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Advice regarding Octalink BB/Crank



 
 
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  #21  
Old June 9th 09, 02:37 PM posted to rec.bicycles.tech
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Default Advice regarding Octalink BB/Crank

On Jun 9, 5:53*am, somebody wrote:
On Mon, 8 Jun 2009 14:17:26 -0700 (PDT), Jay Beattie

wrote:

If I were looking for something used, I would go with square drive.
Isis and Octalink BBs have the whole bearing failure issue (ISIS more
than Octalink), so even if you mount the cranks right, the BB has got
a severely limited life expectancy. I never had a problem with square
drive, notwithstanding the claims about spindle breakage, etc.
Bearings would wear out, but only after a good long time. -- Jay
Beattie.


What bearing failure issues do ISIS have, and why does the BB have a
limited life? *I have a couple ISIS and want to know what to look for.


I believe that because the axle spindle is a larger diameter the space
between the BB shell and the axle is less, meaning only smaller ball
bearings can be used-
Ads
  #22  
Old June 9th 09, 03:28 PM posted to rec.bicycles.tech
Jay Beattie
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Default Advice regarding Octalink BB/Crank

On Jun 8, 8:43*pm, wrote:
Jay Beattie wrote:
I have owned one Octalink setup. *I consistently had problems
with the crank bolts loosening, and the cranks loosening on the
splines. *Very frustrating.
I'm now looking for a compact crank, and the majority of the
offerings on the Bay are Octalink. *Can I learn to install an
Octalink set-up satisfactorily? *What's the trick?
Problem with Octalink and Isis is that if you didn't install
them properly the first time and you damaged the teeth or groves
you are screwed. *You need to make sure that you install them
and the fit is exact. *Either square taper or the new external
BB's are a lot more tolerant of mistakes. *If you have a choice
go for either one. *You'll find a lot of Octalink and ISIS on
sale because they are getting phased out. *I have had ISIS and
it has worked fine. *But I am always very careful making sure to
get proper fit. *However I'd rather use square taper. I have a
brand new campy chorus triple square taper that I bought for $30
on ebay. *If the Isis fails, I'll toss it and install the
campy. *You should be able to find some compact square taper
cheap if you look around.
Not so. *All Octalink transmitting high torque loosen their
retaining bolt, new or used, and installed by experts and
amateurs alike. *What do you perceive is the opposite from
"install them properly the first time"? *How does one "damaged
the teeth or groves" on installation?
How are you "always very careful making sure to get proper
fit". *How does one not get a "proper fit?"
Because with the Octalink BB (at least the original design) you
could get the feeling of proper engagement and actually be slightly
off. *You had to look carefully to make sure the splines were
properly engaged. *This is not myth or lore -- lots of people made
this mistake, including me (working in a hurry). *It results in
early crank death.


This is a digital system. *How can one be "slightly off". *Either the
spline is engaged or not. *You are still hedging on what goes wrong.

You didn't exactly say so, but it sounds like some installations
are made without engaging the spline and trying to tighten it into
place, tooth on tooth. *Why don't you come right out and say
so. *That way people who have these cranks would be able to use the
information. *The word "properly" is suitably mysterious for
someone not skilled in mechanical assembly.

Properly means that by feel, it seems to fit like a puzzle piece,
but in fact, there is a misfit. I have not had any problem with
loosening with an Octalink absent a problem with the initial
installation.


This is an amazing dodge and weave diversion from what is happening.
Are you saying users put cranks on randomly and hoped that with enough
tightening the spline would find its way? *This sounds absurd!


One more time with emphasis: you can misinstall Octalink cranks and
permanently ruin the interface. I have a day job (which isn't being an
engineer) and do not have time to pull my cranks apart or get the old
ruined one out of a box and do CSI basement bike shop, so I will leave
that to others with more time and talent. I could make a guess at
what happens, but that would just be more dodging, weaving, diversion,
myth, lore, absurdity, baloney, hedging, etc., etc. -- Jay Beattie.
  #23  
Old June 9th 09, 03:30 PM posted to rec.bicycles.tech
Peter Cole[_2_]
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Default Advice regarding Octalink BB/Crank

wrote:
On Jun 9, 4:38 am, Chalo wrote:



the tool I am refering too is

http://www.parktool.com/products/det...13&item=TW%2D1

I have heard it called a strain guage, I have seen this type of tool
at at a local automotive store for a lot less than other types of
torque wrenches. I am trying to help the OP.


