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Headset dead spot?



 
 
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  #11  
Old April 3rd 08, 03:19 AM posted to rec.bicycles.tech
Ryan Cousineau
external usenet poster
 
Posts: 4,044
Default Headset dead spot?

In article ,
wrote:

On Wed, 02 Apr 2008 21:59:23 GMT, "Williams"
wrote:

[Note: Normally I would search the archives to find previous messages, but
the Google Advanced Groups Search no longer works. Is there another tool
for that?]

It seems that my front wheel steering has a "dead spot" such that the front
wheel wants to point straight ahead (like there is a detent). Is a headset
adjustment called for?

This is a Chris King threaded headset on a road bike.

thanks,
Craig


Dear Craig,

Most likely, your headset bearing races are pitted, with pits spaced
one ball apart.

It's a familiar problem known as indexed steering--the handlebar will
turn in small steps, as if indexed like a shift lever. It's exactly as
if there are the little detents that you describe because that's what
they are.

The fix is new bearings and races.

Here's an artificially dented headset:
http://home.comcast.net/~carlfogel/download/brinell.jpg

Dear Carl:

fine photo of wanton bike-part destruction (sure, sure, in the name of
science...) but my curiosity is piqued by the rather curious artifact in
the top left of the photo.

No, not the dime. Further left.

--
Ryan Cousineau http://www.wiredcola.com/
"In other newsgroups, they killfile trolls."
"In rec.bicycles.racing, we coach them."
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  #12  
Old April 3rd 08, 03:35 AM posted to rec.bicycles.tech
Teh bike guy
external usenet poster
 
Posts: 1
Default Headset dead spot?

This is common and easy to fix, just squirt some toothpaste (whitening
formulations work best) into the headset and ride around for a few miles,
it will become all smooth again, after that you can flush with water and
add grease.


On Wed, 02 Apr 2008 21:59:23 GMT, Williams wrote:

[Note: Normally I would search the archives to find previous messages, but
the Google Advanced Groups Search no longer works. Is there another tool
for that?]

It seems that my front wheel steering has a "dead spot" such that the front
wheel wants to point straight ahead (like there is a detent). Is a headset
adjustment called for?

This is a Chris King threaded headset on a road bike.

thanks,
Craig

  #13  
Old April 3rd 08, 03:48 AM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 7,934
Default Headset dead spot?

On Thu, 03 Apr 2008 02:19:20 GMT, Ryan Cousineau
wrote:

Here's an artificially dented headset:
http://home.comcast.net/~carlfogel/download/brinell.jpg


Dear Carl:

fine photo of wanton bike-part destruction (sure, sure, in the name of
science...) but my curiosity is piqued by the rather curious artifact in
the top left of the photo.

No, not the dime. Further left.


Dear Ryan,

Hmmm . . .

http://i31.tinypic.com/e9yzhi.jpg

It could be a modern version of this:
http://en.wikipedia.org/wiki/Image:H...mbassadors.jpg

Put one eye at the lower left edge of your screen and the anamorphic
blob turns into a skull:

http://upload.wikimedia.org/wikipedi...mbassadors.jpg

But it's more likely just an icon (a sort of red-faced Mr. Potato Head
with a yellow cap?) introduced by some shareware used to trim photos
made with the original $12.95 USB camera that led Fogel Labs down the
well-paved path to its present location.

It appears in several other priceless early works:
http://home.comcast.net/~carlfogel/download

http://home.comcast.net/~carlfogel/d...d/brinell2.jpg
http://home.comcast.net/~carlfogel/d...nell2setup.jpg
http://home.comcast.net/~carlfogel/download/C1.jpg
http://home.comcast.net/~carlfogel/download/
http://home.comcast.net/~carlfogel/download/C3.jpg

Cheers,

Carl Fogel
  #14  
Old April 3rd 08, 04:13 AM posted to rec.bicycles.tech
jim beam
external usenet poster
 
Posts: 5,758
Default Headset dead spot?

Williams wrote:
[Note: Normally I would search the archives to find previous messages, but
the Google Advanced Groups Search no longer works. Is there another tool
for that?]

