Cycling Equipment · Public discussion

Problem with Nexus hub

Started by Sven Agardh · · Last activity · 3 posts · 2,229 views

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Cycling Equipment
Published
9 November 2004
Last activity
9 November 2004
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Sven Agardh
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  1. I have a Shimano Nexus SG-7C21 7 gear internal hub. An exploded view of
    the hub can be found here:

    http://www.shimano-europe.com/cycling/phpimages/product/exp_view/SG_7C22.pdf

    The bike is used 20-25 km/day all year round in southern scandinavia,
    with lots of salt on the roads in the winter, so I guess I shouldn't
    expect it to last forever, but I still hope it will survive a little longer.

    Last year it started to be squeeky in first and third gear. After a
    while the sound (and the extra resistance) spread to the other gears.
    When I disassembled the hub it was quite dirty and some parts were
    defenitely ruined. Because of a stupid mistake I ruined the threads on
    the axle so I replaced the axle and driver unit (#10 in the exploded
    view), which I guess means that it is actually a SG-7C22 hub now.

    After that everything was fine for a while, but now I can't engage first
    and third gear. The wire is adjusted and it seems to move freely while
    changing gear, so I guess it is something inside the hub. Unfortunately
    I haven't been able to figure out how the gears work, so I don't know
    which parts are active in which gear. Which part should be replaced this
    time? Or is it time to get rid of the hub?

    /Sven

  2. "Sven Agardh" <[email hidden]> wrote in message
    news:[email hidden]...

    Quoted message said:

    I have a Shimano Nexus SG-7C21 7 gear internal hub. An exploded view of the
    hub can be found here:

    http://www.shimano-europe.com/cycling/phpimages/product/exp_view/SG_7C22.pdf

    The bike is used 20-25 km/day all year round in southern scandinavia, with
    lots of salt on the roads in the winter, so I guess I shouldn't expect it
    to last forever, but I still hope it will survive a little longer.

    Last year it started to be squeeky in first and third gear. After a while
    the sound (and the extra resistance) spread to the other gears. When I
    disassembled the hub it was quite dirty and some parts were defenitely
    ruined. Because of a stupid mistake I ruined the threads on the axle so I
    replaced the axle and driver unit (#10 in the exploded view), which I
    guess means that it is actually a SG-7C22 hub now.

    After that everything was fine for a while, but now I can't engage first
    and third gear. The wire is adjusted and it seems to move freely while
    changing gear, so I guess it is something inside the hub. Unfortunately I
    haven't been able to figure out how the gears work, so I don't know which
    parts are active in which gear. Which part should be replaced this time?
    Or is it time to get rid of the hub?

    /Sven


    These hubs were sold as maintainace free but it is now recognised by shimano
    that they need servicing every 12 months and they have set up trained
    service stations with dealers.
    The seals have been improved on the SG-7C22 compared to the seals on the
    SG-7C21.
    I would see what a service center could do with your hub before buying a new
    one.

    PK

  3. In article <[email hidden]>, [email hidden] says...

    Quoted message said:

    I have a Shimano Nexus SG-7C21 7 gear internal hub. An exploded view of
    the hub can be found here:

    http://www.shimano-europe.com/cycling/phpimages/product/exp_view/SG_7C22.pdf

    The bike is used 20-25 km/day all year round in southern scandinavia,
    with lots of salt on the roads in the winter, so I guess I shouldn't
    expect it to last forever, but I still hope it will survive a little longer.

    Last year it started to be squeeky in first and third gear. After a
    while the sound (and the extra resistance) spread to the other gears.
    When I disassembled the hub it was quite dirty and some parts were
    defenitely ruined. Because of a stupid mistake I ruined the threads on
    the axle so I replaced the axle and driver unit (#10 in the exploded
    view), which I guess means that it is actually a SG-7C22 hub now.

    After that everything was fine for a while, but now I can't engage first
    and third gear. The wire is adjusted and it seems to move freely while
    changing gear, so I guess it is something inside the hub. Unfortunately
    I haven't been able to figure out how the gears work, so I don't know
    which parts are active in which gear. Which part should be replaced this
    time? Or is it time to get rid of the hub?

    I went to the Shimano Tech seminar at interbike. The tech there basically
    said you can take it apart to a certain point and then stop. If there are
    problems with the internals, part 1 in your diagram, just send it to shimano
    to have them look at it. What you may want to try is pulling the internals
    out of the shell. Then putting the shifting mechanism and the cog back on.
    Then working the shifter and cog to see if you can see which parts turn
    when you move the cog and the shifter is in 3rd gear.
    ----------------
    Alex

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