Chain slipping off freewheel after installing a new chain

Discussion in 'Cycling Equipment' started by JBAfromNY, May 14, 2004.

  1. JBAfromNY

    JBAfromNY Guest

    Here's the situation:

    I have a 7-speed indexing Suntour freewheel/triple front drivetrain
    (not cassette; yes, it's an old bike). I just replaced the chain
    (some flavor of Sedis, IIRC), after many years, with a new SRAM PC 48.
    When I had the bike up on the stand, it shifted perfectly with the
    new chain. However, when I actually rode it, the chain slipped on the
    3 middle cogs, .

    I fiddled extensively with both the indexing adjustment and the
    b-tension adjustment. This didn't help.

    The chain length looks OK (no obvious slack in small-middle combos; no
    trouble shifting to big-big combos).

    The cogs from which the chain slips all show greater wear than the
    cogs that work OK, leading me to think that the freewheel is the
    likely culprit. Is this it, or is there something else I should check
    out before going on a parts hunt?

    TIA,
    John
     
    Tags:


  2. John Everett

    John Everett Guest

    On 14 May 2004 08:13:10 -0700, [email protected] (JBAfromNY) wrote:

    >Here's the situation:
    >
    >I have a 7-speed indexing Suntour freewheel/triple front drivetrain
    >(not cassette; yes, it's an old bike). I just replaced the chain
    >(some flavor of Sedis, IIRC), after many years, with a new SRAM PC 48.
    > When I had the bike up on the stand, it shifted perfectly with the
    >new chain. However, when I actually rode it, the chain slipped on the
    >3 middle cogs, .
    >
    >I fiddled extensively with both the indexing adjustment and the
    >b-tension adjustment. This didn't help.
    >
    >The chain length looks OK (no obvious slack in small-middle combos; no
    >trouble shifting to big-big combos).
    >
    >The cogs from which the chain slips all show greater wear than the
    >cogs that work OK, leading me to think that the freewheel is the
    >likely culprit. Is this it, or is there something else I should check
    >out before going on a parts hunt?


    Pretty typical symptoms following replacement of a chain that has been
    used far beyond acceptable wear. As a chain wears the distance between
    pins increases beyond the 1/2 inch at which it started out. This
    increase subsequently wears the rings and cogs, especially the cogs
    that are most heavily used. A new chain will no longer register
    properly in the worn cogs, this the slipping/shipping you're
    experiencing.

    If you still have the old chain, try measuring it. There should be a
    pin exactly every half inch. If the 24th pin falls more than 12 1/8
    inches from the first, you probably waited too long to replace it. I'm
    guessing "after many years" of use you'll find it measures noticeably
    more than that.

    Good luck finding new cogs for your Suntour freewheel. ;-)


    jeverett3<AT>earthlink<DOT>net http://home.earthlink.net/~jeverett3
     
  3. daveornee

    daveornee Guest

    Jbafromny wrote:
    > Here's the situation:
    > I have a 7-speed indexing Suntour freewheel/triple front drivetrain (not
    > cassette; yes, it's an old bike). I just replaced the chain (some flavor
    > of Sedis, IIRC), after many years, with a new SRAM PC 48. When I had the
    > bike up on the stand, it shifted perfectly with the new chain. However,
    > when I actually rode it, the chain slipped on the 3 middle cogs, .
    > I fiddled extensively with both the indexing adjustment and the b-
    > tension adjustment. This didn't help.
    > The chain length looks OK (no obvious slack in small-middle combos; no
    > trouble shifting to big-big combos).
    > The cogs from which the chain slips all show greater wear than the cogs
    > that work OK, leading me to think that the freewheel is the likely
    > culprit. Is this it, or is there something else I should check out
    > before going on a parts hunt?
    > TIA, John




    Yes, it sounds like new freewheel time.

    <http://www.yellowjersey.org/stfw.html>

    Yellow Jersey specializes in these things. The tooth profile on your old
    cogs has worn so that when you put a good load on the chain it rides up
    and jumps.

    A good article on chains that will help explain is on Sheldon
    Brown's site:

    <http://sheldonbrown.com/chains.html>



    --
     
  4. Ken

    Ken Guest

    [email protected] (JBAfromNY) wrote in news:13f5f670.0405140713.5e103f23
    @posting.google.com:
    > I have a 7-speed indexing Suntour freewheel/triple front drivetrain
    > (not cassette; yes, it's an old bike). I just replaced the chain
    > (some flavor of Sedis, IIRC), after many years, with a new SRAM PC 48.
    > When I had the bike up on the stand, it shifted perfectly with the
    > new chain. However, when I actually rode it, the chain slipped on the
    > 3 middle cogs, .


    Sounds like the freewheel is worn out.
     
  5. A Muzi

    A Muzi Guest

    JBAfromNY wrote:
    > I have a 7-speed indexing Suntour freewheel/triple front drivetrain
    > (not cassette; yes, it's an old bike). I just replaced the chain
    > (some flavor of Sedis, IIRC), after many years, with a new SRAM PC 48.
    > When I had the bike up on the stand, it shifted perfectly with the
    > new chain. However, when I actually rode it, the chain slipped on the
    > 3 middle cogs, .
    >
    > I fiddled extensively with both the indexing adjustment and the
    > b-tension adjustment. This didn't help.
    >
    > The chain length looks OK (no obvious slack in small-middle combos; no
    > trouble shifting to big-big combos).
    >
    > The cogs from which the chain slips all show greater wear than the
    > cogs that work OK, leading me to think that the freewheel is the
    > likely culprit. Is this it, or is there something else I should check
    > out before going on a parts hunt?


    Yes. Read this:
    http://draco.acs.uci.edu/rbfaq/FAQ/8d.2.html

    and then maybe this:
    http://www.yellowjersey.org/stfw.html

    --
    Andrew Muzi
    www.yellowjersey.org
    Open every day since 1 April, 1971
     
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