MTB cone type wheel bearings.

On Wed, 24 Apr 2013 19:52:20 -0700 (PDT), Frank Krygowski
wrote:

On Apr 24, 9:10*pm, James wrote:
On 23/04/13 21:09, J.B.Slocomb wrote:









On Tue, 23 Apr 2013 10:21:29 +1000,
wrote:

On 23/04/13 09:38, J.B.Slocomb wrote:
On Tue, 23 Apr 2013 08:25:39 +1000,
wrote:

On 23/04/13 02:45, Phil W Lee wrote:
* *considered Mon, 22 Apr 2013 08:27:11
+1000 the perfect time to write:

On 19/04/13 13:50, David Scheidt wrote:
Frank * * wrote:
:On Apr 18, 8:11 pm, * * wrote:
: * * On 19/04/13 08:38, Phil W Lee wrote:
:
: * * * * * * * considered Thu, 18 Apr 2013 08:11:06
: * * * * +1000 the perfect time to write:
: * * * * The quote is not clear because it does not define what the increase is
: * * * * with respect to. *I have read other papers that say cageless bearings
: * * * * run hotter than caged bearings - thus more friction losses in the
: * * * * cageless variety.
:
: * * * * Unless you can explain how adding multiple points of sliding contact
: * * * * can reduce friction over a design with only rolling contact, that
: * * * * falls well short of sensible.
:
: * * What is a design with only rolling contact? *If you mean a cage less
: * * rolling bearing (ball or roller), then please explain how sliding
: * * contact is avoided when there is no cage to keep the rolling elements
: * * from touching?
:
: * * Please also explain to me, as I've obviously lost me bearings, why a
: * * google search yields results such as;
:
: * * "Ball Cage Effect
: * * The early forms of ball bearings were full-ball types without ball
: * * cages. Friction between balls caused loud
: * * noise, made high-speed rotation impossible and shortened the service
: * * life. Twenty years later, a Caged Ball
: * * design was developed for ball bearings. The new design enabled
: * * high-speed rotation at a low noise level,
: * * and extended the service life despite the reduced number of balls used.
: * * It marked a major development in
: * * the history of ball bearings.
: * * Similarly, the quality of needle bearings was significantly improved by
: * * the caged needle structure.
: * * With cage-less, full-ball types of ball bearings, balls make metallic
: * * contact with one another and
: * * produce loud noise. In addition, they rotate in opposite directions,
: * * causing the sliding contact between two
: * * adjacent balls to occur at a speed twice the ball-spinning rate. It
: * * results in severe wear and shortens the
: * * service life.
: * * In addition, without a cage, balls make point contact to increase
: * * bearing stress, thus facilitating
: * * breakage of the oil film. In contrast, each caged ball contacts the cage
: * * over a wide area. Therefore, the oil
: * * film does not break, the noise level is low and balls can rotate at a
: * * high speed, resulting in a long
: * * service life."
:
: * * (google "site:tech.thk.com Caged Ball SHS")

:Looks to me like they're advertising their design feature.

:I left all my bearing catalogs behind when I retired, but I know for
:sure that a bearing's load capacity is increased when the number of
:balls increases. For ordinary industrial ball bearings, the type with
:the cage is called a Conrad bearing; it's the basic type. *The type
:that crams an extra ball or two into the groove is called a slot-fill
:bearing, or full complement bearing. *Its radial load capacity is
:definitely higher, due to the higher ball count. *(Its axial load
:capacity is far lower, due to the groove.)

Conrad and slot fill bearings are relevant to bearings designed to
carry a purely radial load. *Remember, of course, that a cup and cone
bicycle bearing is an angular contact bearing, which can carry radial and
axial loads in different proportion by varying the angles of the races.
Importantly, they can be made as a full complement bearing without
needing the slot for assembly, since they come apart axially. *The Conrad
bearing solved James's objection that without a cage, the balls will
move, which does lead to bearing failure. *But with a full complement of
balls, you don't need a cage to maintain spacing, since there's no extra
space to dispalce into. *The cage is really just for easy of assembly
(and maybe stocking spares). *It's often used to reduce the number of
balls in the bearing, but it needn't be.

