Jockey wheels

Alan Walker said:

Bicycle derailleurs have two small wheels on the chain tension cage. They are normally called
"jockey wheels" in the bicycle world. In my experience, wheels performing a similar function in
other types of machinery are usually called "idler wheels" or "tension wheels".

Quoted message said:

Am I correct about the usage in general engineering? If so, why a different term for the bicycle
industry? Is the term "jockey wheel" used in other industries?

Quoted message said:

Perhaps I should consult "The Dancing Chain"!

Not to worry. In bicycling, many terms are odd and even mis-applied. This is probably beyond repair
because people love their jargon and don't relinquish it freely. Take rims, for instance. There are
rims with eyelets, ones with sockets and eyelets and plain drilled rims. Just the same, we hear of
"double eyelets" a design hard to visualize. Rear wheels don't have a left and right side, but
rather "drive-side" and "non-drive-side".

Jobst Brandt [email hidden]

(Alan Walker) said:

Bicycle derailleurs have two small wheels on the chain tension cage. They are normally called
"jockey wheels" in the bicycle world. In my experience, wheels performing a similar function in
other types of machinery are usually called "idler wheels" or "tension wheels".

Am I correct about the usage in general engineering? If so, why a different term for the bicycle
industry? Is the term "jockey wheel" used in other industries?

Perhaps I should consult "The Dancing Chain"!

AW

I always thought that the upper wheel (nearest the cogs or whatever the correct term may be) is the
jockey or guide wheel/pulley, and the lower wheel is the tension wheel/pulley. I assumed that this
is some play on 'jockeying for position' or steering/guiding the chain to the correct position.

(Alan Walker) said:

Bicycle derailleurs have two small wheels on the chain tension cage. They are normally called
"jockey wheels" in the bicycle world. In my experience, wheels performing a similar function in
other types of machinery are usually called "idler wheels" or "tension wheels".

Am I correct about the usage in general engineering? If so, why a different term for the bicycle
industry? Is the term "jockey wheel" used in other industries?

Perhaps I should consult "The Dancing Chain"!

The top one is sometimes referred to as the derailleur pulley and I think the bottom one is
the jocky.

Alan Walker said:

Quoted message said:

Bicycle derailleurs have two small wheels on the chain tension cage. They are normally called
"jockey wheels" in the bicycle world. In my experience, wheels performing a similar function in
other types of machinery are usually called "idler wheels" or "tension wheels".

Am I correct about the usage in general engineering? If so, why a different term for the bicycle
industry? Is the term "jockey wheel" used in other industries?

Paul Kopit said:

The top one is sometimes referred to as the derailleur pulley and I think the bottom one is
the jocky.

I've always understood the term "jockey pulley" to refer to the upper pulley.

The lower is called the "tension pulley."

Sheldon "Cyclexicographer" 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 ↗

Alan Walker said:

Quoted message said:

Bicycle derailleurs have two small wheels on the chain tension cage. They are normally called
"jockey wheels" in the bicycle world. In my experience, wheels performing a similar function in
other types of machinery are usually called "idler wheels" or "tension wheels".

Am I correct about the usage in general engineering? If so, why a different term for the bicycle
industry? Is the term "jockey wheel" used in other industries?

Paul Kopit said:

The top one is sometimes referred to as the derailleur pulley and I think the bottom one is
the jocky.

I've always understood the term "jockey pulley" to refer to the upper pulley. This is because it
"jockeys" or guides the chain from sprocket to sprocket. It isn't used in other industries because
derailers are not used in other industries.

The lower is called the "tension pulley."

Sheldon "Cyclexicographer" 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 said:

Quoted message said:

Quoted message said:

Bicycle derailleurs have two small wheels on the chain tension cage. They are normally called
"jockey wheels" in the bicycle world. In my experience, wheels performing a similar function in
other types of machinery are usually called "idler wheels" or "tension wheels".

Quoted message said:

Quoted message said:

Quoted message said:

Am I correct about the usage in general engineering? If so, why a different term for the bicycle
industry? Is the term "jockey wheel" used in other industries?

Quoted message said:

Quoted message said:

The top one is sometimes referred to as the derailleur pulley and I think the bottom one is the
jockey.

