Which frames have italian thread bottom brackets?
Chemnitz
bb. I know that Colnago's have this threading but do any others, as
well? Do some other Italian frames or is it mostly the older ones?
Thanks for any information you might be able to give.
i_am_cyc...@yahoo.ca
Hi there.
My old Cinelli (1980's) frame has an Italian bottom bracket.
Cheers from Peter
russell...@yahoo.com
http://www.probikekit.com/display.php?code=J1076
http://www.probikekit.com/display.php?code=J00001
Pro Bike Kits team bikes have Italian bottom brackets. Why, I don't
know since every intelligent company in the world has settled on the
standard of British threading.
jobst....@stanfordalumni.org
> I want to build a relatively inexpensive road bike and have an
> Italian BB. I know that Colnagos have this threading but do any
> others, as well? Do some other Italian frames or is it mostly the
> older ones? Thanks for any information you might be able to give.
I believe that was only with older fames because the need for left
hand threads on this flawed design have become apparent and
manufacturing and stocking two types of thread is expensive and
clutters inventory.
Wherever you see a left hand thread that isn't a turnbuckle, you have
a faulty design because the thread is supporting a rotating radial
load directly. As I pointed out, cars formerly had left hand threaded
lug nuts on the left side of the car to prevent wheels from falling
off. The conical lug nut got rid of the problem. Threads should be
used to press parts together, not to support radial loads. That is
only done well with a press fit or clamp as one sees in tandem BB
cartridges.
Ultimately, I see only that solution for BB attachment with a
precision spindle and bearing assembly just as the threadless steer
tube has solved the head bearing/bar attachment problem.
Jobst Brandt
jobst....@stanfordalumni.org
>> I want to build a relatively inexpensive road bike and have an
>> Italian BB. I know that Colnagos have this threading but do any
>> others, as well? Do some other Italian frames or is it mostly the
>> older ones? Thanks for any information you might be able to give.
http://www.probikekit.com/display.php?code=J1076
http://www.probikekit.com/display.php?code=J00001
> Pro Bike Kits team bikes have Italian bottom brackets. Why, I don't
> know since every intelligent company in the world has settled on the
> standard of British threading.
It's less the British threading than the left hand thread. It still
moves but does not unscrew. However, with enough miles climbing steep
hills, even these fail from the radial motion that erodes the threads
out of BB shells that are substantially softer than the bearing cups.
If there were no radial motion, no left hand thread would be needed,
here or in pedals. Eroded threads of the BB bore (on the right side)
become almost smooth with a ripple of "thread" from impressions of the
bearing cup during the last miles ridden.
Unfortunately when such thread loss occurs, it is believed that it was
not properly tightened. Were it not for motion that cause unscrewing
of right hand threads, there would be no left hand thread.
Jobst Brandt
Lou Holtman
That is funny. Building a bike and start with the BB. ;-)
Lou
Jay Beattie
wrote:
> On 15 Apr 2009 18:02:30 GMT, jobst.bra...@stanfordalumni.org wrote:
>
> >Ultimately, I see only that solution for BB attachment with a
> >precision spindle and bearing assembly just as the threadless steer
> >tube has solved the head bearing/bar attachment problem.
>
The one that was solved with current outboad bearing, two piece
cranks. Except that now we have fretting against the spindle by the
bearing cartridge -- except in the Campagnolo design (and maybe
others; I haven't done a market survey). -- Jay Beattie.
Jay Beattie
Thank God it wasn't a French BB. He'd have to go shopping around for
old PX10s. -- Jay Beattie.
jobst....@stanfordalumni.org
>>> Ultimately, I see only that solution for BB attachment with a
>>> precision spindle and bearing assembly just as the threadless
>>> steer tube has solved the head bearing/bar attachment problem.
>> What problem was that?
> The one that was solved with current outboard bearing, two piece
> cranks. Except that now we have fretting against the spindle by the
> bearing cartridge -- except in the Campagnolo design (and maybe
> others; I haven't done a market survey).
Outboard bearings are not directed at the problem of radially loaded
fretting threads but rather to accommodate a larger tubular spindle
for crank attachment while retaining reasonable bearing ball size, for
which there is no space inside the BB shell. To make up for that, the
overhung bearing besides having rotating radial loaded threads, has
overhung loads, worsening thread fretting.
Both Shimano and Campagnolo are grasping at straws to solve difficult
BB problems. I think their crank attachment schemes are an
improvement but the Shimano solution is a tried and a true solution
gleaned from prior art. To make up for that, the overhung bearing
worsens the Bearing to BB shell attachment.
Jobst Brandt
jobst....@stanfordalumni.org
>>> I want to build a relatively inexpensive road bike and have an
>>> Italian bb. I know that Colnago's have this threading but do any
>>> others, as well? Do some other Italian frames or is it mostly the
>>> older ones? Thanks for any information you might be able to give.
>> That is funny. Building a bike and start with the BB.
> Thank God it wasn't a French BB. He'd have to go shopping around for
> old PX10s.
The four kinds of BB threads in common use today are Italian, British,
French, and Swiss, possibly in that order of occurrence.
Diameter Pitch Right Cup Left
-------- ----- ----- -----
British 1.370" x 24F tpi left right
Italian 36mm x 24F tpi right right
French 35mm x 1mm right right
Swiss 35mm x 1mm left right
tpi (threads per inch)
Jobst Brandt
AMuzi
> On Wed, 15 Apr 2009 07:26:40 -0700 (PDT), "russell...@yahoo.com"
> <russell...@yahoo.com> wrote:
>
>> Pro Bike Kits team bikes have Italian bottom brackets. Why, I don't
>> know since every intelligent company in the world has settled on the
>> standard of British threading.
>
or Chater Lea? Which standard?
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
Jay Beattie
I thought you were just talking about the crank attachment which was
"fixed" with the Shimano pinch bolt approach.
And to be honest, I did not know there was a problem with BB thread
fretting or obliteration. I have never had that problem, at least in
terms of seeing thread degredation, not even in my aluminum BB bikes.
