I greased my crank and now it's split!
Rinards
A few years ago I inherited an old (1992) Dura-Ace FC 7410 crankset
from a pro team. I've used it for about 3000 miles in addition to the
mileage the pro rider put on it.
I never used to grease the tapers, but the FAQ convinced me otherwise.
So the next time I had the arms off, I greased the tapers and torqued
the bolts once to 300 inch pounds. I was surprised how
much farther the arms slid up the taper on installation with grease.
About 200 miles later the bike began making a creaking sound
when I pedalled. When I removed the left crank I saw two cracks, one
in each of two opposite corners of the taper.
I installed a crank from my other bike, and now the creaking noise is gone.
Did grease do this crank in, or was it just too old anyway?
Damon Rinard
Matt O'Toole
Rinards <rin...@aol.com> wrote in article
<19970910020...@ladder02.news.aol.com>...
My guess is that the cranks were already cracked, especially if you got
them from a pro rider. They would have had a lot of hard miles on them.
The second time you installed with grease, the cranks slid on further
because the cracks allowed the hole to widen, and the crank to slide
further up onto the taper. The cracks got worse as you rode, and the
creaking started.
I broke a crank once that had been owned by a racer, a big, strong rider
who also toured extensively in the Alps. Those cranks were probably close
to death when I acquired them, and they broke on me in traffic, an
experience I don't care to repeat. Racers' hand-me-downs are probably not
a good idea. The loads and the number of fatigue cycles experienced by
these parts are many, many times greater than what even an avid
recreational cyclist can dish out.
Matt O.
Chris Phillipo
In message <p-mcnally-100...@mac068.physio.nwu.edu> -
p-mc...@nwu.edu (Patrick McNally) writes:
:>
:>
:>In article <19970910020...@ladder02.news.aol.com>,
:>rin...@aol.com (Rinards) wrote:
:>
:>> I never used to grease the tapers, but the FAQ convinced me otherwise.
:>> the bolts once to 300 inch pounds. I was surprised how
:>> much farther the arms slid up the taper on installation with grease.
:>>
:>> About 200 miles later the bike began making a creaking sound
:>> when I pedalled. When I removed the left crank I saw two cracks, one
:>> in each of two opposite corners of the taper.
:>It is very obvious that you did not use bike-specific grease.
:>
:>Ask Jobst, you have to use cycling-specific lubricants.
:>
Hmm, what's constitutes a cycling-specific lubricant anyway? When Pedro puts
their name on a formula made by an oil company?
___________________________________________
Chris Phillipo - webm...@tread.pair.com
TREAD Publications - TREAD Online! Cycle Magazine. <07-30-97>
http://www.tread.pair.com/ - http://www.tread.pair.com/bikemag/
Matt O'Toole
Chris Phillipo <webm...@tread.pair.com> wrote in article
<5v7ec6$ok4$1...@news.istar.ca>...
> Hmm, what's constitutes a cycling-specific lubricant anyway? When Pedro
puts
> their name on a formula made by an oil company?
Would it be more "noble" to you if a real guy named Pedro dug an oil well,
refined the oil in a homemade still using Jed Clampett's recipe, and then
sold it from the back of a covered wagon along with other snake oils and
homemade vitamin supplements?
Or, would you have more confidence in a product that was
formulated-to-order by trained engineers at an oil company, to specs given
them by avid mountain bikers like yourself? (Example, make me an oil that
does this, but not that, etc.)
What is more important to you anyway, cute imagery (the former), or quality
product created by folks who actually know what they're doing (the latter)?
Matt O.
Chris Phillipo
In message <01bcbe83$812f86a0$decab2cc@user-2> - "Matt O'Toole"
<ma...@deltanet.com>11 Sep 1997 07:25:41 GMT writes:
:>
:>
:>
:>Chris Phillipo <webm...@tread.pair.com> wrote in article
:><5v7ec6$ok4$1...@news.istar.ca>...
:>
:>> Hmm, what's constitutes a cycling-specific lubricant anyway? When Pedro
:>puts
:>> their name on a formula made by an oil company?
:>
:>Would it be more "noble" to you if a real guy named Pedro dug an oil well,
:>refined the oil in a homemade still using Jed Clampett's recipe, and then
:>sold it from the back of a covered wagon along with other snake oils and
:>homemade vitamin supplements?