My objection was not only that the balls can move and not be evenly
spaced, but that they press against one another without a cage, and the
relative motion between the rubbing surfaces is in opposing directions.

But they won't press against each other any more than they would press
against a cage, and certainly not as continuously.

Where is your evidence?

The pressure and speed of relative motion is greater than that seen when
there is a cage to keep the balls separated.

The pressure is (at most) the same as for a cage, and is between two
hardened, curved, surfaces, and only intermittently.

Again, your evidence?

It has been noted that full compliment bearings run hotter, and need
better lubrication flow (than a caged bearing) to maintain a lubrication
film between the balls. *I.e. there is more friction and wear. *The type
of lubrication required for longevity is not so easy to achieve in a
bicycle hub or BB.

No more difficult than in a wheel bearing or suspension pivot of a
car, and much less heavily loaded.

Car wheel bearings (tapered roller) have a cage - at least all those
that I've worked on have. *And in fact wheel bearings on car trailers
are notorious for self destruction because the lubrication is
insufficient, they tend to not be used often, and the hub tends to let
moisture in - much like bicycle hubs.

I've yet to hear of any bicycle application where heat is a problem in
any (properly maintained) bearing.

Heat is indicative of friction. *The research papers and other sources
I've read say that full compliment bearings get hotter, therefore there
is more friction.

Friction usually leads to wear, therefore I conclude they wear out
faster too.

On the other hand the more balls the more the bearing will support,
attested by research papers also. So which is better, the pillar or
the post :-)

Yes, John, we've been over that before. *The more balls support more
load, and provided the speed is kept low (gee, think why that might be),
and the lubrication adequate (which is unlikely in a bicycle hub or BB),
they are ok.

Much better though to increase the size of the housing just a smidge to
allow for larger balls and bearing surfaces and a cage. *Then there is
less friction, less wear and a lubrication reservoir in the cage.

On the other hand, I suspect that if you look into it you'll find that
no bearing on a bicycle turns at what the Bearing World considers
anything but slow speed. Didn't someone calculate that the wheel
bearings turned 600 rpm, max? The bottom bracket might hit 200 rpm and
the head bearings are probably rated in turns per hour.

As for lubrication I recently disassembled an aluminum frame bike that
I know was ten years old and had no maintenance for that period....
both the bottom bracket and head bearings still had adequate amounts
of grease and appeared, to a casual look, to still be perfectly
serviceable.

10, 20 or 30 years means little if the bike is not used.

Anybody know how many miles a bike's hub bearing would last if, say,
it were greased every couple years but the balls were not replaced?

- Frank Krygowski

Bearing life appears to be a factor of the bearing load and RPM so
you'll have to be more specific. A Fat boy on a fast bike wears out
bearings far more rapidly that a skinny guy on a slow bike :-)

--
Cheers,

John B.

On Apr 25, 12:26*am, davethedave wrote:
On Thu, 25 Apr 2013 11:54:12 +1000, James wrote:
In another post I mention that I recently changed wheels, from a set
using Shimano cage less bearing hubs to a set with cartridge bearings,
and really couldn't tell the difference. Which is true, I think, for
many of the "very important things" that we discuss here :-)

You not telling the difference between wheels while you're riding and
service life are two different things.

The discussion is not about whether the bearing choice makes you 0.01
km/h slower or faster, but whether the bearings wear out faster or not.

Given the fairly reasonable price of bearings in regards to their
lifetime why are we worrying about it?


Time for sleep, etc., vs. out in the garage servicing wheel bearings
at 10:00 PM when I've got to get up in six hours and get ready to ride
into the hills (?)

They only start getting expensive when they are press fit into a nicely
machined lump of aluminium and called a bottom bracket assembly.