I currently have one bike with an outboard BB, and it seems to make a
lot more noise that prior BBs, even with grease or Teflon on the
threads. -- Jay Beattie.
russell...@yahoo.com
wrote:
> On Wed, 15 Apr 2009 14:19:19 -0700 (PDT), Jay Beattie
>
> <jbeat...@lindsayhart.com> wrote:
> >> >Ultimately, I see only that solution for BB attachment with a
> >> >precision spindle and bearing assembly just as the threadless steer
> >> >tube has solved the head bearing/bar attachment problem.
>
> >> What problem was that?
>
> >The one that was solved with current outboad bearing, two piece
> >cranks. Except that now we have fretting against the spindle by the
> >bearing cartridge -- except in the Campagnolo design (and maybe
> >others; I haven't done a market survey). -- Jay Beattie.
>
> steer tube has solved the head bearing/bar attachment problem."
Mr. Brandt was talking about the quill stems getting stuck in the
steel threaded steerer tubes when using threaded headsets. Threadless
headsets have eliminated the stem getting stuck in the fork steerer.
>
> My headsets seem to last just about forever.
jobst....@stanfordalumni.org
>>>>> Ultimately, I see only that solution for BB attachment with a
>>>>> precision spindle and bearing assembly just as the threadless
>>>>> steer tube has solved the head bearing/bar attachment problem.
>>>>> >>>> What problem was that?
>>> The one that was solved with current outboard bearing, two piece
>>> cranks. Except that now we have fretting against the spindle by
>>> the bearing cartridge -- except in the Campagnolo design (and
>>> maybe others; I haven't done a market survey).
>> Outboard bearings are not directed at the problem of radially
>> loaded fretting threads but rather to accommodate a larger tubular
>> spindle for crank attachment while retaining reasonable bearing
>> ball size, for which there is no space inside the BB shell. To
>> make up for that, the overhung bearing besides having rotating
>> radial loaded threads, has overhung loads, worsening thread
>> fretting.
>> Both Shimano and Campagnolo are grasping at straws to solve
>> difficult BB problems. I think their crank attachment schemes are
>> an improvement but the Shimano solution is a tried and a true
>> solution gleaned from prior art. To make up for that, the overhung
>> bearing worsens the Bearing to BB shell attachment.
> I thought you were just talking about the crank attachment which was
> "fixed" with the Shimano pinch bolt approach.
> And to be honest, I did not know there was a problem with BB thread
> fretting or obliteration. I have never had that problem, at least
> in terms of seeing thread degredation, not even in my aluminum BB
> bikes. I currently have one bike with an outboard BB, and it seems
> to make a lot more noise that prior BBs, even with grease or Teflon
> on the threads.
You must have wondered why BB's have left hand threaded right bearing
cups. As I said, wherever you see left hand thread fastenings, you
are looking at faulty design. At least the ancients that specified
the left hand thread recognized the loosening problem and invoked the
left hand thread dodge, not having a clear understanding of the
mechanics of radial load bearing threads.
Even if the threads do not unscrew, they fret and cause failures as
right pedals in aluminum cranks do. I haven't seen steel cranks fail,
but they show rouge and fretting damage on contact faces with chrome
plating worn off and a countersink formed under pedal spindle faces.
Jobst Brandt
Jay Beattie
Have you seen bottom bracket shell threads degrade due to fretting? --
Jay Beattie.
jobst....@stanfordalumni.org
>>>> Ultimately, I see only that solution for BB attachment with a
>>>> precision spindle and bearing assembly just as the threadless
>>>> steer tube has solved the head bearing/bar attachment problem.
>>> What problem was that?
>> The one that was solved with current outboard bearing, two piece
>> cranks. Except that now we have fretting against the spindle by the
>> bearing cartridge -- except in the Campagnolo design (and maybe
>> others; I haven't done a market survey).
> My question wasn't clear: What is the problem cited in "threadless
> steer tube has solved the head bearing/bar attachment problem."
> My headsets seem to last just about forever.
Attachment of handlebars to the fork had a twofold problem. Quill bar
stems use an expander at the insertion end securing the stem only at
its lower end. Because the expanded part frets and loosens it
requires re-tightening which leads to over tightening that causes a
bulge the steer tube. Some quill stems used a slant wedge "expander"
to give a longer attachment but this had a new problem. The slant
wedge was poor in preventing stem rotation and unscrewed the expander
bolt leaving riders with freely rotating bars. With either kind of
expander, the upper end of the stem was free to yaw, giving bars a
flexible feel.
By the yaw motion, aluminum stems, regardless of seals, ingested sweat
and rain water to corrode the stem permanently to the steer tube so
that removal required cutting it off and boring it out. All this came
to an end with the advent of the MTB with "bull moose" handlebars that
broke quill stems giving rise to a stem clamped to outside of a
threadless steertube.
Superior rigidity and strength of this method is striking, as is the
simplicity of head bearing adjustment and handle bar removal without
un-taping and removal of brake levers. The octagonal threaded head
bearing nuts that required clumsy special headset wrenches are gone,
being replaced by an Allen key threadless steer tubes.
Jobst Brandt
jobst....@stanfordalumni.org
>>>>>> What problem was that?
Yes. As I described earlier under this heading, the BB shell had no
threads on the right side except beyond the depth of bearing cup
engagement. I know a frame builder who repairs such steel frames by
boring the frame and silver brazing a steel tube in for new threads.
Jobst Brandt
Sandy
news:49e755d6$0$1616$742e...@news.sonic.net...
The removal of handlebars without untaping, etc., was achieved in several
models by different manufacturers, entirely separately and before the advent
of threadless headsets. Not to discount the value of the new type of stem
attachment, just to distinguish the two.
--
Bonne route !
Sandy
Verneuil-sur-Seine FR
Tom Ace
> Even if the threads do not unscrew,
> they fret and cause failures as
> right pedals in aluminum cranks do.
If an Italian-thread right-side cup is in
tight enough to not unscrew, is it still
moving and fretting with use?
Tom Ace
AMuzi
Yes.
jobst....@stanfordalumni.org
>> Attachment of handlebars to the fork had a twofold problem. Quill
>> bar stems use an expander at the insertion end securing the stem
>> only at its lower end. Because the expanded part frets and loosens
>> it requires re-tightening which leads to over tightening that
>> causes a bulge the steer tube. Some quill stems used a slant wedge
>> "expander" to give a longer attachment but this had a new problem.
