Which frames have italian thread bottom brackets?

On 17 Apr, 13:36, _
wrote:
On Thu, 16 Apr 2009 16:48:38 -0700 (PDT), Nick L Plate wrote:
On 17 Apr, 00:18, AMuzi wrote:
wrote:
Even if the threads do not unscrew,
they fret and cause failures as
right pedals in aluminum cranks do.
Tom Ace wrote:
If an Italian-thread right-side cup is in
tight enough to not unscrew, is it still
moving and fretting with use?

Fretting wear occurs in all crank bearing thread formats
with high mileage or high loads. A cup which is "not moving"
isn't moving, by definition. In the case of your right side
cup, it probably is moving though. The movement from cyclic
loading frets the threaded area whether it unscrews or not.

Just checked thread forms and whitworth is 55deg while a cycle thread
is 60deg. *There could lie the problem. *

No.

a) I know of no bottom bracket cups or shells that used Whitworth threads;
please supply an example.

CBA The worshop tool to cut the frame thread may be wrong. It's
possible. I have not seen the problem on any of my bikes, nor any
other quality bike.

b) even if you can do a), at the size of the thread in question a five
degree difference in thread angle gives a depth difference of just about a
thousandth of an inch; which I suspect is not only smaller than the
manufacturing tolerances but also smaller than the fit allowances.

But would it make a difference?

...and in passing, if you do manage to do a), could you get to work on your
job of supplying that example of spokes worn through by a third at the
crossing point?

CBA

On 17 Apr, 05:26, " wrote:
On Apr 16, 8:18*pm, --D-y wrote:



On Apr 16, 8:00*pm, Still Just Me
wrote:

(Jobst):

What extreme conditions? *This design change was not made almost
universally in the bicycle industry as a whim as you seem to depict
it, done for extremists. *My local frame builders can tell you of the
many fork/stem rescues they have performed.

(SJM):

Care to estimate the percentage of frames that have this issue?
Something like .000000001% perhaps?

Seatposts, too. Many many occurrences. If SJM hasn't seen them,
perhaps that's because he's more careful about maintenance ("pull and
regrease") than some, including me. I've had a few tough extractions
and one solid freeze (stem) over the years.

Common enough IME to suggest to bike sellers that one advantage of
parting out "vintage" bikes is to show the seatpost and stem will in
fact come out and are not corroded in place.

A google search of this newsgroup will find that
how to remove a stuck stem or seatpost is a common
question (it's also covered at length in Sheldon Brown's
webpages), and that quite a few of the regulars have
had to deal with it. *Sometimes on used bikes with
dodgy histories, but occasionally on their own bikes
that have been neglected, perhaps, but not abused.
It's certainly more than .0 and a lot of zeroes percent.

I don't care too much about the threaded/threadless war,
and nearly all my bikes have threaded stems.
But I have had a nice threaded stem that just wouldn't
work in the bike I used it for. *It had a conical expansion
nut rather than a wedge. *Even a mild tightening
force would get it super-stuck and I'd have to whale on
it with a mallet to remove it. *To add insult to injury,
when installed, the actual stem shaft was just a tiny
bit undersized (as they mostly are) and it would
rock and creak a little when pedaling while standing.
So the damn thing was stuck fast, but it wasn't even
tight. *I replaced it with a wedge stem and the bike's
fine, but experiences like this make you think the
whole stem-threaded steerer interface was really
not engineered for the long term, and that its
commonness is a legacy issue more than a
desirability issue.


Use grease on expander cone. Use hammer directly on bolt to release
cone. Bigger is quicker.

On 17 Apr, 16:54, Mike wrote:
On 16 Apr 2009 23:04:05 GMT, wrote:

How do you explain the nearly universal adoption of the threadless steertube?

Sometimes there is really no logic to the widespread adoption of
something new, for most practical purposes this is one of them.

Lack of skills, unable to swing hammer without smacking the top tube.
Saves the shop by employing unsupervised teenager.

On 17 Apr, 17:54, wrote:
Trevor Jeffry wrote:

Be said ...

