Brake pad question

"daveornee" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

It is nearly impossible to guess from here, but I have had
a cable housing end come out of the frame "braze-on" and
re-seat itself on the edge of the braze-on, thus pulling
the cable tighter. This happened on our tandem, which has
lots of rear cable and a few extra frame fittings to
check. I have also come up on other riders who were
experiencing similar brake rub issues (wouldn't have
caught them without their handicap) and seen the housing
end problem... and even one time when they put the
slightly wider rimmed wheel on an alternate bicycle....
the regular rim was 19 mm outside width, but the
substitute was 20 mm wide.

Thanks for the suggestion, I hadn't checked this. I'll take
a look in the morning.
--
Mark South: World Citizen, Net Denizen

" S o r n i" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Mark South said:

OK, can we change the terms of the question now? Can we
assume, just for one moment, that it wasn't some twit
thing that I did, could there be anything else that woud
produce this effect? Has anyone else ever seen or heard
of this?

One-line shots are more than acceptable, but best when
they are funny.

I think a bike fairy injected the pads with some fat
surreptitiously sucked from your left butt cheek.

Line allowance exceeded!

Quoted message said:

Bill "look to the turkey baster" S.

C'mere, I'll give you a close look at my turkey
baster. :-) :-)
--
"...and his pants appeared to have exploded," police said.

"jdc" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Did you take the pads off (out of the cartridge) and
examine them? perhaps they have come apart or split.

Worth double checking, but the pads are almost new and
braking function is good.
--
Mark South: World Citizen, Net Denizen

"Jeff Wills" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

"Mark South" <[email hidden]> wrote in message

news:<[email hidden]>...

Quoted message said:

Quoted message said:

The brakes were binding, both sides clamped down on the
(true) rim.

Quoted message said:

Check to see if your dual-pivot brakes need a bit of
lube on the pivots.

They worked fine after a bit of cable was fed through
the binder bolt.

Quoted message said:

The rubber wouldn't expand that much before melting...

I have started wondering if the cables suddenly bedded
in in some mysterious

way

Quoted message said:

Quoted message said:

due to hard braking, not that I had to do a lot of that
on a gentle ride in

the

Quoted message said:

Quoted message said:

country.

This is a possible explanation. Somehow the cable housing
slipped out of the adjuster and then caught in the
compressed position. This is *extremely* unlikely though.

Well, I know they didn't come out of the adjuster barrel,
which is pretty deep anyway, because I checked that that
hadn't backed up and I would have noticed.

Quoted message said:

Was the bike left parked or unattended for some period?
Some vandal may have come along and used the cable
adjuster to clamp the brakes shut. Since the brakes are in
otherwise perfect working order, I'd suspect this first.

No, the brakes were fine, I rode 20km and they were binding.
The change happened with me on the bike and probably while I
was moving.
--
"I would recommend Iowa or North Dakota for your dip
into reality."
- Ed Dolan in alt.rec.bicycles.recumbent

"Mark South" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

No, the brakes were fine, I rode 20km and they were
binding. The change happened with me on the bike and
probably while I was moving.

OK... unlikely explanation #3: how old are the rims? Could
they be worn to the point where they are bulging outward and
meeting the brake pads? This would require that the rims be
quite worn *and* that they bulge evenly around their
circumference. Also, the adjustment would have to be very
close to begin with.

What kind of rim is it? Are the rim walls parallel or do
they taper somewhat, like this: \__/ ?? I'm thinking that
the center bolt of the caliper could have bent upwards
somehow, binding the brake pads against the rim.

Could one or both of the brake pads have come slightly
loose, allowing them to rotate in the caliper? I've had this
happen- and the pads remain pretty tight afterwards.

Jeff (grasping at straws now)

ZeeExSixAre said:

Mark South said:

Today I exeperienced something new to me.

About 20 km into my Sunday morning ride, I was coming up a
gentle hill into a tiny village and thinking "Hell, I must
be getting weaker every day, why is this incline so hard?"

So, I stopped for a breather and hopped of the bike. When
I was about to get on I noticed that the bike didn't roll
easily. Lifting the front wheel and spinning it showed the
front brake was binding hard, which explained the
difficulty up the gentle hill.