>> The slant wedge was poor in preventing stem rotation and unscrewed
>> the expander bolt leaving riders with freely rotating bars. With
>> either kind of expander, the upper end of the stem was free to yaw,
>> giving bars a flexible feel.
>> By the yaw motion, aluminum stems, regardless of seals, ingested
>> sweat and rain water to corrode the stem permanently to the steer
>> tube so that removal required cutting it off and boring it out.
>> All this came to an end with the advent of the MTB with "bull
>> moose" handlebars that broke quill stems giving rise to a stem
>> clamped to outside of a threadless steertube.
> The conditions you cite are extreme and don't occur in bicycles that
> are either routinely maintained or not subjected to extreme
> conditions. They are the exception, not the rule.
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.
> If you are going to add extreme conditions to every test (and that
> might be valid for your personal circumstances) then there are all
> sorts of equipment that will fail. Equipment is manufactured to
> match common usages, not extremes of use, or disuse, or neglect.
> For your sort of extreme use, you personally need something labeled
> the equivalent of "commercial use".
I think those manufacturers who recognize that getting rid of the
quill stem is necessary to reliably serve demanding bicyclists, don't
agree with your perception of use.
>> Superior rigidity and strength of this method is striking, as is
>> the simplicity of head bearing adjustment and handle bar removal
>> without un-taping and removal of brake levers. The octagonal
>> threaded head bearing nuts that required clumsy special headset
>> wrenches are gone, being replaced by an Allen key threadless steer
>> tubes.
> Yet this method/design also comes with its own set of disadvantages,
> like any other. Not to mention, that while a few of us play with
> handlebar changes, the percentage of those who do is very small; and
> the small percentage of those who do and then do not actually _want_
> to change brake levers as part of the package smaller still.
Sounds like a lot of beginners who didn't get a bicycle or stem that
fit. I don't believe that reliable handlebar stems and adjustable
headsets are extreme uses. How do you explain the nearly universal
adoption of the threadless steertube?
> As for head bearing adjustment - that never seemed particularly
> challenging to me. Syncing the carbs on an early English roadster
> (pick any) was a challenge; doing a triple bypass is a challenge; -
> adjusting a head bearing and a lock nut can be done with your eyes
> closed (aside from the issue of missfitting the large wrench and
> marring an expensive lock nut).
I guess you rely on the LBS for that work. I've been annoyed by the
adjustment of the head bearing for at least 50 years and then some.
So why are there hardly any new bicycles with threaded steerers and
quill stems?
Jobst Brandt
Jay Beattie
Gee, I must not be trying hard enough. Even the threads in my
aluminum shells look pretty sharp. I had some steel frames with a lot
of rust, but nothing to suggest that fretting was destroying the
threads. Live and learn. -- Jay Beattie.
jobst....@stanfordalumni.org
>> Even if the threads do not unscrew, they fret and cause failures as
>> right pedals in aluminum cranks do.
> If an Italian-thread right-side cup is in tight enough to not
> unscrew, is it still moving and fretting with use?
Just as with pedals, you can't make them tight enough that they don't
move. Just look at the faces of your cranks when removing a pedal.
There is no way a right BB cup will not move if the rider rides
standing, and probably even when seated if the rider is strong.
Left hand thread in that place is not idly chosen. Manufacturers and
most bicycle shops know about this but do not go so far as to
recognize it as a design error. You ask if this cup can be tightened
tight enough... tight enough for what? How can it unscrew if it isn't
moving. I had right hand threads on my old early Cinellis and
re-tightened the right hand cup at major maintenance intervals.
After that I had Cinelli build my frames with British BB threads but
with the standard Italian 70mm wide BB shell.
Jobst Brandt
AMuzi
>> 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.
jobst....@stanfordalumni.org
>>> Have you seen bottom bracket shell threads degrade due to
>>> fretting?
>> Yes.
> Gee, I must not be trying hard enough. Even the threads in my
> aluminum shells look pretty sharp. I had some steel frames with a
> lot of rust, but nothing to suggest that fretting was destroying the
> threads. Live and learn.
I don't think there is an open request for admitting you don't ride
forcefully. This is not an idle design problem, and solving it will
take time even at Shimano, where there seem to be some project
managers who sense that BB's are not entirely up to their reliability
standards.
Jobst Brandt
Nick L Plate
Simpler to cut and close the BB shell then tap it. Even a lightweight
pressed shell will handle this once.
jobst....@stanfordalumni.org
>>> Even if the threads do not unscrew, they fret and cause failures
>>> as right pedals in aluminum cranks do.
>> 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.
Mine only backed out when the treads were entirely gone. Fortunately
my frame builder is primarily a machine shop and was able to bore out
the frame and insert a high grade steel tube, silver brazing, boring
and threading it. As you can see from the pictures on:
http://www.sheldonbrown.com/brandt/
I've used this frame for much more than 100,000 miles.
Jobst Brandt
Andre Jute
Those suffering fretting, or worried about it, should get bottom
brackets with plastic cups both sides. They allow a certain amount of
movement and won't strip your bike's threads or corrode in. Kinex is a
favourite with high-end European manufacturers of "maintenance-free"
bikes among other reasons because Kinex BB are optionally available
with plastic cups both sides. The reasons I remember include fretting
but in the main that a plastic cup doesn't have to be regreased; the
bottom bracket is in the shell for its life, fit and forget.
Andre Jute
Visit Jute on Bicycles at
http://www.audio-talk.co.uk/fiultra/BICYCLE%20%26%20CYCLING.html
Nick L Plate
> > jobst.bra...@stanfordalumni.org 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. I have never seen any
fretting on either pedal threads or bottom bracket threads on any of
my bikes. I remember the economy FAG BB bearing a bugger to get in,
and perhaps this was because of the mismatch, it was a resin body so
it was just a matter of keep cranking it until it abutted the shell.
Nick L Plate
> > > > Jay Beattie.
>
> > > Yes.
>
> > Gee, I must not be trying hard enough. Even the head on my
> > minumum bell looks pretty sharp. I had some steel frames with a lot
> > of bust, but nothing to suggest that fretting was destroying the
> > threads. Live and learn. -- Jay Beattie.
