Re: Why no internal gears on Bianchi Castro Valley?

Discussion in 'Cycling Equipment' started by Sheldon Brown, Jan 12, 2006.

  1. David L. Johnson wrote:

    > I just took a Shimano Nexus 7-speed off of my commuter. This hub is, IMO,
    > less than ideal.


    What isn't?

    > The reliability is not sufficient to use on a commuter
    > that will be exposed to rain/snow/ice.
    >
    > Under strain, the shifter lever will sometimes rotate (backwards), which
    > screws up shifting. Once that happens, you risk gear skipping, which can
    > result in pain.


    I've sold a lot of these hubs, own 3 Nexi myself, a 7-speed and two
    8-speeds. I commuted on one of the 8-speeds today.

    I have never before heard of anybody having this problem with a Nexus
    hub. My guess is that there is something wrong with your installation,
    either:

    •You don't have the correct anti-rotation washers on the axle or

    •Your dropout slots have been damaged so that it no longer mates
    properly with the anti-rotation washers's tabs or

    •You have not properly lubricated and tightened the axle nuts or

    •You're running an excessively low sprocket ratio, thus applying too
    much torque to the hub.

    I must admit that I like the 8-speed model a LOT better than the
    7-speed, for reasons that are not entirely clear to me.

    It has become my favorite gear shifting system for situations that don't
    require an extremely wide gear range. Since I installed one on my old
    Raleigh International, that bike has become my favorite ride.

    (Just put up some new pix today:
    http://sheldonbrown.com/raleigh-international )

    Sheldon "Nexophile" Brown
    +---------------------------------------------------------------+
    | The man with a new idea is a Crank until the idea succeeds. |
    | . --Mark Twain |
    +---------------------------------------------------------------+
    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
     
    Tags:


  2. On Thu, 12 Jan 2006 22:35:26 -0500, Sheldon Brown wrote:

    > I have never before heard of anybody having this problem with a Nexus
    > hub. My guess is that there is something wrong with your installation,
    > either:
    >
    > •You don't have the correct anti-rotation washers on the axle or
    >

    I have what was there when I got it, only one anti-rotation washer, on the
    right side.

    •Your dropout slots have been damaged so that it no
    longer mates
    > properly with the anti-rotation washers's tabs


    It seems to be OK, but it is an old bike.

    > •You have not properly lubricated and tightened the axle nuts or


    I got them as tight as I could with a peanut-butter wrench.
    >
    > •You're running an excessively low sprocket ratio, thus applying too
    > much torque to the hub.


    Ah. That may have something to do with it. I have a 48 on the front, and
    a larger-than-standard sprocket in the back. That along with only one
    anti-rotation washer (but I understand they only came with one) might be
    enough to make a difference. I seem to recall that, with these sprockets,
    4th was less than 70 gear inches; maybe 67.

    > I must admit that I like the 8-speed model a LOT better than the
    > 7-speed, for reasons that are not entirely clear to me.


    Well, I never felt that the lower gears gave me enough added advantage; I
    suspect that the lower gears are not the most efficient; when efficiency
    drops to 80% or so, it can seem like a significantly higher gear than it
    is. I really do much prefer the bike now, with a single-speed freewheel.
    Simpler, no shifter, and no problems. It's a low enough gear for the
    commute, which is the bike's purpose in life.

    I am selling the hub to one of the other participants on this thread; I
    hope we're both happier that way.

    --

    David L. Johnson

    __o | "It doesn't get any easier, you just go faster." --Greg LeMond
    _`\(,_ |
    (_)/ (_) |
     
  3. "Sheldon Brown" <[email protected]> wrote in message
    news:[email protected]
    David L. Johnson wrote:

    > I just took a Shimano Nexus 7-speed off of my commuter. This hub is, IMO,
    > less than ideal.


    What isn't?

    > The reliability is not sufficient to use on a commuter
    > that will be exposed to rain/snow/ice.
    > Under strain, the shifter lever will sometimes rotate (backwards), which
    > screws up shifting. Once that happens, you risk gear skipping, which can
    > result in pain.


    I've sold a lot of these hubs, own 3 Nexi myself, a 7-speed and two
    8-speeds. I commuted on one of the 8-speeds today.

    I have never before heard of anybody having this problem with a Nexus
    hub. My guess is that there is something wrong with your installation,
    either:

    ..You don't have the correct anti-rotation washers on the axle or

    ..Your dropout slots have been damaged so that it no longer mates
    properly with the anti-rotation washers's tabs or

    ..You have not properly lubricated and tightened the axle nuts or

    ..You're running an excessively low sprocket ratio, thus applying too
    much torque to the hub.

