Lever suddenly went slack on new BB7 rear brake...

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Manc33
Posts: 1833
Joined: 25 Apr 2015, 9:37pm

Lever suddenly went slack on new BB7 rear brake...

Post by Manc33 »

I fitted a new rear BB7 caliper and pads. The pads were already in the caliper and seated properly. Everything was setup and working. The next day I pulled the rear brake, heard a click and the lever suddenly went really slack, with the bite on the brakes about 1cm from the handlebar, when I set it up initially so the bite was quite soon into the lever pull.

It's a full run of cable housing so there's only two brake ferrules (one at each end of the housing) and they were both seated fully, with the housing fully seated into them.

It's worrying to think this could have happened out riding, albeit this was on a rear brake. I've had this happen in the past setting up BB7 brakes and still don't know what causes it! I pulled about another 15mm to 20mm of cable through the caliper and tightened it again, that has presumably fixed it.

What causes this? Is it the brake lever end of the cable snapping into place? I don't think it was that because it doesn't explain the cable going slack by 15mm.

What's 15mm? A ferrule...

Maybe what happened is, the brakes were slack when setting up and a ferrule ended up resting on the lip of the rear caliper ferrule hole - you wouldn't see this, because it's got a rubber boot on it. The same effect would happen if the housing came out of the ferrule and the ferrule stayed in the caliper, then it would be the housing resting on the lip, but the exact same end result would happen.

Pulling the brake several times re-seated it. This is the only thing I can think happened but I wondered if it's happened to anyone else or is a common "schoolboy error" :lol:
When two cyclists get married, they should throw anodized cable crimps instead of confetti.
Stradageek
Posts: 1000
Joined: 17 Jan 2011, 1:07pm

Re: Lever suddenly went slack on new BB7 rear brake...

Post by Stradageek »

Pretty common error, rest assured that you are not alone :)
Eyebrox
Posts: 437
Joined: 5 Aug 2015, 8:56pm
Location: Ayrshire

Re: Lever suddenly went slack on new BB7 rear brake...

Post by Eyebrox »

Happens all the time with ferrules. They often don't fully fit onto the cable end until the lever is pulled. Out on the road provides even more purchase and so more slackness in the operation. A small amount of WD40 in the ferrule generally helps during set-up.
Manc33
Posts: 1833
Joined: 25 Apr 2015, 9:37pm

Re: Lever suddenly went slack on new BB7 rear brake...

Post by Manc33 »

EDIT: Made a new thread since this reply wasn't on topic and it's a handy fix for something.
viewtopic.php?f=5&t=147981
When two cyclists get married, they should throw anodized cable crimps instead of confetti.
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andrew_s
Posts: 5428
Joined: 7 Jan 2007, 9:29pm
Location: Gloucestershire

Re: Lever suddenly went slack on new BB7 rear brake...

Post by andrew_s »

Road or MTB levers?

If road, it's quite easy to pull the ferrule out of the lever body whilst taping the bars.
Manc33
Posts: 1833
Joined: 25 Apr 2015, 9:37pm

Re: Lever suddenly went slack on new BB7 rear brake...

Post by Manc33 »

andrew_s wrote: 24 Sep 2021, 6:06am Road or MTB levers?

If road, it's quite easy to pull the ferrule out of the lever body whilst taping the bars.
MTB. It must have happened mid-faff.
When two cyclists get married, they should throw anodized cable crimps instead of confetti.
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