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

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

you need a centering tool.

http://www.parktool.com/repair_help/sidepull.shtml

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

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.