On Apr 25, 5:02*am, J.B.Slocomb wrote:
On Wed, 24 Apr 2013 19:52:20 -0700 (PDT), Frank Krygowski









wrote:
On Apr 24, 9:10*pm, James wrote:
On 23/04/13 21:09, J.B.Slocomb wrote:

On Tue, 23 Apr 2013 10:21:29 +1000,
wrote:

On 23/04/13 09:38, J.B.Slocomb wrote:
On Tue, 23 Apr 2013 08:25:39 +1000,
wrote:

On 23/04/13 02:45, Phil W Lee wrote:
* *considered Mon, 22 Apr 2013 08:27:11
+1000 the perfect time to write:

On 19/04/13 13:50, David Scheidt wrote:
Frank * * wrote:
:On Apr 18, 8:11 pm, * * wrote:
: * * On 19/04/13 08:38, Phil W Lee wrote:
:
: * * * * * * * considered Thu, 18 Apr 2013 08:11:06
: * * * * +1000 the perfect time to write:
: * * * * The quote is not clear because it does not define what the increase is
: * * * * with respect to. *I have read other papers that say cageless bearings
: * * * * run hotter than caged bearings - thus more friction losses in the
: * * * * cageless variety.
:
: * * * * Unless you can explain how adding multiple points of sliding contact
: * * * * can reduce friction over a design with only rolling contact, that
: * * * * falls well short of sensible.
:
: * * What is a design with only rolling contact? *If you mean a cage less
: * * rolling bearing (ball or roller), then please explain how sliding
: * * contact is avoided when there is no cage to keep the rolling elements
: * * from touching?
:
: * * Please also explain to me, as I've obviously lost me bearings, why a
: * * google search yields results such as;
:
: * * "Ball Cage Effect
: * * The early forms of ball bearings were full-ball types without ball
: * * cages. Friction between balls caused loud
: * * noise, made high-speed rotation impossible and shortened the service
: * * life. Twenty years later, a Caged Ball
: * * design was developed for ball bearings. The new design enabled
: * * high-speed rotation at a low noise level,
: * * and extended the service life despite the reduced number of balls used.
: * * It marked a major development in
: * * the history of ball bearings.
: * * Similarly, the quality of needle bearings was significantly improved by
: * * the caged needle structure.
: * * With cage-less, full-ball types of ball bearings, balls make metallic
: * * contact with one another and
: * * produce loud noise. In addition, they rotate in opposite directions,
: * * causing the sliding contact between two
: * * adjacent balls to occur at a speed twice the ball-spinning rate. It
: * * results in severe wear and shortens the
: * * service life.
: * * In addition, without a cage, balls make point contact to increase
: * * bearing stress, thus facilitating
: * * breakage of the oil film. In contrast, each caged ball contacts the cage
: * * over a wide area. Therefore, the oil
: * * film does not break, the noise level is low and balls can rotate at a
: * * high speed, resulting in a long
: * * service life."
:
: * * (google "site:tech.thk.com Caged Ball SHS")

:Looks to me like they're advertising their design feature.

:I left all my bearing catalogs behind when I retired, but I know for
:sure that a bearing's load capacity is increased when the number of
:balls increases. For ordinary industrial ball bearings, the type with
:the cage is called a Conrad bearing; it's the basic type. *The type
:that crams an extra ball or two into the groove is called a slot-fill
:bearing, or full complement bearing. *Its radial load capacity is
:definitely higher, due to the higher ball count. *(Its axial load
:capacity is far lower, due to the groove.)

Conrad and slot fill bearings are relevant to bearings designed to
carry a purely radial load. *Remember, of course, that a cup and cone
bicycle bearing is an angular contact bearing, which can carry radial and
axial loads in different proportion by varying the angles of the races.
Importantly, they can be made as a full complement bearing without
needing the slot for assembly, since they come apart axially. *The Conrad
bearing solved James's objection that without a cage, the balls will
move, which does lead to bearing failure. *But with a full complement of
balls, you don't need a cage to maintain spacing, since there's no extra
space to dispalce into. *The cage is really just for easy of assembly
(and maybe stocking spares). *It's often used to reduce the number of
balls in the bearing, but it needn't be.

My objection was not only that the balls can move and not be evenly
spaced, but that they press against one another without a cage, and the
relative motion between the rubbing surfaces is in opposing directions.

But they won't press against each other any more than they would press
against a cage, and certainly not as continuously.

Where is your evidence?

The pressure and speed of relative motion is greater than that seen when
there is a cage to keep the balls separated.

The pressure is (at most) the same as for a cage, and is between two
hardened, curved, surfaces, and only intermittently.