Quoted message said:

I've always understood the term "jockey pulley" to refer to the upper pulley.

Quoted message said:

The lower is called the "tension pulley."

I don't use the term for either wheel because it is undefined. I find it used to refer to either of
the two idler wheels. Idler is in contrast to drive sprockets, since some early derailleurs used
sprockets for these wheels. In many derailleurs they are identical parts as they were in all the
early ones by Campagnolo, Huret, Simplex and others.

Avoid vague jargon (AVJ)!

Jobst Brandt [email hidden]

(Alan Walker) said:

Bicycle derailleurs have two small wheels on the chain tension cage. They are normally called
"jockey wheels" in the bicycle world. In my experience, wheels performing a similar function in
other types of machinery are usually called "idler wheels" or "tension wheels".

Am I correct about the usage in general engineering? If so, why a different term for the bicycle
industry? Is the term "jockey wheel" used in other industries?

They're apparently also used on trailers -- the small wheel attached to the front of a trailer to
allow it to be moved around by hand. See <http://www.winterhoff.de/html/wheels.html> for a picture.

Google hits for "jockey wheels" seem to be about evenly divided between bicycles and trailers.

There's also a linear accelerator in the Netherlands that has them, though it's not clear what their
function is. <http://www.radiotherapie.nl/linaceng/linacfaq/>

--
Ray Heindl (remove the X to reply)

Ray Heindl said:

There's also a linear accelerator in the Netherlands that has them, though it's not clear what
their function is. <http://www.radiotherapie.nl/linaceng/linacfaq/>

I don't know what a linear accelerator is, but it sure sounds cool. What is it?

Lots of things sound cool lately. Learning C++, teacher introduced the "destructor", and I was
rather impressed with that term.

--
Rick Onanian

[email hidden] wrote in message news:<[email hidden]>...

Quoted message said:

Sheldon Brown said:

Quoted message said:

> Bicycle derailleurs have two small wheels on the chain tension cage. They are normally called
> "jockey wheels" in the bicycle world. In my experience, wheels performing a similar function
> in other types of machinery are usually called "idler wheels" or "tension wheels".

Quoted message said:

Quoted message said:

> Am I correct about the usage in general engineering? If so, why a different term for the
> bicycle industry? Is the term "jockey wheel" used in other industries?

Quoted message said:

Quoted message said:

The top one is sometimes referred to as the derailleur pulley and I think the bottom one is the
jockey.

Quoted message said:

I've always understood the term "jockey pulley" to refer to the upper pulley.

Quoted message said:

Quoted message said:

The lower is called the "tension pulley."

I don't use the term for either wheel because it is undefined. I find it used to refer to either
of the two idler wheels. Idler is in contrast to drive sprockets, since some early derailleurs
used sprockets for these wheels. In many derailleurs they are identical parts as they were in all
the early ones by Campagnolo, Huret, Simplex and others.

Avoid vague jargon (AVJ)!

Jobst Brandt [email hidden]

Is there any mechanical difference between the two pulleys? That is, might one be expected to handle
a different load?

I'm curious because I recently replaced a badly worn pair on a Schwinn LeTour by robbing parts from
spare LeTours that I bought for that purpose and for visiting friends to ride.

To my surprise, the upper and lower 10-tooth plastic pulleys are different parts. One is stamped
on both sides "SHIMANO NARROW" and has a noticeably narrower profile. The other is stamped
"SHIMANO CENTERON G-PULLEY NARROW" and has a thicker shoulder extending to the base of the worn
plastic teeth.

Below are crude illustrations of the upper halves of each pulley with a tooth on top. Only the tooth
is worn, not the other parts.

| _|_
/ \ | |
/ \ | |
/ \ / \
| | | |
------------ -----------

narrow g-pulley

Obviously, Shimano thought that there was some functional difference. The only thing that I can
think of is that the lower pulley where the chain arrives from the front gears might be blockier and
thicker without causing any trouble, but the pulley where the chain exits to the rear cogs might
somehow profit from being narrower to allow the chain to flex sideways without wearing the pulley?

