chainwheel cogs need a dentist

Discussion in 'UK and Europe' started by Antony, May 23, 2004.

  1. Antony

    Antony Guest

    Hi, I've not owned a bike for a long time and never have done anything
    other than basic maintenance. Yesterday I bought a £20 hack to get
    about on. It's just a bog-standard mtb-style thing with 15 gears, but
    needs a bit of work. It needs a new chainwheel as teeth are missing so
    I have a few questions . . .

    Do I have to replace chainwheel, rear cogs and chain together?
    What is involved in replacing the chainwheel?
    Are there standard fittings (screwthread sizes etc) for
    chainwheel/bottom bracket etc?
    What should I expect to pay for a steel chainwheel and rear cogs?
    Where's the best place to get the parts?
    Any good sources on the net?

    TIA

    Antony
     
    Tags:


  2. See below....

    HTH

    Huw Francis

    "Antony" <[email protected]> wrote in message
    news:[email protected]
    > Hi, I've not owned a bike for a long time and never have done anything
    > other than basic maintenance. Yesterday I bought a £20 hack to get
    > about on. It's just a bog-standard mtb-style thing with 15 gears, but
    > needs a bit of work. It needs a new chainwheel as teeth are missing so
    > I have a few questions . . .
    >
    > Do I have to replace chainwheel, rear cogs and chain together?

    In general the chain wears out first, then the "rear cogs", then the
    chainrings. But if a chainring has teeth missing then it hasn't worn out,
    it's been dropped or hit a kerb or something, so you *might* get away with
    just a new outer chainring
    > What is involved in replacing the chainwheel?

    You *might* get lucky and be able to replace just the big chainring but,
    more likely, you'll need a complete chainset, including both cranks.
    > Are there standard fittings (screwthread sizes etc) for
    > chainwheel/bottom bracket etc?

    Yup - you'll probably need a new chainset (ie 3 rings plus both cranks)
    which you can replace yourself (if you have a crank-removing tool) or you
    can get your LBS to do it for you at minimal cost - it takes about 5 minutes
    with the correct tools
    > What should I expect to pay for a steel chainwheel and rear cogs?

    No idea
    > Where's the best place to get the parts?

    Your LBS if you want them to fit it for you. Otherwise, Wiggle or Settle
    Cycles or Edinburgh Bicycle Co or Spa Cycles or St John St Cycles or.....
    > Any good sources on the net?

    (see above)
    >
    > TIA
    >
    > Antony
     
  3. Tony Raven

    Tony Raven Guest

    Antony wrote:
    >
    > It needs a new chainwheel as teeth are missing so
    >


    Before you go any further, some modern chainwheels can give the impression of
    missing teeth. Some teeth are deliberately made low profile to assist
    changing gear. I suspect its that rather than teeth missing - the latter
    being somewhat difficult to achieve.

    Tony
     
  4. Simon Brooke

    Simon Brooke Guest

    in message <[email protected]>, Antony
    ('[email protected]') wrote:

    > Hi, I've not owned a bike for a long time and never have done anything
    > other than basic maintenance. Yesterday I bought a £20 hack to get
    > about on. It's just a bog-standard mtb-style thing with 15 gears, but
    > needs a bit of work. It needs a new chainwheel as teeth are missing so
    > I have a few questions . . .
    >
    > Do I have to replace chainwheel, rear cogs and chain together?


    You don't have to but it's usually better to, particularly if they are
    in poor conditions - which yours sound as if they are.

    > What is involved in replacing the chainwheel?


    The chainrings usually bolt onto a 'spider' on the drive-side crank.
    There are, unfortunately, a number of different patterns of spider -
    the five-spoke ones and two different patterns of four-spoke ones are
    quite common but there are others.

    However, if they're all fscked, it may be more straightforward to get a
    new chainset (i.e. cranks with chainrings already fitted) which you can
    get for twenty quid upwards

    > Are there standard fittings (screwthread sizes etc) for
    > chainwheel/bottom bracket etc?


    Most bottom brackets these days are the square taper type. There are a
    few splined ones around but they rare. Having said that where the
    chainset sits laterally on the taper varies... so you can have lots of
    fun with this.

    There's what's called the 'pitch circle diameter' - this is the diameter
    of the circle which passes through the centre of the bolt holes.
    Usually the big and middle chainrings use the same bolt holes (often
    110mm PCD) and the small ring uses different boltholes. There's a
    useful chart here:
    <URL:http://www.sjscycles.com/boltcirclediameter.asp>

    > What should I expect to pay for a steel chainwheel and rear cogs?


    Between a fiver and about fifty quid for the chain ring, depending how
    posh it is. The problem with your five speed rear cogs, they're
    probably a 'freewheel' rather than a modern cassette. About a tenner
    for a reasonable basic one. You won't get a really expensive one,
    because the new bikes are all on cassettes. Note that freewheels are
    famous for being a complete bugger to remove.

    > Where's the best place to get the parts?


    If you've got a good Local Bike Shop it may be worth frequenting because
    it is a source of high quality advice. It will be more expensive
    than...

    > Any good sources on the net?


    Plenty.

    <URL:http://www.sjscycles.com/>
    <URL:http://www.chainreactioncycles.com/>
    <URL:http://www.wiggle.co.uk/>
    <URL:http://www.edinburgh-bicycle.co.uk/>

    --
    [email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

    ;; lovely alternative to rice.
     
  5. Antony

    Antony Guest

    "Tony Raven" <[email protected]> wrote in message news:<[email protected]>...
    > Antony wrote:
    > >
    > > It needs a new chainwheel as teeth are missing so
    > >

    >
    > Before you go any further, some modern chainwheels can give the impression of
    > missing teeth. Some teeth are deliberately made low profile to assist
    > changing gear. I suspect its that rather than teeth missing - the latter
    > being somewhat difficult to achieve.
    >
    > Tony


    After a brief inspection this evening . . . I still think I'm missing
    a few teeth but that's not the problem. It seems to be a stiff
    chainlink, giving the impression of the chain jumping. It seemed to be
    pulling the derailleur and making a right noise when it went thru it.
    I WD40-ed the chain, bent the offending link around a bit and it's a
    lot better. Prob time for a service in the near future tho.

    ta for the help guys

    Antony
     
  6. Pete Biggs

    Pete Biggs Guest

    Antony wrote:

    > After a brief inspection this evening . . . I still think I'm missing
    > a few teeth but that's not the problem. It seems to be a stiff
    > chainlink, giving the impression of the chain jumping. It seemed to be
    > pulling the derailleur and making a right noise when it went thru it.
    > I WD40-ed the chain, bent the offending link around a bit and it's a
    > lot better. Prob time for a service in the near future tho.


    Here's some instructions if the link stiffens up again (or is still not
    quite right) :

    www.parktool.com/repair_help/FAQtchan.shtml

    ~PB
     
  7. Simon Brooke

    Simon Brooke Guest

    in message <[email protected]>, Antony
    ('[email protected]') wrote:

    > After a brief inspection this evening . . . I still think I'm missing
    > a few teeth but that's not the problem. It seems to be a stiff
    > chainlink, giving the impression of the chain jumping. It seemed to be
    > pulling the derailleur and making a right noise when it went thru it.
    > I WD40-ed the chain, bent the offending link around a bit and it's a
    > lot better. Prob time for a service in the near future tho.


    WD40 will get your chain moving, but then it will evaporate off leaving
    your chain unlubricated and it will wear out very fast. Get some proper
    chain lube like chainsaw oil or Finish Line Cross Country.

    --
    [email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

    ;; When all else fails, read the distractions.
     
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