>
> rackets with plastic cups both sides. They allow a certain amount of
> favourite with high-end Europeans, manufacturers of "maintenance-free"
> bikes among others reason because Kinsex BB (before breakfast) are optionally > available to the largest families, the requirement is best fulfilled
> with plastic cups both sides. The reasons I remember include fretting
> but in the main that a plastic cup doesn't have to be regreased; the
I'm sure that's not right.
--D-y
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.
> I'm not saying it was done for extremists, but the percentage of the
> population that benefits from it in any way is very, very small.
IMHO everyone benefits from being able to adjust headsets with an
allen key instead of the old headset wrenches, simply because the tool
is much cheaper <g>. But really, and the process is so much easier,
with no slipping wrenches or rounded corners. I think that trumps any
personal facility with tools.
> You mean MTB's as "demanding"? Yeah, they had issues. Bikes were not
> designed for severe off road use, at least not in the early days. But
> for road riding? Headsets were not an issue and the stuck quill was
> not the norm.
> >> Yet this method/design also comes with its own set of disadvantages,
> >> like any other. Not to mention, that while a few of us play with
> >> handlebar changes, the percentage of those who do is very small; and
> >> the small percentage of those who do and then do not actually _want_
> >> to change brake levers as part of the package smaller still.
How about not scratching bars while feeding them through old-style
clamps? I mean, easily, no spreader needed (improvised or integral as
with 3ttt) needed, and a more secure attachment via a "faceplate" with
two or four bolts that does less bending than the old style single
bolt clamps on stems without removable faceplates? Those "z" scars on
Cinelli engraved bars were a pretty common sight, and never pretty.
Bars that rotate in my old-style stems (Cinelli and 3ttt) don't in the
faceplate style.
After some experimentation over the past several years, I've settled
on a favorite handlebar. Three bikes, maybe four if you count the FG.
I tried several handlebars with different bends and widths. Much
easier via removable faceplate. I'm planning on one more swap between
bikes because of handlebar tape color/pattern "mixup"-- IOW, I decided
I should have put A tape on bike B and B tape on bike A. All Campy
brifters, so the swap will be much easier, not much to take apart.
Truly rare in your universe, I understand <g>. But, "me like".
--D-y
Tom Ace
> > If an Italian-thread right-side cup is in tight enough to not
> > unscrew, is it still moving and fretting with use?
>
> Just as with pedals, you can't make them tight enough
> that they don't move.
That's the answer to my question; thanks.
> Just look at the faces of your cranks when removing a pedal.
Yeah, those wear visibly. But count me with
Jay Beattie among those who haven't seen
their BB threads deteriorate-- although I have
no reason to doubt your and Andy Muzi's
reports that they can and do.
> Left hand thread in that place is not idly chosen. Manufacturers and
> most bicycle shops know about this but do not go so far as to
> recognize it as a design error. You ask if this cup can be tightened
> tight enough... tight enough for what? How can it unscrew if it isn't
> moving. I had right hand threads on my old early Cinellis and
> re-tightened the right hand cup at major maintenance intervals.
Tight enough for what? To not come loose in use.
I've had an Italian frame for 30 years. Early on,
I learned how tight to install the right-hand cup
so that it didn't loosen with use. (I can't give
a torque value, I only have the simple hand BB
tools--but it has to be on notably tighter than
I bother to install cups in English BBs.)
Since I learned how tight to install it, it has never
come loose--I never retighten it in between the
times I take it out for cleaning and regreasing--
which made me wonder whether it ceases to
move altogether if it's screwed in hard enough.
You say no, and I'll take your word for it.
Tom Ace
AMuzi
>>> 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?
--D-y wrote:
> 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.
>-snip-
Quite common :
http://www.yellowjersey.org/goodn.html
bjwe...@gmail.com
> On Apr 16, 8:00 pm, Still Just Me <stillnoEm...@stillnodomains.com>
> 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.
Ben
Michael Press
Still Just Me <stilln...@stillnodomains.com> wrote:
> On 16 Apr 2009 15:59:18 GMT, jobst....@stanfordalumni.org wrote:
>
> >Attachment of handlebars to the fork had a twofold problem. Quill bar
> >stems use an expander at the insertion end securing the stem only at
> >its lower end. Because the expanded part frets and loosens it
> >requires re-tightening which leads to over tightening that causes a
> >bulge the steer tube. Some quill stems used a slant wedge "expander"
> >to give a longer attachment but this had a new problem. The slant
> >wedge was poor in preventing stem rotation and unscrewed the expander
> >bolt leaving riders with freely rotating bars. With either kind of
> >expander, the upper end of the stem was free to yaw, giving bars a
> >flexible feel.
> >
> >By the yaw motion, aluminum stems, regardless of seals, ingested sweat
> >and rain water to corrode the stem permanently to the steer tube so
> >that removal required cutting it off and boring it out. All this came
> >to an end with the advent of the MTB with "bull moose" handlebars that
> >broke quill stems giving rise to a stem clamped to outside of a
> >threadless steertube.
>
> The conditions you cite are extreme and don't occur in bicycles that
> are either routinely maintained or not subjected to extreme
> conditions. They are the exception, not the rule.
>
> If you are going to add extreme conditions to every test (and that
> might be valid for your personal circumstances) then there are all
> sorts of equipment that will fail. Equipment is manufactured to match
> common usages, not extremes of use, or disuse, or neglect. For your
> sort of extreme use, you personally need something labeled the
> equivalent of "commercial use".
Why not build to last? On a bicycle it is just as easy
as what we have. Ashtabula bottom bracket shells are
as simple as the puny undersized bottom bracket shells
on many bicycles. Threadless steering tubes are _simpler_
than threaded steering tubes. The correct geometry on
the thread engagement of pedals is _simpler_ than the
current bodge using left threads on the left side. You
speak as if doing it right is a huge project. Not so.
--
Michael Press
bjwe...@gmail.com
For my sins, I have a bike sporting an Italian thread
bottom bracket that actually now has a cheap Shimano
cartridge BB with a plastic cup. But the plastic cup is
_only_ on the non-drive side. It's one of their BBs (maybe
an LP-27) where the drive side "cup" and threads are an
integral part of the steel cartridge. I am skeptical that
one could tighten a plastic cup enough to hold an
Italian drive-side plastic cup in place, without destroying
the plastic threads and splines and eventually splitting
the cup. I had to really reef on the steel cup (and yeah,
I did use a long-handled torque wrench)
to get the steel BB threads tight enough.
