Check your brake cables

[UR2KLOS]

I just noticed something really scary. I was trying to adjust my rear mechanical disc brake and discovered that almost all of the cable strands were broken except for 2 strands. It wasn't even noticeable until I pushed on the cable.

I would consider the Shimano M465 rear brake to have a design flaw because every time the brake is actuated the cable flexes right where the washer and screw are pushing on the cable. There is no strain relief or gradual transition to reduce the chance of cable fatigue right at that spot. When I adjusted the brake a few months ago the cable looked fine.

I'm not sure if other mechanical disc brakes have a similar design flaw. It is probably not a bad idea to check your cables every so often.

I'm glad I slept in instead of going on the furnace ride Monday.

[CeeDubb]

My brake lines have some yucky liquid stuff inside 'em. I'll check my road bike.

[DownhillWebKook]

You should try no brakes for a few days. I bet you'll get some sick drifting.

[Neccros]

I run Avids on one of my bikes and I love them....

[CeeDubb]

Originally Posted by DownhillWebKook

You should try no brakes for a few days. I bet you'll get some sick drifting.

I think I'm in a good place with having brakes on my bikes.

I remember l lost hydraulic pressure on my rear brake while going down Marshall Canyon. It was very disturbing... I never realized how much I used the rear to help settle the bike into corners.

I know there's more bias towards front brake use, but the rear is just as important for fine-tuning your descents.

So be it brake cables or hydraulic lines...keep your bikes in working order!!

[UR2KLOS]

okay, okay, here is a photo. The cable looked perfectly normal before I pushed the broken strands out of the way.

[CeeDubb]

Originally Posted by UR2KLOS

okay, okay, here is a photo. The cable looked perfectly normal before I pushed the broken strands out of the way.

You've got some cleaning to do!!

A clean bike is a happy bike. You get the opportunity to inspect your bike on every wash and you can catch mechanical problems before they become an unsafe issue.

Glad you caught that before a mishap occurred.

[UR2KLOS]

Actually the cable looked fine before I pushed the strands away. A visual inspection alone would not have found this. I got lucky.

[CeeDubb]

Originally Posted by UR2KLOS

Actually the cable looked fine before I pushed the strands away. A visual inspection alone would not have found this. I got lucky.

There should be a crimped cable cap at the end of that cable to prevent fraying.

[UR2KLOS]

There is a crimped cap at the very end of the cable that is doing its job. The cap has no effect on the part of the cable that has the broken strands.

[2wheel_lee]

Originally Posted by UR2KLOS

I'm not sure if other mechanical disc brakes have a similar design flaw. It is probably not a bad idea to check your cables every so often.

Yes, all mechanical brakes have the same design flaw (technically, most all derailleurs do, too). If they'd only use hydraulic principles, they wouldn't have cable failures.

The warning is good for derailleur cables, too.

[RustyIron]

Originally Posted by UR2KLOS

There is a crimped cap at the very end of the cable that is doing its job. The cap has no effect on the part of the cable that has the broken strands.

Maybe you could install some of those crimped caps in the middle of the cable to prevent fraying

Last week I had a similar problem. It was near the beginning of a ride, and I couldn't shift to the biggest chainring. WTF? Dismount, take a look, and the cable was holding on by two strands.

I decided to continue the ride on the small and middle rings, shifting as little as necessary, expecting the cable to break at any time.

The dumb part is that there had been a broken strand for a couple months, but I figured there would be more warning before the rest of the strands let go.

The lesson was learned. I'll have spare cables in the garage to replace those that show any signs of wear.

Rob

[UR2KLOS]

UPDATE: Just got my bike back with its new brake cable. It turns out the problem was not caused by a design flaw, it was caused by user error. When the rear brake lever would get too close to the handlebars I would shorten the cable instead of extending the pads. The brakes have a nice gradual u-shape curved channel that the cable is supposed to sit in so that the cable doesn't have to make any sharp bends. By shortening the cable I kept it from sitting in the channel properly and it was flexed at the screw every time I used the brakes. This greatly reduced the cable life.

[CeeDubb]

Sweet! The bike is back in order so let the riding recommence!!

Again, glad you caught it in time!

[osmarandsara]

UR2KLOS.....that's funny......I had the exact same situation happening to me with my rear brake cable on my Avid rear disk brakes.......

I always work on my own bike so the first time it happened I attributed it to an old cable so I replaced it, less than a month later my new cable was already frayed and down to two strands....I was on a ride and just happened to glance down and noticed this one was already frayed as well......so now i was getting pissed off and i started to think my brakes were just bad or something......too make a long story short my cable length was actually TOO LONG which caused the cable to kink...I also noticed my brake housing had a sharp edge from wear and tear where the cable exits and that was probably also contributing to the fraying.....so i adjusted the length, sanded down the sharp edge of the cable housing, and greased the cable up really well before re-installing it....this was two months ago and my cable has not frayed again......

however i now always look at my cables before each and every ride........

[mottmcfly]

Originally Posted by CeeDubb

My brake lines have some yucky liquid stuff inside 'em. I'll check my road bike.

I just spit my beer all over the screen.