Again, your evidence?

It has been noted that full compliment bearings run hotter, and need
better lubrication flow (than a caged bearing) to maintain a lubrication
film between the balls. *I.e. there is more friction and wear.. *The type
of lubrication required for longevity is not so easy to achieve in a
bicycle hub or BB.

No more difficult than in a wheel bearing or suspension pivot of a
car, and much less heavily loaded.

Car wheel bearings (tapered roller) have a cage - at least all those
that I've worked on have. *And in fact wheel bearings on car trailers
are notorious for self destruction because the lubrication is
insufficient, they tend to not be used often, and the hub tends to let
moisture in - much like bicycle hubs.

I've yet to hear of any bicycle application where heat is a problem in
any (properly maintained) bearing.

Heat is indicative of friction. *The research papers and other sources
I've read say that full compliment bearings get hotter, therefore there
is more friction.

Friction usually leads to wear, therefore I conclude they wear out
faster too.

On the other hand the more balls the more the bearing will support,
attested by research papers also. So which is better, the pillar or
the post :-)

Yes, John, we've been over that before. *The more balls support more
load, and provided the speed is kept low (gee, think why that might be),
and the lubrication adequate (which is unlikely in a bicycle hub or BB),
they are ok.

Much better though to increase the size of the housing just a smidge to
allow for larger balls and bearing surfaces and a cage. *Then there is
less friction, less wear and a lubrication reservoir in the cage.

On the other hand, I suspect that if you look into it you'll find that
no bearing on a bicycle turns at what the Bearing World considers
anything but slow speed. Didn't someone calculate that the wheel
bearings turned 600 rpm, max? The bottom bracket might hit 200 rpm and
the head bearings are probably rated in turns per hour.

As for lubrication I recently disassembled an aluminum frame bike that
I know was ten years old and had no maintenance for that period....
both the bottom bracket and head bearings still had adequate amounts
of grease and appeared, to a casual look, to still be perfectly
serviceable.

10, 20 or 30 years means little if the bike is not used.

Anybody know how many miles a bike's hub bearing would last if, say,
it were greased every couple years but the balls were not replaced?

- Frank Krygowski

Bearing life appears to be a factor of the bearing load and RPM so
you'll have to be more specific. A Fat boy on a fast bike wears out
bearings far more rapidly that a skinny guy on a slow bike :-)


Myriad environmental factors also play a huge role.

And I guess we'll just assume ideal adjustment for the sake of
argument, though this is very unlikely in practice with the kind of
bearings under discussion.

"J.B.Slocomb" wrote in message
...
On Thu, 25 Apr 2013 11:54:12 +1000, James
wrote:

On 24/04/13 08:46, J.B.Slocomb wrote:
On Tue, 23 Apr 2013 15:42:53 +0100, "Ian Field"
wrote:



wrote in message
news On Mon, 22 Apr 2013 22:01:22 -0700 (PDT), Frank Krygowski
wrote:

On Apr 22, 8:56 pm, wrote:
On 23/04/13 10:32, wrote:


With most sealed cartridge bearings I've examined, there's far more
friction from the seals than there would ever be from inter-ball
contact. Nonetheless, even that seal friction is negligible in any
practical sense.

Do you have any evidence?

You mean that I'm remembering correctly, or not lying? No, but I'd
prefer finding out whether anyone really doubts me before I go
downstairs, pull out a wheel, remove a quick release and take some
very fine torque readings.

I'd think it would be hard to believe that an elastomer seal rubbing
agains a bearing's race would not have a _little_ more friction than
a
bearing lacking such a seal.

It is likely that it does have more drag than a seal less bearing but
like many things in the bicycle world there is probably so little
difference that no one can actually tell the difference.

There could be a cumulative effect on how knackered you feel after a 30
mile
ride.

In another post I mention that I recently changed wheels, from a set
using Shimano cage less bearing hubs to a set with cartridge bearings,
and really couldn't tell the difference. Which is true, I think, for
many of the "very important things" that we discuss here :-)

You not telling the difference between wheels while you're riding and
service life are two different things.