    I must admit that I like the 8-speed model a LOT better than the
    7-speed, for reasons that are not entirely clear to me.

    It has become my favorite gear shifting system for situations that don't
    require an extremely wide gear range. Since I installed one on my old
    Raleigh International, that bike has become my favorite ride.

    (Just put up some new pix today:
    http://sheldonbrown.com/raleigh-international )
    Sheldon "Nexophile" Brown
    +---------------------------------------------------------------+
    | The man with a new idea is a Crank until the idea succeeds. |
    | . --Mark Twain |
    +---------------------------------------------------------------+

    Nice unique bike,
    Now is that considered a bar-end shifter or the Mark Twain shifter?
    -tom
     
  4. I observed:

    >>I have never before heard of anybody having this problem with a Nexus
    >>hub. My guess is that there is something wrong with your installation,
    >>either:
    >>
    >>•You don't have the correct anti-rotation washers on the axle or
    >>

    David L. Johnson replied:
    >
    > I have what was there when I got it, only one anti-rotation washer, on the
    > right side.


    It's better to use two, as these hubs are now supplied. Earlier
    versions did only come with one anti-rotation washer.

    >>•You have not properly lubricated and tightened the axle nuts or

    >
    >
    > I got them as tight as I could with a peanut-butter wrench.


    And had you lubricated the threads and the nut/washer interface?

    >>•You're running an excessively low sprocket ratio, thus applying too
    >>much torque to the hub.

    >
    >
    > Ah. That may have something to do with it. I have a 48 on the front, and
    > a larger-than-standard sprocket in the back. That along with only one
    > anti-rotation washer (but I understand they only came with one) might be
    > enough to make a difference. I seem to recall that, with these sprockets,
    > 4th was less than 70 gear inches; maybe 67.


    That's not so terribly low that it should cause a problem. My Nexus 8
    runs 52/18, and didn't slip even when I was using it on a tandem.
    >
    >>I must admit that I like the 8-speed model a LOT better than the
    >>7-speed, for reasons that are not entirely clear to me.

    >
    > Well, I never felt that the lower gears gave me enough added advantage;I
    > suspect that the lower gears are not the most efficient; when efficiency
    > drops to 80% or so, it can seem like a significantly higher gear than it
    > is.


    My perception of the efficience of these hubs is that they're nothing
    like that inefficient.

    When I first got my Nexus 7, it replaced a Sturmey-Archer FM 4-speed,
    and my perception was that the Nexus was notably more efficient. I
    never noticed any apparent difference in efficiency from one gear to
    another on the Nexi.

    > I really do much prefer the bike now, with a single-speed freewheel.
    > Simpler, no shifter, and no problems. It's a low enough gear for the
    > commute, which is the bike's purpose in life.


    That's dandy if you don't need the gears. Lately I've been needing
    gears more than I used to, for medical reasons...

    Sheldon "Neck's Us" Brown
    +-----------------------------------------------+
    | Many workmen |
    | Built a huge ball of masonry |
    | Upon a mountaintop. |
    | Then they went to the valley below, |
    | And turned to behold their work. |
    | "It is grand," they said; |
    | They loved the thing. |
    | |
    | Of a sudden, it moved: |
    | It came upon them swiftly; |
    | It crushed them all to blood. |
    | But some had opportunity to squeal. |
    | --Stephen Crane |
    +-----------------------------------------------+
    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
     
  5. On Fri, 13 Jan 2006 15:05:40 -0500, Sheldon Brown wrote:

    > And had you lubricated the threads and the nut/washer interface?


    The threads, yeah, but the nut/washer, no.

    > That's not so terribly low that it should cause a problem. My Nexus 8
    > runs 52/18, and didn't slip even when I was using it on a tandem.


    Well, I think I had a 48/20 or maybe 48/19, but the one anti-rotation
    washer probably makes that worse.

    > My perception of the efficience of these hubs is that they're nothing
    > like that inefficient.
    >

    I remember reading specs at some point, but can't find them now. At any
    rate, most of the gears had efficiencies in the 80%-90% range.

    --

    David L. Johnson

    __o | "A foolish consistency is the hobgoblin of little minds, adored
    _`\(,_ | by little statesmen and philosophers and divines." --Ralph Waldo
    (_)/ (_) | Emerson
     
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