Items like this are rare. You can't generally even buy a
cheapo BB in Italian thread anymore, and the selection
of spindle lengths in decent Italian BBs (aluminum or
steel cups) is now limited.
A friend gave me the cheapo item as a temporary fix so
I could build up the frame. It is, incidentally, not an
Italian frame at all, but a ~30 year old US-made
custom frame, an Andy Gilmour. Back in the day,
custom builders would sometimes use Italian threading.
Mr. Gilmour told me he'd used both Italian and
English then (I don't know whether it was at his or the
customer's whim).
Ben
_
> On 17 Apr, 00:18, AMuzi <a...@yellowjersey.org> wrote:
>>> jobst.bra...@stanfordalumni.org 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?
Mike
> 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.
--
russell...@yahoo.com
> On 16 Apr 2009 23:04:05 GMT, jobst.bra...@stanfordalumni.org 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.
Nick L Plate
wrote:
> On Thu, 16 Apr 2009 16:48:38 -0700 (PDT), Nick L Plate wrote:
> > On 17 Apr, 00:18, AMuzi <a...@yellowjersey.org> wrote:
> >>> jobst.bra...@stanfordalumni.org 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
Nick L Plate
Use grease on expander cone. Use hammer directly on bolt to release
cone. Bigger is quicker.
Nick L Plate
> On 16 Apr 2009 23:04:05 GMT, jobst.bra...@stanfordalumni.org 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.
jobst....@stanfordalumni.org
>>> 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, 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
jobst....@stanfordalumni.org
>>>>> 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.
>>>> 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 re-grease") 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 web pages), 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.
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
Nick L Plate
> 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.
russell...@yahoo.com
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 -
jobst....@stanfordalumni.org
>> attached and detached, as well as 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.
> 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.
You seem to not believe there is any connection between product
performance and customer satisfaction, which ultimately affects sales.
I believe this is the feedback that brought about the design change as
well as the experience of some of their sponsored riders. Therefore,
there is more than "nothing in it for the bike factory".
>> 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.
I'm unsure what point you are trying to make with your response. Can
you explain?
Jobst Brandt
bjwe...@gmail.com
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
Jay Beattie
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.
AMuzi
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.
_
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.
Nick L Plate
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.
Michael Press
AMuzi <a...@yellowjersey.org> wrote:
They used to show VD scare documentaries that were not as bad as this.
--
Michael Press
Tom Ace
> Where did you find that their thread form
> for those BB cups and shells was 55 degree?
I can't speak for Andrew Muzi (who this
question was addressed to),
but I learned about the thread angle in
Italian BBs from Sheldon Brown's site. See
http://www.sheldonbrown.com/gloss_i-k.html#italian
Tom Ace
jobst....@stanfordalumni.org
>> Where did you find that their thread form for those BB cups and
>> shells was 55 degree?
> I can't speak for Andrew Muzi (who this question was addressed to),
> but I learned about the thread angle in Italian BB's from Sheldon
> Brown's site:
http://www.sheldonbrown.com/gloss_i-k.html#italian
I don't know why this thread profile was chosen, but I can guess.
With a flatter 55° angle thread, radial loads can be supported
slightly better than with a steeper 60° profile. That suggests that
those who made this decision knew that supporting loads on threads is
bad practice, while the left hand thread may have been a later
response to unscrewing.
As I said, I believe the solution lies in a split BB shell that clamps
a cartridge, with an insertion shoulder, containing spindle and
bearings with labyrinth seals rather than contact seals. Design of
the cartridge is difficult but manageable, but bright enthusiastic
engineers under good management could do it. However, most bicycle
oriented engineering doesn't pay well enough to attract the best
project leader talent.
Jobst Brandt
Chalo
>
> As I said, I believe the solution lies in a split BB shell that clamps
> a cartridge, with an insertion shoulder, containing spindle and
> bearings with labyrinth seals rather than contact seals. Design of
> the cartridge is difficult but manageable, but bright enthusiastic
> engineers under good management could do it. However, most bicycle
> oriented engineering doesn't pay well enough to attract the best
> project leader talent.
The problem was solved generations ago by the Ashtabula-type BB and
shell. There is no reason this system can't be made to any level of
finish and used for two- or three-piece cranks as appropriate. But
because it worked so well on the cheapest and crudest bikes, it
developed a reputation for being cheap and crude.
Chalo
AMuzi
>>> shells was 55 degree?
> Tom Ace wrote:
>> I can't speak for Andrew Muzi (who this question was addressed to),
>> but I learned about the thread angle in Italian BB's from Sheldon
>> Brown's site:
jobst....@stanfordalumni.org wrote:
> http://www.sheldonbrown.com/gloss_i-k.html#italian
>
> I don't know why this thread profile was chosen, but I can guess.
> With a flatter 55° angle thread, radial loads can be supported
> slightly better than with a steeper 60° profile. That suggests that
> those who made this decision knew that supporting loads on threads is
> bad practice, while the left hand thread may have been a later
> response to unscrewing.
>
> As I said, I believe the solution lies in a split BB shell that clamps
> a cartridge, with an insertion shoulder, containing spindle and
> bearings with labyrinth seals rather than contact seals. Design of
> the cartridge is difficult but manageable, but bright enthusiastic
> engineers under good management could do it. However, most bicycle
> oriented engineering doesn't pay well enough to attract the best
> project leader talent.
I believe it's simpler than that.
Those thread standards were set when Whitworth thread form
was current and good British machine tools of the era had WW
lead screws, etc. No conspiracy, just a sort of Commodore or
KayPro computer or Beta video tape analog (relic?) from a
hundred years ago.
I don't have a BB comparison graphic handy but check out
freewheel threads for a similar situation:
http://www.yellowjersey.org/photosfromthepast/FWTHREAD.JPG
jobst....@stanfordalumni.org
The design is full of unacceptable interfaces. The pressed steel
cups/races Have poor support and positioning in the BB shell. Notice
that the adjustable cone is supported on fine pitch threads and has a
left hand thread locknut because the cone moves in use. These
interfaces are a fretting nightmare. The cranks are too thin and
pedals are attached to that small cross section. It demands steel
cranks, something I believe is not marketable for high end bicycles.