I don't care too much about the threaded/threadless war, and nearly
all my bikes have threaded stems. *But I have had a nice threaded
stem that just wouldn't work in the bike I used it for. *It had a
conical expansion nut rather than a wedge. *Even a mild tightening
force would get it super-stuck and I'd have to whale on it with a
mallet to remove it. *To add insult to injury, when installed, the
actual stem shaft was just a tiny bit undersized (as they mostly
are) and it would rock and creak a little when pedaling while
standing. *So the damn thing was stuck fast, but it wasn't even
tight. *I replaced it with a wedge stem and the bike's fine, but
experiences like this make you think the whole stem-threaded
steerer interface was really not engineered for the long term, and
that its commonness is a legacy issue more than a desirability
issue.

Use grease on expander cone. *Use hammer directly on bolt to release
cone. *Bigger is quicker.

It is not freeing the expander that presents a problem but removing an
aluminum quill stem from the steertube into which it has become
permanently attached by corrosion. *I suppose you missed the picture
of the bored out stem or that quill stems often need such removal.
That a hammer must be used on stem bolts to disengage expander cones
from stems is standard procedure.

Jobst Brandt

Stop bitchin'

Read what Ben said. He DOESN'T care. My explanation was specific to
his previous problem, which he DOESN'T have now because he replaced
the expander cone. Your'e as bad as jb for your failure to understand
the relevant.

On Apr 17, 11:38*am, wrote:
Russell Seaton wrote:
How do you explain the nearly universal adoption of the threadless
steertube?
Sometimes there is really no logic to the widespread adoption of
something new, for most practical purposes this is one of them.
There is great logic behind the adoption of the threadless steerer
tube on forks. *Cheaper. *One fork fits all sizes of a particular
frame. *48cm to 62cm, same fork. *No need to cut forks to fit the
different sizes within a frame range and thread every single one of
them. *And cut the keyhole slot. *That takes time and money and
machining and people. *Cheaper stems too. *I suspect threadless
stems are cheaper and easier to make than quill stems. *Assembly
time is likely reduced. *Probably you can tape and assemble the bars
before beginning to assemble the bike. *Use lower cost labor for
this. *Maybe contract with a supplier to deliver already taped up
bars with brake levers on them to the final assembly plant. *Then
just bolt the completed bars to the bike with the removable
faceplates now used on all stems. *And of course the threadless
fork/stem configuration allows for the use of aluminum or carbon
fork steerers instead of steel. *Weight consideration. *Only steel
for threaded forks.
Your claim that there is no logic to the widespread adoption of the
threadless fork/stem is illogical.

I don't believe the reasons you list are the motivating reason for
development of the bar stem clamped to the outside of the steertube,
but rather the failure of the quill stem to be reliably attached and
detached,

This failure of the quill stem to be reliably attached and detached
happens long after the bike factory sells the bike and gets its
profit. Bike factories have no connection to attaching or detaching
quill stems that may have become corroded. Bike factories have no
financial stake in bike shops that may have to deal with corroded
quill stems. Once a bike is sold, bike factories could care less what
happens to it. Bike factories don't service bikes or fix bikes. If
there was nothing in it for the bike factory, they would not do it.



as well is strength considerations for MTB use where quill
stems broke off or came loose. *The secondary benefits you list come
along for free but were surely not the reason for the design change,
although they may be why there is no manufacturer resistance to it.

I recall when the first of these stems with threadless steer tubes
came along and what the foremost reason was. *It came with the advent
of MTB's and broader handlebars that received greater shock loads than
road bars.

Jobst Brandt- Hide quoted text -

- Show quoted text -

On Apr 17, 10:05*am, Nick L Plate wrote:
On 17 Apr, 17:54, wrote:

Trevor Jeffry wrote:

Be said ...



I don't care too much about the threaded/threadless war, and nearly
all my bikes have threaded stems. *But I have had a nice threaded
stem that just wouldn't work in the bike I used it for. *It had a
conical expansion nut rather than a wedge. *Even a mild tightening
force would get it super-stuck and I'd have to whale on it with a
mallet to remove it. *To add insult to injury, when installed, the
actual stem shaft was just a tiny bit undersized (as they mostly
are) and it would rock and creak a little when pedaling while
standing. *So the damn thing was stuck fast, but it wasn't even
tight. *I replaced it with a wedge stem and the bike's fine, but
experiences like this make you think the whole stem-threaded
steerer interface was really not engineered for the long term, and
that its commonness is a legacy issue more than a desirability
issue.
Use grease on expander cone. *Use hammer directly on bolt to release
cone. *Bigger is quicker.

