Sprockets for AW3 hub and 3/32 chain?

Discussion in 'Cycling Equipment' started by Andrew Webster, Jul 10, 2003.

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  1. I have just fitted a double chainset to my Brompton with Sturmey Archer AW3 rear gears.

    The old chain (1/8") clanked a lot with the new chainset so I put a standard 3/32 chain on which
    slipped like mad on the rear sprocket.

    New rear sprocket needed clearly, but I can't source a 3/32 sprocket for a Sturmey Archer hub.

    Q1. Does such a sprocket exist.

    Q2. If not should I use the 3/32 chain or will the rear sprocket prise it apart. Would I be better
    off with a new 1/8 chain?

    In the meanwhile I have filed down an old Shimano splined sprocket. Runs well, but I am doubtful
    that this will last as there seems to be precious little engagement with the three cut outs on the
    hub centre. (If the three little dimples work on this hub, why does Shimano need all those splines?)

    Q3. Is this approach a good idea? Any experiences?

    Q4. Any other approaches to this problem welcome.

    (Just for completeness I wanted a lower gearing for steep hills, I now have a 28/48 at the front and
    the AW3 on the back giving a fairly evenly spaced gears over a wide range, 26-79 inches- albeit with
    fairly large gaps).

    Andrew Webster
     
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  2. Andrew Webster wrote:

    > I have just fitted a double chainset to my Brompton with Sturmey Archer AW3 rear gears.
    >
    > The old chain (1/8") clanked a lot with the new chainset so I put a standard 3/32 chain on which
    > slipped like mad on the rear sprocket.
    >
    > New rear sprocket needed clearly, but I can't source a 3/32 sprocket for a Sturmey Archer hub.
    >
    > Q1. Does such a sprocket exist.

    Sturmey-Archer doesn't do that size, but Shimano and SRAM do. Shimano and SRAM sprockets fit just
    fine on Sturmey-Archer hubs. Not all sizes are available, and you neglected to mention which size
    you desire.

    > Q2. If not should I use the 3/32 chain or will the rear sprocket prise it apart. Would I be better
    > off with a new 1/8 chain?

    For your double chainset, you're probably better off with 3/32.

    > In the meanwhile I have filed down an old Shimano splined sprocket. Runs well, but I am doubtful
    > that this will last as there seems to be precious little engagement with the three cut outs on the
    > hub centre. (If the three little dimples work on this hub, why does Shimano need all those
    > splines?)
    >
    > Q3. Is this approach a good idea? Any experiences?

    Yes, this generally works fine. I've got my kids' tandem set up that way.
    http://sheldonbrown.org/images/kkt.jpeg

    In fact, you can put two modified Shimano cassette sprockets on your AW...since you already have a
    rear derailer, you might as well make it work!

    Sheldon "Hybrid Gearing" Brown +------------------------------------------+
    | To invent, you need a good imagination | and a pile of junk. --Thomas Edison |
    +------------------------------------------+ 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
     
  3. Sheldon Brown <[email protected]> wrote in message
    news:<[email protected]>...
    > Andrew Webster wrote:
    >

    > Sturmey-Archer doesn't do that size, but Shimano and SRAM do. Shimano and SRAM sprockets fit just
    > fine on Sturmey-Archer hubs. Not all sizes are available, and you neglected to mention which size
    > you desire.

    Thanks for this, didn't know they were the same fitting. I'm replacing a 13 tooth.

    > In fact, you can put two modified Shimano cassette sprockets on your AW...since you already have a
    > rear derailer, you might as well make it work!

    Well, no, the Brompton has a chain tensioner at the back to accomodate changes in length wile
    folding (and, incidentally for the extra chainring I have fitted), but not a derailleur as such(it
    has no in and out movement). This is a good idea, though, I'll try fitting a derailleur at the back
    with another sprocket - it could fill in some of the big gaps between the gears (the shift pattern
    might take a bit of learning though).

    Andrew Webster
     
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