Regrettably, I paid no attention when removing the pulleys on three different LeTours, so I don't
know which pulley was upper or lower.

Actually, the top pully is properly called the jockey wheel, because it "jockeys" the chain from one
cog to the next.

The lower is usually called the tension wheel (or some similar name).

May you have the wind at your back. And a really low gear for the hills! Chris

Chris'Z Corner "The Website for the Common Bicyclist": geocities.comczcornerOpen ↗

Rick Onanian said:

Ray Heindl wrote:

Quoted message said:

Quoted message said:

There's also a linear accelerator in the Netherlands that has them, though it's not clear what
their function is. <http://www.radiotherapie.nl/linaceng/linacfaq/>

I don't know what a linear accelerator is, but it sure sounds cool. What is it?

Type the phrase into the box provided by MWCD10 at www.m-w.com and you'll find out.

--
Skitt (in Hayward, California) www.geocities.com/opus731/

Rick Onanian said:

Lots of things sound cool lately. Learning C++, teacher introduced the "destructor", and I was
rather impressed with that term.

If you're learning C++, you'll be even more impressed once you get to the definition of "friend".

--
Peter Moylan [email hidden] eepjm.newcastle.edu.aueepjm.newcastle.edu.auOpen ↗ (OS/2 and eCS information
and software)

Skitt said:

Quoted message said:

I don't know what a linear accelerator is, but it sure sounds cool. What is it?

Type the phrase into the box provided by MWCD10 at www.m-w.com and you'll find out.

So, it's a particle accelerator that doesn't go in circles? How long does a linear accelerator have
to be in order to be useful?

--
Rick Onanian

Rick Onanian said:

Skitt wrote:

Quoted message said:

Quoted message said:

Quoted message said:

I don't know what a linear accelerator is, but it sure sounds cool. What is it?

Type the phrase into the box provided by MWCD10 at www.m-w.com and you'll find out.

So, it's a particle accelerator that doesn't go in circles? How long does a linear accelerator
have to be in order to be useful?

Gosh, I wouldn't know. The one at Stanford is two miles long.
--
Skitt (in Hayward, California) www.geocities.com/opus731/

Quoted message said:

Alan Walker said:

Quoted message said:

Bicycle derailleurs have two small wheels on the chain tension cage. They are normally called
"jockey wheels" in the bicycle world. In my experience, wheels performing a similar function in
other types of machinery are usually called "idler wheels" or "tension wheels".

Am I correct about the usage in general engineering? If so, why a different term for the bicycle
industry? Is the term "jockey wheel" used in other industries?

Paul Kopit said:

The top one is sometimes referred to as the derailleur pulley and I think the bottom one is the
jocky.

"Sheldon Brown" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

I've always understood the term "jockey pulley" to refer to the upper pulley. This is because it
"jockeys" or guides the chain from sprocket to sprocket. It isn't used in other industries because
derailers are not used in other industries.

The lower is called the "tension pulley."

Sheldon "Cyclexicographer" Brown

Hmmm. I find "upper" and "lower" pulley sufficient.

Do you really say "jockey pulley" when writing service with a non-afficionado?

--
Andrew Muzi, who also likes "crank bearing assembly" instead of "BB" www.yellowjersey.org Open every
day since 1 April, 1971

Carl Fogel said:

Quoted message said:

Quoted message said:

I've always understood the term "jockey pulley" to refer to the upper pulley.

Quoted message said:

Quoted message said:

Quoted message said:

The lower is called the "tension pulley."

Quoted message said:

Quoted message said:

I don't use the term for either wheel because it is undefined. I find it used to refer to either
of the two idler wheels. Idler is in contrast to drive sprockets, since some early derailleurs
used sprockets for these wheels. In many derailleurs they are identical parts as they were in all
the early ones by Campagnolo, Huret, Simplex and others.

Quoted message said:

Quoted message said:

Avoid vague jargon (AVJ)!

Quoted message said:

Is there any mechanical difference between the two pulleys? That is, might one be expected to
handle a different load?

It depends on the included angle between entry and exit of the chain, and its tension. Since tension
is the same, only the angle between the two chain lines has a differentiating effect. That would be
T * sin A = idler load.

