gear question

Discussion in 'Cycling Equipment' started by Ian, Jan 27, 2004.

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  1. Ian

    Ian Guest

    have just been given a mountain bike by a friend and have been cycling to work. it's quite a flat
    journey but i find i am constantly on the big wheel of the front mech.

    i calculated the ratio and with a max ratio of 3:1 i need to change it to get up from 74"
    towards 90"+.

    i'm thinking if the smallest hub on the rear mech had less teeth this would do it - currently has
    14. does anyone know if it is possible to change just one sprocket to achieve this or does more
    need changing.

    any advice appreciated.

    Ian
     
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  2. Someone wrote:

    > have just been given a mountain bike by a friend and have been cycling to work. it's quite a flat
    > journey but i find i am constantly on the big wheel of the front mech.
    >
    > i calculated the ratio and with a max ratio of 3:1 i need to change it to get up from 74"
    > towards 90"+.
    >
    > i'm thinking if the smallest hub on the rear mech had less teeth this would do it - currently has
    > 14. does anyone know if it is possible to change just one sprocket to achieve this or does more
    > need changing.

    Your bike has an old-fashioned thread-on freewheel, which rather limits the options.

    Replacing just a single rear sprockets is not practical, but a whole freewheel cluster of 6 or 7
    sprockets is not all that expensive, typically about US$20.

    The smallest size commonly available in thread-on freewheels is 13 teeth, but there is one Shimano
    7-speed model that goes from 11-34.

    See: http://sheldonbrown.com/harris/freewheels.html

    Depending on the specific hardware on your bike, it might be better to go to bigger chainrings in
    front instead.

    Sheldon "Gears" Brown +------------------------------------------+
    | Genius is one per cent inspiration and | ninety-nine per cent perspiration. |
    |. --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 wrote:

    > Someone wrote:
    >
    >> have just been given a mountain bike by a friend and have been cycling to work. it's quite a flat
    >> journey but i find i am constantly on the big wheel of the front mech.
    >>
    >> i calculated the ratio and with a max ratio of 3:1 i need to change it to get up from 74"
    >> towards 90"+.
    >>
    >> i'm thinking if the smallest hub on the rear mech had less teeth this would do it - currently has
    >> 14. does anyone know if it is possible to change just one sprocket to achieve this or does more
    >> need changing.
    >
    >
    > Your bike has an old-fashioned thread-on freewheel, which rather limits the options.
    >
    > Replacing just a single rear sprockets is not practical, but a whole freewheel cluster of 6 or 7
    > sprockets is not all that expensive, typically about US$20.
    >
    > The smallest size commonly available in thread-on freewheels is 13 teeth, but there is one Shimano
    > 7-speed model that goes from 11-34.
    >
    > See: http://sheldonbrown.com/harris/freewheels.html
    >
    > Depending on the specific hardware on your bike, it might be better to go to bigger chainrings in
    > front instead.

    Or learn to pedal faster ;-) 42 x 14 is a pretty impressive cruising gear if you pedal at 100rpm
    (that's 23mph on 26" wheels)

    Spin, don't push.
     
  4. Tcmedara

    Tcmedara Guest

    Sheldon Brown <[email protected]> wrote: (snip OP).
    >
    > Your bike has an old-fashioned thread-on freewheel, which rather limits the options.
    >
    I'll probably feel stupid when I see the answer, but here goes.....I re-read the OP several times,
    but remain confused. Excuse my ignorance, but how do you know it's a thread-on freewheel rather than
    a cassette?

    Humbly,

    Tom
     
  5. meb

    meb New Member

    Joined:
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    74g.i. is 40T, 42T is 78g.i..
     
  6. tcmedara wrote:

    > Sheldon Brown <[email protected]> wrote: (snip OP).
    >
    >>Your bike has an old-fashioned thread-on freewheel, which rather limits the options.
    >>
    >
    > I'll probably feel stupid when I see the answer, but here goes.....I re-read the OP several times,
    > but remain confused. Excuse my ignorance, but how do you know it's a thread-on freewheel rather
    > than a cassette?

    Onaccounta his top sprocket is a 14.

    While 14-top cassettese exist, they're very, very rare, probably not more than one in 100,000.

    14-top freewheels are very common on cheap bikes, and many of the bottom of the line bikes mate
    them with cranksets that are inappropriate for such a low top gear. I surmise this is the situation
    of the O.P.

    Sheldon "Inferences" Brown +-----------------------------------------------------+
    | Life is the art of drawing sufficient conclusions | from insufficient premises. --Samuel Butler |
    +-----------------------------------------------------+ 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
     
  7. Smmb

    Smmb Guest

    "Sheldon Brown" <[email protected]> a écrit dans le message de :
    news:[email protected]...
    > tcmedara wrote: how do
    > > you know it's a thread-on freewheel rather than a cassette?
    >
    > Onaccounta his top sprocket is a 14.
    >
    > While 14-top cassettese exist, they're very, very rare, probably not more than one in 100,000.

