Threadless BB Cartridges: Why/Why Not?

(PeteCresswell) said:

Thanks to Werehatrack for introducing me to the concept...

Now it begs the question:
Why are BB shells threaded in the first place?
i.e. Why don't most bikes just come with threadless
already installed?

Sounds like there's a downside...

systems like that have been tried (merlin, klein, pinnarello), the
trick would be to settle on a standard.

it will also be denounced by the lugs and espressos crowd as a cost
cutting scheme.

Pete Cresswell said:

Thanks to Werehatrack for introducing me to the concept...

Quoted message said:

Now it begs the question:
Why are BB shells threaded in the first place?
i.e. Why don't most bikes just come with threadless
already installed?

Quoted message said:

Sounds like there's a downside...

I must have missed it but could you direct me to a web site where I
can see the cross section of a threadless BB? The only ones I know of
were on Ashtabula cranks and they had a larger diameter.

Jobst Brandt

here's pinarello's version:

http://www.pinarello.com/eng/products_technology_gear.php

-Amit

Quoted message said:

Pete Cresswell said:

Thanks to Werehatrack for introducing me to the concept...

Quoted message said:

Now it begs the question:
Why are BB shells threaded in the first place?
i.e. Why don't most bikes just come with threadless
already installed?

Quoted message said:

Sounds like there's a downside...

I must have missed it but could you direct me to a web site where I
can see the cross section of a threadless BB? The only ones I know of
were on Ashtabula cranks and they had a larger diameter.

Jobst Brandt

Mavic did a very successful one for many years.. it's disappearance is
probably the most unfortunate by-product of the take over.. NOS ones
turn up from time to time but I wish someone would buy or steal the
design and make new ones.

Amit Ghosh said:

here's Pirandello's version:

http://www.pinarello.com/eng/products_technology_gear.php

Unfortunately the mechanism remains secret. What holds the spindle
radially or laterally and how is the spindle attached to the bearing.
Without a press fit, this will become a creaking rouge generating
interface as will the bearings inside the BB shell. As I mentioned in
another thread, what are these folks thinking when they build their
web sites. Their 3-D image is a useless fuzzy picture unlike a cross
section line drawing.

Jobst Brandt

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

Quoted message said:

Mavic did a very successful one for many years.. it's disappearance is
probably the most unfortunate by-product of the take over.. NOS ones
turn up from time to time but I wish someone would buy or steal the
design and make new ones.

Nearly certain that the "Mavic" is still made, and marketed by Stronglight
these days.

Gary Jacobson
Rosendale, NY

Quoted message said:

Pete Cresswell said:

Thanks to Werehatrack for introducing me to the concept...
Now it begs the question:
Why are BB shells threaded in the first place?
i.e. Why don't most bikes just come with threadless
already installed?
Sounds like there's a downside...

Quoted message said:

I must have missed it but could you direct me to a web site where I
can see the cross section of a threadless BB? The only ones I know of
were on Ashtabula cranks and they had a larger diameter.

Surely, you recall the Mavic system of the eigties? Conical
rings on both sides screw onto a threaded Phil-ish
cartridge. IN Mavic's design, the frame gets milled with a
4mm chamfer on each end of the BB. The later
all-nylon-casing types (KSS brand) seem to work fine
without that chamfer.

They are both more expensive to make and much more time
consuming to install. As such they can't be an OEM part and
in today's world that is a kiss of death. Low volume means
high prices which leads to low volume and therefore high
prices, etc.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

Andrew Muzi said:

Quoted message said:

Quoted message said:

Thanks to Werehatrack for introducing me to the concept...
Now it begs the question:
Why are BB shells threaded in the first place?
i.e. Why don't most bikes just come with threadless
already installed?
Sounds like there's a downside...

Quoted message said:

Quoted message said:

I must have missed it but could you direct me to a web site where I
can see the cross section of a threadless BB? The only ones I know
of were on Ashtabula cranks and they had a larger diameter.

Quoted message said:

Surely, you recall the Mavic system of the eigties? Conical rings on
both sides screw onto a threaded Phil-ish cartridge. IN Mavic's
design, the frame gets milled with a 4mm chamfer on each end of the
BB. The later all-nylon-casing types (KSS brand) seem to work fine
without that chamfer.

I don't recall, and don't call me Shirley.

Quoted message said:

They are both more expensive to make and much more time consuming to
install. As such they can't be an OEM part and in today's world
that is a kiss of death. Low volume means high prices which leads
to low volume and therefore high prices, etc.

