sanding bearing cones

"Captain Bike" <[email hidden]> queried...

Quoted message said:

Jim, have you ever actually _tried_ to obtain a replacement cone for a
Bontrager hub?

In the first place, Trek/Bontrager won't sell parts to shops that are
not Trek/Bontrager dealers.

In the second place, at least _some_ Bontrager labeled hubs use
oddball, non-standard cones that are not available at any price to
anybody.

It's tough enough to obtain replacement cones for current model major
brand hubs...basically forget it for off-brand and house-brand oddball
stuff like this.

I admire the shop for attempting a repair. When I ran into this on a
customer's bike the best I could do was tell him he needed a new wheel.

Hope I wasn't misrepresenting you. When I said you advocate replacement, I
was referring to
"Now that the' parts are clean, they should be carefully examined for wear.
The cones should have a shiny track running around them where the balls roll
against them. Examine this track very carefully to see if there are any
irregularities or pits. A magnifying glass may be of help here. If there is
any sign of a flaw, no matter how small, the cone should be replaced."
under Cleaning at http://sheldonbrown.com/tooltips/hubs.html

Thanks for taking the time to respond. Like me, this bike is Canadian
immigrant. I got it from an LBS in PA.
--
Snippy

Captain Bike said:

I admire the shop for attempting a repair. When I ran into this on a
customer's bike the best I could do was tell him he needed a new wheel.

Exactly. It would be just about impossible to screw the cones up worse
than throwing away the whole wheel. Or if the cones and hubs are
otherwise shot there's not really anything that they could do to make
them worse.

Quoted message said:

AndyMorris said:

Quoted message said:

Even assuming that the sanding worked, how expensive are new cones?

isn't its usually the availability, not the cost?

--
Andy Morris

Dear Andy,

As far as I know, Bontrager still sells mountain bike cones, so
they're available.

The shop has to stock them, but that's true of spokes, tubes, tires,
bearings, chains, and just about everything else.

Out of curiosity, I clicked on the "Find a Dealer" at the U.S.
Bontrager site (scroll down in the small window and you can search
Canada and the U.K., too).

My Pueblo zip code is 81004, a non-bicyling-oriented city 50 miles
from the next city. (I'll be surprised if I see more than three riders
with drop bars when I leave for my 15 mile ride in a few minutes on a
Saturday evening.)

http://direct.where2getit.com/cwc/apps/w2gi.php?sid=44b979ab96ae2&ADDRESS=&POSTALCODE=81004&COUNTRY=US&STATE=CO&CITY=PUEBLO&PRODUCT=&PRODUCTFCT=&LAT=&LON=&UNITS=MILES&RADIUS=15%7C50&USECENTERPOINT=&W2GI_LASTEXTENT=-104.979479551%7C38.0206076581%7C-104.283322573%7C38.4553902668&SORTBY_Dealers=DISTANCE&START_Dealers=0&COUNT_Dealers=8&REVERSE_Dealers=FALSE&W2GI_QUICK_ZOOM=&W2GI_QFIELD=DEALERID&W2GI_QVALUE=&DISTANCE=&W2GI_DNAME=&W2GI_DADDR=&W2GI_DCITY=&W2GI_DSTATE=&W2GI_DPOSTALCODE=&W2GI_DID=&W2GI_DINDEX=&NAV_INPUT_TYPE=POINT&NAV_CMD=SCALE_ZOOM&NAV_ALLOW_RECTANGLE=0&SCALE_ZOOM=90000&client=bontrager&template=locator
or http://tinyurl.com/hhlkq

That may be the longest url I've seen, but it shows that the Great
Divide bike shop is a Bontrager dealer, so they probably have parts or
can get them instead of trying to sand damaged cones into acceptable
shapes. They're about three miles away.

Trying to sand a damaged cone into shape when it's available at a
Bontrager dealer or overnight doesn't sound promising. Of course, it
may turn out to be some part that Bontrager no longer sells, but I'll
be startled if that's the case.

Cheers,

Carl Fogel

So much for the wonders of the internet!

I came back to use the link above and now find that "my session has
expired" and no help.

Sigh.

Back to Bontrager.

http://www.bontrager.com/Dealer_Network/Dealer_Locator.php

Click on find a dealer.

Put in U.S. zip code or scroll down for Canada and the UK.

