French cottered crank singlespeed conversion?

Discussion in 'Road Cycling' started by Luigi de Guzman, Feb 8, 2006.

  1. I'm delurking to post this.

    Say I've got an old French road bike that I want to convert to a
    singlespeed (or, more probably, a three-speed). It has a double chainring
    with cottered cranks.

    Ideal chainline is probably on the inner chainring. Conceivably, I could
    just leave the outer chainring on there...but if I decided to remove it,
    I'd have to remove the crankarm and use stack bolts to space everything
    out correctly--right?

    Anyway, my question is: is it worth doing this? It's French cottered
    crank--so my odds of finding a new cotter pin are about nil, I'm guessing.

    -Luigi
     
    Tags:


  2. Paul Hobson

    Paul Hobson Guest

    Luigi de Guzman wrote:
    > I'm delurking to post this.
    >
    > Say I've got an old French road bike that I want to convert to a
    > singlespeed (or, more probably, a three-speed). It has a double chainring
    > with cottered cranks.
    >
    > Ideal chainline is probably on the inner chainring. Conceivably, I could
    > just leave the outer chainring on there...but if I decided to remove it,
    > I'd have to remove the crankarm and use stack bolts to space everything
    > out correctly--right?


    Shorter chainring bolts or spaces would do the trick, yes.

    > Anyway, my question is: is it worth doing this? It's French cottered
    > crank--so my odds of finding a new cotter pin are about nil, I'm guessing.


    Cotter pins aren't that hard to find. The bigger LBS's around Atlanta
    have them. What I'd look into is buying a new spindle for your cup.cone
    bottome bracket so you can have a new standard square taper cranks.
    That maybe be a bit out of budget. In that case, just leave the outer
    ring or get some spacers.
    hope this helps/hope I'm not wrong/an idiot.
    \\paul

    --
    Paul M. Hobson
    Georgia Institute of Technology
    ..:change the f to ph to reply:.
     
  3. On Wed, 08 Feb 2006 23:17:41 -0500, Paul Hobson wrote:
    > Cotter pins aren't that hard to find. The bigger LBS's around Atlanta
    > have them. What I'd look into is buying a new spindle for your cup.cone
    > bottome bracket so you can have a new standard square taper cranks.
    > That maybe be a bit out of budget. In that case, just leave the outer
    > ring or get some spacers.
    > hope this helps/hope I'm not wrong/an idiot.
    > \\paul


    So, wait, sorry if I'm being thick here--

    But is there any way of getting the chainring off without having to remove
    the crank-arm?

    -L
     
  4. On Thu, 09 Feb 2006 00:25:47 -0500, Luigi de Guzman wrote:

    > But is there any way of getting the chainring off without having to remove
    > the crank-arm?


    I guess that depends on the crank design, but most indeed do come off
    without having to remove the crank arm. A picture (pointer to, not posted
    here) would help.

    --

    David L. Johnson

    __o | A mathematician is a machine for turning coffee into theorems.
    _`\(,_ | -- Paul Erdos
    (_)/ (_) |
     
  5. mark

    mark Guest

    "Luigi de Guzman" wrote ...
    > I'm delurking to post this.
    >
    > Say I've got an old French road bike that I want to convert to a
    > singlespeed (or, more probably, a three-speed). It has a double chainring
    > with cottered cranks.
    >
    > Ideal chainline is probably on the inner chainring. Conceivably, I could
    > just leave the outer chainring on there...but if I decided to remove it,
    > I'd have to remove the crankarm and use stack bolts to space everything
    > out correctly--right?
    >
    > Anyway, my question is: is it worth doing this? It's French cottered
    > crank--so my odds of finding a new cotter pin are about nil, I'm guessing.
    >
    > -Luigi


    IIRC, it's theoretically possible to remove the chainrings on old French
    cottered steel cranks. As I recall, though, they were usually bolted down so
    tightly that you would round off the bolts before you got them off. At least
    that was the case with the Motobecane 10 speed I had in high school.
    --
    mark
     
  6. "Luigi de Guzman" <[email protected]> wrote in message
    news:p[email protected]
    > I'm delurking to post this.
    >
    > Say I've got an old French road bike that I want to convert to a
    > singlespeed (or, more probably, a three-speed). It has a double chainring
    > with cottered cranks.
    >
    > Ideal chainline is probably on the inner chainring. Conceivably, I could
    > just leave the outer chainring on there...but if I decided to remove it,
    > I'd have to remove the crankarm and use stack bolts to space everything
    > out correctly--right?
    >
    > Anyway, my question is: is it worth doing this? It's French cottered
    > crank--so my odds of finding a new cotter pin are about nil, I'm guessing.
    >
    > -Luigi


    It should not be a big issue to get the cottered crank off so you can mess
    with the chainrings.
    http://www.sheldonbrown.com/cotters.html goes into how to remove one for
    maintenance.
    You really probably need to regrease the bottom bracket bearings anyway.
     