It seems that my front wheel steering has a "dead spot" such that the front
wheel wants to point straight ahead (like there is a detent). Is a headset
adjustment called for?

This is a Chris King threaded headset on a road bike.

thanks,
Craig



probably the product of over-zealous fitting by the installer and
subsequent brinelling damage. c.k. headsets require a custom attachment
for the bearing press, and not everyone bothers to use one.
  #15  
Old April 3rd 08, 04:14 AM posted to rec.bicycles.tech
jim beam
external usenet poster
 
Posts: 5,758
Default Headset dead spot?

wrote:
Craig Williams wrote:

[Note: Normally I would search the archives to find previous
messages, but the Google Advanced Groups Search no longer works. Is
there another tool for that?]


It seems that my front wheel steering has a "dead spot" such that
the front wheel wants to point straight ahead (like there is a
detent). Is a headset adjustment called for?


This is a Chris King threaded headset on a road bike.


http://www.sheldonbrown.com/brandt/i...-steering.html

I think Google can find that one. Anyway, you might add that to your
favorites.


not only is the premise of that article incorrect, it contains other
significant inaccuracies. rotating bearings /do/ indeed have metallic
contact up until the point of hydrodynamic separation.

http://www.tribology-abc.com/calculators/e12_3.htm

separation only occurs at significant speed. at higher loads, it may
never occur. for you to contend that headset bearings are somehow
different from all the other bearings on a bike for which hydrodynamic
separation also does /not/ occur, is both ignorant and misleading.

furthermore, another poster to this group actually bothered to do
hardness testing of some headset bearings and found that low hardness
bearing races indexed quickly, while those with harder races didn't.
this is entirely in accordance with indexing being the product of
overload, [true brinelling] not "fretting" [false brinelling].

  #16  
Old April 3rd 08, 04:17 AM posted to rec.bicycles.tech
jim beam
external usenet poster
 
Posts: 5,758
Default Headset dead spot?

wrote:
someone wrote:

[Note: Normally I would search the archives to find previous
messages, but the Google Advanced Groups Search no longer works.
Is there another tool for that?]


It seems that my front wheel steering has a "dead spot" such that
the front wheel wants to point straight ahead (like there is a
detent). Is a headset adjustment called for? This is a Chris
King threaded headset on a road bike.


http://www.sheldonbrown.com/brandt/i...-steering.html

I think Google can find that one. Anyway, you might add that to
your favorites.


Why did you object to the word Brinell in that article? The term
itself is not at fault, nor was the - not surprisingly uncredited -
OP in describing the problem. That is what indexed headsets refer
to - the only question is whether it is Brinelling due to excessive
load or ambient conditions.


Brinell is a forceful indentation of a ball into a surface and it
leaves a shiny dimple the shape of the ball. Head bearing races are
eroded by fretting and have dimples that are neither shiny nor
spherical. They are causes by the balls rolling across their design
path in tiny excursions.


so how do /you/ know which is which? did the o.p. sent you the headset
and you've had a chance to examine it? since in reality you have NOT
actually made these inspections, you're simply presenting underinformed
presumption as fact.



To the OP: is there a single dead spot, or do you find other
'resting spots' as you rotate the handlebars?


They occur at regular intervals, one ball space apart, but the
straight ahead one is largest because that is the position in which
this damage occurs.

The bearing balls in the front and rear of the head bearing leave
fretting impressions and I think the article explains that adequately.


no it doesn't [you don't] because it [you] fails to recognize true
brinelling - something easily caused by overload.
  #17  
Old April 3rd 08, 05:02 AM posted to rec.bicycles.tech
RicodJour
external usenet poster
 
Posts: 3,142
Default Headset dead spot?

On Apr 2, 7:48 pm, wrote:
someone wrote:
[Note: Normally I would search the archives to find previous
messages, but the Google Advanced Groups Search no longer works.
Is there another tool for that?]
It seems that my front wheel steering has a "dead spot" such that
the front wheel wants to point straight ahead (like there is a
detent). Is a headset adjustment called for? This is a Chris
King threaded headset on a road bike.


http://www.sheldonbrown.com/brandt/i...-steering.html

I think Google can find that one. Anyway, you might add that to
your favorites.


