banged bottom bracket bearing

Elsewhere in a current thread, posters are debating whether banging a
stubborn cotter out of a crank could damage a bottom bracket bearing
and whether the crank should be supported while smacking the cotter to
protect the bearing.

I threw my last cottered crank away years ago.

My first thought was that I might as well bang on my road bike's
crank, but the weather forecast claims that I might see temperatures
above freezing by Monday.

Huddled asleep out in the cold was my faithful, trusting Fury
Roadmaster. A bit rusty in spots, about 1200 miles on it, front wheel
long since cannibalized for inhuman experiments, handsome Ashtabula
crank with big, brawny bearing balls . . .

I gently brought the Fury Roadmaster inside without waking it up,
placed it upside down on the basement floor, and--

Wham! Wham! Wham!

The poor thing never knew what hit it (a big hammer on the end of the
pedal to simulate banging on a reluctant crank cotter).

The Ashtabula crank came apart surprisingly easily, and the corpse of
the bearing was laid out reverently on a 1 mm graph paper after
cleaning:

http://i15.tinypic.com/433cnf5.jpg

The angle and lighting actually minimize the damage to the race. The
layout reverses things--the ball with the most damage hit the upper
pit, while the ball above it hit the lower pit.

There's a third pit in the race, but it doesn't show up well, and I
couldn't find a third damaged ball.

I expect the usual comments about how higher-quality bearings must be
invulnerable to impacts, but it seems to me that it couldn't hurt to
support the crank if you're reduced to hammering out stubborn cotters.

The steel cotter press mentioned in the thread seems like a much
better idea than hammering, though it's expensive:

http://bikesmithdesign.com/CotterPress/index.html

The page mentions that an oversized press is available for cotters
larger than 10 mm in antique bicycles.

Cheers,

Carl Fogel

wrote:
Elsewhere in a current thread, posters are debating whether banging a
stubborn cotter out of a crank could damage a bottom bracket bearing
and whether the crank should be supported while smacking the cotter to
protect the bearing.

I threw my last cottered crank away years ago.

My first thought was that I might as well bang on my road bike's
crank, but the weather forecast claims that I might see temperatures
above freezing by Monday.

Huddled asleep out in the cold was my faithful, trusting Fury
Roadmaster. A bit rusty in spots, about 1200 miles on it, front wheel
long since cannibalized for inhuman experiments, handsome Ashtabula
crank with big, brawny bearing balls . . .

I gently brought the Fury Roadmaster inside without waking it up,
placed it upside down on the basement floor, and--

Wham! Wham! Wham!

The poor thing never knew what hit it (a big hammer on the end of the
pedal to simulate banging on a reluctant crank cotter).

The Ashtabula crank came apart surprisingly easily, and the corpse of
the bearing was laid out reverently on a 1 mm graph paper after
cleaning:

http://i15.tinypic.com/433cnf5.jpg

The angle and lighting actually minimize the damage to the race. The
layout reverses things--the ball with the most damage hit the upper
pit, while the ball above it hit the lower pit.

ok, but let's be clear, the race pits existed before hammering - they
are classic spalling of low quality case hardening.


There's a third pit in the race, but it doesn't show up well, and I
couldn't find a third damaged ball.

I expect the usual comments about how higher-quality bearings must be
invulnerable to impacts, but it seems to me that it couldn't hurt to
support the crank if you're reduced to hammering out stubborn cotters.

The steel cotter press mentioned in the thread seems like a much
better idea than hammering, though it's expensive:

http://bikesmithdesign.com/CotterPress/index.html

The page mentions that an oversized press is available for cotters
larger than 10 mm in antique bicycles.

Cheers,

Carl Fogel

On Thu, 01 Feb 2007 20:04:30 -0800, jim beam
wrote:

wrote:
Elsewhere in a current thread, posters are debating whether banging a
stubborn cotter out of a crank could damage a bottom bracket bearing
and whether the crank should be supported while smacking the cotter to
protect the bearing.

