Brake pad question

Discussion in 'Cycling Equipment' started by Mark South, Jun 6, 2004.

  1. Mark South

    Mark South Guest

    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
     
    Tags:


  2. Dan Brussee

    Dan Brussee Guest

    Cycling Pixies

    On Sun, 6 Jun 2004 22:59:17 +0200, "Mark South"
    <[email protected]> wrote:

    >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?
     
  3. Tcmedara

    Tcmedara Guest

    Mark South <[email protected]> wrote:
    >
    > 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
     
  4. x

    x Guest

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

    >

    >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
     
  5. Steve Knight

    Steve Knight Guest

    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.
     
  6. Jeff Wills

    Jeff Wills Guest

    "Mark South" <[email protected]> wrote in message news:<[email protected]>...
    > 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>
    >
    > 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
     
  7. Zeeexsixare

    Zeeexsixare Guest

    Mark South wrote:
    > 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
     
  8. Mark South

    Mark South Guest

    "tcmedara" <[email protected]> wrote in message
    news:[email protected]...
    > Mark South <[email protected]> wrote:
    > >
    > > 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
     
  9. Mark South

    Mark South Guest

    "(Pete Cresswell)" <[email protected]> wrote in message
    news:[email protected]...
    > RE/
    > >Lifting the front wheel and spinning it showed the front
    > >brake was binding hard, which explained the difficulty up
    > >the gentle hill.
    >
    > >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?

    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.

    > 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.

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

    Mark South Guest

    "Steve Knight" <[email protected]> wrote in message
    news:[email protected]...
    > I had a loose back hub that caused the brake to rub when
    > riding but not while
    on
    > 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
     
  11. Mark South

    Mark South Guest

    "Jeff Wills" <[email protected]> wrote in message
    news:[email protected]...
    > "Mark South" <[email protected]> wrote in message
    news:<[email protected]>...
    > > 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>
    > >
    > > 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.

    > 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.

    > Recenter the brake and get on with your life.

    It's centred. Was before, is now.

    > 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
     
  12. Mark South

    Mark South Guest

    "ZeeExSixAre" <[email protected]> wrote in message
    news:G_Swc.108$n%[email protected]...
    >
    > 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.

    > 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.

    > 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
     
  13. Dianne_1234

    Dianne_1234 Guest

    On Sun, 6 Jun 2004 22:59:17 +0200, "Mark South"
    <[email protected]> wrote:

    >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? ;-)
     
  14. Ned Mantei

    Ned Mantei Guest

    In article <[email protected]>,
    "Mark South" <[email protected]> wrote:

    >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
     
  15. Mark South

    Mark South Guest

  16. Mark South

    Mark South Guest

    "Ned Mantei" <[email protected]> wrote in message
    news:[email protected]...
    > In article <[email protected]>, "Mark South"
    > <[email protected]> wrote:
    >
    > >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
     
  17. daveornee

    daveornee New Member

    Joined:
    Sep 18, 2003
    Messages:
    2,763
    Likes Received:
    0
    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.
     
  18. S O R N I

    S O R N I Guest

    Mark South wrote:

    > 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.
     
  19. Jdc

    Jdc Guest

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

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

    Jeff Wills Guest

    "Mark South" <[email protected]> wrote in message news:<[email protected]>...
    > The brakes were binding, both sides clamped down on the
    > (true) rim.
    >
    > > 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.
    >
    > > 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
     
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