The discussion is not about whether the bearing choice makes you 0.01
km/h slower or faster, but whether the bearings wear out faster or not.

Ah.. well, how much faster does one sort of bearing wear than another.
In minutes, hours, days, years, decades?


IME - when they're neglected long enough to go rusty.

Ive had a couple of wheel bearing failures on motorcycles, both were on
(very) second hand machines so I don't know the prior history.

"Frank Krygowski" wrote in message
...
On Apr 24, 9:10 pm, James wrote:
On 23/04/13 21:09, J.B.Slocomb wrote:









On Tue, 23 Apr 2013 10:21:29 +1000,
wrote:

On 23/04/13 09:38, J.B.Slocomb wrote:
On Tue, 23 Apr 2013 08:25:39 +1000,
wrote:

On 23/04/13 02:45, Phil W Lee wrote:
considered Mon, 22 Apr 2013
08:27:11
+1000 the perfect time to write:

On 19/04/13 13:50, David Scheidt wrote:
Frank wrote:
:On Apr 18, 8:11 pm, wrote:
: On 19/04/13 08:38, Phil W Lee wrote:
:
: considered
Thu, 18 Apr 2013 08:11:06
: +1000 the perfect time to write:
: The quote is not clear because it does not define
what the increase is
: with respect to. I have read other papers that say
cageless bearings
: run hotter than caged bearings - thus more friction
losses in the
: cageless variety.
:
: Unless you can explain how adding multiple points of
sliding contact
: can reduce friction over a design with only rolling
contact, that
: falls well short of sensible.
:
: What is a design with only rolling contact? If you mean a
cage less
: rolling bearing (ball or roller), then please explain how
sliding
: contact is avoided when there is no cage to keep the
rolling elements
: from touching?
:
: Please also explain to me, as I've obviously lost me
bearings, why a
: google search yields results such as;
:
: "Ball Cage Effect
: The early forms of ball bearings were full-ball types
without ball
: cages. Friction between balls caused loud
: noise, made high-speed rotation impossible and shortened
the service
: life. Twenty years later, a Caged Ball
: design was developed for ball bearings. The new design
enabled
: high-speed rotation at a low noise level,
: and extended the service life despite the reduced number
of balls used.
: It marked a major development in
: the history of ball bearings.
: Similarly, the quality of needle bearings was
significantly improved by
: the caged needle structure.
: With cage-less, full-ball types of ball bearings, balls
make metallic
: contact with one another and
: produce loud noise. In addition, they rotate in opposite
directions,
: causing the sliding contact between two
: adjacent balls to occur at a speed twice the ball-spinning
rate. It
: results in severe wear and shortens the
: service life.
: In addition, without a cage, balls make point contact to
increase
: bearing stress, thus facilitating
: breakage of the oil film. In contrast, each caged ball
contacts the cage
: over a wide area. Therefore, the oil
: film does not break, the noise level is low and balls can
rotate at a
: high speed, resulting in a long
: service life."
:
: (google "site:tech.thk.com Caged Ball SHS")

:Looks to me like they're advertising their design feature.

:I left all my bearing catalogs behind when I retired, but I know
for
:sure that a bearing's load capacity is increased when the number
of
:balls increases. For ordinary industrial ball bearings, the type
with
:the cage is called a Conrad bearing; it's the basic type. The
type
:that crams an extra ball or two into the groove is called a
slot-fill
:bearing, or full complement bearing. Its radial load capacity
is
:definitely higher, due to the higher ball count. (Its axial
load
:capacity is far lower, due to the groove.)

Conrad and slot fill bearings are relevant to bearings designed
to
carry a purely radial load. Remember, of course, that a cup and
cone
bicycle bearing is an angular contact bearing, which can carry
radial and
axial loads in different proportion by varying the angles of the
races.
Importantly, they can be made as a full complement bearing
without
needing the slot for assembly, since they come apart axially.
The Conrad
bearing solved James's objection that without a cage, the balls
will
move, which does lead to bearing failure. But with a full
complement of
balls, you don't need a cage to maintain spacing, since there's
no extra
space to dispalce into. The cage is really just for easy of
assembly
(and maybe stocking spares). It's often used to reduce the
number of
balls in the bearing, but it needn't be.