I threw my last cottered crank away years ago.

My first thought was that I might as well bang on my road bike's
crank, but the weather forecast claims that I might see temperatures
above freezing by Monday.

Huddled asleep out in the cold was my faithful, trusting Fury
Roadmaster. A bit rusty in spots, about 1200 miles on it, front wheel
long since cannibalized for inhuman experiments, handsome Ashtabula
crank with big, brawny bearing balls . . .

I gently brought the Fury Roadmaster inside without waking it up,
placed it upside down on the basement floor, and--

Wham! Wham! Wham!

The poor thing never knew what hit it (a big hammer on the end of the
pedal to simulate banging on a reluctant crank cotter).

The Ashtabula crank came apart surprisingly easily, and the corpse of
the bearing was laid out reverently on a 1 mm graph paper after
cleaning:

http://i15.tinypic.com/433cnf5.jpg

The angle and lighting actually minimize the damage to the race. The
layout reverses things--the ball with the most damage hit the upper
pit, while the ball above it hit the lower pit.

ok, but let's be clear, the race pits existed before hammering - they
are classic spalling of low quality case hardening.


There's a third pit in the race, but it doesn't show up well, and I
couldn't find a third damaged ball.

I expect the usual comments about how higher-quality bearings must be
invulnerable to impacts, but it seems to me that it couldn't hurt to
support the crank if you're reduced to hammering out stubborn cotters.

The steel cotter press mentioned in the thread seems like a much
better idea than hammering, though it's expensive:

http://bikesmithdesign.com/CotterPress/index.html

The page mentions that an oversized press is available for cotters
larger than 10 mm in antique bicycles.

Cheers,

Carl Fogel

Dear Jim,

When I tried to take better pictures, I only proved that I don't know
how to light shiny rounded metal objects for extreme close ups.

Sorry that I can't give clearer pictures.

But this appears to be hammer damage to a specific section of an
otherwise unpitted bottom bracket.

The massive damage to the race consists of two huge smashed pits and a
third tiny pit, from say noon to 3 o'clock. The rest of the race is
smooth and unpitted, about what you'd expect from only 1200 miles of
pavement riding with a huge, heavily greased bearing.

Much of the race damage is jagged, not worn smooth--spalling, I think.
Some of the spalling has been smashed flat again, but lots of rough
surface is still visible.

Two big spalls go through the edge of the race, where material was
knocked off. Here are two side views:

x
x
x
x
x ball
x x x --lip or edge of race
x
x
x
x
x

x
x
x
x
s d ball
s d d d d = damaged, removed
s d s = spalled-out section
s d
s d
s
x

One ball is massively damaged, another has a tiny damaged spot, and I
couldn't find any damage on the others.

Cheers,

Carl Fogel

On Thu, 01 Feb 2007 22:04:32 -0700, wrote:

On Thu, 01 Feb 2007 20:04:30 -0800, jim beam
wrote:

wrote:
Elsewhere in a current thread, posters are debating whether banging a
stubborn cotter out of a crank could damage a bottom bracket bearing
and whether the crank should be supported while smacking the cotter to
protect the bearing.

I threw my last cottered crank away years ago.

My first thought was that I might as well bang on my road bike's
crank, but the weather forecast claims that I might see temperatures
above freezing by Monday.

Huddled asleep out in the cold was my faithful, trusting Fury
Roadmaster. A bit rusty in spots, about 1200 miles on it, front wheel
long since cannibalized for inhuman experiments, handsome Ashtabula
crank with big, brawny bearing balls . . .

I gently brought the Fury Roadmaster inside without waking it up,
placed it upside down on the basement floor, and--

Wham! Wham! Wham!

The poor thing never knew what hit it (a big hammer on the end of the
pedal to simulate banging on a reluctant crank cotter).

