Atom Freewheel indexing.

Discussion in 'Cycling Equipment' started by meb, Nov 6, 2004.

  1. meb

    meb New Member

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    I’ve got a 6 speed Atom 14-28 freewheel on a friction shifting bike.
    Want to upgrade that bike to 7 speed freewheel (friction shifting) and move that freewheel to a 6 speed with SIS indexed shifting that has a freewheel with tooth wear on the two smallest sprockets (chain measures unworn, only found a single link with perceptible play).
    The Atom freewheel has the word compact on it’s carrier body. Is it SIS compatible?

    Thanks
     
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  2. meb wrote:

    > I’ve got a 6 speed Atom 14-28 freewheel on a friction shifting bike.
    > Want to upgrade that bike to 7 speed freewheel (friction shifting) and
    > move that freewheel to a 6 speed with SIS indexed shifting that has a
    > freewheel with tooth wear on the two smallest sprockets (chain measures
    > unworn, only found a single link with perceptible play).
    > The Atom freewheel has the word compact on it’s carrier body. Is it
    > SIS compatible?


    Don't think so. A "compact 6" freewheel is simply one which fits into
    the space of a 5 speed freewheel and avoids the need to spread the frame
    from 120mm. Standard 6 speed (and 7 speed, which are all "compact")
    used 126mm, you see.
     
  3. On 2004-11-06, meb <[email protected]> wrote:

    > I’ve got a 6 speed Atom 14-28 freewheel on a friction shifting bike.
    > Want to upgrade that bike to 7 speed freewheel (friction shifting) and
    > move that freewheel to a 6 speed with SIS indexed shifting that has a
    > freewheel with tooth wear on the two smallest sprockets (chain measures
    > unworn, only found a single link with perceptible play).
    > The Atom freewheel has the word compact on it’s carrier body. Is it
    > SIS compatible?


    No. If you expect decent shifting, buy the appropriate freewheel for the
    derailleur you're using.

    --

    -John ([email protected])
     
  4. Dave Mayer

    Dave Mayer Guest

    "meb" <[email protected]> wrote in message
    news:[email protected]
    >
    > I've got a 6 speed Atom 14-28 freewheel on a friction shifting bike....
    > Is it SIS compatible?
    >

    If the cog spacing on these matches 6-speed indexing, it will just be a
    coincidence. I used these in the 70's. They were junk. There is a good
    reason that the Japanese took over the freewheel market. Mechanically the
    Atoms were poorly made and featured mediocre shifting due to primitive cog
    profiles (Hyperglide is much much better). The spacers used on these likely
    vary in width all over the map.

    Do yourself a favor and throw it in the garbage. Buy a 6-speed Shimano HG20
    freewheel. Costs about $12 where I shop.
     
  5. meb <[email protected]> writes:


    >I've got a 6 speed Atom 14-28 freewheel on a friction shifting bike.
    >Want to upgrade that bike to 7 speed freewheel (friction shifting) and
    >move that freewheel to a 6 speed with SIS indexed shifting that has a
    >freewheel with tooth wear on the two smallest sprockets (chain measures
    >unworn, only found a single link with perceptible play).


    If you have an Atom freewheel remover, why don't you try it, it cannot
    hurt anything. Don't struggle to make it work, just give it a
    short-term try and if it doesn't work then buy a modern freewheel. I
    think that modern freewheels like sunrace will index and only cost
    about $15. In the meantime, you might learn something new about
    indexing with this experiment.

    - Don Gillies
    San Diego, CA

    P.S. if it doesn't work, i've been looking for a compact atom
    freewheel for a 1973 project bike of mine, and may be willing to buy
    it from you - contact me off-list.
     
  6. meb

    meb New Member

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    Measured, the sprockets on the Atom compact 6 speed-they are about .2mm closer together than SIS indexed 6 speed (I notice Sheldon's page lists narrow 6 speed as having 124 mm dropouts).

    I swapped rear wheels between the bikes and thus far am finding with indexed shifting I get a skip over the second largest or third largest sprockets. I'll play with adjustments to see if I can move the misalign from 2-3 to the small cog and make it work-I believe sprockt 3 is where proper align should be for this to have its best chance at working.
     
  7. meb

    meb New Member

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    Came close on a couple of adjustmenst, but no exact match on indexing calibration that matches SIS.

    Was thinking this freewheel might have a thread compatibliy issue if I shift it to an SIS bike. Anyone know if this is a French theaded freewheel?
    This came off a Mavic wheel on a Peugot.
     
  8. meb wrote:
    >
    > Was thinking this freewheel might have a thread compatibliy issue if

    I
    > shift it to an SIS bike. Anyone know if this is a French theaded
    > freewheel?
    > This came off a Mavic wheel on a Peugot.


    Normally, the threading is stamped on the hub as well as on the
    freewheel. Anyway, iirc an ISO freewheel will fit on a french threaded
    hub.
     
  9. "meb" wrote:
    >
    >>Was thinking this freewheel might have a thread compatibliy issue if
    >>I shift it to an SIS bike. Anyone know if this is a French theaded
    >>freewheel?
    >>This came off a Mavic wheel on a Peugot.


    If it's a Mavic hub, it's almost certainly ISO standard (_not_ French
    thread.) French threading went extinct for medium/high-end bikes
    sometime in the 1980s.

    A well-intentioned poster wrote optimistically.

    > Normally, the threading is stamped on the hub as well as on the
    > freewheel.


    That was true of Campagnolo hubs for a while, and some freewheels with
    oddball (i.e. French or Italian) threading) but in most cases there is
    no such marking.

    > Anyway, iirc an ISO freewheel will fit on a french threaded hub.


    That part is absolutely false. Old French-thread freewheel threading is
    34.7 mm diameter, whilst ISO/English freewheels are 1 3/8" (34.93 mm)
    diameter.