Let sleeping dogs lie. Leave them alone and avoid new problems.
Jobst Brandt
jobst....@stanfordalumni.org
> Good point. It's odd that the "standard" BB even evolved considering
> that the axles always use a more conventional cone and cup
> arrangement.
> But, one of the issues with the Ashtabula design, even if "improved"
> is having a much larger opening for dirt to enter. Even with
> precision engineering, you have a circle many times the diameter of
> the standard BB's small opening around the crank axle. A problem
> like that could be overcome today with seals but likely not back the
> good ol' days. Plus there would be added friction from the seal.
> Maybe with sealed bearings it would work better.
http://www.sheldonbrown.com/brandt/sealed-bearings.html
Jobst Brandt
AMuzi
>> As I said, I believe the solution lies in a split BB shell that clamps
>> a cartridge, with an insertion shoulder, containing spindle and
>> bearings with labyrinth seals rather than contact seals. Design of
>> the cartridge is difficult but manageable, but bright enthusiastic
>> engineers under good management could do it. However, most bicycle
>> oriented engineering doesn't pay well enough to attract the best
>> project leader talent.
Chalo wrote:
> The problem was solved generations ago by the Ashtabula-type BB and
> shell. There is no reason this system can't be made to any level of
> finish and used for two- or three-piece cranks as appropriate. But
> because it worked so well on the cheapest and crudest bikes, it
> developed a reputation for being cheap and crude.
Much agreed; one of the best engineered designs in our
industry.
Ashatbula/OPC are exceptionally fault tolerant, use common
non-cycle-specific tools, can be made inexpensively but also
exist in elegant forged CrMo versions. Widely
underappreciated.
AMuzi
>>> As I said, I believe the solution lies in a split BB shell that clamps
>>> a cartridge, with an insertion shoulder, containing spindle and
>>> bearings with labyrinth seals rather than contact seals. Design of
>>> the cartridge is difficult but manageable, but bright enthusiastic
>>> engineers under good management could do it. However, most bicycle
>>> oriented engineering doesn't pay well enough to attract the best
>>> project leader talent.
> Chalo <chalo....@gmail.com> wrote:
>> The problem was solved generations ago by the Ashtabula-type BB and
>> shell. There is no reason this system can't be made to any level of
>> finish and used for two- or three-piece cranks as appropriate. But
>> because it worked so well on the cheapest and crudest bikes, it
>> developed a reputation for being cheap and crude.
Still Just Me wrote:
> Good point. It's odd that the "standard" BB even evolved considering
> that the axles always use a more conventional cone and cup
> arrangement.
>
> But, one of the issues with the Ashtabula design, even if "improved"
> is having a much larger opening for dirt to enter. Even with precision
> engineering, you have a circle many times the diameter of the standard
> BB's small opening around the crank axle. A problem like that could be
> overcome today with seals but likely not back the good ol' days. Plus
> there would be added friction from the seal. Maybe with sealed
> bearings it would work better.
Unlike other designs, water runs out and dirt gets rapidly
pushed aside. With such a large bearing track, few problems
even when abused, immersed, crud-encrusted, whatever.
jobst....@stanfordalumni.org
>>>> As I said, I believe the solution lies in a split BB shell that
>>>> clamps a cartridge, with an insertion shoulder, containing
>>>> spindle and bearings with labyrinth seals rather than contact
>>>> seals. Design of the cartridge is difficult but manageable, but
>>>> bright enthusiastic engineers under good management could do it.
>>>> However, most bicycle oriented engineering doesn't pay well
>>>> enough to attract the best project leader talent.
>>> The problem was solved generations ago by the Ashtabula-type BB
>>> and shell. There is no reason this system can't be made to any
>>> level of finish and used for two- or three-piece cranks as
>>> appropriate. But because it worked so well on the cheapest and
>>> crudest bikes, it developed a reputation for being cheap and
>>> crude.
>> The design is full of unacceptable interfaces. The pressed steel
>> cups/races Have poor support and positioning in the BB shell.
>> Notice that the adjustable cone is supported on fine pitch threads
>> and has a left hand thread locknut because the cone moves in use.
>> These interfaces are a fretting nightmare. The cranks are too thin
>> and pedals are attached to that small cross section. It demands
>> steel cranks, something I believe is not marketable for high end
>> bicycles.
>> Let sleeping dogs lie. Leave them alone and avoid new problems.
> Much agreed; one of the best engineered designs in our industry.
> Ashtabula/OPC are exceptionally fault tolerant, use common
> non-cycle-specific tools, can be made inexpensively but also exist
> in elegant forged CrMo versions. Widely underappreciated.
Could you give a URL to a web site where an elegant CrMo version is
shown. I would also like to see a cross section of such an assembly
so I can see what advances, if any, have occurred since I last worked
on these BB's.
Jobst Brandt
AMuzi
Here's one on ebay with a decent photo:
http://cgi.ebay.com/GT-POWER-SERIES-BMX-Crank-One-Piece-180mm-CrMo-NOS_W0QQitemZ330317449991QQcmdZViewItemQQptZCycling_Parts_Accessories?hash=item330317449991&_trksid=p3286.c0.m14&_trkparms=72%3A1205|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A1|293%3A1|294%3A50
or
http://tinyurl.com/czv3ch
Sergio Moretti
> orhttp://tinyurl.com/czv3ch
>
> --
> Andrew Muzi
> <www.yellowjersey.org/>
> Open every day since 1 April, 1971- Hide quoted text -
>
> - Show quoted text -
One issue with that crank is weight.
Another is the large BB shell diameter needed to snake a one-peice
crank through.
Sergio Moretti
Ryan Cousineau
<682b8be8-26a8-4634...@w40g2000yqd.googlegroups.com>,
Sergio Moretti <morett...@comcast.net> wrote:
Look did an insane boutique version:
http://www.roadcyclinguk.com/news/article/mps/uan/3468
Special for Jobst: they changed the pedal interface. As well as being a
socket design, the pedal spindle is offset from the socket so that the
orientation of the triangular spindle-socket thingy determines whether
the effective crank length is 170, 172.5, or 175.