My objection was not only that the balls can move and not be
evenly
spaced, but that they press against one another without a cage,
and the
relative motion between the rubbing surfaces is in opposing
directions.

But they won't press against each other any more than they would
press
against a cage, and certainly not as continuously.

Where is your evidence?

The pressure and speed of relative motion is greater than that
seen when
there is a cage to keep the balls separated.

The pressure is (at most) the same as for a cage, and is between
two
hardened, curved, surfaces, and only intermittently.

Again, your evidence?

It has been noted that full compliment bearings run hotter, and
need
better lubrication flow (than a caged bearing) to maintain a
lubrication
film between the balls. I.e. there is more friction and wear.
The type
of lubrication required for longevity is not so easy to achieve in
a
bicycle hub or BB.

No more difficult than in a wheel bearing or suspension pivot of a
car, and much less heavily loaded.

Car wheel bearings (tapered roller) have a cage - at least all those
that I've worked on have. And in fact wheel bearings on car
trailers
are notorious for self destruction because the lubrication is
insufficient, they tend to not be used often, and the hub tends to
let
moisture in - much like bicycle hubs.

I've yet to hear of any bicycle application where heat is a problem
in
any (properly maintained) bearing.

Heat is indicative of friction. The research papers and other
sources
I've read say that full compliment bearings get hotter, therefore
there
is more friction.

Friction usually leads to wear, therefore I conclude they wear out
faster too.

On the other hand the more balls the more the bearing will support,
attested by research papers also. So which is better, the pillar or
the post :-)

Yes, John, we've been over that before. The more balls support more
load, and provided the speed is kept low (gee, think why that might
be),
and the lubrication adequate (which is unlikely in a bicycle hub or
BB),
they are ok.

Much better though to increase the size of the housing just a smidge
to
allow for larger balls and bearing surfaces and a cage. Then there is
less friction, less wear and a lubrication reservoir in the cage.

On the other hand, I suspect that if you look into it you'll find that
no bearing on a bicycle turns at what the Bearing World considers
anything but slow speed. Didn't someone calculate that the wheel
bearings turned 600 rpm, max? The bottom bracket might hit 200 rpm and
the head bearings are probably rated in turns per hour.

As for lubrication I recently disassembled an aluminum frame bike that
I know was ten years old and had no maintenance for that period....
both the bottom bracket and head bearings still had adequate amounts
of grease and appeared, to a casual look, to still be perfectly
serviceable.

10, 20 or 30 years means little if the bike is not used.

Anybody know how many miles a bike's hub bearing would last if, say,
it were greased every couple years but the balls were not replaced?

IMO it was rarely an issue in the lifetime of the owner before they stopped
putting an oil hole in the middle of the hub with a little spring clip that
covered the hole.

On Apr 25, 8:02*am, J.B.Slocomb wrote:
On Wed, 24 Apr 2013 19:52:20 -0700 (PDT), Frank Krygowski


Anybody know how many miles a bike's hub bearing would last if, say,
it were greased every couple years but the balls were not replaced?

- Frank Krygowski

Bearing life appears to be a factor of the bearing load and RPM so
you'll have to be more specific. A Fat boy on a fast bike wears out
bearings far more rapidly that a skinny guy on a slow bike :-)

It's obvious that there are various factors that affect bearing life.
To take load, for perhaps the most important example: In the
relatively controlled and predictable environment of most industrial
machinery bearings, the equation relating life to load is well-enough
documented that it's an ISO standard: L10=(C/P)^3. Inherent in the
use of that equation is the statistical fact that there is always
random variation (L10 represents the lifetime in revolutions expected
for 90% of the bearings, i.e. 10% failure rate.) In typical machine
bearings, the variation comes from unavoidable variables such as
impurities in alloys, microscopic differences in heat treating, etc.
But you can see that load relative to rated dynamic load capacity has
a tremendous impact. Picking a bearing with double the rated capacity
(C) yields eight times as much life. OTOH, running the bearing with a
"not recommended" level of lubrication would yield far less than
predicted life.

