Safety of splicing brake housing with electrical tape

This question has come up at a community bike shop where I volunteer:

When a long piece of brake housing is not available, is it safe to use
two smaller pieces end-to-end, with a wrapping of electrical tape around
the joint?

I have my own opinion on the issue, but I was hoping to get a more
authoritative reaction -- for instance, from engineers or bike shop
owners. Better still if you can point to some kind of authoritative
documentation on this question.

Gary Young wrote:
This question has come up at a community bike shop where I volunteer:

When a long piece of brake housing is not available, is it safe to use
two smaller pieces end-to-end, with a wrapping of electrical tape around
the joint?

I have my own opinion on the issue, but I was hoping to get a more
authoritative reaction -- for instance, from engineers or bike shop
owners. Better still if you can point to some kind of authoritative
documentation on this question.

There's a cute little Shimano ferrule made just for that
(goes at the end of the tape so you can service damaged
cables without re-wrapping). Works well but costs more than
a complete double-ended wire with teflon lined casing, which
is probably what you seek. Those are dirt cheap.


Electrical tape? Really?
--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

JEEEEEZ yawl get meals outta a dumpster or what ?

On Thu, 22 Mar 2012 21:59:31 -0400, Gary Young
wrote:

This question has come up at a community bike shop where I volunteer:

When a long piece of brake housing is not available, is it safe to use
two smaller pieces end-to-end, with a wrapping of electrical tape around
the joint?

I have my own opinion on the issue, but I was hoping to get a more
authoritative reaction -- for instance, from engineers or bike shop
owners. Better still if you can point to some kind of authoritative
documentation on this question.

Well the "electrical tape" is a bit tatty but essentially there is no
difference then butting the cable into a cable stop somewhere.

--
Cheers,

John B.

and he said "GOD MAKE IT A DREAM.."

electrical tape may not prevent a debutting with one cable end passing over the other....like the stuff was made to stick to itself in a pliable and yielding, conforming way

there just no telling what it'll do !!

On Friday, March 23, 2012 8:16:23 AM UTC-6, datakoll wrote:
and he said "GOD MAKE IT A DREAM.."

electrical tape may not prevent a debutting with one cable end passing over the other....like the stuff was made to stick to itself in a pliable and yielding, conforming way

there just no telling what it'll do !!

which is on second thought duhduhduhduh an answer. Place buttees next to tubing then wrap buttees to tubing and tape over tape, pulling tightly as wound over tube, fastening housing to tube and wollaaah you got it 1!!!

eeyeyehahahhahahahh....

so what's for breakfast ? any nused pizza ?

On Mar 22, 9:59*pm, Gary Young wrote:
This question has come up at a community bike shop where I volunteer:

When a long piece of brake housing is not available, is it safe to use
two smaller pieces end-to-end, with a wrapping of electrical tape around
the joint?

I have my own opinion on the issue, but I was hoping to get a more
authoritative reaction -- for instance, from engineers or bike shop
owners. Better still if you can point to some kind of authoritative
documentation on this question.

I doubt you'll ever find an authoritative document on that. You won't
find one on using electrical tape to repair your car's brake lines,
either.

Although bike brakes are usually applied gently, they occasionally get
squeezed hard, even if just for a stationary test. So a bike's brake
cable needs to support a tension of perhaps 200 pounds (50 pounds grip
strength, 4:1 force multiplication). The housing needs to support
that same force in compression. Any slight misalignment of the two
ends will cause it to buckle at the splice, or at least shift out of
alignment to the point that the housing will be trying to saw the
cable in two.

If I were forced to try such a thing, I'd at least scrounge a close-
fitting metal tube to reinforce the joint. But it's so much simpler
to spend a buck or two on a new piece of housing, and just do the job
right.

- Frank Krygowski

Gary Young wrote:

This question has come up at a community bike shop where I volunteer:

When a long piece of brake housing is not available, is it safe to use
two smaller pieces end-to-end, with a wrapping of electrical tape around
the joint?

I have my own opinion on the issue, but I was hoping to get a more
authoritative reaction -- for instance, from engineers or bike shop
owners. Better still if you can point to some kind of authoritative
documentation on this question.

To directly address your question: As long as the housing ends that
are butted together are treated such that the cut surfaces sit flat
against each other and the cable remains taut at all times, there
would be no significant safety implications of using brake housing
that way. However, if the brake cable goes slack for whatever reason
(e.g. very loose adjustment, or brakes that fail to fully return due
to friction), movement and vibration could overwork and eventually
break the cable at the location of the housing joint.

My shop gets basic brake housing, with various colored jackets and
plastic liner, for $0.15 per foot. Other cable housings can be *much*
more expensive, but generic brake housing is cheap. If your community
bike shop has a wholesale account somewhere (and it should, for basic
consumables at least), then someone should pony up the few bucks for a
roll of the stuff.

I'll reuse housing if the jacket is in good shape, there are no kinks,
and the damaged ends are trimmed away. But if reused housing isn't
long enough to do the job, you should just use a piece that is.

Chalo

Gary Young wrote:

This question has come up at a community bike shop where I volunteer:

When a long piece of brake housing is not available, is it safe to use
two smaller pieces end-to-end, with a wrapping of electrical tape around
the joint?

the only reason to do this is to save a bar tape wrap. You can get
double sided cable caps (Shimano used to include them with some old
Ultegra stuff) or you can hide the joint with an inline cable adjuster.

Tape is just silly

--
/Marten

info(apestaartje)m-gineering(punt)nl

On Mar 22, 7:59*pm, Gary Young wrote:
This question has come up at a community bike shop where I volunteer:

When a long piece of brake housing is not available, is it safe to use
two smaller pieces end-to-end, with a wrapping of electrical tape around
the joint?

I have my own opinion on the issue, but I was hoping to get a more
authoritative reaction -- for instance, from engineers or bike shop
owners. Better still if you can point to some kind of authoritative
documentation on this question.

Provided that the respective ends of the cable housing are squared and
smooth (think dremel tool, file or grinding wheel) to butt against one
another solidly, this should work with little issue.
Look at the right figure he
http://sheldonbrown.com/images/cable-cuts.gif

from
http://sheldonbrown.com/cables.html

However it would probably be desirable to avoid having such a butted
joint on any tightly curved section of cable.
The cable itself helps insure that housing alignment is maintained,
especially if it is not dramatically undersized with respect to the
inner diameter of the housing.

Note: This is not remotely akin to repairing a car's hydraulic brake
lines with electrical tape. That would be utterly foolish.

DR