Brake pad question

Cycling Pixies

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?

Mark South said:

Has anyone else ever seen this happen?

Or is there another explanation?

Maybe check your cables? I can sorta see how everything else may be in
great shape but enough gunk gets worked into the brake housing that it
finally starts binding. You don't say if or how you released the binding
brake, but I'll offer that as a possibility.

Tom

RE/

Quoted message said:

Lifting the front wheel and
spinning it showed the front brake was binding hard, which explained the
difficulty up the gentle hill.

Quoted message said:

Quoted message said:

D. I adjusted these brakes 6 weeks ago and they have been perfect since then,
until today.

Any chance the bike took some kind of hit that you didn't notice at the
time...like getting bumped up against something when loading/unloading?

I blew out a sidewall once. Had a minor crash, didn't think to check the
brakes...turned out one of the front pads had gotten pushed out of adjustment so
that when braking, it was bearing on the sidewall.
--
PeteCresswell

I had a loose back hub that caused the brake to rub when riding but not while on
the stand.

--
Knight-Toolworks & Custom Planes
Custom made wooden planes at reasonable prices
See http://www.knight-toolworks.com For prices and ordering instructions.

"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

<snip>

Quoted message said:

Or is there another explanation?

You didn't say *how* the brakes were binding. Was *one* brake shoe
bearing on the rim, or were *both* brake shoes bearing on the rim?

If one, then I'd suspect the brake caliper was knocked off-center at
some point. This can happen fairly easily if the bike was parked, fell
over, or was attacked by pixies. Recenter the brake and get on with
your life.

If both, either the cable is gunked or rusted or the caliper is gunked
and rusted. Replace the cable, clean and lube the caliper, and get on
with your life.

Jeff

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...

--
Phil, Squid-in-Training

"tcmedara" <[email hidden]> wrote in message
news:Y1Nwc.8168$Qv1.4225@lakeread03...

Quoted message said:

Mark South said:

Has anyone else ever seen this happen?

Or is there another explanation?

Maybe check your cables? I can sorta see how everything else may be in
great shape but enough gunk gets worked into the brake housing that it
finally starts binding. You don't say if or how you released the binding
brake, but I'll offer that as a possibility.

Brand new cables, lubricated at installation 6 weeks ago. No extra play.

I released the bind by undoing the cable binder bolt and letting out a couple
more mm of cable.
--
Mark South: World Citizen, Net Denizen

"(Pete Cresswell)" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

RE/

Quoted message said:

Lifting the front wheel and
spinning it showed the front brake was binding hard, which explained the
difficulty up the gentle hill.

Quoted message said:

D. I adjusted these brakes 6 weeks ago and they have been perfect since

then,

Quoted message said:

Quoted message said:

until today.

Any chance the bike took some kind of hit that you didn't notice at the
time...like getting bumped up against something when loading/unloading?

Nope, fine when I got on the bike, binding 20 km down the road. I hadn't been
off the bike in that space of time.

Quoted message said:

I blew out a sidewall once. Had a minor crash, didn't think to check the
brakes...turned out one of the front pads had gotten pushed out of adjustment

so

Quoted message said:

that when braking, it was bearing on the sidewall.

No crashes here. Both pads were hard down on the brake track.
--
Mark South: World Citizen, Net Denizen

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

Quoted message said:

I had a loose back hub that caused the brake to rub when riding but not while

on

Quoted message said:

the stand.

As I said, this was binding hard enough to make riding difficult, with the pads
pressing on both sides of the rim equally, even with me off the bike.

The hubs are in perfect shape, quite new and recently adjusted.
--
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:

Today I exeperienced something new to me.

About 20 km into my Sunday morning ride, I was coming up a gentle hill into

a

Quoted message said:

<snip>

Quoted message said:

Or is there another explanation?

You didn't say *how* the brakes were binding. Was *one* brake shoe
bearing on the rim, or were *both* brake shoes bearing on the rim?

Sorry, the pads were squeezing the rim on both sides. The bike was hard to push
when I stopped.

Quoted message said:

If one, then I'd suspect the brake caliper was knocked off-center at
some point. This can happen fairly easily if the bike was parked, fell
over, or was attacked by pixies.

None of those happened. I got on the bike with the brake riding off the rim
just fine. The brakes were adjusted 6 weeks ago, and the bike has been ridden
regularly, and the brakes used with no problem, since then.

Quoted message said:

Recenter the brake and get on with your life.

It's centred. Was before, is now.

Quoted message said:

If both, either the cable is gunked or rusted or the caliper is gunked
and rusted. Replace the cable, clean and lube the caliper, and get on
with your life.

I would be a stupid person to post the question if there was an obvious
corrosion problem. The brakes are newish and in perfect condition, the cables
are new and well-lubricated.

Perhaps I should get on with my life, but can one not be permitted to ask
questions in a tech group?

I cannot find an explanation for what happened that seems plausible, especially
since I don't believe in pixies.
--
Mark South: World Citizen, Net Denizen

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

Quoted message said:

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.

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
due to hard braking, not that I had to do a lot of that on a gentle ride in the
country.
--
Mark South: World Citizen, Net Denizen

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?

The same folks who worked on Lance's bike worked on yours? ;-)

In article <[email hidden]>,

Mark South said:

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.

Do modern road brakes still have a small lever to partly release the
brakes (allowing one to keep riding without wheel rub in case a spoke
breaks)? Could it be that such a lever was accidentally left partly
"open", and then got nudged enough to close it?
(My 1986 Shimano 600 brakes had such a lever--my most recent road brakes)

--
Ned Mantei
Department of Cell Biology, Swiss Federal Institute of Technology
CH-8093 Zurich, Switzerland

"dianne_1234" <[email hidden]> wrote in message
news:[email hidden]...
....

Quoted message said:

The same folks who worked on Lance's bike worked on yours? ;-)

No, but thank you for your contribution.

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

Quoted message said:

In article <[email hidden]>,

Mark South said:

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.

Do modern road brakes still have a small lever to partly release the
brakes (allowing one to keep riding without wheel rub in case a spoke
breaks)? Could it be that such a lever was accidentally left partly
"open", and then got nudged enough to close it?
(My 1986 Shimano 600 brakes had such a lever--my most recent road brakes)

My brakes do have such a lever. It was in the closed position and had been. I
check that before I ride away too.

I could unbind the brakes by opening the quick release. The brakes then allow
the lever to come to the bars. Since I had used the brakes regularly, we can
rule this explanation out.

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.

--
Mark South: World Citizen, Net Denizen

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?
--
Mark South: World Citizen, Net Denizen

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.
OK.... I am done guessing.

--

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.

Bill "look to the turkey baster" S.

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

Quoted message said:

My brakes do have such a lever. It was in the closed position and had

been. I

Quoted message said:

check that before I ride away too.

I could unbind the brakes by opening the quick release. The brakes then

allow

Quoted message said:

the lever to come to the bars. Since I had used the brakes regularly, we

can

Quoted message said:

rule this explanation out.

OK, can we change the terms of the question now? Can we assume, just for

one

Quoted message said:

moment, that it wasn't some twit thing that I did, could there be anything

else

Quoted message said:

that woud produce this effect? Has anyone else ever seen or heard of

this?

Quoted message said:

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

--
Mark South: World Citizen, Net Denizen

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

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

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

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.

Jeff