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. 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

    "dianne_1234" <[email protected]> wrote in message
    news:eek:[email protected]
    ....
    > The same folks who worked on Lance's bike worked on yours? ;-)


    No, but thank you for your contribution.
     
  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 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?
    > --
    > 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.



    --
     
  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
     
Loading...
Loading...