Picture reference please. I don't have much hope though because these
folks seldom show a cross section drawing where the function is
revealed. You might suspect they don't trust their patent protection.

Jobst Brandt

aka Jobst Brandt but not Shirley said:

Andrew Muzi said:

Quoted message said:

> Thanks to Werehatrack for introducing me to the concept...
> Now it begs the question:
> Why are BB shells threaded in the first place?
> i.e. Why don't most bikes just come with threadless
> already installed?
> Sounds like there's a downside...

Quoted message said:

Quoted message said:

I must have missed it but could you direct me to a web site where I
can see the cross section of a threadless BB? The only ones I know
of were on Ashtabula cranks and they had a larger diameter.

Quoted message said:

Surely, you recall the Mavic system of the eigties? Conical rings on
both sides screw onto a threaded Phil-ish cartridge. IN Mavic's
design, the frame gets milled with a 4mm chamfer on each end of the
BB. The later all-nylon-casing types (KSS brand) seem to work fine
without that chamfer.

I don't recall, and don't call me Shirley.

Quoted message said:

They are both more expensive to make and much more time consuming to
install. As such they can't be an OEM part and in today's world
that is a kiss of death. Low volume means high prices which leads
to low volume and therefore high prices, etc.

Picture reference please. I don't have much hope though because these
folks seldom show a cross section drawing where the function is
revealed. You might suspect they don't trust their patent protection.

Is this the referenced BB? See
<http://www.bikepro.com/products/bottom_brackets/mavic.html>.

--
Tom Sherman

Tom Sherman said:

Quoted message said:

Quoted message said:

>> Thanks to Werehatrack for introducing me to the concept...
>> Now it begs the question:
>> Why are BB shells threaded in the first place?
>> i.e. Why don't most bikes just come with threadless
>> already installed?
>> Sounds like there's a downside...

Quoted message said:

Quoted message said:

Quoted message said:

> I must have missed it but could you direct me to a web site where I
> can see the cross section of a threadless BB? The only ones I know
> of were on Ashtabula cranks and they had a larger diameter.

Quoted message said:

Quoted message said:

Quoted message said:

Surely, you recall the Mavic system of the eigties? Conical rings on
both sides screw onto a threaded Phil-ish cartridge. IN Mavic's
design, the frame gets milled with a 4mm chamfer on each end of the
BB. The later all-nylon-casing types (KSS brand) seem to work fine
without that chamfer.

Quoted message said:

Quoted message said:

I don't recall, and don't call me Shirley.

Quoted message said:

Quoted message said:

Quoted message said:

They are both more expensive to make and much more time consuming to
install. As such they can't be an OEM part and in today's world
that is a kiss of death. Low volume means high prices which leads
to low volume and therefore high prices, etc.

Quoted message said:

Quoted message said:

Picture reference please. I don't have much hope though because these
folks seldom show a cross section drawing where the function is
revealed. You might suspect they don't trust their patent protection.

Quoted message said:

Is this the referenced BB? See

http://www.bikepro.com/products/bottom_brackets/mavic.html

Insterding! Just the outer picture leaves me wondering what else they
didn't test. At least the text explains what the intent was. In this
design, the tube pictured is centered on threads that Mavic hoped
would be radially clearance free, unlike standard BB cups. I don't
believe that is a reasonable supposition unless the conical rings had
at least two splits to allow them to clamp, as my pedal attachments
do.

What's worse is that there is no explanation of how the spindle is
secured in the bearings and what sort of bearings these are.

Just to give an idea of the fragility of BB retention, I recently had
the right hand cup loosen and not be tightenable. When I removed it,
I discovered that more than 100000 miles of riding had eroded the
threads from the steel BB shell. The right side thread was completely
gone and the left side close behind. The right hand cup had been
brutally tightened and never removed during that time. Fretting
gradually ate up the threads leaving nothing but grey paste.

My frame maker bored the BB shell and silver soldered in steel
threaded sleeves abut 12mm deep on either side.

It is from this sort of experiences that I am suspicious of the
Shimano over-hung BB bearing design. How can that work even nearly as
well as internal BB cups?

Jobst Brandt

On Fri, 24 Feb 2006 14:03:24 -0500, "(PeteCresswell)" <[email hidden]>

Quoted message said:

Thanks to Werehatrack for introducing me to the concept...

Now it begs the question:
Why are BB shells threaded in the first place?
i.e. Why don't most bikes just come with threadless
already installed?

Sounds like there's a downside...