Quoted message said:

I'm curious because I recently replaced a badly worn pair on a Schwinn LeTour by robbing parts
from spare LeTours that I bought for that purpose and for visiting friends to ride.

The wear has more to do with side loads and chain pitch. A worn chain widens the round recesses in
the idler.

Quoted message said:

To my surprise, the upper and lower 10-tooth plastic pulleys are different parts. One is stamped
on both sides "SHIMANO NARROW" and has a noticeably narrower profile. The other is stamped
"SHIMANO CENTERON G-PULLEY NARROW" and has a thicker shoulder extending to the base of the worn
plastic teeth.

I am not familiar with these parts. I can't say what that is about.

Quoted message said:

Below are crude illustrations of the upper halves of each pulley with a tooth on top. Only the
tooth is worn, not the other parts.

Quoted message said:

| _|_
/ \ | |
/ \ | |
/ \ / \
| | | |
------------ -----------

Quoted message said:

narrow g-pulley

Quoted message said:

Obviously, Shimano thought that there was some functional difference. The only thing that I can
think of is that the lower pulley where the chain arrives from the front gears might be
blockier and thicker without causing any trouble, but the pulley where the chain exits to the
rear cogs might somehow profit from being narrower to allow the chain to flex sideways without
wearing the pulley?

Quoted message said:

Regrettably, I paid no attention when removing the pulleys on three different LeTours, so I don't
know which pulley was upper or lower.

I don't think it makes any difference, knowing how fast these things wear. The old wobbly pulley was
designed to help people pre-shift before starting to pedal, they bing unable to pedal and shift at
the same time. That was before brake/shift levers.

Jobst Brandt [email hidden]

(Carl Fogel) said:

Below are crude illustrations of the upper halves of each pulley with a tooth on top. Only the
tooth is worn, not the other parts.

| _|_
/ \ | |
/ \ | |
/ \ / \
| | | |
------------ -----------

narrow g-pulley

Obviously, Shimano thought that there was some functional difference. The only thing that I can
think of is that the lower pulley where the chain arrives from the front gears might be
blockier and thicker without causing any trouble, but the pulley where the chain exits to the
rear cogs might somehow profit from being narrower to allow the chain to flex sideways without
wearing the pulley?

Regrettably, I paid no attention when removing the pulleys on three different LeTours, so I don't
know which pulley was upper or lower.

The 'G-Pulley' is for the upper/jockey and the other is for the lower/tension. That is Shimano's
system and designation.

I haven't looked for a while, but the 'G-pulley' used to have a certain amount of 'float,' lateral
movement. This was either to help with shifting, or to allow a small amount of slop in alignment of
the derailleur. Maybe someone else knows the technical reason.

I never swapped the two on older derailleurs to see if their position made any difference in
shifting or noise. And I do not know if newer shifting/indexing makes this difference moot.

Peter Moylan said:

Rick Onanian said:

Lots of things sound cool lately. Learning C++, teacher introduced the "destructor", and I was
rather impressed with that term.

If you're learning C++, you'll be even more impressed once you get to the definition of "friend".

I got that the same day, but it wasn't nearly as exciting.

I'd have more fun as a Destructor than a Friend. 😉

--
Rick "The Friendly Destructor" Onanian

Rick Onanian said:

Peter Moylan said:

Rick Onanian said:

Lots of things sound cool lately. Learning C++, teacher introduced the "destructor", and I was
rather impressed with that term.

If you're learning C++, you'll be even more impressed once you get to the definition of
"friend".

I got that the same day, but it wasn't nearly as exciting.

Not even the fact that a friend has full access to your private member?

--
Evan Kirshenbaum +------------------------------------ HP Laboratories |Ye knowe ek, that in forme
of speche 1501 Page Mill Road, 1U, MS 1141 | is chaunge Palo Alto, CA 94304 |Withinne a thousand
yer, and wordes
| tho
[email hidden] |That hadden prys now wonder nyce and
(650)857-7572 | straunge |Us thenketh hem, and yet they spake
kirshenbaum.netkirshenbaum.netOpen ↗ | hem so
| Chaucer