It's a "beam" type torque wrench, a strain gauge is something quite
different.

uhhh, you say normal use- I indicated under varying environmental
conditions to suggest more exceptional use- don't try to put words in
my mouth to try to make a point, K-o ?


"varying environmental conditions" sounds like rain to me. Bit vague, no?
  #24  
Old June 9th 09, 03:42 PM posted to rec.bicycles.tech
DirtRoadie
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Default Advice regarding Octalink BB/Crank

On Jun 8, 9:43*pm, wrote:
Jay Beattie wrote:
This is an amazing dodge and weave diversion from what is happening.
Are you saying users put cranks on randomly and hoped that with enough
tightening the spline would find its way? *This sounds absurd!


Count me as another data point in the "ocatalink crank can be
installed incorrectly" camp.
My experience is limited, but is actual rather than hypothetical.
DR


  #25  
Old June 9th 09, 04:01 PM posted to rec.bicycles.tech
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Default Advice regarding Octalink BB/Crank

On Jun 9, 9:42 am, DirtRoadie wrote:
On Jun 8, 9:43 pm, wrote:

Jay Beattie wrote:
This is an amazing dodge and weave diversion from what is happening.
Are you saying users put cranks on randomly and hoped that with enough
tightening the spline would find its way? This sounds absurd!


Count me as another data point in the "ocatalink crank can be
installed incorrectly" camp.
My experience is limited, but is actual rather than hypothetical.
DR


And "actual" experience is what counts, not the hypothetical
bloviations of an internet gasbag.
  #26  
Old June 9th 09, 04:26 PM posted to rec.bicycles.tech
M-gineering
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Default Advice regarding Octalink BB/Crank

Chalo wrote:
The gold standard of reliability and ease of service is the one-piece
crank.


if all you've got is a hammer

Square taper BBs are several steps more finicky, demanding,
and unreliable. ISIS BBs are even worse, and Octalink is, as far as I
know, the worst system that ever got significant market penetration--
both in reliability and in ease of service.



Octalink BB's are much better than the usual ISIS crap with tiny
industrial bearings.

Splined 2-piece cranks
conforming to Roger Durham's patent are worlds better than anything
road bikes and MTBs have used in threaded shells in living memory.


if you call bearing replacement together with the new chain an
improvement. They can also be pretty hard on the threads in the BB shell

I'm sure Shimano has figured out some way to fawk them up, but they
are a fundamentally sound design (unlike Octalink).


Apart from the basic error that the pressfits are the wrong way round
you mean?


--
/Marten

info(apestaartje)m-gineering(punt)nl
  #27  
Old June 9th 09, 04:30 PM posted to rec.bicycles.tech
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Default Advice regarding Octalink BB/Crank

On Jun 9, 10:18 am, wrote:
ozark bicycles wrote:
I'm now looking for a compact crank, and the majority of the
offerings on the Bay are Octalink. Can I learn to install an
Octalink set-up satisfactorily? What's the trick?
Use a torque wrench. A strain guage should be fairly inexpensive
make certain everything is very clean, I put some lithium grease
on the splines to eliminate creaking; I install the adjusting
crank onto the axle to the max torque spec and feel to make sure
there is no play. I think Loctite is recommended, but I don't
like to use that because if there is any play it makes adjustment
difficult and leaves a residue on the threads. Then the crank
fixing screws get one turn each in alternating pattern untill I
reach more than half-way of the torque spec.range.
And then there is the way that people _actually_ service their
bikes. Although I don't think you were talking about what is
usually called a "strain gauge", a strain gauge is a great example
of what should never, ever be required for the safe and reliable
operation or maintenance of a bicycle:


http://tinyurl.com/kustmy



The gold standard of reliability and ease of service is the
one-piece crank. Square taper BBs are several steps more finicky,
demanding, and unreliable. ISIS BBs are even worse, and Octalink
is, as far as I know, the worst system that ever got significant
market penetration-- both in reliability and in ease of service.
Splined 2-piece cranks conforming to Roger Durham's patent are
worlds better than anything road bikes and MTBs have used in
threaded shells in living memory. I'm sure Shimano has figured out
some way to fawk them up, but they are a fundamentally sound design
(unlike Octalink).
I have encountered some lossening after a number of rides in
varying environmental conditions (very slight, minimal play), but
I reinstall cranks as described so I have not observed any damage
to the cranks or bb spindle; doubtless, if I leave things they
would get damaged.
So after your laboratory-grade installation procedure, Octalink
cranks still loosen in normal use. That's a perfect illustration
of the problem with them, and why they should never have been
foisted on an unsuspecting consumer market.