  7. innamaze

    innamaze Guest

    it bears mentioning that you are using a french bike ....the french do
    everything backwards and in their own sizes...their bottom brackets and
    such are unique, and what is now standard won't work, you may wish to
    leave the outerchainring alone....you could file off the teeth and use
    it as a chainguard however, and remove the front derailluer
     
  8. Dane Buson

    Dane Buson Guest

    Luigi de Guzman <[email protected]> wrote:
    > I'm delurking to post this.
    >
    > Say I've got an old French road bike that I want to convert to a
    > singlespeed (or, more probably, a three-speed). It has a double chainring
    > with cottered cranks.
    >
    > Ideal chainline is probably on the inner chainring. Conceivably, I could
    > just leave the outer chainring on there...but if I decided to remove it,
    > I'd have to remove the crankarm and use stack bolts to space everything
    > out correctly--right?


    Well, the alternative I suggest is to grind off the teeth from the outer
    chainring. The outer ring would then act as a bashguard and help keep
    grease marks off your pants/leg. Then you wouldn't have to worry about
    fiddling with spacers or getting new chainring bolts.

    --
    Dane Buson - [email protected]
    "Benson, you are so free of the ravages of intelligence"
    -- Time Bandits
     
  9. Dane Buson

    Dane Buson Guest

    Luigi de Guzman <[email protected]> wrote:
    >
    > But is there any way of getting the chainring off without having to remove
    > the crank-arm?


    Doubles you *usually* can. If it was the inner ring of a triple you'd
    have to take off the crank.

    --
    Dane Buson - [email protected]
    "Benson, you are so free of the ravages of intelligence"
    -- Time Bandits
     
  10. Tom Keats

    Tom Keats Guest

    In article <[email protected]>,
    "Earl Bollinger" <[email protected]> writes:

    > It should not be a big issue to get the cottered crank off so you can mess
    > with the chainrings.
    > http://www.sheldonbrown.com/cotters.html goes into how to remove one for
    > maintenance.


    The first trick, though, is to have a replacement cotter pin handy in case
    the original's threaded end becomes gibbled during removal, which has
    been known to occur despite the utmost care being taken. Having such a
    replacement is dependent on finding a LBS that has a selection of cotter
    pins /including/ ones having the exact dimensions needed. So the second
    trick is to have a sample to compare with or measure at the bike shop.
    But if you remove a cotter pin, you run the risk of wrecking it and then
    not being able to get a replacement.

    > You really probably need to regrease the bottom bracket bearings anyway.


    This might be one case where installing an oil cap (a la Raleigh 3-speed)
    would be expedient.


    cheers,
    Tom

    --
    -- Nothing is safe from me.
    Above address is just a spam midden.
    I'm really at: tkeats [curlicue] vcn [point] bc [point] ca
     
  11. Tom Keats

    Tom Keats Guest

    In article <[email protected]>,
    [email protected] (Tom Keats) writes:

    > Having such a
    > replacement is dependent on finding a LBS that has a selection of cotter
    > pins /including/ ones having the exact dimensions needed.


    If you're lucky enough to find a bike shop that has cotter pins,
    chances are they'll have an array of 'em in every size & taper
    except the one you need.


    cheers,
    Tom

    --
    -- Nothing is safe from me.
    Above address is just a spam midden.
    I'm really at: tkeats [curlicue] vcn [point] bc [point] ca
     
  12. trg

    trg Guest

    "innamaze" <[email protected]> a √©crit dans le message de news:
    [email protected]...
    > it bears mentioning that you are using a french bike ....the french do
    > everything backwards and in their own sizes...their bottom brackets and
    > such are unique, and what is now standard won't work, you may wish to
    > leave the outerchainring alone....you could file off the teeth and use
    > it as a chainguard however, and remove the front derailluer
    >


    What are you talking about? It's the rest of the world that's backwards.
     
  13. innamaze

    innamaze Guest

    pardon!!! I rode motobecanes for many years and loved the bikes, and
    it was only after I went to a different brand I found everyone else
    shifted the opposite direction, which caused a lot of missed gears for
    a while as I adapted to "the rest of the world" My use of the word
    "backwards" was perhaps not as appropriate as say "quirky"or "in
    reverse" hope no offense was taken, I forgot for a moment how far
    these notes travel....inna
     
  14. Yes, keeping the outer ring on as a guard is a good alternative, and
    solves a bunch of issues. I did this for my hybrid bike, though I just
    crudely sawed off the outer ring's teeth instead of grinding:

    http://drumbent.com/hybrid.html (scroll towards bottom of page)

    Mark
     
  15. In my experience almost all new cotter pins have to be slightly
    (sometimes heavily) shaped to fit. But since they're of a fairly soft
    alloy one can easily do this with a file.

    Mark
     
  16. Dane Buson

    Dane Buson Guest

    [email protected] wrote:
    > Yes, keeping the outer ring on as a guard is a good alternative, and
    > solves a bunch of issues. I did this for my hybrid bike, though I just
    > crudely sawed off the outer ring's teeth instead of grinding:
    >
    > http://drumbent.com/hybrid.html (scroll towards bottom of page)


    See, that's a classic amateur mistake. You should have used that as
    an excuse to buy an angle grinder. Mmmmm, angle grinder.

    --
    Dane Buson - [email protected]
    "Our wines leave you nothing to hope for."
    -On the Menu of a Swiss Restaurant
     
  17. innamaze

    innamaze Guest

    ah yes, the second best thing to riding ones bike is getting all the
    specialized tools required to fix it...and I do have a great collection
    now...
     
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