Common "thunk" in drive

Discussion in 'Mountain Bikes' started by Cycloneme, Feb 22, 2003.

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  1. Cycloneme

    Cycloneme Guest

    Maybe someone could please point me in the right technical direction as I just don't see anything
    upon inspection and I've lost trust in my bike shop technican's expertise (long story). When
    pedaling uphill where the bike has the most load on the gears, chain, etc., I feel a clunk
    throughout the drive. Problem happens frequently but not readily repeatable. I'm sure this is a
    common problem and my question to this posting is primarily most common sources that people have
    seen. Any inputs would be greatly appreciated. Thanks.
     
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  2. In article <[email protected]>, [email protected] (Cycloneme) wrote:

    > Maybe someone could please point me in the right technical direction as I just don't see anything
    > upon inspection and I've lost trust in my bike shop technican's expertise (long story). When
    > pedaling uphill where the bike has the most load on the gears, chain, etc., I feel a clunk
    > throughout the drive. Problem happens frequently but not readily repeatable. I'm sure this is a
    > common problem and my question to this posting is primarily most common sources that people have
    > seen. Any inputs would be greatly appreciated. Thanks.

    First guess is a skipping chain due to wear on the cog and chain. Does it happen primarily in just
    one gear? Have you checked the chain for wear (1/16" in 12" is a useful wear limit)?

    --
    Ryan Cousineau, [email protected] http://www.sfu.ca/~rcousine President, Fabrizio Mazzoleni Fan Club
     
  3. Cycloneme

    Cycloneme Guest

    I'll have to check. I tends to happen in multiple gears. I thought that the derailer was not setup
    properly but I don't really see a problem there. Thanks for your input.
     
  4. Tbf

    Tbf Guest

    "Ryan Cousineau" <[email protected]> wrote in message
    news:[email protected]...
    > In article <[email protected]>, [email protected] (Cycloneme) wrote:
    >
    > > Maybe someone could please point me in the right technical direction as
    I
    > > just don't see anything upon inspection and I've lost trust in my bike shop technican's
    > > expertise (long story). When pedaling uphill where the bike
    has
    > > the most load on the gears, chain, etc., I feel a clunk throughout the
    drive.
    > > Problem happens frequently but not readily repeatable. I'm sure this is
    a
    > > common problem and my question to this posting is primarily most common sources that people have
    > > seen. Any inputs would be greatly appreciated. Thanks.
    >
    > First guess is a skipping chain due to wear on the cog and chain. Does it happen primarily in just
    > one gear? Have you checked the chain for wear (1/16" in 12" is a useful wear limit)?
    >
    > --
    > Ryan Cousineau, [email protected] http://www.sfu.ca/~rcousine President, Fabrizio Mazzoleni Fan Club

    Check each link in the chain to ensure that one or more of them isn't seized. It's one of those
    litle things that will be missed except under hard pedaling such as up a hill.
     
  5. R.H.

    R.H. Guest

    skipping chain could also be caused by a twisted ring tooth or a tight link.

    --
    ______________________________________

    "It's never too late to have a happy childhood."
    ______________________________________
    "Ryan Cousineau" <[email protected]> wrote in message
    news:[email protected]...
    > In article <[email protected]>, [email protected] (Cycloneme) wrote:
    >
    > > Maybe someone could please point me in the right technical direction as
    I
    > > just don't see anything upon inspection and I've lost trust in my bike shop technican's
    > > expertise (long story). When pedaling uphill where the bike
    has
    > > the most load on the gears, chain, etc., I feel a clunk throughout the
    drive.
    > > Problem happens frequently but not readily repeatable. I'm sure this is
    a
    > > common problem and my question to this posting is primarily most common sources that people have
    > > seen. Any inputs would be greatly appreciated. Thanks.
    >
    > First guess is a skipping chain due to wear on the cog and chain. Does it happen primarily in just
    > one gear? Have you checked the chain for wear (1/16" in 12" is a useful wear limit)?
    >
    > --
    > Ryan Cousineau, [email protected] http://www.sfu.ca/~rcousine President, Fabrizio Mazzoleni Fan Club