--
Ryan Cousineau rcou...@gmail.com http://www.wiredcola.com/
"In other newsgroups, they killfile trolls."
"In rec.bicycles.racing, we coach them."
jobst....@stanfordalumni.org
Thanks. The GT has a nice polish with space for drilling pedal bores
at various crank lengths, but no detail on bearings, cups and cones.
The devil is in the details. I didn't see a solution for the fretting
interfaces and radially loaded threads.
Jobst Brandt
Chalo
>
> Chalo Colina wrote:
> >
> > Jobst Brandt wrote:
> >>
> >>
> >> As I said, I believe the solution lies in a split BB shell that
> >> clamps a cartridge, with an insertion shoulder, containing spindle
> >> and bearings with labyrinth seals rather than contact seals.
> >> Design of the cartridge is difficult but manageable, but bright
> >> enthusiastic engineers under good management could do it. However,
> >> most bicycle oriented engineering doesn't pay well enough to
> >> attract the best project leader talent.
> >
> > The problem was solved generations ago by the Ashtabula-type BB and
> > shell. There is no reason this system can't be made to any level of
> > finish and used for two- or three-piece cranks as appropriate. But
> > because it worked so well on the cheapest and crudest bikes, it
> > developed a reputation for being cheap and crude.
>
> The design is full of unacceptable interfaces. The pressed steel
> cups/races Have poor support and positioning in the BB shell.
And yet they work well with no maintenance for decades.
> Notice
> that the adjustable cone is supported on fine pitch threads and has a
> left hand thread locknut because the cone moves in use.
And yet they work well with no maintenance for decades.
> These
> interfaces are a fretting nightmare. The cranks are too thin and
> pedals are attached to that small cross section.
And they continue to run freely on bikes that haven't been greased let
alone adjusted since, well, ever.
> It demands steel
> cranks, something I believe is not marketable for high end bicycles.
Does it? I think steel one-piece cranks are more of a convention than
a necessity. Forged aluminum or tubular steel cranks could be made in
the OPC pattern if there were sufficient respect for it.
> The thickness of
> Let sleeping dogs lie. Leave them alone and avoid new problems.
New problems? The problems as I have observed them belong to the
weaker threaded BB standards.
Chalo
jobst....@stanfordalumni.org
>>>>> As I said, I believe the solution lies in a split BB shell that
>>>>> clamps a cartridge, with an insertion shoulder, containing
>>>>> spindle and bearings with labyrinth seals rather than contact
>>>>> seals. Design of the cartridge is difficult but manageable, but
>>>>> bright enthusiastic engineers under good management could do
>>>>> it. However, most bicycle oriented engineering doesn't pay well
>>>>> enough to attract the best project leader talent.
>>>> The problem was solved generations ago by the Ashtabula-type BB
>>>> and shell. There is no reason this system can't be made to any
>>>> level of finish and used for two- or three-piece cranks as
>>>> appropriate. But because it worked so well on the cheapest and
>>>> crudest bikes, it developed a reputation for being cheap and
>>>> crude.
>>> The design is full of unacceptable interfaces. The pressed steel
>>> cups/races Have poor support and positioning in the BB shell.
>> And yet they work well with no maintenance for decades.
> Just to play the other side: I saw plenty of these in my shop days
> that were destroyed by dirt and neglect.
>>> It demands steel cranks, something I believe is not marketable for
>>> high end bicycles.
>> Does it? I think steel one-piece cranks are more of a convention
>> than a necessity. Forged aluminum or tubular steel cranks could be
>> made in the OPC pattern if there were sufficient respect for it.
> Why does the concept demand a one piece crank? Cut off the crank
> arms, machine the ends to square taper (or whatever), and get the
> best of both worlds.
Restart! The problems with BB's are bearings, retention of bearing
cups in the frame, and attachment of cranks to a spindle. The
Ashtabula solves only crank attachment, but does so only in a one
piece steel version.
That they don't fail in clean use has not been established. I know of
no one who has climbed many thousand road miles with them. I rode
mine to grade school on level streets and wasn't thrilled withe the
mechanics of the interfaces, the problem still facing BB designers
today.
Jobst Brandt
Chalo
>
> Chalo wrote:
> >
> > Jobst Brandt wrote:
> >>
> >> It demands steel
> >> cranks, something I believe is not marketable for high end bicycles.
> >
> >Does it? I think steel one-piece cranks are more of a convention than
> >a necessity. Forged aluminum or tubular steel cranks could be made in
> >the OPC pattern if there were sufficient respect for it.
>
> machine the ends to square taper (or whatever), and get the best of
> both worlds.
My point was to express to Mr. Brandt that the geometric limitations
of the one-piece do not preclude different designs from what is now
available in OPC. In the 1990s, there was an oversized one-piece
crank and BB standard (actually oversized crank, undersized bearings)
that had its day in the sun before cheap three-piece BMX cranks took
over that market niche. That one could easily have been made from
ordinary aluminum alloy, titanium, or hollow steel. With a stronger
aluminum alloy like forged 7075, a reliable one-piece crank could be
made to fit a normal OPC BB.
The scheme you suggest is currently available in the form of "adapter
spindles", which are square taper spindles threaded in the OPC
pattern. Such spindles can also be made with 19mm splined interfaces
for BMX-style 3-piece cranks. The first version of Redline's
venerable Flite cranks had such a spindle. Inexpensive tubular
chromoly 3-piece cranks on OEM bikes are often fitted with a threaded
OPC-type spindle.
http://www.danscomp.com/451053.php
Chalo
--D-y
> > Here's one on ebay with a decent photo:
>
> http://tinyurl.com/czv3ch
>
> Thanks. The GT has a nice polish with space for drilling pedal bores
> at various crank lengths, but no detail on bearings, cups and cones.
> The devil is in the details. I didn't see a solution for the fretting
> interfaces and radially loaded threads.
http://www.bikepro.com/products/bottom_brackets/mavic.html
http://poehali.net/content/b00007/10_Cartridge_Bottom_brackets.pdf
(fig. 10-5)
http://equusbicycle.com/bike/mavic/images/33and34.jpg
(scroll down for blow-up, actual devil not pictured)
The conical rings are plastic, so the once-chamfered BB shell should
last long enough for human consumption.