It is not freeing the expander that presents a problem but removing an
aluminum quill stem from the steertube into which it has become
permanently attached by corrosion. *I suppose you missed the picture
of the bored out stem or that quill stems often need such removal.
That a hammer must be used on stem bolts to disengage expander cones
from stems is standard procedure.

Jobst Brandt

Stop bitchin'

Read what Ben said. *He DOESN'T care. *My explanation was specific to
his previous problem, which he DOESN'T have now because he replaced
the expander cone. *Your'e as bad as jb for your failure to understand
the relevant.

Trevor honey,

What Jobst said is not wrong.

I did use grease on the expander cone. It got so
stuck with even the barest tightening that I had to
loosen the bolt and put a hex key in the head and
whale on that repeatedly with a rubber mallet to remove
the stem. This is after a day, or a minute, of installation.
That's a weakness of expander cones. Wedges provide
more contact area and are slightly easier to remove, but
you still wind up with the fact that the stem isn't really in
full contact with the steerer at the top (unlike
a seatpost) and so it rocks. Plus water gets in
and it gets stuck as Jobst describes.

I have mostly threaded stems, but I think it's
not a particularly good method of attachment.

Ben

On Apr 17, 9:22*am, "
wrote:
On Apr 17, 10:54*am, Mike wrote:

On 16 Apr 2009 23:04:05 GMT, wrote:

How do you explain the nearly universal adoption of the threadless steertube?

Sometimes there is really no logic to the widespread adoption of
something new, for most practical purposes this is one of them.

--

There is great logic behind the adoption of the threadless steerer
tube on forks. *Cheaper. *One fork fits all sizes of a particular
frame. *48cm to 62cm, same fork. *No need to cut forks to fit the
different sizes within a frame range and thread every single one of
them. *And cut the keyhole slot. *That takes time and money and
machining and people. *Cheaper stems too. *I suspect threadless stems
are cheaper and easier to make than quill stems. *Assembly time is
likely reduced. *Probably you can tape and assemble the bars before
beginning to assemble the bike. *Use lower cost labor for this. *Maybe
contract with a supplier to deliver already taped up bars with brake
levers on them to the final assembly plant. *Then just bolt the
completed bars to the bike with the removable faceplates now used on
all stems. *And of course the threadless fork/stem configuration
allows for the use of aluminum or carbon fork steerers instead of
steel. *Weight consideration. *Only steel for threaded forks.

Your claim that there is no logic to the widespread adoption of the
threadless fork/stem is illogical.

Although some of the threadless headset options are pretty
inexplicable -- internal, external, quasi internal, pseudo external,
semi-stupid, etc. I wouldn't mind seeing some standardization there.
I am also a little worried about the current proprietary BB free-for-
all. I want a 120mm BB! Put big pie-plate, pump bearings in there. --
Jay Beattie.

_ wrote:
On Thu, 16 Apr 2009 16:48:38 -0700 (PDT), Nick L Plate wrote:

On 17 Apr, 00:18, AMuzi wrote:
wrote:
Even if the threads do not unscrew,
they fret and cause failures as
right pedals in aluminum cranks do.
Tom Ace wrote:
If an Italian-thread right-side cup is in
tight enough to not unscrew, is it still
moving and fretting with use?
Fretting wear occurs in all crank bearing thread formats
with high mileage or high loads. A cup which is "not moving"
isn't moving, by definition. In the case of your right side
cup, it probably is moving though. The movement from cyclic
loading frets the threaded area whether it unscrews or not.
Just checked thread forms and whitworth is 55deg while a cycle thread
is 60deg. There could lie the problem.

No.

a) I know of no bottom bracket cups or shells that used Whitworth threads;
please supply an example.

b) even if you can do a), at the size of the thread in question a five
degree difference in thread angle gives a depth difference of just about a
thousandth of an inch; which I suspect is not only smaller than the
manufacturing tolerances but also smaller than the fit allowances.

...and in passing, if you do manage to do a), could you get to work on your
job of supplying that example of spokes worn through by a third at the
crossing point?

