Re: [CR] Brakes and flex

Example: Framebuilding:Technology
Date: Wed, 05 Jan 2011 08:17:26 -0800
From: "verktyg" <>
References: <> <> <>
Subject: Re: [CR] Brakes and flex

To all,

Having installed many hundreds of brake cables, I have to say it used to be SOP to set them up fairly tight with no slack and then apply as much pressure to the brake lever as possible (by hand).

If I were lucky then I didn't have to readjust the cable length again. If not then I had to shorten the cable. If that wasn't stretching then what was it?

A small amount of the cable "lengthening" was the result of the ends seating into the levers.

This usually wasn't a problem with Campy cables but with most other brand cables it was. Most common with MAFAC, Weinmann and cheaper replacement cables.

The procedure was also somewhat of a safety test as I had a number of cable ends pop off back when I checked them that way back in the day.

The stretching only occurred on the first or second application of the test.

It's not as much of a problem these days as I only buy premium quality stainless cables and they seem to manufactured better and don't have much initial stretch.

I agree with another poster, the rolled Dia-Compe cables are very nice but I haven't seen them anywhere local (haven't looked too hard either).

Chas. Colerich Oakland, CA USA

Ken Freeman wrote:
> Are we speaking about elastic stressing of the cable or inelastic? Elastic
> stretching would cause a "spongy" feeling, where inelastic would feel spongy
> until the length began to change permanently. After this point one would
> have to adjust the cable slack.
> If we're talking about housing compression or taking up the cable play
> inherent in a loosely-fitting housing, inelastic stress cycling is pretty
> unlikely, in my thought experiment.
> On Wed, Jan 5, 2011 at 3:24 AM, M-gineering <> wrote:
>> On 1/5/2011 6:58 AM, Jon Spangler wrote:
>>> John Betamus, thank you for making me not feel alone in the world of
>>> bicycle
>>> mechanics with regard to cables not stretching. I'm always shagrined (not
>>> crestfallen) when I hear someone who says their mechanic said this or that
>>> about cable stretch. I think of it this way: If you try to hang a car from
>>> a
>>> bridge with a bicycle cable, it will stretch...and then break. But the
>>> forces we put on these cables are not stretching them.
>> Sorry, but you are stressing and stretching the cables with braking forces,
>> only not very much otherwise they wouldn't last at all.
>> It is steel, so if you apply force to it it deforms, period
>> But in the total of armflex, squirm and compression of the blocks and cable
>> it is not the most significant. Still stretching the rear brake cable by a
>> millimeter shouldn't be beyond most of us, provided the other bits in the
>> system are stiff enough to allow it.
>> --
>> mvg
>> Marten Gerritsen
>> Kiel Windeweer
>> Netherlands