CF

Captain Bike said:

Snippy Bobkins said:

Quoted message said:

I just had my Bontrager MTB hubs serviced at my LBS. The guy said they
sanded the bearing cones. I assume that is for pitting from worn bearings.
If I wanted to do that myself, how would I go about it? By hand? What grit
sandpaper?

jim beam said:

ugh. don't do it. don't go to any shop that does.

you really need to find a better lbs - and those guys should go find
work as plumbers.

Jim, have you ever actually _tried_ to obtain a replacement cone for a
Bontrager hub?

In the first place, Trek/Bontrager won't sell parts to shops that are
not Trek/Bontrager dealers.

In the second place, at least _some_ Bontrager labeled hubs use
oddball, non-standard cones that are not available at any price to
anybody.

It's tough enough to obtain replacement cones for current model major
brand hubs...basically forget it for off-brand and house-brand oddball
stuff like this.

I admire the shop for attempting a repair. When I ran into this on a
customer's bike the best I could do was tell him he needed a new wheel.

Sheldon "Cone Replacemen Has Always Been A Nightmare In This Industry"
Brown
+----------------------------------------------------+
| I reckon there's more things told than are true, |
| And more things true than are told. |
| --Rudyard Kipling |
+----------------------------------------------------+
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

Dear Sheldon,

Yes, cone replacement can be a nightmare.

This is awfully hard to type, but . . .

It sounds like the original poster needs a Bontrager dealer.

I suppose that Ferrari or Nash owners need to find Ferrari or Nash
dealers for parts--and even then they might be out of luck.

But go to http://www.bontrager.com/Dealer_Network/Dealer_Locator.php

Click on "Find a dealer" and put in 02465.

Six Bontrager dealers are shown on the map within 11 miles of West
Newton, half of them within 3 miles. Two of them are even what
Bontrager calls "demo centers."

Of course, the original poster may not be so lucky.

I've only got one Bontrager dealer 3 miles away here in Pueblo at
81004, but this neck of the woods hasn't been settled for quite as
long as the Commonwealth of Massachusetts.

Let's hope the the sanded cone lasts long enough for the original
poster to find a new cone. Few local bike shops are likely to have
much experience at sanding damaged cones.

I understand the other bike shop's urge to try to fix things (and
maybe they succceeded), but I admire you more for telling a customer
to get a new wheel instead of trying to fix a probably unfixable cone.

Probably the best thing to do would be to send them to a Bontrager
dealer. (And maybe the shop that's sanding cones is a Bontrager shop
and found that no cones are to be had for love or money.)

Cheers,

Carl Fogel

Captain Bike said:

Snippy Bobkins said:

Quoted message said:

I just had my Bontrager MTB hubs serviced at my LBS. The guy said they
sanded the bearing cones. I assume that is for pitting from worn bearings.
If I wanted to do that myself, how would I go about it? By hand? What grit
sandpaper?

jim beam said:

ugh. don't do it. don't go to any shop that does.

you really need to find a better lbs - and those guys should go find
work as plumbers.

Jim, have you ever actually _tried_ to obtain a replacement cone for a
Bontrager hub?

did i address the peculiarities of any particular manufacturer? my
response is entirely regarding the engineering facts of life, i.e. that
if it's a case hardened cone, you're pretty much committed to
replacement, and if it's a through hardened cone, it's at best a
temporary kludge.

Quoted message said:

In the first place, Trek/Bontrager won't sell parts to shops that are
not Trek/Bontrager dealers.

nothing peculiar about that! mercedes won't discount parts to anyone
but a mercedes dealer - independent repair shops pay full retail.

Quoted message said:

In the second place, at least _some_ Bontrager labeled hubs use
oddball, non-standard cones that are not available at any price to
anybody.

looks like a damned fine reason to use sealed bearings to me!

Quoted message said:

It's tough enough to obtain replacement cones for current model major
brand hubs...basically forget it for off-brand and house-brand oddball
stuff like this.

I admire the shop for attempting a repair. When I ran into this on a
customer's bike the best I could do was tell him he needed a new wheel.

agreed, but big picture, that's not necessarily a bad thing. the
manufacturer gets to control product quality by keeping inadequately
"repaired" product off the road. and the cyclist isn't taking chances
on high mileage product where the rims are wearing thin and potentially
about to have a sidewall blowout. i know a rim is not a bearing, but
the mileages go hand in hand.

don't get me wrong, i go to substantial lengths to repair my own bikes,
including replacing rims on a pair of mavic cosmos that would have cost
more to repair than to replace if i'd had the lbs do the work, but in
this situation, sanding cones is a neanderthal hack. it may get you
home and even last for another month or two, but the bearing is
essentially dead and needs to be replaced.

