind of problem - Has there been a recurrence over the past two years???
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Old 12-01-10, 10:11 PM
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based on the pics i would say these levers are the real problem, i just put together a bike with this lever set up and they had pviots for the cables in order to prevent the bend that caused this break. As for the one strand that's longer, i wouldn't be surprised if that strand is split somwhere else aswell and just slid up higher than the rest for the photo.
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Old 12-01-10, 10:22 PM
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Originally Posted by zandoval View Post
Thanks for leaving this post up - I just switched over to bar end brakes on bullhorn handle bars and will keep a close eye out for this kind of problem - Has there been a recurrence over the past two years???
judging by the fact that we haven't heard of anything similar, I'd say you're perfectly safe in the "all those not here, raise your hands" sort of way.
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