7/8/9 speed upgrading on MTB

Discussion in 'UK and Europe' started by James Annan, Jan 26, 2003.

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  1. James Annan

    James Annan Guest

    Time to update an old bike drivetrain, for various reasons.

    The bike is about 6 years old with 135mm rear spacing and a shimano freehub. It was actually
    previously equipped with a 7 speed shimano cassette using campag 8 speed ergo shifters and rear
    derailler, which is a perfect match (5mm per shift). Back in those days I thought I knew about the
    compatibility of the different options...but that was before 9 speed (before _I_ was interested in 9
    speed, at least).

    I'm now trying to put on a new 9 speed gripshift system. A 9 speed cassette doesn't seem to fit on
    the hub but I can put on 8 of the cogs (actually the biggest 7 from a 9-speed cassette and then a
    12T with lockring from an old 8). I've got new gripshifters and a matching rear derailleur (I've
    been told the front shimano derailleur should work ok with non-indexed shifting, it can be changed
    later if it causes trouble).

    AIUI this ought to work fine as it's only the last 12-14 jump which may be fractionally incorrect.
    I'm not really all that fussed about the 9th gear, since (a) it's only an 11T for a non-racing and
    non-road-riding MTB which already sports a 50T front chainring (b) it's not my bike! But if I did
    want to change to a full 9 speed, would it be difficult? Obviously it needs a few freehub, and maybe
    respacing the axle, or is this not necessary?

    Thanks,

    James
     
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  2. James Annan <[email protected]> wrote in message
    news:[email protected]...
    > Time to update an old bike drivetrain, for various reasons.
    >
    > The bike is about 6 years old with 135mm rear spacing and a shimano freehub. It was actually
    > previously equipped with a 7 speed shimano cassette using campag 8 speed ergo shifters and rear
    > derailler, which is a perfect match (5mm per shift). Back in those days I thought I knew about the
    > compatibility of the different options...but that was before 9 speed (before _I_ was interested in
    > 9 speed, at least).
    >
    > I'm now trying to put on a new 9 speed gripshift system. A 9 speed cassette doesn't seem to fit on
    > the hub but I can put on 8 of the cogs (actually the biggest 7 from a 9-speed cassette and then a
    > 12T with lockring from an old 8). I've got new gripshifters and a matching rear derailleur (I've
    > been told the front shimano derailleur should work ok with non-indexed shifting, it can be changed
    > later if it causes trouble).
    >
    > AIUI this ought to work fine as it's only the last 12-14 jump which may be fractionally incorrect.
    > I'm not really all that fussed about the 9th gear, since (a) it's only an 11T for a non-racing and
    > non-road-riding MTB which already sports a 50T front chainring (b) it's not my bike! But if I did
    > want to change to a full 9 speed, would it be difficult? Obviously it needs a few freehub, and
    > maybe respacing the axle, or is this not necessary?
    >

    A new wheel (hub) is required I'm afraid - the hub is different for 8 & 9 speed as opposed to 7
    speed, no respacing however - an 8 speed cassette is spaced the same as a 7 speed and is therefore
    wider by 1 ring - a 9 speed cassette is the same width as an 8 speed but with closer spacings. 8 and
    9 speed hubs are the same.

    You might have fun with running the narrow 9 speed chain on an 8 speed 12T ring - I suspect it'll
    slip a bit but this may not be an issue.

    Russ
     
  3. "Russell Pinder" <[email protected]> wrote in message
    > > AIUI this ought to work fine as it's only the last 12-14 jump which may be fractionally
    > > incorrect. I'm not really all that fussed about the 9th gear, since (a) it's only an 11T for a
    > > non-racing and non-road-riding MTB which already sports a 50T front chainring (b) it's not my
    > > bike! But if I did want to change to a full 9 speed, would it be difficult? Obviously it needs a
    > > few freehub, and maybe respacing the axle, or is this not necessary?
    > >
    > A new wheel (hub) is required I'm afraid - the hub is different for 8 & 9 speed as opposed to 7
    > speed, no respacing however - an 8 speed cassette is spaced the same as a 7 speed and is therefore
    > wider by 1 ring - a 9 speed cassette is the same width as an 8 speed but with closer spacings. 8
    > and 9 speed hubs are the same.

    I've just upgraded from 7-9 speed on my emptyb, and I was able to keep my rear hub, I just had my
    wheel redished, and had to move the spacers on the axle (and a new freehub, natch) and it's
    running fine. The axle now only fills about 2/3s of the drops, but with QRs I believe they don't
    need to be fully there (see what Sheldon says about using this to enable him to build a fixer with
    vertical dropouts)

    Take it into your lbs and see if they can re-dish it.

    E
     
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