Quoted message said:

Sheldon "Cone Replacemen Has Always Been A Nightmare In This Industry"
Brown
+----------------------------------------------------+
| I reckon there's more things told than are true, |
| And more things true than are told. |
| --Rudyard Kipling |
+----------------------------------------------------+
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

<[email hidden]> wrote ...

Quoted message said:

This is awfully hard to type, but . . .

It sounds like the original poster needs a Bontrager dealer.

Twenty-six miles away. Could be worse.

--
Snippy Flom

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

Quoted message said:

Keiron said:

Quoted message said:

Too true, i concede to the fact that things certainly do need to be

replaced

Quoted message said:

Quoted message said:

at times when performance and saftey become issues. I was refering

to the

Quoted message said:

Quoted message said:

attitude that wanting to understand ideas/concepts, even if the

result is

Quoted message said:

Quoted message said:

not logically ideal, is dismissed as irrelevant/unimportant

especially if

Quoted message said:

Quoted message said:

money can be thrown at the problem as an easy solution. What then

would be

Quoted message said:

Quoted message said:

the point in knowing anything? Also a live and let live man so

forgive my

Quoted message said:

Quoted message said:

existential evangelising.

many things which can't be repaired can be recycled. I suspect cones

are

Quoted message said:

in this category.

Bicycle hub wheel bearing cones weigh only a few grams each.

The prices paid for scrap alloy and carbon steel is so low that high
volume producers almost have to pay to have it carted away. Most scrap
dealers in the US think in 40,000 lb. truck load quantities.

So there's not value in used worn out bicycle hub wheel bearing cones.
34% of the earth's mass is made up of iron which is the main constituent
in steel.

"Iron is notable for being the final element produced by stellar
nucleosynthesis, and thus the heaviest element which does not require a
supernova or similarly cataclysmic event for its formation. It is
therefore the most abundant heavy metal in the universe." (From
Wikipedia)

Your heart may be in the right place but your suggestions don't make
economic sense.

Chas. ;-)

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

Quoted message said:

Snippy Bobkins said:

Quoted message said:

I just had my Bontrager MTB hubs serviced at my LBS. The guy said

they

Quoted message said:

Quoted message said:

Quoted message said:

sanded the bearing cones. I assume that is for pitting from worn

bearings.

Quoted message said:

Quoted message said:

Quoted message said:

If I wanted to do that myself, how would I go about it? By hand?

What grit

Quoted message said:

Quoted message said:

Quoted message said:

sandpaper?

<sip>

Quoted message said:

Jim, have you ever actually _tried_ to obtain a replacement cone for a
Bontrager hub?

In the first place, Trek/Bontrager won't sell parts to shops that are
not Trek/Bontrager dealers.

In the second place, at least _some_ Bontrager labeled hubs use
oddball, non-standard cones that are not available at any price to
anybody.

It's tough enough to obtain replacement cones for current model major
brand hubs...basically forget it for off-brand and house-brand oddball
stuff like this.

I admire the shop for attempting a repair. When I ran into this on a
customer's bike the best I could do was tell him he needed a new

wheel.

Quoted message said:

Sheldon "Cone Replacemen Has Always Been A Nightmare In This

Industry"

Quoted message said:

Brown

Sheldon,

When I ran a pro bike shop during the 70's we always kept a supply of
hollow axles and cones to fit so that we could repair just about any
aluminum alloy quick release hub. We sold the customer a new wheel in
the case of steel or non QR hubs.

Are you saying that Bontrager hubs are so non standard (read %^^*#$#&%
junk) that no other cones will fit them???

Thank you for you info in advance oh great sage (said with complete
respect for your experience and reputation).

Chas.

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

Quoted message said:

Quoted message said:

AndyMorris said:

[email hidden] wrote:

<snip>

Quoted message said:

Quoted message said:

My Pueblo zip code is 81004, a non-bicyling-oriented city 50 miles
from the next city. (I'll be surprised if I see more than three

riders

Quoted message said:

Quoted message said:

with drop bars when I leave for my 15 mile ride in a few minutes on a
Saturday evening.)

<snip>

Quoted message said:

Quoted message said:

Carl,

There ain't a whole lot out there in "West Kansas" besides the bridge
over the Arkansas River. ;-)

I ran a shop down in New Mexico during the 70's. We used to go up to
Durango and ride the Iron Horse Race every year. We'ed usually ride part
of US 160 east to Pagossa Springs on the way back home.

