A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Techniques
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Threadless BB Cartridges: Why/Why Not?



 
 
Thread Tools Display Modes
  #31  
Old February 27th 06, 12:51 PM posted to rec.bicycles.tech
external usenet poster
 
Posts: n/a
Default Threadless BB Cartridges: Why/Why Not?

"A Muzi" wrote:

Luns Tee wrote:


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 don't think that sounds too promising. But in the '50s and
'60s the British frame shops made a similar beginning. To
cure a stripped shell, they slit the bb crosswise, forced
the edges together, welded the seam and rethreaded the
resulting smaller bore.


I had the modification that Luns describes performed as a repair to the
bottom bracket shell of a Dawes Super Galaxy touring bike in London in the
early nineties. I'd bought the frame used, and the flange of the fixed cup
sheared off when I first tried to remove it. My local repairer cut open the
shell to remove the remains of the cup, then brazed on a pair of pinch
bolts. The repair gave me no trouble for the 30,000 or so miles I
subsequently rode on that frame.

James Thomson


Ads
  #32  
Old February 27th 06, 08:50 PM posted to rec.bicycles.tech
external usenet poster
 
Posts: n/a
Default Threadless BB Cartridges: Why/Why Not?

Charles Beristain writes:

Does the Cannondale Hollowgram SI integrated BB qualify as
threadless?


I don't believe the term "threadless" does much for anything but the
steertube that has traditionally been a headache in assembly.

Both my road bike and MTB have them with some very tough miles on
the MTB and a year of racing on the road bike. Claims to be lighter
and stiffer than the equivalent Dura-Ace.


http://www.cannondale.com/Asset/iu_files/115861a.pdf

Interesting. Fig. 6, showing the BB cross section is the one that
shows what interests me. I am not so thrilled with their leaving out
the bearings, possibly because they are amazingly small and probably
not angular contact as they should be. Maybe Shimano angular contact
head bearings would fit. That would be a bonus.

There is no reference to Isis, so I guess Cannondale are using their
own spline profile. That's too bad because a bit of unity in the face
of Shimano might help.

Jobst Brandt
  #33  
Old February 27th 06, 08:59 PM posted to rec.bicycles.tech
external usenet poster
 
Posts: n/a
Default Threadless BB Cartridges: Why/Why Not?

Marten Gerritsen writes:

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.


I would imagine that the purpose of this pinching was either simply
forgotten, or deemed not worth the extra complication and weight
(and then forgotten).


I'm curious though - what's the threading of this BB? Is the right
side cup a normal or a left-handed thread?


See www.m-gineering.nl/oldtechg.htm (last entry)


This is refreshing to see that in those days the inventor apparently
understood that a clamped BB cup doesn't need a left thread and that
the BB width could be assured with a sleeve, split so that the clamp
action would secure the threaded cups.

Elegant!

Jobst Brandt
  #34  
Old February 27th 06, 09:13 PM posted to rec.bicycles.tech
external usenet poster
 
Posts: n/a
Default Threadless BB Cartridges: Why/Why Not?

wrote:

There is no reference to Isis, so I guess Cannondale are
using their own spline profile. That's too bad because a
bit of unity in the face of Shimano might help.


To give them credit, Cannondale were selling splined cranks (initially with
external bearing cups) long before Shimano's versions and ISIS came on the
market, beginning with the M900 Magic (Magic Motorcycle) model. The axle
was designed to be made from aluminium.

http://pardo.net/pardo/bike/pic/fail/FAIL-014.html

There've been a few revisions of the design, and I'm not sure whether or
not the model pictured in the .pdf pre-dates ISIS.

James Thomson


  #35  
Old February 27th 06, 11:44 PM posted to rec.bicycles.tech
external usenet poster
 
Posts: n/a
Default Threadless BB Cartridges: Why/Why Not?

"James Thomson" writes:

wrote:

There is no reference to Isis, so I guess Cannondale are using
their own spline profile. That's too bad because a bit of unity in
the face of Shimano might help.


To give them credit, Cannondale were selling splined cranks
(initially with external bearing cups) long before Shimano's
versions and ISIS came on the market, beginning with the M900 Magic
(Magic Motorcycle) model. The axle was designed to be made from
aluminium.

http://pardo.net/pardo/bike/pic/fail/FAIL-014.html

There've been a few revisions of the design, and I'm not sure
whether or not the model pictured in the .pdf pre-dates ISIS.


British crank maker Williams offered what appeared to be an
interference fit splined crank 40 years ago. Hilary Stone just had
one up for auction on eBay. I've never seen one in person.

http://tinyurl.com/no575
  #36  
Old February 28th 06, 12:17 AM posted to rec.bicycles.tech
external usenet poster
 
Posts: n/a
Default Threadless BB Cartridges: Why/Why Not?