    ---
    Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com).
    Version: 6.0.456 / Virus Database: 256 - Release Date: 2/18/2003
     
  6. Bob

    Bob Guest

    "Cycloneme" <[email protected]> wrote in message news:[email protected]...
    > Maybe someone could please point me in the right technical direction as I
    just
    > don't see anything upon inspection and I've lost trust in my bike shop technican's expertise (long
    > story). When pedaling uphill where the bike
    has
    > the most load on the gears, chain, etc., I feel a clunk throughout the
    drive.
    > Problem happens frequently but not readily repeatable. I'm sure this is a common problem and my
    > question to this posting is primarily most common
    sources
    > that people have seen. Any inputs would be greatly appreciated. Thanks.

    Couldn't this be a bad bb bearing or hub bearing? I had a thunk in my bb and replaced the sealed
    bearing that was shot and it works great.

    Bob
     
  7. Tbf

    Tbf Guest

    Sounds more like a chain problem, check the links to see if one of them is seized. Work backwards
    from there.

    "Bob" <[email protected]> wrote in message news:[email protected]...
    >
    > "Cycloneme" <[email protected]> wrote in message
    > news:[email protected]...
    > > Maybe someone could please point me in the right technical direction as
    I
    > just
    > > don't see anything upon inspection and I've lost trust in my bike shop technican's expertise
    > > (long story). When pedaling uphill where the bike
    > has
    > > the most load on the gears, chain, etc., I feel a clunk throughout the
    > drive.
    > > Problem happens frequently but not readily repeatable. I'm sure this is
    a
    > > common problem and my question to this posting is primarily most common
    > sources
    > > that people have seen. Any inputs would be greatly appreciated. Thanks.
    >
    > Couldn't this be a bad bb bearing or hub bearing? I had a thunk in my bb and replaced the sealed
    > bearing that was shot and it works great.
    >
    > Bob
     
  8. Shaun Rimmer

    Shaun Rimmer Guest

    Ryan Cousineau <[email protected]> wrote in message
    news:[email protected]...
    > In article <[email protected]>, [email protected] (Cycloneme) wrote:
    >
    > > Maybe someone could please point me in the right technical direction as
    I
    > > just don't see anything upon inspection and I've lost trust in my bike shop technican's
    > > expertise (long story). When pedaling uphill where the bike
    has
    > > the most load on the gears, chain, etc., I feel a clunk throughout the
    drive.
    > > Problem happens frequently but not readily repeatable. I'm sure this is
    a
    > > common problem and my question to this posting is primarily most common sources that people have
    > > seen. Any inputs would be greatly appreciated. Thanks.
    >
    > First guess is a skipping chain due to wear on the cog and chain. Does it happen primarily in just
    > one gear? Have you checked the chain for wear (1/16" in 12" is a useful wear limit)?

    Loose crank arms?

    Shaun aRe - heh.....
     
  9. Bob

    Bob Guest

    "Shaun Rimmer" <[email protected]> wrote in message
    news:[email protected]...
    >
    > Ryan Cousineau <[email protected]> wrote in message
    > news:[email protected]...
    > > In article <[email protected]>, [email protected] (Cycloneme) wrote:
    > >
    > > > Maybe someone could please point me in the right technical direction
    as
    > I
    > > > just don't see anything upon inspection and I've lost trust in my bike shop technican's
    > > > expertise (long story). When pedaling uphill where the
    bike
    > has
    > > > the most load on the gears, chain, etc., I feel a clunk throughout the
    > drive.
    > > > Problem happens frequently but not readily repeatable. I'm sure this
    is
    > a
    > > > common problem and my question to this posting is primarily most
    common
    > > > sources that people have seen. Any inputs would be greatly appreciated.
    Thanks.
    > >
    > > First guess is a skipping chain due to wear on the cog and chain. Does it happen primarily in
    > > just one gear? Have you checked the chain for wear (1/16" in 12" is a useful wear limit)?
    >
    > Loose crank arms?
    >
    > Shaun aRe - heh.....
    >

    I'm with you Shaun. Check the bb and crank arms....

    Bob
     
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