    There's also a mismatch in thread pitch.

    Since the ISO freewheel is larger, you can fit it over a French thread
    hub, but the thread engagement will be so poor that you'll strip the
    threads almost immediately.

    Sheldon "No Go" Brown
    +----------------------------------------+
    | Promote the institution of marriage: |
    | Make it available to all adults! |
    +----------------------------------------+
    Harris Cyclery, West Newton, Massachusetts
    Phone 617-244-9772 FAX 617-244-1041
    http://harriscyclery.com
    Hard-to-find parts shipped Worldwide
    http://captainbike.com http://sheldonbrown.com
     
  10. Diablo Scott

    Diablo Scott Guest

    Sheldon Brown wrote:
    > "meb" wrote:
    >
    >>
    >>> Was thinking this freewheel might have a thread compatibliy issue if
    >>> I shift it to an SIS bike. Anyone know if this is a French theaded
    >>> freewheel?
    >>> This came off a Mavic wheel on a Peugot.

    >
    >
    > If it's a Mavic hub, it's almost certainly ISO standard (_not_ French
    > thread.) French threading went extinct for medium/high-end bikes
    > sometime in the 1980s.
    >


    Maybe so, but Atom made a LOT of French-threaded freewheels for Peugeot;
    chances are high he's got one. Peugeot also went pretty much extinct
    (at least in USA) in the mid 80's so chances are even higher. OP didn't
    say if it was a Mavic hub or Mavic rim so chances are still high.

    Unfortunately, I've forgotten the original question now, but I suspect
    the answer is "probably not".

    --
    My bike blog:
    http://diabloscott.blogspot.com/
     
  11. Diablo Scott wrote:

    > Maybe so, but Atom made a LOT of French-threaded freewheels for Peugeot;
    > chances are high he's got one. Peugeot also went pretty much extinct
    > (at least in USA) in the mid 80's so chances are even higher. OP didn't
    > say if it was a Mavic hub or Mavic rim so chances are still high.


    Peugeots exported to the U.S. through normal wholesale channels
    generally used ISO/English hubs/freewheels, at least if they had 630 mm
    (27 inch) wheels.

    These bikes did have French-size bottom brackets and headsets, but
    usually went ISO/English for the hubs/freewhweels and also for the pedals.

    Sheldon "http://sheldonbrown.com/velos" Brown
    +--------------------------------------------------+
    | Some of my brother's paintings may be seen at: |
    | http://junila.com |
    +--------------------------------------------------+
    Harris Cyclery, West Newton, Massachusetts
    Phone 617-244-9772 FAX 617-244-1041
    http://harriscyclery.com
    Hard-to-find parts shipped Worldwide
    http://captainbike.com http://sheldonbrown.com
     
  12. Diablo Scott

    Diablo Scott Guest

    Sheldon Brown wrote:

    > Diablo Scott wrote:
    >
    >> Maybe so, but Atom made a LOT of French-threaded freewheels for
    >> Peugeot; chances are high he's got one. Peugeot also went pretty much
    >> extinct (at least in USA) in the mid 80's so chances are even higher.
    >> OP didn't say if it was a Mavic hub or Mavic rim so chances are still
    >> high.

    >
    >
    > Peugeots exported to the U.S. through normal wholesale channels
    > generally used ISO/English hubs/freewheels, at least if they had 630 mm
    > (27 inch) wheels.
    >
    > These bikes did have French-size bottom brackets and headsets, but
    > usually went ISO/English for the hubs/freewhweels and also for the pedals.
    >



    I had a Peugeot (P8 I think... circa 1984), purchased new through a
    normal bike shop that presumably got it through normal channels (they
    were mostly a Peugeot shop) and it definitely had the French headset
    with oddball stem size, 27" wheels with tires labeled "Michelin Bib
    Sport 1" " (but were actually more like 1-1/4") and an Atom 6-speed
    freewheel with French FW threads (I'm SURE - that was one of the reasons
    I later bought new wheels for it). In fact I never saw an Atom
    freewheel that didn't have French threads (admittedly a small sample
    size). Don't remember what kind of hub came with the bike but I think
    it had Weinmann rims. And I'm still not sure what the OQ was.

    > Sheldon "http://sheldonbrown.com/velos" Brown


    Welldone Sheldon, that bit about the Maillard Helicomatic hubs evoked
    some memories. I note though, that the table at the bottom doesn't show
    that Atom made freewheels.
    --
    My bike blog:
    http://diabloscott.blogspot.com/
     
  13. meb

    meb New Member

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    OQ was whether the compact 6 Atom was close enought to SIS-6 to be adjustably compatible. During the experiment (which appears heading toward a poor compatibility answer per the .2mm/sprocket difference), a theading compatibity question occurred to me.

    The hub is Maillard, has a 21 (I think-unless it's a strange font 27) stamped in it.
     
  14. A Muzi

    A Muzi Guest

    > meb wrote:
    >>Was thinking this freewheel might have a thread compatibliy issue if
    >>shift it to an SIS bike. Anyone know if this is a French theaded
    >>freewheel?
    >>This came off a Mavic wheel on a Peugot.


    Christoph Strauch wrote:
    > Normally, the threading is stamped on the hub as well as on the
    > freewheel. Anyway, iirc an ISO freewheel will fit on a french threaded
    > hub.


    With difficulty, possibly fatally. A 34.85mm freewheel on a
    35mm hub is not a good idea.

    Unmarked freeweheels are country of origin. A blank Atom is
    French, a blank Regina is Italian. Any mark is the other
    thread. A Regina with a F (franchese) or an X is metric. An
    Atom with an A (anglaise) or frequently a zero or an X is BSC.

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