Pulling Wolf Creek Pass (10,850ft, 6.5% grade) has always been on my
to-do list. I'm 62 now so I better get started before the snow comes
in... :-)

Chas.

In article <[email hidden]>,
[email hidden] wrote:

SNIP

Quoted message said:

But go to http://www.bontrager.com/Dealer_Network/Dealer_Locator.php

Click on "Find a dealer" and put in 02465.

Six Bontrager dealers are shown on the map within 11 miles of West
Newton, half of them within 3 miles. Two of them are even what
Bontrager calls "demo centers."

snip

If I were within 100 miles of West Newton, there is only ONE LBS to use.
Its at 1535 Washington Street.

Unfortunately I am 440 miles away ( by I-95 ).

If Sheldon or Norm Shackly cannot fix it, it cannot be fixed PERIOD

Harris Cyclery may soon be my LBS

HAND

YO! Scotty. Can you beam me.....🙂

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

Quoted message said:

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

Quoted message said:

Keiron said:

>
Too true, i concede to the fact that things certainly do need to be

replaced

Quoted message said:

Quoted message said:

at times when performance and saftey become issues. I was refering

to the

Quoted message said:

Quoted message said:

attitude that wanting to understand ideas/concepts, even if the

result is

Quoted message said:

Quoted message said:

not logically ideal, is dismissed as irrelevant/unimportant

especially if

Quoted message said:

Quoted message said:

money can be thrown at the problem as an easy solution. What then

would be

Quoted message said:

Quoted message said:

the point in knowing anything? Also a live and let live man so

forgive my

Quoted message said:

Quoted message said:

existential evangelising.

many things which can't be repaired can be recycled. I suspect cones

are

Quoted message said:

in this category.

Bicycle hub wheel bearing cones weigh only a few grams each.

The prices paid for scrap alloy and carbon steel is so low that high
volume producers almost have to pay to have it carted away. Most scrap
dealers in the US think in 40,000 lb. truck load quantities.

So there's not value in used worn out bicycle hub wheel bearing cones.
34% of the earth's mass is made up of iron which is the main constituent
in steel.

"Iron is notable for being the final element produced by stellar
nucleosynthesis, and thus the heaviest element which does not require a
supernova or similarly cataclysmic event for its formation. It is
therefore the most abundant heavy metal in the universe." (From
Wikipedia)

Your heart may be in the right place but your suggestions don't make
economic sense.

Chas. ;-)

While I appreciate the natural abundance of iron i'm sure you'll concede
that it takes less energy to manufacture one set of cones than 2, so if
everyone was able to maintain cones for longer (while still effective)
lifespan then economy of scales would change. If the demand for a trillion
units wasn't there, they wouldnt make them. I accept this is rather more
idealised than practical but should not be lost sight of(?). I'm no
tree-hugging luddite but "there is a code you know".

* * Chas said:

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

Quoted message said:

Snippy Bobkins said:

> I just had my Bontrager MTB hubs serviced at my LBS. The guy said
> they sanded the bearing cones. I assume that is for pitting from
> worn bearings. If I wanted to do that myself, how would I go about
> it? By hand? What grit sandpaper?

<sip>

Quoted message said:

Jim, have you ever actually _tried_ to obtain a replacement cone for
a Bontrager hub?

In the first place, Trek/Bontrager won't sell parts to shops that are
not Trek/Bontrager dealers.

In the second place, at least _some_ Bontrager labeled hubs use
oddball, non-standard cones that are not available at any price to
anybody.

It's tough enough to obtain replacement cones for current model major
brand hubs...basically forget it for off-brand and house-brand
oddball stuff like this.

I admire the shop for attempting a repair. When I ran into this on a
customer's bike the best I could do was tell him he needed a new
wheel.

Sheldon "Cone Replacemen Has Always Been A Nightmare In This
Industry" Brown

Sheldon,

When I ran a pro bike shop during the 70's we always kept a supply of
hollow axles and cones to fit so that we could repair just about any
aluminum alloy quick release hub. We sold the customer a new wheel in
the case of steel or non QR hubs.

Are you saying that Bontrager hubs are so non standard (read %^^*#$#&%
junk) that no other cones will fit them???

Thank you for you info in advance oh great sage (said with complete
respect for your experience and reputation).

I was thinking the same thing. 10x1mm cones should fit almost anything. If
it's a little longer/shorter, just get rid of the dust caps and avoid rain.
Or buy new.