Now the question: how did this happen? Before you answer,
some facts:

A. The rim was and is true to within better than 1mm.
B. The wheel spun freely at the start of the ride (I
always check).
C. The brake adjuster had not moved - it was locked onto
the locknut.
D. I adjusted these brakes 6 weeks ago and they have been
perfect since then, until today.
E. Ambient conditions were blue sky, sun, steady cool
breeze, temps about 25 Celsius with wind cooling,
hotter out of the wind.
F. I hadn't done any heavy braking on the ride so far.
G. These are dual pivots on a road bike, with plain black
stock Shimano pads. H. The pads were running just
clear of the rim all round.

So, could the pads have absorbed enough sun to heat and
expand and bind on the rim?

Has anyone else ever seen this happen?

Or is there another explanation?

Although it's probably not the problem here, many often
don't put the wheel all the way into the dropouts after
taking the wheels off. Check to see if it's askew,
especially if the brakes rub on one side. Check to see if
your dual-pivot brakes need a bit of lube on the pivots.

The rubber wouldn't expand that much before melting...

A brake shoe adjusted low will wear to a ridge that can
catch below the rim. Trim it away with a blade and raise the
shoe if that's the problem

--
Andrew Muzi www.yellowjersey.org Open every day since 1
April, 1971

"Jeff Wills" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

"Mark South" <[email hidden]> wrote in message

news:<[email hidden]>...

Quoted message said:

Quoted message said:

No, the brakes were fine, I rode 20km and they were
binding. The change happened with me on the bike and
probably while I was moving.

OK... unlikely explanation #3: how old are the rims? Could
they be worn to the point where they are bulging outward
and meeting the brake pads? This would require that the
rims be quite worn *and* that they bulge evenly around
their circumference. Also, the adjustment would have to be
very close to begin with.

The rims only have about 1200km on them, with very little
heavy braking. They are non-machine, non-anodized 32-spoke
Ambrosio semi-aero rims.

Quoted message said:

What kind of rim is it? Are the rim walls parallel or do
they taper somewhat, like this: \__/ ?? I'm thinking that
the center bolt of the caliper could have bent upwards
somehow, binding the brake pads against the rim.

Very close to parallel.

Quoted message said:

Could one or both of the brake pads have come slightly
loose, allowing them to rotate in the caliper? I've had
this happen- and the pads remain pretty tight afterwards.

I'm going to treble-check that next time I have a moment to
look at the bike carefully.

Thanks for all the responses, BTW. I'm appreciative of all
the suggestions everyone has made.
--
"I would recommend Iowa or North Dakota for your dip
into reality."
- Ed Dolan in alt.rec.bicycles.recumbent

"A Muzi" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

A brake shoe adjusted low will wear to a ridge that can
catch below the rim.

Good point.

Quoted message said:

Trim it away with a blade and raise the shoe if that's
the problem

The rim is semi-aero, so doesn't have an edge to the brake
track, it just curves gently round to the spoke bed.

Thanks for the suggestion.
--
Mark South: World Citizen, Net Denizen

you need a centering tool.

parktool.comsidepull.shtmlOpen ↗

so far you have not said if you actually tried centering
them or not.

did you say if the friction was on one side or equally
distributed?

i know someone asked..

wle.

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

"daveornee" <[email hidden]> wrote in
message "]news:[email hidden]...

Quoted message said:

It is nearly impossible to guess from here, but I have
had a cable housing end come out of the frame "braze-on"
and re-seat itself on the edge of the braze-on, thus
pulling the cable tighter. This happened on our tandem,
which has lots of rear cable and a few extra frame
fittings to check. I have also come up on other riders
who were experiencing similar brake rub issues (wouldn't
have caught them without their handicap) and seen the
housing end problem... and even one time when they put
the slightly wider rimmed wheel on an alternate
bicycle.... the regular rim was 19 mm outside width, but
the substitute was 20 mm wide.

Thanks for the suggestion, I hadn't checked this. I'll take
a look in the morning.
--
Mark South: World Citizen, Net Denizen

my brakes go off center quite a lot. as someone said, center
them using a centering tool.

heat and humidity changes seem to cause this. possibly also
your calipers are loose.

or the centering adjustment is loose [this can be a separate
nut inside the calipers. hard to explain]

what i think is they are not meant to stay centered closer
than a mm or so.

it;s all friction, in standard road bike brakes.

also, the centering is usually not changed if someone came
along and tried to rotate the calipers around their pivot.
they will stay like that only til the brakes are applied and
then go right back to where they were.

center pull brakes are different but can also go off center.

wle.