"Tim McNamara" wrote:

British crank maker Williams offered what appeared to be
an interference fit splined crank 40 years ago. Hilary Stone
just had one up for auction on eBay. I've never seen one
in person.


I have, on a mid-sixties Moulton S-Speed, and of course there were other
splined cranks even earlier: Gnutti springs to mind, though I'm no
historian.

Just to clarify, I wasn't suggesting that Cannondale produced the first
splined cranks, but only that their use of tapered splines pre-dates both
Octalink and ISIS.

James Thomson


  #37  
Old February 28th 06, 02:00 AM posted to rec.bicycles.tech
external usenet poster
 
Posts: n/a
Default Threadless BB Cartridges: Why/Why Not?

James Thomson writes:

British crank maker Williams offered what appeared to be an
interference fit splined crank 40 years ago. Hilary Stone just had
one up for auction on eBay. I've never seen one in person.


I have, on a mid-sixties Moulton S-Speed, and of course there were
other splined cranks even earlier: Gnutti springs to mind, though
I'm no historian.


Just to clarify, I wasn't suggesting that Cannondale produced the
first splined cranks, but only that their use of tapered splines
pre-dates both Octalink and ISIS.


Octalink was not a tapered spline and that was its downfall. It was a
slip fit spline that had elastic and clearance backlash that allowed
enough fretting to loosen its retaining bolt for "goofy footed" riders
of which there are enough to present systematic failures. We have had
user testimony to that effect on this forum.

I bring this up because the manufacturers involved in BB design are
not well versed in the failure modes, bringing designs to market that
have built in failures. Octalink solved spindle strength problem but
failed in crank attachment... and bearing size. All of them up to now
have failed in pedal attachment, and most fail in lateral crank
bending strength, the mode in which nearly all cranks break. Cranks
rarely break form pedaling torque. They break off at the bottom of
the pedal stroke in side bending. This is apparent from all the
failed cranks shown here and ones I have inspected.

Jobst Brandt
  #38  
Old February 28th 06, 05:11 AM posted to rec.bicycles.tech
external usenet poster
 
Posts: n/a
Default Threadless BB Cartridges: Why/Why Not?

On Tue, 28 Feb 2006 03:00:18 +0100, "James Thomson"
wrote:

Since Cannondale seem committed to aluminium as a spindle material, I
suspect they feel that the dimensions of the ISIS interface are unsuitable
for their uses.


And they're probably right, for what it's worth. Of course, inventing
yet another proprietary interface, and then marrying it to a BB design
that is just as quirky, is hardly a route to getting the product
generally accepted in the marketplace. It may be the best thing out
there, but if it's not installable in the bikes that other people are
already riding, it's not going to catch on.

CDale seems to be making a tactical error that has been committed over
and over in the past; come up with something that may very well be
better than the competition can provide, and then ensure that it will
not be a success by keeping it from being widely available.

Someday, someone is going to recognize that the English/Italian BB
shell diameter is the real problem, and will propose a new open
standard for a larger diameter of shell that can carry a more useful
size of bearing and shaft. For those who wish to stay with the old
tech, an adapter bushing could provide backward compatibility with
prior designs.

Unfortunately, I don't think that this is a move that's likely to be
made anytime soon.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.
  #39  
Old February 28th 06, 12:57 PM posted to rec.bicycles.tech
external usenet poster
 
Posts: n/a
Default Threadless BB Cartridges: Why/Why Not?

"Werehatrack" wrote:

"James Thomson" wrote:


Since Cannondale seem committed to aluminium as a
spindle material, I suspect they feel that the dimensions
of the ISIS interface are unsuitable for their uses.


And they're probably right, for what it's worth. Of course,
inventing yet another proprietary interface, and then marrying
it to a BB design that is just as quirky, is hardly a route to
getting the product generally accepted in the marketplace.
It may be the best thing out there, but if it's not installable in
the bikes that other people are already riding, it's not going
to catch on.


CDale seems to be making a tactical error that has been
committed over and over in the past; come up with something
that may very well be better than the competition can provide,
and then ensure that it will not be a success by keeping it from
being widely available.


To be frank, I doubt that Hollowgram (and Coda Magic before it) has ever
been seen by Cannondale as a bridgehead into the mass market, but rather as
a selling feature of their most expensive models. Mass market acceptance
(which is probably precluded by the extravagant machining and expensive
materials) would undermine the exclusivity necessary to marketing the
system to the elite.