:>
:>Or, would you have more confidence in a product that was
:>formulated-to-order by trained engineers at an oil company, to specs given
:>them by avid mountain bikers like yourself? (Example, make me an oil that
:>does this, but not that, etc.)
Did I say there was anything WRONG with it? I just get a kick out of people
saying buy a bike specific lube when you can buy an almost identical product
for half the price at Canadian Tire.
:>What is more important to you anyway, cute imagery (the former), or quality
:>product created by folks who actually know what they're doing (the latter)?
Not paying for a name is what's important to me, not believing the sales hype
is up there too.
Mike Dearing
more likely 300 lbspsi - that is way too much - Im surprised it didnt
pull the crankpin thru the crankarm!!! more like 30 is required
Mike :7)
David Rees
I live in Montreal, so I'd like to know what that identical-to-Pedro's lube
is. Is it a canadian Tire (Motomaster) product? Is there a dry formula,
too?
Chris Phillipo
In message <01bcbeb2$f5839a30$31f7eccd@hal> - "David Rees"
<dr...@microtec.net>11 Sep 1997 13:02:34 GMT writes:
:>
:>I live in Montreal, so I'd like to know what that identical-to-Pedro's lube
:>is. Is it a canadian Tire (Motomaster) product? Is there a dry formula,
:>too?
:>
If you look back on Deja news you might find the discussion about where
Pedro's comes from. I can't remember which company makes it.
I wasn't claiming that there are identical items at Canadian tire to Pedro's,
just that things like Castrol MP and Synquest are cheaper and similar to
cycling products.
For example, Finish Lines Teflon Fortified Lube is nearly identical to
Superlube (found in motorcycle and snow mobile shops) in it's claims and mode
of operation.
Pedro's Syngrease is similar to Castrol's and everyone's Lithium grease seems
to be the same as the 2 lb tub you can buy in any automotive department.
Jeffrey L. Bell
In a previous article, David Rees <dr...@microtec.net> wrote:
>... I'd like to know what that identical-to-Pedro's lube is....
As I recall from the last time this came up....
There is no identical-to-Pedro's lube. There may be things that are
almost identical, and things that work as well, but nothing exactly
the same.
According to posts from last year Pedro's is blended to Pedro's
specifications by Mobil. Mobil makes a variety of synthetic oils, and
Pedro's tell them which base to use and what other additives and
colorings they want. Mobil stirs them in, and sends it by barrel to
Pedro's who puts in little bottles and ships it around to bike shops.
If you knew exactly what you want in your barrel, I'm sure you could
ask Mobil to mix some up for you at a greatly reduced cost.
Whether it works significantly better than motor oil or not is a
matter of debate.
-Jeff Bell
Dr. Memory
A mist arosy from the scrying-bowl, and rin...@aol.com (Rinards) was
heard to utter:
>I never used to grease the tapers, but the FAQ convinced me otherwise.
>So the next time I had the arms off, I greased the tapers and torqued
>the bolts once to 300 inch pounds. I was surprised how
>much farther the arms slid up the taper on installation with grease.
It's possible you applied more than 300 in/lbs to the bolts. I read a
BMW tech bulletin that said that applying anti-sieze to spark plug
threads was a bad idea, because it could lead to over-torquing and
stripping the threads in the (aluminum) head. Not sure if that's
directly applicable, but it's food for thought.
Matt O'Toole
Chris Phillipo <webm...@tread.pair.com> wrote in article
<5v923o$dvk$1...@news.istar.ca>...
> If you look back on Deja news you might find the discussion about where
> Pedro's comes from. I can't remember which company makes it.
It's Mobil, the world's biggest supplier of synthetic lubricants.
> I wasn't claiming that there are identical items at Canadian tire to
Pedro's,
> just that things like Castrol MP and Synquest are cheaper and similar to
> cycling products.
> For example, Finish Lines Teflon Fortified Lube is nearly identical to
> Superlube (found in motorcycle and snow mobile shops) in it's claims and
mode
> of operation.
> Pedro's Syngrease is similar to Castrol's and everyone's Lithium grease
seems
> to be the same as the 2 lb tub you can buy in any automotive department.
Any of those products will lube a bicycle chain quite well. Some
bike-specific lubes have detergents in them so that they will wash out of
the inside of a chain easily, leaving it as grit-free as possible, and
without caked-on dirt.