The Ashtabula crank came apart surprisingly easily, and the corpse of
the bearing was laid out reverently on a 1 mm graph paper after
cleaning:

http://i15.tinypic.com/433cnf5.jpg

The angle and lighting actually minimize the damage to the race. The
layout reverses things--the ball with the most damage hit the upper
pit, while the ball above it hit the lower pit.

ok, but let's be clear, the race pits existed before hammering - they
are classic spalling of low quality case hardening.


There's a third pit in the race, but it doesn't show up well, and I
couldn't find a third damaged ball.

I expect the usual comments about how higher-quality bearings must be
invulnerable to impacts, but it seems to me that it couldn't hurt to
support the crank if you're reduced to hammering out stubborn cotters.

The steel cotter press mentioned in the thread seems like a much
better idea than hammering, though it's expensive:

http://bikesmithdesign.com/CotterPress/index.html

The page mentions that an oversized press is available for cotters
larger than 10 mm in antique bicycles.

Cheers,

Carl Fogel

Dear Jim,

When I tried to take better pictures, I only proved that I don't know
how to light shiny rounded metal objects for extreme close ups.

Sorry that I can't give clearer pictures.

But this appears to be hammer damage to a specific section of an
otherwise unpitted bottom bracket.

The massive damage to the race consists of two huge smashed pits and a
third tiny pit, from say noon to 3 o'clock. The rest of the race is
smooth and unpitted, about what you'd expect from only 1200 miles of
pavement riding with a huge, heavily greased bearing.

Much of the race damage is jagged, not worn smooth--spalling, I think.
Some of the spalling has been smashed flat again, but lots of rough
surface is still visible.

Two big spalls go through the edge of the race, where material was
knocked off. Here are two side views:

x
x
x
x
x ball
x x x --lip or edge of race
x
x
x
x
x

x
x
x
x
s d ball
s d d d d = damaged, removed
s d s = spalled-out section
s d
s d
s
x

One ball is massively damaged, another has a tiny damaged spot, and I
couldn't find any damage on the others.

Cheers,

Carl Fogel

Here's my best effort to show the chunk taken out of the race:

http://i15.tinypic.com/2vl5vld.jpg

The race threads onto the "spindle" of the Ashtabula crank.

The impact (from the far side of the race) drives the ball into the
race, creating the high side of the pit.

At the same time, pressure builds up until it breaks out the big chunk
on the low side of the pit in an unexpected direction.

Imagine the damage on the bottom, at 6 o'clock, with the hammer
banging down on an upright crank and pedal:


hammer
|
V
pedal
|
|
|
_____|
| x
|
|
_|

Here's x before damage:

XXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXX
XXXXXXXXXX
XXXXXXXX
XXXXXXX
lip

Here's x after damage:

XXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXX,..XXXXXXXXXXXX
XXXX. ' ',XXXXXXXXXX
'XXXXXXXX
'XXXXXXX
.XXXXX
.XXXX
/\ \
/ \ \ /
ball ___\/
driven material breaks
upward out downward at angle
into race as lip fails


The effect is that the damage above extends both to the left and to
the right.

The right-hand damage is more dramatic, partly because it's bigger,
but mostly because it's going in an unexpected direction--the lip
fails and material moves sideways and in the opposite direction that
the ball is bedding itself into the race.

CF

On Thu, 01 Feb 2007 20:39:16 -0700, wrote:

Elsewhere in a current thread, posters are debating whether banging a
stubborn cotter out of a crank could damage a bottom bracket bearing
and whether the crank should be supported while smacking the cotter to
protect the bearing.

I wonder about a more modern practice. People hammer in the star nut
into a fork with the fork attached to the bicycle. I wonder about the
damage to headset bearings.

Paul Kopit Wrote:
...I wonder about a more modern practice. People hammer in the star nut
into a fork with the fork attached to the bicycle. I wonder about the
damage to headset bearings.

But wouldn't the natural way to do this be to support the fork on
something rather than the frame? In that case the headset might see
some jarring, but not much of direct impact. Front wheel(hub) OTOH if
left in place could see a fairly direct impact.
Or do people insert star nuts with the bike clamped in a work stand?
Seems wobbly for such an operation, but would channel some impact to
headset.