So what I was wondering is: Given the typical or "average" loads,
quality, sizes, lubrication & other service maintenance seen by bike
hub bearings, how many miles do they typically last? I wondered if
anyone has kept records for their own bikes, or if someone like Mr.
Muzi knew about bearing life based on shop experience.

I'm not very diligent about maintenance nor record keeping. But so
far, I'm aware of only one "failure": a rough or pitted spot on a rear
axle cone, showing up about three years ago, on the bike I've had
since 1976 and still ride very frequently. (I upgraded from the
original Normandy hubs to Shimano 600 hubs in maybe late '80s or early
'90s.) Mileage on that hub would have to be a tremendously rough
guess, but I can't imagine it's less than 10,000 miles.

My suspicion is that the typical life is far more than 10,000 miles,
even if bearing balls are not replaced in normal tuneups. IOW, I'm
betting that failure rate is low enough that we could not tell
anything about the reliability of full-complement bearings vs.
bearings with retainers, because there won't be much data, and the
data we might be able to find would show very wide variation.

- Frank Krygowski

On Wed, 24 Apr 2013 19:52:20 -0700 (PDT), Frank Krygowski
wrote:

Anybody know how many miles a bike's hub bearing would last if, say,
it were greased every couple years but the balls were not replaced?
- Frank Krygowski

If the bearing is clean and dry, forever. Under the relatively light
loads and low RPM's of cycling, a *CLEAN* bearing should last forever
while a dirty or wet bearing will have a short life.

The purpose of regular re-lubrication is mostly to push the dirty
grease out of the bearing and replace it with clean grease. The life
of the hub bearings doesn't have much to do with lube and ball
replacement. Mostly, it's water and dirt. Water rusts the balls and
bearing race, causing a rough surface, which eventually kills the
bearings. Dirt plus grease makes something like tar, which doesn't
flow very well. This pulls the grease out of the contact area,
resulting in an unlubricated contact area (by preventing the grease
from flowing around the bearings). This is also why steel bearings
are not mirror finish smooth. If they were, the grease would not
stick to the bearing surface, and the bearing would die prematurely. I
don't know the recommended surface finish for bicycle bearings, but
it's intentionally not as smooth as might be possible.

One thing nice about ceramic ball bearings... they don't rust.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Apr 25, 10:34*am, Frank Krygowski wrote:
On Apr 25, 8:02*am, J.B.Slocomb wrote:

On Wed, 24 Apr 2013 19:52:20 -0700 (PDT), Frank Krygowski

Anybody know how many miles a bike's hub bearing would last if, say,
it were greased every couple years but the balls were not replaced?

- Frank Krygowski

Bearing life appears to be a factor of the bearing load and RPM so
you'll have to be more specific. A Fat boy on a fast bike wears out
bearings far more rapidly that a skinny guy on a slow bike :-)

It's obvious that there are various factors that affect bearing life.
To take load, for perhaps the most important example: In the
relatively controlled and predictable environment of most industrial
machinery bearings, the equation relating life to load is well-enough
documented that it's an ISO standard: *L10=(C/P)^3. *Inherent in the
use of that equation is the statistical fact that there is always
random variation (L10 represents the lifetime in revolutions expected
for 90% of the bearings, i.e. 10% failure rate.) *In typical machine
bearings, the variation comes from unavoidable variables such as
impurities in alloys, microscopic differences in heat treating, etc.
But you can see that load relative to rated dynamic load capacity has
a tremendous impact. *Picking a bearing with double the rated capacity
(C) yields eight times as much life. *OTOH, running the bearing with a
"not recommended" level of lubrication would yield far less than
predicted life.

So what I was wondering is: Given the typical or "average" loads,
quality, sizes, lubrication & other service maintenance seen by bike
hub bearings, how many miles do they typically last? *I wondered if
anyone has kept records for their own bikes, or if someone like Mr.
Muzi knew about bearing life based on shop experience.

I'm not very diligent about maintenance nor record keeping. *But so
far, I'm aware of only one "failure": a rough or pitted spot on a rear
axle cone, showing up about three years ago, on the bike I've had
since 1976 and still ride very frequently. *(I upgraded from the
original Normandy hubs to Shimano 600 hubs in maybe late '80s or early
'90s.) *Mileage on that hub would have to be a tremendously rough
guess, but I can't imagine it's less than 10,000 miles.