Why did you object to the word Brinell in that article? The term
itself is not at fault, nor was the - not surprisingly uncredited -
OP in describing the problem. That is what indexed headsets refer
to - the only question is whether it is Brinelling due to excessive
load or ambient conditions.


Brinell is a forceful indentation of a ball into a surface and it
leaves a shiny dimple the shape of the ball. Head bearing races are
eroded by fretting and have dimples that are neither shiny nor
spherical. They are causes by the balls rolling across their design
path in tiny excursions.


Brinell is a hardness test and leaves indentation as you mention.
Brinelling is the result of overloaded bearings and may or may not
leave identical impressions. Brinelling, whether 'true' or 'false',
of actual bearings in use does not happen in a single test at 3000 kg,
hence the markings will vary. The word migrated due to the similarity
in bearing race damage. As an example, if someone called you a
horse's ass, that does not mean you are an actual horse's ass, they
are just commenting on the similarity.

To the OP: is there a single dead spot, or do you find other
'resting spots' as you rotate the handlebars?


They occur at regular intervals, one ball space apart, but the
straight ahead one is largest because that is the position in which
this damage occurs.

The bearing balls in the front and rear of the head bearing leave
fretting impressions and I think the article explains that adequately.


I am surprised that you were unable to decipher 'To the OP:'
correctly. It seemed straightforward when I wrote it...

R
  #19  
Old April 3rd 08, 06:46 AM posted to rec.bicycles.tech
Ryan Cousineau
external usenet poster
 
Posts: 4,044
Default Headset dead spot?

In article ,
wrote:

On Thu, 03 Apr 2008 02:19:20 GMT, Ryan Cousineau
wrote:

Here's an artificially dented headset:
http://home.comcast.net/~carlfogel/download/brinell.jpg

Dear Carl:

fine photo of wanton bike-part destruction (sure, sure, in the name of
science...) but my curiosity is piqued by the rather curious artifact in
the top left of the photo.

No, not the dime. Further left.


Dear Ryan,

Hmmm . . .

http://i31.tinypic.com/e9yzhi.jpg

It could be a modern version of this:
http://en.wikipedia.org/wiki/Image:H...mbassadors.jpg

Put one eye at the lower left edge of your screen and the anamorphic
blob turns into a skull:

http://upload.wikimedia.org/wikipedi...mbassadors.jpg

But it's more likely just an icon (a sort of red-faced Mr. Potato Head
with a yellow cap?) introduced by some shareware used to trim photos
made with the original $12.95 USB camera that led Fogel Labs down the
well-paved path to its present location.

It appears in several other priceless early works:
http://home.comcast.net/~carlfogel/download

http://home.comcast.net/~carlfogel/d...d/brinell2.jpg


&c.

Well, that explanation was surprising, the creature is still confusing
(surprised they didn't at least use something that advertised their
software), and I learned about Holbein's remarkable painting.

Another good evening for Usenet.

--
Ryan Cousineau http://www.wiredcola.com/
"In other newsgroups, they killfile trolls."
"In rec.bicycles.racing, we coach them."
  #20  
Old April 3rd 08, 09:28 AM posted to rec.bicycles.tech
Ben C
external usenet poster
 
Posts: 3,084
Default Headset dead spot?

On 2008-04-03, jim beam wrote:
Williams wrote:
[Note: Normally I would search the archives to find previous messages, but
the Google Advanced Groups Search no longer works. Is there another tool
for that?]

It seems that my front wheel steering has a "dead spot" such that the front
wheel wants to point straight ahead (like there is a detent). Is a headset
adjustment called for?

This is a Chris King threaded headset on a road bike.

thanks,
Craig



probably the product of over-zealous fitting by the installer and
subsequent brinelling damage. c.k. headsets require a custom attachment
for the bearing press, and not everyone bothers to use one.


Do you mean they got brinelled as they were hammered into the frame?

That's one I've not heard. I thought in the usual "true brinelling"
version of events, the brinelling happens when you ride over a nasty
bump with the front wheel?
 




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