--
dabac

On Thu, 01 Feb 2007 20:39:16 -0700, carlfogel wrote:

but it seems to me that it couldn't hurt to
support the crank if you're reduced to hammering out stubborn cotters.

I would think so, to support that part directly and solidly instead of
with a sloppy bearing.

Matt O.

wrote:
On Thu, 01 Feb 2007 22:04:32 -0700, wrote:

On Thu, 01 Feb 2007 20:04:30 -0800, jim beam
wrote:

wrote:
Elsewhere in a current thread, posters are debating whether banging a
stubborn cotter out of a crank could damage a bottom bracket bearing
and whether the crank should be supported while smacking the cotter to
protect the bearing.

I threw my last cottered crank away years ago.

My first thought was that I might as well bang on my road bike's
crank, but the weather forecast claims that I might see temperatures
above freezing by Monday.

Huddled asleep out in the cold was my faithful, trusting Fury
Roadmaster. A bit rusty in spots, about 1200 miles on it, front wheel
long since cannibalized for inhuman experiments, handsome Ashtabula
crank with big, brawny bearing balls . . .

I gently brought the Fury Roadmaster inside without waking it up,
placed it upside down on the basement floor, and--

Wham! Wham! Wham!

The poor thing never knew what hit it (a big hammer on the end of the
pedal to simulate banging on a reluctant crank cotter).

The Ashtabula crank came apart surprisingly easily, and the corpse of
the bearing was laid out reverently on a 1 mm graph paper after
cleaning:

http://i15.tinypic.com/433cnf5.jpg

The angle and lighting actually minimize the damage to the race. The
layout reverses things--the ball with the most damage hit the upper
pit, while the ball above it hit the lower pit.
ok, but let's be clear, the race pits existed before hammering - they
are classic spalling of low quality case hardening.

There's a third pit in the race, but it doesn't show up well, and I
couldn't find a third damaged ball.

I expect the usual comments about how higher-quality bearings must be
invulnerable to impacts, but it seems to me that it couldn't hurt to
support the crank if you're reduced to hammering out stubborn cotters.

The steel cotter press mentioned in the thread seems like a much
better idea than hammering, though it's expensive:

http://bikesmithdesign.com/CotterPress/index.html

The page mentions that an oversized press is available for cotters
larger than 10 mm in antique bicycles.

Cheers,

Carl Fogel
Dear Jim,

When I tried to take better pictures, I only proved that I don't know
how to light shiny rounded metal objects for extreme close ups.

Sorry that I can't give clearer pictures.

But this appears to be hammer damage to a specific section of an
otherwise unpitted bottom bracket.

The massive damage to the race consists of two huge smashed pits and a
third tiny pit, from say noon to 3 o'clock. The rest of the race is
smooth and unpitted, about what you'd expect from only 1200 miles of
pavement riding with a huge, heavily greased bearing.

Much of the race damage is jagged, not worn smooth--spalling, I think.
Some of the spalling has been smashed flat again, but lots of rough
surface is still visible.

Two big spalls go through the edge of the race, where material was
knocked off. Here are two side views:

x
x
x
x
x ball
x x x --lip or edge of race
x
x
x
x
x

x
x
x
x
s d ball
s d d d d = damaged, removed
s d s = spalled-out section
s d
s d
s
x

One ball is massively damaged, another has a tiny damaged spot, and I
couldn't find any damage on the others.

Cheers,

Carl Fogel

Here's my best effort to show the chunk taken out of the race:

http://i15.tinypic.com/2vl5vld.jpg

The race threads onto the "spindle" of the Ashtabula crank.

The impact (from the far side of the race) drives the ball into the
race, creating the high side of the pit.

At the same time, pressure builds up until it breaks out the big chunk
on the low side of the pit in an unexpected direction.