--
Phil Lee, Squid

* * Chas said:

Aside from possible incompetence, perhaps his LBS was like some auto
repair places that recommend you get your "chrome muffler bearings"
replaced! ;-)

Ooh! You can get them in chrome?

Mark

Keiron said:

While I appreciate the natural abundance of iron i'm sure you'll concede
that it takes less energy to manufacture one set of cones than 2, so if
everyone was able to maintain cones for longer (while still effective)
lifespan then economy of scales would change. If the demand for a trillion
units wasn't there, they wouldnt make them. I accept this is rather more
idealised than practical but should not be lost sight of(?). I'm no
tree-hugging luddite but "there is a code you know".

The problem is that a refinished cone lasts essentially no time, so it's
effectively more like 1.01 cones worth out of the 1 cone.

Jasper

Jasper Janssen said:

On Sun, 16 Jul 2006 20:50:33 GMT, "Keiron" <[email hidden]> wrote:

Quoted message said:

Quoted message said:

While I appreciate the natural abundance of iron i'm sure you'll concede
that it takes less energy to manufacture one set of cones than 2, so if
everyone was able to maintain cones for longer (while still effective)
lifespan then economy of scales would change.

Many bear surfaces are surface-hardened. This means that if you sand
the bearing surface then the soft metal down below will be exposed,
leading to a much earlier wear-out period.

Sanding a bearing surface (or using grit and disposable bearings to
achieve the same thing) is called "Lapping" - look it up on google to
learn more.

- Don Gillies
San Diego, CA

Captain Bike said:

I admire the shop for attempting a repair. When I ran into this on a
customer's bike the best I could do was tell him he needed a new wheel.

Sheldon "Cone Replacemen Has Always Been A Nightmare In This Industry"
Brown

Sheldon,

Are Shimano road cones generally interchangeable? Specifically,
would current Shimano DA or Ultegra cones work in older RSX hubs?

Related, are the DA or Ultegra cones superior in any way to the cones
in RSX hubs that would make a significant difference in either
durability or rolling resistance?

Many thanks,

-- Dave
==============================================
"It is impossible, or not easy, to do noble acts
without the proper equipment."
Aristotle, <<Politics>>, 1323a-b, trans Jowett
==============================================

"pinnah" <[email hidden]> a écrit:

Quoted message said:

Are Shimano road cones generally interchangeable? Specifically,
would current Shimano DA or Ultegra cones work in older RSX
hubs?

Generally (with some exceptions), no, and specifically almost certainly not.

While many older and newer hubs have the same axle threading and ball counts
and sizes, sealing arrangements have changed. Modern Shimano cones generally
have an integral dust cap. In older hubs, the dust cap was pressed into the
hub, and the cone often had a pair of sealing rings. Using newer cones in an
older hub, one dustcap will tend to foul the other.

Modern Dura Ace hubs also use oversized aluminium axles, so the threading
isn't compatible with older steel axles.

In the USA, QBP supply various types of cone:

http://harriscyclery.net/page.cfm?PageID=49&action=list&searchtype=search&keywords=cone

Wheels Manufacturing sell replacement cone kits for Shimano
hubs, if Shimano can't supply the parts you need:

http://www.wheelsmfg.com/downloads.php

Another option would be to keep an eye on eBay for a hub you could
canibalize for parts.

James Thomson

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

Quoted message said:

Jasper Janssen said:

On Sun, 16 Jul 2006 20:50:33 GMT, "Keiron" <[email hidden]> wrote:

Quoted message said:

Quoted message said:

While I appreciate the natural abundance of iron i'm sure you'll

concede

Quoted message said:

Quoted message said:

Quoted message said:

that it takes less energy to manufacture one set of cones than 2, so

if

Quoted message said:

Quoted message said:

Quoted message said:

everyone was able to maintain cones for longer (while still

effective)

Quoted message said:

Quoted message said:

Quoted message said:

lifespan then economy of scales would change.

Many bear surfaces are surface-hardened. This means that if you sand
the bearing surface then the soft metal down below will be exposed,
leading to a much earlier wear-out period.

Sanding a bearing surface (or using grit and disposable bearings to
achieve the same thing) is called "Lapping" - look it up on google to
learn more.

- Don Gillies
San Diego, CA

Needle and Roller Bearings that are used in most transportation and
machinery applications are made from high alloy 52100 bearing steel that
is through hardened to the mid 60's on the Rockwell C hardness scale.
They're very hard and the bearing surfaces will generally chip or flake
rather brinell (where the balls create indentations in the race).

