Advice regarding Octalink BB/Crank

Dans le message de ,
a
réfléchi, et puis a déclaré :
ozark bicycles wrote:

IMO, the biggest problem with Octalink was the fact that Shimano has
abandoned the design, leaving buyers up the creek. Hardly the first
time Shimano (and others, including Campy)has done this sort of
thing.

There it is again, begging the question: "The fact that...".

I believe you don't actually understand the textual meaning of what you
wrote in the part that precedes the colon.

And if in the second part you are suggesting that it is NOT a fact that the
design has been abandoned, you could have said that more elegantly, don't
you think?

And in the second part - are you suggesting that the design remains current
and foward looking? Even after Shimano has learned of your masterful
criticism of their engineering? Do tell.....
--
Bonne route !

Sandy
Verneuil-sur-Seine FR

On 09 Jun 2009 16:24:39 GMT, wrote:

Ron Bales 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.

If that were true, you could not make the landing, but would collapse
onto the bicycle, knees making a maximum bend until you land on the
bars and saddle. Ouch!

Go find a wall say four feet tall. Jump from it landing on your feet.
Stand there for a moment. Now jump back up.

Toldja.

On the bike the same relative leg strengths exist - you can absorb far more
energy as a shock absorber than you can apply to the pedals for propulsion. If
that were not true you'd be able to hop right back up that wall.

And back to the original point, landing a jump with the pedals horizontal
applies vastly more force to the BB than pedaling.

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

You must mean relative to the pelvis or there would be a large spinal
compression between hips and head. The human CG is about at the belly
button. The legs absorb the acceleration force of slowing descent of
the body. Try some small landings and note how you do it and how
great the force on the ball of the feet is. You could also try it
with the arches of your feet on the pedals, as the recent thread here
discussed.

The point is that the feet and the surface they land on receive the full brunt
however the rest is suspended and cushioned.

wrote:
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

Never happened with square tapers though. I think you're going too easy
on Shimano, cranks shouldn't loosen.

On Jun 9, 1:15*pm, Peter Cole wrote:
wrote:
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

Never happened with square tapers though. I think you're going too easy
on Shimano, cranks shouldn't loosen.- Hide quoted text -

- Show quoted text -

stock fsa on my cervelo, I don't like them loosening or developing
play at all- maybe I should use locitite, but as I said I don't
because I don't like how it powders in places while in others it is
next to impossible to clean out of the threads, meaning any work done
on the road can be far more problematic. further, I am not debating
the merits of octalink vs. other systems; I am just trying to help the
op.

wrote:

Chalo wrote:

wrote:

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.

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 ?

So you are suggesting it is not normal for bicycles to be used in
varying conditions?

Chalo

M-gineering wrote:

Chalo wrote:

*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.

ISIS cranks have not earned a reputation for consistently working
loose and gutting out their drive splines like Octalink cranks do.
Bearings, especially cartridge bearings, are meant to be replaced.
Crankarms are not meant to be consumables.

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 made outboard cups for my cranks years before Shimano did, and they
are still holding up fine with no follow-up service in ten years.

http://lh3.ggpht.com/_8pxqMHNBvlg/Rt...nF0/redbb..jpg

The bearings in outboard BBs are bigger than any that could be used
inside a threaded shell, and they are easily replaced. In the
meantime, the cranks don't bugger themselves like Octalink and the
spindles don't snap off like square taper. (And if you allow a square
taper crankarm to work loose as often happened with nutted spindles,
and it's ready for the recycler just like the Octalink version.) One-
piece cranks and splined three-piece BMX cranks for one-piece shells
are more reliable, but there is nothing for a threaded shell that
improves upon a two-piece crank with outboard bearing cups.

Chalo

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? What changes and how does that change occur?

IMO, the biggest problem with Octalink was the fact that Shimano has
abandoned the design, leaving buyers up the creek. Hardly the first
time Shimano (and others, including Campy)has done this sort of
thing.

There it is again, begging the question: "The fact that...".

I also think the original Dura-Ace BB-7700 Octalink BB assembly was
a very nice item. OTOH, the BB-5500 105 level cartridge unit is
mediocre, at best.

The dirt is in the details, and when making such a judgment, I think
the reason for it should be detailed.

oh, how delicious - let's repeat that:
"The dirt is in the details, and when making such a judgment, I think
the reason for it should be detailed."

yes indeed jobst, it most definitely should. and you miss the detail,
but judge anyway, thus proving yourself to be underinformed, ignorant,
and incapable of any reasoning ability.

tell us jobst, you you hate your alma mater? why do you shame them so?

pb in sdca wrote:


I have owned one octalink setup. I consistently had problems with the
crankbolts loosening, and the cranks loosening on the splines. Very
frustrating.
I never had any problem with it and I did over 100000 miles with Octalink
BB's......

Derk