I did wonder whether it was a means of seeking market acceptance for a new
bottom bracket shell standard, but whatever the intention, that hasn't
happened.

Someday, someone is going to recognize that the English/Italian BB
shell diameter is the real problem, and will propose a new open
standard for a larger diameter of shell that can carry a more useful
size of bearing and shaft.


ISIS Overdrive?

http://www.isisdrive.com/isisoverdrive/

There's an interesting contrast between the scramble to adopt a wild array
of mutually incompatible integrated headset standards that nobody seemed to
want or need, and the general disinclination of the industry to update the
bottom bracket standard to a design that would appear to have real benefits
and simple backward compatibility.

In any case, the market seems to have accepted external bearing cups (a
feature of the orginal Coda Magic system, incidentally), which may remove
any immediate impetus to update the shell standard.

James Thomson


  #40  
Old February 28th 06, 05:48 PM posted to rec.bicycles.tech
external usenet poster
 
Posts: n/a
Default Threadless BB Cartridges: Why/Why Not?

James Thomson writes:

Since Cannondale seem committed to aluminium as a spindle
material, I suspect they feel that the dimensions of the ISIS
interface are unsuitable for their uses.


And they're probably right, for what it's worth. Of course,
inventing yet another proprietary interface, and then marrying it
to a BB design that is just as quirky, is hardly a route to getting
the product generally accepted in the marketplace. It may be the
best thing out there, but if it's not installable in the bikes that
other people are already riding, it's not going to catch on.


Cannondale seems to be making a tactical error that has been
committed over and over in the past; come up with something that
may very well be better than the competition can provide, and then
ensure that it will not be a success by keeping it from being
widely available.


To be frank, I doubt that Hollowgram (and Coda Magic before it) has
ever been seen by Cannondale as a bridgehead into the mass market,
but rather as a selling feature of their most expensive models.
Mass market acceptance (which is probably precluded by the
extravagant machining and expensive materials) would undermine the
exclusivity necessary to marketing the system to the elite.


I did wonder whether it was a means of seeking market acceptance for
a new bottom bracket shell standard, but whatever the intention,
that hasn't happened.


Someday, someone is going to recognize that the English/Italian BB
shell diameter is the real problem, and will propose a new open
standard for a larger diameter of shell that can carry a more
useful size of bearing and shaft.


Not soon but in harder times, the major manufacturers will have to
bury the hatchet and have a standards agreement in which standards are
not only set but designed so that there will be interchangeability as
we have in the computer business for I/O and storage devices as well
as data formats. For that to happen a strong leader must emerge who
engages both the manufacturers and the market. That need not come
from within the industry but could be achieved by an international
trade board that sets guidelines.

ISIS Overdrive?


http://www.isisdrive.com/isisoverdrive/

This is hopelessly lost. This does not address the failures of BB
threads the under size of the shell to house both a sturdy spindle AND
bearings and above all, I find the Isis spline not ideal for the task.
Nothing on that assembly strikes me as a significant advance. As was
demonstrated, spindles have broken because the transition from spline
to shaft was too abrupt, in spite of it's larger diameter than the old
square taper.

There's an interesting contrast between the scramble to adopt a wild
array of mutually incompatible integrated headset standards that
nobody seemed to want or need, and the general disinclination of the
industry to update the bottom bracket standard to a design that
would appear to have real benefits and simple backward
compatibility.


We don't need no "integrated headsets". That's fashion. The current
external pressed-in cups are ideal mechanically, being easy to install
and weather proof (facing downward). Now that fretting damage has
been addressed they also work and work well with threadless steer
tubes. What problem is the "integration" solving?

In any case, the market seems to have accepted external bearing cups
(a feature of the original Coda Magic system, incidentally), which
may remove any immediate impetus to update the shell standard.


We'll have to see how that works. If internal cups are difficult to
install and subsequently fail even when ideally installed, external
ones with overhung loads ought to accelerate failure while being no
easier to install. Getting rid of special (maintenance) tools should
also be a goal for the industry.

Jobst Brandt
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Bad idea to upgrade to 1" threadless headset/fork? Dan Lenski Techniques 15 June 30th 05 04:02 PM
Threadless stems and carbon steerers in crashes George Herbert Walker Techniques 10 October 2nd 04 06:16 PM
handlebar height n crowley General 35 April 19th 04 07:12 PM
YST threadless headsets Ian Szekeres Techniques 5 February 25th 04 10:30 AM
Threadless headset questions/problems Scott Ghiz Techniques 4 February 18th 04 02:51 PM


All times are GMT +1. The time now is 06:28 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 CycleBanter.com.
The comments are property of their posters.