gear question

Someone said:

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: sheldonbrown.comfreewheels.htmlOpen ↗

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 harriscyclery.comharriscyclery.comOpen ↗ Hard-to-find parts shipped Worldwide
captainbike.comcaptainbike.comOpen ↗ sheldonbrown.comsheldonbrown.comOpen ↗

Sheldon Brown said:

Someone said:

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: sheldonbrown.comfreewheels.htmlOpen ↗

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.

Sheldon Brown <[email hidden]> wrote: (snip OP).

Quoted message said:

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

Quoted post said:

Originally posted by Zog The Undenia

BSheldon Brown said:

Someone said:

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: sheldonbrown.comfreewheels.htmlOpen ↗

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. [/B]

74g.i. is 40T, 42T is 78g.i..

tcmedara said:

Sheldon Brown <[email hidden]> wrote: (snip OP).

Quoted message said:

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 harriscyclery.comharriscyclery.comOpen ↗ Hard-to-find parts shipped Worldwide
captainbike.comcaptainbike.comOpen ↗ sheldonbrown.comsheldonbrown.comOpen ↗

"Sheldon Brown" <[email hidden]> a écrit dans le message de :
"]news:[email hidden]...

Quoted message said:

tcmedara wrote: how do

Quoted message said:

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

I said:

Quoted message said:

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

Quel'qu'un inconnu a =E9crit:

Quoted message said:

I see a great number of Miche cassettes - we Europeans just can't maste=

r

Quoted message said:

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

Quoted message said:

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: sheldonbrown.comgain.htmlOpen ↗

+----------------------------------------------------------+
| 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 harriscyclery.comharriscyclery.comOpen ↗ Hard-to-find parts
shipped Worldwide captainbike.comcaptainbike.comOpen ↗ sheldonbrown.comsheldonbrown.comOpen ↗

Sheldon Brown said:

(snip)

Quoted message said:

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

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

...

Quoted message said:

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.

Quoted message said:

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.

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?

(ian) said:

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