I don't know if the threads for the lock rings would be considered to
be radially loaded but the point is made moot by the fact that if/when
they do wear out, you just put a new BB cartridge and go on.
I "inherited" one of these on a race bike that was set up with Mavic
components apparently at the PoM. I didn't tell it the difference when
I put a Campy crank on and it has provided good service for what,
eight years now (noting limited mileage compared to the days of yore).
Back in the day, these were apparently a go-to for frames with ruined
BB threads, as the chamfering (steel bikes, of course) was a pretty
simple operation that didn't require heat and lost paint.
Last I looked, Stronglight is making same or similar and the price
isn't out of line with comparables. --D-y
jobst....@stanfordalumni.org
>>> Here's one on ebay with a decent photo:
>> Thanks. The GT has a nice polish with space for drilling pedal
>> bores at various crank lengths, but no detail on bearings, cups and
>> cones. The devil is in the details. I didn't see a solution for
>> the fretting interfaces and radially loaded threads.
http://www.bikepro.com/products/bottom_brackets/mavic.html
http://poehali.net/content/b00007/10_Cartridge_Bottom_brackets.pdf
> (fig. 10-5)
http://equusbicycle.com/bike/mavic/images/33and34.jpg
> (scroll down for blow-up, actual devil not pictured)
> The conical rings are plastic, so the once-chamfered BB shell should
> last long enough for human consumption.
> I don't know if the threads for the lock rings would be considered
> to be radially loaded but the point is made moot by the fact that
> if/when they do wear out, you just put a new BB cartridge and go on.
They seem not to understand the problem AND these are square taper
units, not an Ashtabula (one piece crank) that is the matter under
discussion. Consider the plastic bearing area in these units bearing
a force that deforms steel threads enough to generate elastic
clearance enough to unscrew right hand threads and erode away either
kind of steel thread, left or right.
> I "inherited" one of these on a race bike that was set up with Mavic
> components apparently at the PoM. I didn't tell it the difference
> when I put a Campy crank on and it has provided good service for
> what, eight years now (noting limited mileage compared to the days
> of yore).
> Back in the day, these were apparently a go-to for frames with
> ruined BB threads, as the chamfering (steel bikes, of course) was a
> pretty simple operation that didn't require heat and lost paint.
> Last I looked, Stronglight is making same or similar and the price
> isn't out of line with comparables.
I notice that the cartridge bearing used in these units are not secure
on the spindle or in the housing, so they just walk around and fret.
How is bearing clearance adjusted? With the high loads of a BB
spindle, BB bearings need to be adjusted with some preload to avoid
"ball hop" as each ball supports the load as it rolls under the load.
So from this one could assume that neither Campagnolo or Shimano are
aware of how simple plastic rings would solve the BB problem.
Jobst Brandt
--D-y
> They seem not to understand the problem
Which problem?
> AND these are square taper
> units, not an Ashtabula (one piece crank) that is the matter under
> discussion.
Fretting is and was a matter under discussion. The "Ashtabula" thing
is just a swat at what you consider to be a pesky fly <g>. Not
unusual. But, in direct answer to your jibe, "No, I'm not anywhere
stupid enough to not know the difference."
> Consider the plastic bearing area in these units bearing
> a force that deforms steel threads enough to generate elastic
> clearance enough to unscrew right hand threads and erode away either
> kind of steel thread, left or right.
I guess they chose a good material for the job, as mine seem to have
worked well-- better than Italian threading and Campy alu cups, for
instance, IRT being easy to adjust, and more important, staying put.
> I notice that the cartridge bearing used in these units are not secure
> on the spindle or in the housing, so they just walk around and fret.
> How is bearing clearance adjusted? With the high loads of a BB
> spindle, BB bearings need to be adjusted with some preload to avoid
> "ball hop" as each ball supports the load as it rolls under the load.
<http://www.equusbicycle.com/bike/mavic/images/33and34.jpg>
shows caps (spanner adj.) that hold the bearings in place.
> So from this one could assume that neither Campagnolo or Shimano are
> aware of how simple plastic rings would solve the BB problem.
Since when do you have any good regard for the "awareness" of
Campagnolo ("Delta brakes") or Shimano, either?
I'm guessing this chapter (The Evil of the Mavic Bottom Bracket) is
missing from the "faq" over at S. Brown, or we'd be hearing tales of
the old days in the effort to defeat the interloper.
So, we're back to "throw it away when it wears out", without having to
braze or paint. As a convenient alternative to threaded BB's.
--D-y
Gary Young
> On Apr 17, 10:54 am, Mike <nos...@nospam.com> wrote:
>> On 16 Apr 2009 23:04:05 GMT, jobst.bra...@stanfordalumni.org 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.
Most of Wal-Mart's cheapest bikes seem to use threaded stems:
(I can't tell if they use removable face plates, but I doubt it.)
Granted, Wal-Mart bikes generally only come in one size, but these bikes
still require steps that you say generate increased cost -- threading and
slotting the fork and making stems with quills. Maybe threaded is more
expensive and Wal-Mart invests in the extra expense because their
customers probably aren't familiar with threadless stems. But even if
that were true, the fact that threaded stems are found on bikes at that
price point suggests that the price difference isn't all that great.
> 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.
AMuzi
> On Wed, 22 Apr 2009 02:34:15 -0700 (PDT), Chalo
> <chalo....@gmail.com> wrote:
>
>> The scheme you suggest is currently available in the form of "adapter
>> spindles", which are square taper spindles threaded in the OPC
>> pattern. Such spindles can also be made with 19mm splined interfaces
>> for BMX-style 3-piece cranks. The first version of Redline's
>> venerable Flite cranks had such a spindle. Inexpensive tubular
>> chromoly 3-piece cranks on OEM bikes are often fitted with a threaded
>> OPC-type spindle.
>>
>> http://www.danscomp.com/451053.php
>
> "fretting" problem.
>
> The one piece solution does further eliminate the crank attachment
> issue but would require a BB shell size increase to implement. It
> would not be backwards compatible with older bikes.
>
> A one piece is less convenient when changing chainwheels though and
> requires complete disassembly of the BB. I suppose for the number of
> times we actually change chainwheels (vs thinking or talking about
> it), that it's really not an issue.
Mid seventies innovation - OPC spider for 110mm rings.
Common item still.