My suspicion is that the typical life is far more than 10,000 miles,
even if bearing balls are not replaced in normal tuneups. *IOW, I'm
betting that failure rate is low enough that we could not tell
anything about the reliability of full-complement bearings vs.
bearings with retainers, because there won't be much data, and the
data we might be able to find would show very wide variation.


Unless you're carrying loads 200-300 miles a week in a rainy,
sedimentary region - often riding off the road, catching some air,
etc. - in which case you'd better take better care of your wheel
bearings than "greased every couple years", and in which case you're
going to be more intimate with your wheel's innards, in which case you
are more likely to care what they're made of, how they're put
together, how well they hold up, etc.

On Thu, 25 Apr 2013 07:52:46 -0700, Dan O wrote:

Given the fairly reasonable price of bearings in regards to their
lifetime why are we worrying about it?

Time for sleep, etc., vs. out in the garage servicing wheel bearings at
10:00 PM when I've got to get up in six hours and get ready to ride into
the hills (?)

When my bike was new I serviced the wheel bearings by opening the hub up
and adding what I considered to be a more appropriate amount of grease
than Shimano's rather meagre, yet probably adequate for most situations,
lube offering. When they get shonky I'll replace as needed but I'm
certainly not checking them more than once every two years or so, if at
all. It's a complete waste of valuable drinking time.

I have never had a catastrophic failure of bearings at all. They provide
you with a bit of warning when things aren’t quite all that hunky dory.

Cartridge bearings are better on this front as they don't take out
anything of importance in their final death throes even in irrevocable
seizing. Even if you are particularly abusive of machinery you really
can't go too far wrong.

Realistically bearings are there to reduce friction and be a sacrificial
part to prevent the more expensive bits wearing out. Cost and purpose are
relevant. Bearings with a friction coefficient of a fairy fart and a
similar weight can be obtained for many items of money. Long lived
weighty items come in cheaper by far with a minimal friction penalty.
None of them are short lived unless there is some problem with other
components construction, water ingress(corrosion of steel), foreign body
ingress(shattering of ceramic), err... Degreaser ingress(never a good
plan). Care should be taken when cleaning the chain rings.

Appropriate bearings should be selected for purpose. This is a bit
difficult as there is *much* confusion about bearings. And of course
manufacturers want to sell you the most expensive thing in their line
(surprise). Skateboarders particularly have been taken in by ABEC numbers
which are not particularly relevant past 5 in their particular usage
scenario. Cycling has not really been assaulted by this, but is bombarded
with ceramic this and that. There are gains to be had but they are really
not applicable to most non competitive cyclists at all in terms of
performance. A smoother ride and less fatigue may be all the difference
there is. If that's worth money to you them ceramic's the way to go.

OOooooh! Rant! I must drink less and service my bearings more!
--
davethedave

"davethedave" wrote in message
...
On Thu, 25 Apr 2013 07:52:46 -0700, Dan O wrote:

Given the fairly reasonable price of bearings in regards to their
lifetime why are we worrying about it?

Time for sleep, etc., vs. out in the garage servicing wheel bearings at
10:00 PM when I've got to get up in six hours and get ready to ride into
the hills (?)

When my bike was new I serviced the wheel bearings by opening the hub up
and adding what I considered to be a more appropriate amount of grease
than Shimano's rather meagre, yet probably adequate for most situations,
lube offering. When they get shonky I'll replace as needed but I'm
certainly not checking them more than once every two years or so, if at
all. It's a complete waste of valuable drinking time.

I have never had a catastrophic failure of bearings at all. They provide
you with a bit of warning when things aren’t quite all that hunky dory.

Cartridge bearings are better on this front as they don't take out
anything of importance in their final death throes even in irrevocable
seizing. Even if you are particularly abusive of machinery you really
can't go too far wrong.

On a motorcycle rear wheel cartridge bearing, I had one of the bearing balls
break and lock the inner to the outer ring - it ground out the interference
fit hole it pressed into, so the hub was scrap.

On a bicycle front wheel - it'll either do that or throw you over the
handlebars.