I'm not a big fan of Octalink, but the problems I have seen have
been around somewhat short bearing life and fussy initial
installation.


What is different between "Initial installation" and subsequent
installation?


Shall I assume that your newsreader only allows you to reply to
certain posts? Why else would you reply to this post, made in reply to
Chalo Colina, whilst seemingly ignoring my earlier post directed to
you? the fault must lie in the newsreader, surely you wouldn't be
avoiding a question now, would you Jobst?

So, once again: have you ever installed an Octalink crank on an
Octalink BB spindle? A simple "Yes" or "No" will suffice.

And, once again, have you personally ever experienced the loosening
and subsequent spindle damage you so often describe when using an
Octalink crank/BB?







  #28  
Old June 9th 09, 05:09 PM posted to rec.bicycles.tech
RonSonic
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Posts: 2,658
Default Advice regarding Octalink BB/Crank

On 09 Jun 2009 15:05:13 GMT, wrote:

Chalo Colina wrote:

Again, the only torque the BB spindle carries is that from the left
crank, right crank torque going directly into the chain.


You are aware of the following, because I have seen you say so:
Cranks can be torqued one against the other in either direction.
This torque necessarily transmits through the spindle.


But backing up a bit, for pedaling forces the spindle transmits torque
from the left crank only. Standing on both pedals with the right foot
forward is the only time reverse torque is transmitted through the
spindle.

Landing from a jump or drop in a standing position exerts higher
momentary torque than any amount of pedaling.


I don't think that is correct, because only half the rider's weight is
on each pedal. The legs not being rigid, absorb acceleration forces
putting less force on the pedals than they do on steep climbing while
pulling up on the opposite pedal. That causes greater force on pedals
than a jump.


That one rates a "huh?"

I can jump from a 5 foot high wall.

I cannot jump up a 5 foot high wall.

Landing from a jump involves far more force than the legs can generate.

Legs may absorb landing force relative to the person's head, but not from the
pov of the surface (or pedals) being landed upon.
  #29  
Old June 9th 09, 05:26 PM posted to rec.bicycles.tech
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Default Advice regarding Octalink BB/Crank

On Jun 9, 10:30*am, Peter Cole wrote:
wrote:
On Jun 9, 4:38 am, Chalo wrote:


the tool I am refering too is


http://www.parktool.com/products/det...13&item=TW%2D1


I have heard it called a strain guage, *I have seen this type of tool
at at a local automotive store for a lot less than other types of
torque wrenches. I am trying to help the OP.


It's a "beam" type torque wrench, a strain gauge is something quite
different.

uhhh, you say normal use- *I indicated under varying environmental
conditions to suggest more exceptional use- don't try to put words in
my mouth to try to make a point, K-o ?


"varying environmental conditions" sounds like rain to me. Bit vague, no?


beam type; thanks I'll try to remember that;
more than rain, -10c winter riding from warm indoor environment and
back again, numerous thermal expansion/contraction cycles, up-hill
sprint/hill repeats- all things considered, a consequent loosening or
play developing after several months was understandable
  #30  
Old June 9th 09, 05:32 PM posted to rec.bicycles.tech
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Default Advice regarding Octalink BB/Crank

On Jun 9, 12:09*pm, RonSonic wrote:
On 09 Jun 2009 15:05:13 GMT, wrote:





Chalo Colina wrote:


Again, the only torque the BB spindle carries is that from the left
crank, right crank torque going directly into the chain.


You are aware of the following, because I have seen you say so:
Cranks can be torqued one against the other in either direction.
This torque necessarily transmits through the spindle.


But backing up a bit, for pedaling forces the spindle transmits torque
from the left crank only. *Standing on both pedals with the right foot
forward is the only time reverse torque is transmitted through the
spindle.


Landing from a jump or drop in a standing position exerts higher
momentary torque than any amount of pedaling.


I don't think that is correct, because only half the rider's weight is
on each pedal. *The legs not being rigid, absorb acceleration forces
putting less force on the pedals than they do on steep climbing while
pulling up on the opposite pedal. *That causes greater force on pedals
than a jump.


That one rates a "huh?"

I can jump from a 5 foot high wall.

I cannot jump up a 5 foot high wall.

Landing from a jump involves far more force than the legs can generate.

Legs may absorb landing force relative to the person's head, but not from the
pov of the surface (or pedals) being landed upon.- Hide quoted text -

- Show quoted text -


people use their arms to absorb a lot of the shock from a jump- I
notice a lot less jarring jumping with a bike than jumping down a few
stairs
 




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