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

"Jeff Wills" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

"Mark South" <[email hidden]> wrote in message

news:<[email hidden]>...

Quoted message said:

Quoted message said:

No, the brakes were fine, I rode 20km and they were
binding. The change happened with me on the bike and
probably while I was moving.

OK... unlikely explanation #3: how old are the rims?
Could they be worn to the point where they are bulging
outward and meeting the brake pads? This would require
that the rims be quite worn *and* that they bulge evenly
around their circumference. Also, the adjustment would
have to be very close to begin with.

The rims only have about 1200km on them, with very little
heavy braking. They are non-machine, non-anodized 32-spoke
Ambrosio semi-aero rims.

Quoted message said:

What kind of rim is it? Are the rim walls parallel or do
they taper somewhat, like this: \__/ ?? I'm thinking that
the center bolt of the caliper could have bent upwards
somehow, binding the brake pads against the rim.

Very close to parallel.

Quoted message said:

Could one or both of the brake pads have come slightly
loose, allowing them to rotate in the caliper? I've had
this happen- and the pads remain pretty tight afterwards.

I'm going to treble-check that next time I have a moment to
look at the bike carefully.

Thanks for all the responses, BTW. I'm appreciative of all
the suggestions everyone has made.
--
"I would recommend Iowa or North Dakota for your dip into
reality."
- Ed Dolan in alt.rec.bicycles.recumbent

w l e @ h o t m a i l . c o m (wle - no address harvesting!!) top-posted:

Quoted message said:

you need a centering tool.

Or thumbs.

Bill "not even opposable, necessarily" S.

w l e @ h o t m a i l . c o m (wle - no address harvesting!!) wrote in message news:<[email hidden]>...

Quoted message said:

my brakes go off center quite a lot. as someone said,
center them using a centering tool.

<much snipped>

wle-

Go back through the thread- you'll find that centering the
caliper *was not* the problem. We've eliminated the common
causes, plus a bunch of unlikely causes. What remains,
*however unlikely*, is probably the truth. (Thank you,
Sherlock Holmes.)

And *please* find the "shift" key!

Jeff

"Jeff Wills" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

w l e @ h o t m a i l . c o m (wle - no address
harvesting!!) wrote in message

news:<[email hidden]>...

Quoted message said:

Quoted message said:

my brakes go off center quite a lot. as someone said,
center them using a centering tool.

<much snipped>

Sorry, none of the above.

Quoted message said:

Go back through the thread- you'll find that centering the
caliper *was not* the problem. We've eliminated the common
causes, plus a bunch of unlikely causes. What remains,
*however unlikely*, is probably the truth. (Thank you,
Sherlock Holmes.)

I had a look at the bike and checked over the other
suggestions I hadn't thought of. None of them apply, notably
the barrel adjuster is not implicated.

Recall that I said I unbound the brakes by feeding a little
more cable (couple of mm) through the cable binder nut? Well
today, in a cool garage, the front brake is now running
notably wider than on Sunday, and the brake lever comes
nearer the handlebar. So I'm beginning to think that the
pads must have expanded some in the heat and contracted back
slightly in the cool.
--
Mark South: World Citizen, Net Denizen

"Mark South" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Quoted message said:

Quoted message said:

I noticed that the bike didn't roll easily. Lifting the
front wheel and spinning it showed the front brake was
binding hard, which explained the difficulty up the
gentle hill.

OK, can we change the terms of the question now? Can we
assume, just for one moment, that it wasn't some twit
thing that I did, could there be anything else that woud
produce this effect? Has anyone else ever seen or heard
of this?

You still haven't told us what "this" is. The answer will be
found visually, and since we cannot see your bike, well, ...
it will be found by you.

Quoted message said:

One-line shots are more than acceptable, but best when
they are funny.

Look harder, homer. Something changed. Keep looking until
you see what is.

Doug

"Mark South" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

I had a look at the bike and checked over the other
suggestions I hadn't thought of. None of them apply,
notably the barrel adjuster is not implicated.

Recall that I said I unbound the brakes by feeding a
little more cable (couple of mm) through the cable binder
nut? Well today, in a cool garage, the front brake is now
running notably wider than on Sunday, and the brake lever
comes nearer the handlebar. So I'm beginning to think that
the pads must have expanded some in the heat and
contracted back slightly in the cool.