Virtually all automotive-type greases sold today are lithium-based. Any
will provide more than adequate lubrication for a bicycle, but it really
does help to have a waterproof grease. Not all auto, or bike greases, are
waterproof, even expensive synthetic ones.
It's true that most of this is brand-name marketing. Some products are
just repackaged, marked up, and placed in a flashy POP display to make the
bike shop happy. However, some bike brands do really sell thoughtfully
designed products, which work a little better than generic or universal
ones.
Matt O.
Jeffrey Potoff
That's strange because most mechanics I know recommend putting
anti-seize on sparkplugs, *especially* if you have an aluminum
head. Otherwise, you risk taking out the threads when you try
to remove your plugs 36,000 miles later,
Jeff
Origami TB
"Matt O'Toole" <ma...@deltanet.com> wrote on 10 Sep:
>I broke a crank once that had been owned by a racer, a big, strong >rider
who also toured extensively in the Alps. Those cranks were >probably close
to death when I acquired them, and they broke on me >in traffic, an
experience I don't care to repeat. Racers' >hand-me-downs are probably not
a good idea.
The same thing happened to me with a second-hand Sugino Maxy (remember
them?) on a long ride, and though it was not as hazardous an experience as
Matt's, it made for a VERY long walk to the nearest telephone for help.
Dave Blake
"Matt O'Toole" <ma...@deltanet.com> wrote on 10 Sep:
>I broke a crank once that had been owned by a racer, a big, strong
>rider who also toured extensively in the Alps. Those cranks were
>probably close to death when I acquired them, and they broke on me
>in traffic, an experience I don't care to repeat. Racers'
>hand-me-downs are probably not a good idea.
While trail riding down on the peninsula, I came upon
a secret stash - nearly two dozen Campy Record cranks,
all still covered with grease, and all broken at
either the pedal hole or the crank:spider interface on
the right crank. There were large footprints with SPD
cleats in the center of them nearby, and some perfectly
smooth 28C tire tracks.
Maybe it was a sasquatch ?
--
Dave Blake
dbl...@phy.ucsf.edu
http://www.keck.ucsf.edu/~dblake/
evans-the-swim
orphan...@dont.your-eyes (Dr. Memory) wrote:
>A mist arosy from the scrying-bowl, and rin...@aol.com (Rinards) was
>heard to utter:
>>I never used to grease the tapers, but the FAQ convinced me otherwise.
>>So the next time I had the arms off, I greased the tapers and torqued
>>the bolts once to 300 inch pounds. I was surprised how
>>much farther the arms slid up the taper on installation with grease.
>It's possible you applied more than 300 in/lbs to the bolts. I read a
>BMW tech bulletin that said that applying anti-sieze to spark plug
>threads was a bad idea, because it could lead to over-torquing and
>stripping the threads in the (aluminum) head. Not sure if that's
>directly applicable, but it's food for thought.
Um, no. If he had a torque wrench and it read 300 in-lbs then that's
what the torque was. What you (probably) meant to say was that if
lubricated, 300 might have been too much for the material to withstand
(which is extremely unlikely).
Sheesh. Sometimes I wonder why I even read this group.
Rick Denney
Perhaps it was a Brandtosaurus.
On 12 Sep 1997 02:56:49 GMT, dbl...@phy.ucsf.eduDELETETHISPART (Dave
Blake) wrote:
Rick Denney
Remember--free advice is worth what you pay for it!
Jeffrey Potoff
Heh, heh, probably the same reason people call their old girlfriends.
You just can't help yourself sometimes. :^)
Jeff
Jobst Brandt
Memory writes anonymously:
>> I never used to grease the tapers, but the FAQ convinced me
>> otherwise. So the next time I had the arms off, I greased the
>> tapers and torqued the bolts once to 300 inch pounds. I was
>> surprised how much farther the arms slid up the taper on
>> installation with grease.
> It's possible you applied more than 300 in/lbs to the bolts. I read
> a BMW tech bulletin that said that applying anti-seize to spark plug
> threads was a bad idea, because it could lead to over-torquing and
> stripping the threads in the (aluminum) head. Not sure if that's
> directly applicable, but it's food for thought.
That's another fear monger tale. Anti-seize is just another grease and
if the scenario you repeat is true then we aren't far from grease on
the parts causing failure. Nice try.
Jobst Brandt <jbr...@hpl.hp.com>
Sam Bond
rin...@aol.com (Rinards) wrote:
>
>I never used to grease the tapers, but the FAQ convinced me otherwise.