Case Hardening is a heat treating process that provides a 60Rc hard
layer .005 to .050 (.13mm to 1.3mm) deep in the surface of the part. It
gives a hard, wear resistant surface that can be ground and or polished
while maintaining a tough base material which will resist cracking and
breaking.

Gears, shafts and some lightly loaded wear zone parts are usually made
from 8620, 9310 or other alloy steels. Cheap parts including many
bicycle cups and cones are made from Case Hardened 1018 Carbon Steel.
Case hardened bearings frequently fail due to brinelling caused by
impact that forces the balls to make indentations into the bearing
surface of bicycle cups and cones.

Quality ball bearings have been around for over 100 years. Loose ball
bearing systems are very cheap to manufacture because the tolerances are
very open versus the requirements for precision machined part to use
sealed ball bearings.

The manufacturing cost difference between loose ball bearings and sealed
bearings is minimal when you weigh in labor costs for assembling the
loose ball systems.

Why use 100+ year old technology?

Chas.

On Sun, 23 Jul 2006 12:49:05 -0700, "* * Chas" <[email hidden]>
wrote:

[snip]

Quoted message said:

Gears, shafts and some lightly loaded wear zone parts are usually made
from 8620, 9310 or other alloy steels. Cheap parts including many
bicycle cups and cones are made from Case Hardened 1018 Carbon Steel.
Case hardened bearings frequently fail due to brinelling caused by
impact that forces the balls to make indentations into the bearing
surface of bicycle cups and cones.

[snip]

Dear Chas,

A substantial group of posters on RBT argues that the "brinelling" or
dimpling in badly indexed headsets is due not to any impact at all,
but to fretting, in which the lube is squished out from between the
balls and races, which then repeatedly micro-weld and tear apart as
the rider zooms down a long straight.

Impact may or may not achieve the same thing (or help it along), but
the "brinelling" effect is well-known elsewhere and is sometimes
called "false brinelling" to distinguish impact from fretting:

http://www.timken.com/products/bearings/services/valueadd/prevent.asp

As Jobst has pointed out, cars transported by railway often suffered
from this fretting/false brinelling. The cars sit still on the train,
so their bearings never rotate to replenish their lubrication. The
cars vibrate enough on the train that the balls squished through to
make a metal-to-metal contact with the races, micro-welded to each
other, and tore apart with the next vibration, eroding holes that look
remarkably like impact dents.

The false brinelling/fretting dimples are erosive, so they will lack
the ring of raised metal pushed up by an impact dimple. Regrettably,
it takes a good microscope and camera to show this.

Cheers,

Carl Fogel

Quoted message said:

On Sun, 23 Jul 2006 12:49:05 -0700, "* * Chas" <[email hidden]>
wrote:

[snip]

Quoted message said:

Gears, shafts and some lightly loaded wear zone parts are usually made
from 8620, 9310 or other alloy steels. Cheap parts including many
bicycle cups and cones are made from Case Hardened 1018 Carbon Steel.
Case hardened bearings frequently fail due to brinelling caused by
impact that forces the balls to make indentations into the bearing
surface of bicycle cups and cones.

[snip]

Dear Chas,

A substantial group of posters on RBT argues that the "brinelling" or
dimpling in badly indexed headsets is due not to any impact at all,
but to fretting, in which the lube is squished out from between the
balls and races, which then repeatedly micro-weld and tear apart as
the rider zooms down a long straight.

Impact may or may not achieve the same thing (or help it along), but
the "brinelling" effect is well-known elsewhere and is sometimes
called "false brinelling" to distinguish impact from fretting:

http://www.timken.com/products/bearings/services/valueadd/prevent.asp

As Jobst has pointed out, cars transported by railway often suffered
from this fretting/false brinelling. The cars sit still on the train,
so their bearings never rotate to replenish their lubrication. The
cars vibrate enough on the train that the balls squished through to
make a metal-to-metal contact with the races, micro-welded to each
other, and tore apart with the next vibration, eroding holes that look
remarkably like impact dents.

they /used/ to. but the fact is, cars are still transported today in
exactly the same way today as they were then, but that kind of damage
doesn't occur any more. why? better metallurgy, better tribology.
part of the reason why modern sealed bearing headsets generally don't
index unless they've been crashed.

Quoted message said:

The false brinelling/fretting dimples are erosive, so they will lack
the ring of raised metal pushed up by an impact dimple. Regrettably,
it takes a good microscope and camera to show this.

Cheers,

Carl Fogel