Are you sure that the brake pads are contacting the rims
when the binding occurs? I'm guessing that the sidewall is
shot and the tire is changing shape and is what's contacting
the brake.

Doug

"Douglas Landau" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

"Mark South" <[email hidden]> wrote in message

news:<[email hidden]>...

Quoted message said:

Quoted message said:

I had a look at the bike and checked over the other
suggestions I hadn't

thought

Quoted message said:

Quoted message said:

of. None of them apply, notably the barrel adjuster is
not implicated.

Recall that I said I unbound the brakes by feeding a
little more cable

(couple

Quoted message said:

Quoted message said:

of mm) through the cable binder nut? Well today, in a
cool garage, the

front

Quoted message said:

Quoted message said:

brake is now running notably wider than on Sunday, and
the brake lever comes nearer the handlebar. So I'm
beginning to think that the pads must have expanded some
in the heat and contracted back slightly in the cool.

Are you sure that the brake pads are contacting the rims
when the binding occurs? I'm guessing that the sidewall is
shot and the tire is changing shape and is what's
contacting the brake.

New rims, no sidewall flex.
--
Mark South: World Citizen, Net Denizen

Mark South said:

... No, the brakes were fine, I rode 20km and they were
binding. The change happened with me on the bike and
probably while I was moving.
--
"I would recommend Iowa or North Dakota for your dip into
reality."
- Ed Dolan in alt.rec.bicycles.recumbent

The Usenet Gods made your brakes drag as punishment for
quoting Ed Dolan. 😉

--
Tom Sherman – Quad City Area

"Tom Sherman" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Mark South said:

... No, the brakes were fine, I rode 20km and they were
binding. The change happened with me on the bike and
probably while I was moving.
--
"I would recommend Iowa or North Dakota for your dip
into reality."
- Ed Dolan in alt.rec.bicycles.recumbent

The Usenet Gods made your brakes drag as punishment for
quoting Ed Dolan. 😉

That's the most plausible explanation so far :-)

But I'm pretty sure that I only started using that quote
after Sunday....However, the idea of Ed Dolan directing
someone else toward reality is too funny!
--
"To ... just not care that there are naked triathletes
running across your lawn, that's just a waste of
exhibitionism."
- Kibo, in alt.religion.kibology

[email hidden] (Jeff Wills) wrote in message news:<[email hidden]>...

Quoted message said:

w l e @ h o t m a i l . c o m (wle - no address
harvesting!!) wrote in message
news:<[email hidden]>...

Quoted message said:

my brakes go off center quite a lot. as someone said,
center them using a centering tool.

<much snipped>

wle-

Go back through the thread- you'll find that centering the
caliper *was not* the problem. We've eliminated the common
causes, plus a bunch of unlikely causes. What remains,
*however unlikely*, is probably the truth. (Thank you,
Sherlock Holmes.)

And *please* find the "shift" key!

Jeff

I had this very problem w/the front brake every time I made
a fast decent. The brakes are a pr. of Avid Arch Rival Mag
Linear brakes. At the bottom I would have to detach the
noodle until cool. I completely overhauled the frt. brake.
New noodle, pads, cable, housing, bellows. Cleaned & greased
every friction surface. New pads were Kool stop brick
colored (Scott-M) Thinlines. (Thinlines are the ones w/o a
metal backing. It's possible that the metal backing
transfered more heat to the mag arms from the pads.) Also
tightened the allen set screws @ the bushings. All this has
reduced the problem. As the new pads have worn in, it has
improved even more. (And I now have plenty of lever pull,
which I didn't before). I believe the problem was a
combination of the mag arms, the original black pads. I
think the mag arms are more prone to heat distortion. But
the main cause was the bushing setscrews becoming loose over
time. As a further precaution, I'm going to blue Loctite
them. I realize that you have dbl. pivot road brakes, but
perhaps you might be able to glean some small morsel of info
that could help. Good luck John

"Mark South" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Today I exeperienced something new to me.

About 20 km into my Sunday morning ride, I was coming up a
gentle hill into a tiny village and thinking "Hell, I must
be getting weaker every day, why is this incline so hard?"

well, after all that, what was it?

wle.