Most prevalent downside at present is the difficulty of getting a good
one for a reasonable price. Bike Tools Etc sells one made by YST, but
it's been disparaged for its relatively low durability. OTOH, at $17
plus shipping, it's one way to get a frame back in service quickly
when the threads have been damaged, and even if it only has a lifetime
of a couple of years in moderate service, that might be acceptable to
many riders.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

So far as I have known, the Mavic thread less BB cartage was for fixing
stripped out threads, when the bike owner didn't want to spend enough
$$$ to mill out the BB (frame) & re-thread for an Italian BB. Or the
frame already had an Italian BB. I've (correctly/incorrectly) thought
it was an inferior fix it terms of long-term reliability. And that JIS
version was even poorer.

John

J. Brandt said:

Just to give an idea of the fragility of BB retention, I recently had
the right hand cup loosen and not be tightenable. When I removed it,
I discovered that more than 100000 miles of riding had eroded the
threads from the steel BB shell. The right side thread was completely
gone and the left side close behind. The right hand cup had been
brutally tightened and never removed during that time. Fretting
gradually ate up the threads leaving nothing but grey paste.

Jobst

I don't see how you can seriously use the terms "fragility" & "100,000
miles" in the same paragraph.
It would probably take a pile of 100 bikes @ a scrap yard, to have
acclimated that kind of mileage or a pile of 10 bikes of the average
rbt reader :/)

John

Per [email hidden]:

Quoted message said:

When I removed it,
I discovered that more than 100000 miles of riding had eroded the
threads from the steel BB shell. The right side thread was completely
gone and the left side close behind. The right hand cup had been
brutally tightened and never removed during that time. Fretting
gradually ate up the threads leaving nothing but grey paste.

That's about what I experienced the other day - although I had ridden the frame
nowhere near 100,000 miles... OTOH, I'm about 220# and like to lunge up hills...

Back when I installed the crank set, my initial reaction to Shimano's use of
plastic for the cup side was righteous indignation. Now, after my little
adventure with the drive side eating up the BB threads I'm wondering if having
plastic on both sides wouldn't be the lesser of two evils.
--
PeteCresswell

In article <[email hidden]>,

Quoted message said:

Just to give an idea of the fragility of BB retention, I recently had
the right hand cup loosen and not be tightenable. When I removed it,
I discovered that more than 100000 miles of riding had eroded the
threads from the steel BB shell. The right side thread was completely
gone and the left side close behind. The right hand cup had been
brutally tightened and never removed during that time. Fretting
gradually ate up the threads leaving nothing but grey paste.

One idea I've considered is to have a bottom bracket shell cut
across the bottom, and clamp lugs (like seatpost clamp ears) across
the cut, or perhaps external clamps outside each cup. This would allow
the BB shell to be clamped down on the cups and arrest this fretting.

I'm not sure how good my intuition is for the magnitude of
forces encountered here, but the existance of bottom brackets
with extensive cutouts suggests to me this may be reasonable. The
torsion coming from the downtube would be the same order as what the
handlebar clamp supports, and this is a much larger interface which
should support it easily. On the other hand, vertical pedalling loads
and chain tension that the handlebars don't experience, would be
acting here. I think the chain tension would be benign though, being
in a direction that wouldn't act to open this split.
Vertical loads, I don't expect to be an issue as long as the
clamping is intact, but would be an issue with a clamp bolt failure.
I'm not sure that the BB cups are wide enough to allow for redundant
clamping here.

-Luns

john Drew said:

Quoted message said:

Just to give an idea of the fragility of BB retention, I recently
had the right hand cup loosen and not be tightenable. When I
removed it, I discovered that more than 100000 miles of riding had
eroded the threads from the steel BB shell. The right side thread
was completely gone and the left side close behind. The right hand
cup had been brutally tightened and never removed during that time.
Fretting gradually ate up the threads leaving nothing but grey
paste.

Quoted message said:

I don't see how you can seriously use the terms "fragility" &
"100,000 miles" in the same paragraph. It would probably take a
pile of 100 bikes @ a scrap yard, to have acclimated that kind of
mileage or a pile of 10 bikes of the average RBT reader :/)

The people with whom I ride often total more than 10,000 miles per
year as I have. My Campagnolo hubs from the 1970's are still serving
well and I expect the frame to retain its "static" BB threads at least
as well. The point is that crank threads and BB threads are dynamic
and constantly moving, although they shouldn't. That is why left hand
threads are used there.