Both Raleigh (1.370 x 26t) and Italian (m36x24t) are 55
degree Whitworth form threads.
I agree that is a red herring to this phenomenon.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On Fri, 17 Apr 2009 16:38:17 -0500, AMuzi wrote:

_ wrote:
On Thu, 16 Apr 2009 16:48:38 -0700 (PDT), Nick L Plate wrote:

On 17 Apr, 00:18, AMuzi wrote:
wrote:
Even if the threads do not unscrew,
they fret and cause failures as
right pedals in aluminum cranks do.
Tom Ace wrote:
If an Italian-thread right-side cup is in
tight enough to not unscrew, is it still
moving and fretting with use?
Fretting wear occurs in all crank bearing thread formats
with high mileage or high loads. A cup which is "not moving"
isn't moving, by definition. In the case of your right side
cup, it probably is moving though. The movement from cyclic
loading frets the threaded area whether it unscrews or not.
Just checked thread forms and whitworth is 55deg while a cycle thread
is 60deg. There could lie the problem.

No.

a) I know of no bottom bracket cups or shells that used Whitworth threads;
please supply an example.

b) even if you can do a), at the size of the thread in question a five
degree difference in thread angle gives a depth difference of just about a
thousandth of an inch; which I suspect is not only smaller than the
manufacturing tolerances but also smaller than the fit allowances.

...and in passing, if you do manage to do a), could you get to work on your
job of supplying that example of spokes worn through by a third at the
crossing point?

Both Raleigh (1.370 x 26t) and Italian (m36x24t) are 55
degree Whitworth form threads.

Funny-peculiar.

I did quite a bit of looking, and could not find any reference to Raleigh
cups (or shells) being 55 degree Whitworth. The 1 3/8 is not a BSF thread
(not surprising, the BSF of this size is 8tpi); there once was a
"Whitworth" bottom bracket of that same size and thread, but that reference
does not say anything about thread form and I suspect it is not a form
designation but a cycle brand. Perhaps also relevant is that BSC (British
Cycle Thread) is 60 degree (though with rounded roots and crests), and has
similary fine threads at that range of diameters.

Raleigh was, of course, big enough to have used threads of any pitch and
form they wished.

As for the Italians, 60 degree was standardized for metric threads some
time around the turn of the century (there was a "French" metric thread
system with thread forms of either 50 or 60 degress for small sizes, but
that is not really relevant to BB cups and shells).

Where did you find that their thread form for those BB cups and shells was
55 degree?

I agree that is a red herring to this phenomenon.

A 60 mile-per-hour red herring; I'm shocked, simply shocked to find this on
usenet.

On 17 Apr, 22:38, AMuzi wrote:
_ wrote:
On Thu, 16 Apr 2009 16:48:38 -0700 (PDT), Nick L Plate wrote:

On 17 Apr, 00:18, AMuzi wrote:
wrote:
Even if the threads do not unscrew,
they fret and cause failures as
right pedals in aluminum cranks do.
Tom Ace wrote:
If an Italian-thread right-side cup is in
tight enough to not unscrew, is it still
moving and fretting with use?
Fretting wear occurs in all crank bearing thread formats
with high mileage or high loads. A cup which is "not moving"
isn't moving, by definition. In the case of your right side
cup, it probably is moving though. The movement from cyclic
loading frets the threaded area whether it unscrews or not.
Just checked thread forms and whitworth is 55deg while a cycle thread
is 60deg. *There could lie the problem. *

No.

a) I know of no bottom bracket cups or shells that used Whitworth threads;
please supply an example.

b) even if you can do a), at the size of the thread in question a five
degree difference in thread angle gives a depth difference of just about a
thousandth of an inch; which I suspect is not only smaller than the
manufacturing tolerances but also smaller than the fit allowances.

...and in passing, if you do manage to do a), could you get to work on your
job of supplying that example of spokes worn through by a third at the
crossing point?

Both Raleigh (1.370 x 26t) and Italian (m36x24t) are 55
degree Whitworth form threads.
I agree that is a red herring to this phenomenon.


It was a Raleigh Lightweight (read carlton) frame which I had a little
difficulty in installing the FAG unit bearing. Previous bottom
bracket bearing was a Tange I believe, no evidence of any wear in the
cup or the frame shell. The plating on these cups were easily
scratched revealing the layer of copper underneath. No copper showed
within the cup threads, it did show on the abutment of the flange to
the frame.