Imagine the damage on the bottom, at 6 o'clock, with the hammer
banging down on an upright crank and pedal:


hammer
|
V
pedal
|
|
|
_____|
| x
|
|
_|

Here's x before damage:

XXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXX
XXXXXXXXXX
XXXXXXXX
XXXXXXX
lip

Here's x after damage:

XXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXX,..XXXXXXXXXXXX
XXXX. ' ',XXXXXXXXXX
'XXXXXXXX
'XXXXXXX
.XXXXX
.XXXX
/\ \
/ \ \ /
ball ___\/
driven material breaks
upward out downward at angle
into race as lip fails


The effect is that the damage above extends both to the left and to
the right.

The right-hand damage is more dramatic, partly because it's bigger,
but mostly because it's going in an unexpected direction--the lip
fails and material moves sideways and in the opposite direction that
the ball is bedding itself into the race.

CF

ok, in terms of photo artifact, the first looks like pitting typical of
case hardening breaking up. the bearing can however definitely deform
as you describe - you and i did similar experiments on headset bearings
- but in the absence if better pics, it's hard to see for sure what's
up. on your first photo, the race is lit from behind, not the front, so
the same angle but lit differently would make a big difference in
ability to see. turn off flash sometimes too.

On Feb 1, 8:39 pm, wrote:

The poor thing never knew what hit it (a big hammer on the end of the
pedal to simulate banging on a reluctant crank cotter).


You can damage anything if you hit it hard enough.
Cotters were made out of significantly softer steel
than bearing balls or races, so they deformed,
probably before the bearings were damaged in
most cases.

I expect the usual comments about how higher-quality bearings must be
invulnerable to impacts, but it seems to me that it couldn't hurt to
support the crank if you're reduced to hammering out stubborn cotters.

The steel cotter press mentioned in the thread seems like a much
better idea than hammering, though it's expensive:

The simple solution I came up with, which might have been in "Anybody's Bike
Book", was pretty simple. a foot-long piece of a 2 by 4, with a 1/4" hole
drilled in the end to accept the cotter pin. Then you can bang on the head
of the pin all you want and not have to worry about damaging the bottom
bracket.

We did, at one of the shops I worked, have one of those VAR pin removal
tools. When it worked it was way-cool. Sometimes the threaded end of the pin
would break off though (likely because it was being used on pins that had
prior, unsuccessful attempts at removal.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA


wrote in message
...
Elsewhere in a current thread, posters are debating whether banging a
stubborn cotter out of a crank could damage a bottom bracket bearing
and whether the crank should be supported while smacking the cotter to
protect the bearing.

I threw my last cottered crank away years ago.

My first thought was that I might as well bang on my road bike's
crank, but the weather forecast claims that I might see temperatures
above freezing by Monday.

Huddled asleep out in the cold was my faithful, trusting Fury
Roadmaster. A bit rusty in spots, about 1200 miles on it, front wheel
long since cannibalized for inhuman experiments, handsome Ashtabula
crank with big, brawny bearing balls . . .

I gently brought the Fury Roadmaster inside without waking it up,
placed it upside down on the basement floor, and--

Wham! Wham! Wham!

The poor thing never knew what hit it (a big hammer on the end of the
pedal to simulate banging on a reluctant crank cotter).

The Ashtabula crank came apart surprisingly easily, and the corpse of
the bearing was laid out reverently on a 1 mm graph paper after
cleaning:

http://i15.tinypic.com/433cnf5.jpg

The angle and lighting actually minimize the damage to the race. The
layout reverses things--the ball with the most damage hit the upper
pit, while the ball above it hit the lower pit.

There's a third pit in the race, but it doesn't show up well, and I
couldn't find a third damaged ball.

I expect the usual comments about how higher-quality bearings must be
invulnerable to impacts, but it seems to me that it couldn't hurt to
support the crank if you're reduced to hammering out stubborn cotters.

The steel cotter press mentioned in the thread seems like a much
better idea than hammering, though it's expensive:

http://bikesmithdesign.com/CotterPress/index.html

The page mentions that an oversized press is available for cotters
larger than 10 mm in antique bicycles.

Cheers,

Carl Fogel