    I see a great number of Miche cassettes - we Europeans just can't master those 11 and 12 tooth
    starters like you tough guys. Not to mention, that 16 is a common starter for juniors, which we have
    plenty of. Bad idea to hurt young limbs, just to display chest hairs (if any) ...
    --

    Bonne route,

    Sandy Paris FR
     
  8. I wrote:

    >>While 14-top cassettese exist, they're very, very rare, probably not more than one in 100,000.

    Quel'qu'un inconnu a =E9crit:

    > I see a great number of Miche cassettes - we Europeans just can't maste=
    r
    > those 11 and 12 tooth starters like you tough guys. Not to mention, that 16 is a common starter
    > for juniors, which we have plenty of. Bad idea to hurt young limbs, just to display chest hairs (=
    if
    > any) ...

    I'd guess you're speaking of _racing_ style bikes. I was speaking of=20 the general bicycle
    population, and, in particular cheap mountain style=20 bikes, such as the one the original poster
    had been given.

    The 11 tooth sprockets have nothing to do with toughness or chest hair.=20
    They're part of the misguided "microdrive" system where the drivetrain =

    is shrunken. They are commonly used with chainrings up to 42 teeth, or=20 sometimes 44.

    The resulting top gear is not particularly high at all, for example,=20
    42/11, with 38-559 (26 x 1.5) tires gives a top gain ratio* of only 7.1. (that's 7.6 meters,
    95 inches.)

    I think you'll agree that's not an unreasonably high gear for a bike=20 with three chainrings.
    Indeed, many people, myself included, would find =

    it quite unsatisfactory if there were hills to be descended.

    Sheldon "Doesn't Like To Coast" Brown

    *Gain ratio is a new system for measuring bicycle gearing. It is explained in detail on my Web site
    at: http://sheldonbrown.com/gain.html

    +----------------------------------------------------------+
    | And what are all these mysteries to me, | Whose life is full of indices and surds? | x^2 +
    | 7x + 53 |
    | =3D 11/3 --Lewis Carroll |
    +----------------------------------------------------------+ 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
     
  9. Tcmedara

    Tcmedara Guest

    Sheldon Brown <[email protected]> wrote:
    >
    (snip)
    >
    > Onaccounta his top sprocket is a 14.
    >
    > While 14-top cassettese exist, they're very, very rare, probably not more than one in 100,000.
    >
    > 14-top freewheels are very common on cheap bikes, and many of the bottom of the line bikes mate
    > them with cranksets that are inappropriate for such a low top gear. I surmise this is the
    > situation of the O.P.

    Okay, I don't feel all that stupid now. In retrospect, it seems obvious, as I don't recall ever
    seeing a cassette that tops out at 14 (with due regard to our Euro-racing brethren). As basic as
    that sounds, I wouldn't have suspected.

    Thanks fer the skoolin'

    Tom
     
  10. David Kerber

    David Kerber Guest

    In article <[email protected]>, [email protected] says...

    ...

    > The resulting top gear is not particularly high at all, for example,
    > 42/11, with 38-559 (26 x 1.5) tires gives a top gain ratio* of only 7.1. (that's 7.6 meters, 95
    > inches.)
    >
    > I think you'll agree that's not an unreasonably high gear for a bike with three chainrings.
    > Indeed, many people, myself included, would find it quite unsatisfactory if there were hills to be
    > descended.

    Indeed. I use my 52x11 top gear lots more than I do my 30x32 granny. Actually, that should say
    "did"; I swapped the 11-32 cassette for an 11- 23 for around-town riding, and I use the 30x23
    occasionally, probably about the same as the 52x11.

    >
    > Sheldon "Doesn't Like To Coast" Brown

    Me, neither.

    ....

    --
    Dave Kerber Fight spam: remove the ns_ from the return address before replying!

    REAL programmers write self-modifying code.
     
  11. Ian

    Ian Guest

    thanks for all the help folks, much appreciated. have seen the shimano 11-32 on www.wiggle.co.uk for
    about £14.99

    is it an easy job to fit the new one on?
     
  12. Rick Onanian

    Rick Onanian Guest

    On 29 Jan 2004 02:43:49 -0800, [email protected] (ian) wrote:
    >thanks for all the help folks, much appreciated. have seen the shimano 11-32 on www.wiggle.co.uk
    >for about £14.99
    >
    >is it an easy job to fit the new one on?

    Yes, but removing the old one requires a special tool. The new one just screws on by hand.
    --
    Rick Onanian
     
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