If you ask why we have left hand threads, most shops will
mater-of-fact tell you so they don't unscrew. If you then ask why
these threads aren't tightened, you will get a blank stare. Of course
we tighten them is the reply. So how do they unscrew? These are
classically improper designs and I don't believe anyone has attacked
the BB problem although I have modified my cranks so that pedal
threads don't move and cause crank failures of which I had many. I no
longer need left hand threads on the left pedals.

Because right threaded left cranks are rare and right-right pedal
pairs even rarer, I still use left threaded left pedals.

Jobst Brandt

Luns Tee said:

Quoted message said:

Just to give an idea of the fragility of BB retention, I recently
had the right hand cup loosen and not be tightenable. When I
removed it, I discovered that more than 100000 miles of riding had
eroded the threads from the steel BB shell. The right side thread
was completely gone and the left side close behind. The right hand
cup had been brutally tightened and never removed during that time.
Fretting gradually ate up the threads leaving nothing but grey
paste.

Quoted message said:

One idea I've considered is to have a bottom bracket shell cut
across the bottom, and clamp lugs (like seatpost clamp ears) across
the cut, or perhaps external clamps outside each cup. This would
allow the BB shell to be clamped down on the cups and arrest this
fretting.

That is an idea. but that makes the BB an open sided tube that has no
torsional strength, and there is a rotating force there or the right
hand cup wouldn't need a left thread.

Quoted message said:

I'm not sure how good my intuition is for the magnitude of forces
encountered here, but the existence of bottom brackets with
extensive cutouts suggests to me this may be reasonable. The torsion
coming from the downtube would be the same order as what the
handlebar clamp supports, and this is a much larger interface which
should support it easily. On the other hand, vertical pedaling loads
and chain tension that the handlebars don't experience, would be
acting here. I think the chain tension would be benign though, being
in a direction that wouldn't act to open this split.

Cut-outs OK but not slotted crosswise.

Quoted message said:

Vertical loads, I don't expect to be an issue as long as the
clamping is intact, but would be an issue with a clamp bolt failure.
I'm not sure that the BB cups are wide enough to allow for redundant
clamping here.

I'm sure that is OK, bu the forces on the shell are not so simple as
they first appear judging from the need for a left thread.

Jobst Brandt

Luns Tee said:

One idea I've considered is to have a bottom bracket shell cut
across the bottom, and clamp lugs (like seatpost clamp ears) across
the cut, or perhaps external clamps outside each cup. This would allow
the BB shell to be clamped down on the cups and arrest this fretting.

I have a ~30 year old frame (Belgian) that has exactly this setup. The
BB shell has 2 slots with ears and pinch bolts to clamp both the fixed
and adjustable cups. I assumed, given the age of this bike, it was a
well-known technique. I wondered why it isn't used more often.

In article <[email hidden]>,

Quoted message said:

Luns Tee said:

Quoted message said:

Just to give an idea of the fragility of BB retention, I recently
had the right hand cup loosen and not be tightenable. When I
removed it, I discovered that more than 100000 miles of riding had
eroded the threads from the steel BB shell. The right side thread
was completely gone and the left side close behind. The right hand
cup had been brutally tightened and never removed during that time.
Fretting gradually ate up the threads leaving nothing but grey
paste.

Quoted message said:

One idea I've considered is to have a bottom bracket shell cut
across the bottom, and clamp lugs (like seatpost clamp ears) across
the cut, or perhaps external clamps outside each cup. This would
allow the BB shell to be clamped down on the cups and arrest this
fretting.

That is an idea. but that makes the BB an open sided tube that has no
torsional strength, and there is a rotating force there or the right
hand cup wouldn't need a left thread.

Quoted message said:

I'm not sure how good my intuition is for the magnitude of forces
encountered here, but the existence of bottom brackets with
extensive cutouts suggests to me this may be reasonable. The torsion
coming from the downtube would be the same order as what the
handlebar clamp supports, and this is a much larger interface which
should support it easily. On the other hand, vertical pedaling loads
and chain tension that the handlebars don't experience, would be
acting here. I think the chain tension would be benign though, being
in a direction that wouldn't act to open this split.

Cut-outs OK but not slotted crosswise.

Quoted message said:

Vertical loads, I don't expect to be an issue as long as the
clamping is intact, but would be an issue with a clamp bolt failure.
I'm not sure that the BB cups are wide enough to allow for redundant
clamping here.

I'm sure that is OK, bu the forces on the shell are not so simple as
they first appear judging from the need for a left thread.

Jobst Brandt