Then I would suggest the FAQ is wrong. They should be clean and dry or, at
the most, a film of something like Copperease nearly wiped off.
>So the next time I had the arms off, I greased the tapers and torqued
>the bolts once to 300 inch pounds. I was surprised how
>much farther the arms slid up the taper on installation with grease.
>
>About 200 miles later the bike began making a creaking sound
>when I pedalled. When I removed the left crank I saw two cracks, one
>in each of two opposite corners of the taper.
Because you over-tightened it started to split it - tapers are not designed
to be tightened like that - they should fit well and be just tight enough
to stop movement under load.
>
>
>Did grease do this crank in, or was it just too old anyway?
Yes, and no - unless it had been overtightened before.
Sam
John Serafin
s...@mimosa.demon.co.uk (Sam Bond) writes:
>rin...@aol.com (Rinards) wrote:
>>
>>I never used to grease the tapers, but the FAQ convinced me otherwise.
>Then I would suggest the FAQ is wrong. They should be clean and dry or, at
>the most, a film of something like Copperease nearly wiped off.
Smallpox has been eradicated worldwide several times in my lifetime. I
wonder if we will ever be able to say the same about the "Don't grease
the cranks" myth?
>>Did grease do this crank in, or was it just too old anyway?
>Yes, and no - unless it had been overtightened before.
There is no evidence that greasing cranks makes them split, and lots of
evidence that it does not.
Do you think that an individual can make it rain by washing a car?
It happens quite often.
--
John P. Serafin | Operating a bicycle is more like driving than riding.
jps at pobox com | Operating an automobile is more like riding than driving.
Vincent Huang
> evans-the-swim wrote:
> >
> > orphan...@dont.your-eyes (Dr. Memory) wrote:
> >
> > >A mist arosy from the scrying-bowl, and rin...@aol.com (Rinards)
> was
> > >heard to utter:
> >
> otherwise.
> torqued
> > >>the bolts once to 300 inch pounds. I was surprised how
> > >>much farther the arms slid up the taper on installation with
> grease.
> >
> read a
> > >threads was a bad idea, because it could lead to over-torquing and
> > >stripping the threads in the (aluminum) head. Not sure if that's
> > >directly applicable, but it's food for thought.
> >
> that's
> > what the torque was. What you (probably) meant to say was that if
> > lubricated, 300 might have been too much for the material to
> withstand
> > (which is extremely unlikely).
> >
> > Sheesh. Sometimes I wonder why I even read this group.
>
Shimano recommends 305-465 lbs/sqin on the new Dura Ace BB. It does
have the new splined design but I don't think 300lbs/sqin is too much.
Sam Bond
John Serafin <j...@velo.boxmail.com> wrote:
>There is no evidence that greasing cranks makes them split, and lots of
>evidence that it does not.
with which a taper fitted component can be overtightened when it is
lubricated that splits it. Under tightening can also cause damage as
pedalling squeezes out the grease and the crank moves on its taper.
>
>Do you think that an individual can make it rain by washing a car?
>It happens quite often.
Sam
Richard Strayer
>>>I never used to grease the tapers, but the FAQ convinced me otherwise.
>
>>the most, a film of something like Copperease nearly wiped off.
>
>Smallpox has been eradicated worldwide several times in my lifetime. I
>wonder if we will ever be able to say the same about the "Don't grease
>the cranks" myth?
Unlikely. There's always some "expert" waiting in the wings to spout
this nonsense.
>>>Did grease do this crank in, or was it just too old anyway?
>>Yes, and no - unless it had been overtightened before.
>
>There is no evidence that greasing cranks makes them split, and lots of
>evidence that it does not.
>
>Do you think that an individual can make it rain by washing a car?
>It happens quite often.
I don't know about rain, but washing my car seems to have a laxative
effect on birds.
RES
Sam Bond
kpm...@netcom.com (Richard Strayer) wrote:
> There's always some "expert" waiting in the wings to spout
>this nonsense.
>
"nonsense"? Spend some time with a micrometer and torque gauge - produce
the numbers and with your extensive knowledge of lubrication. the strength
of materials, their metalurgy and the design of taper fitted cranks show
how it is "nonsense" .
Sam
da...@erinet.com
>>> >>I never used to grease the tapers, but the FAQ convinced me
>>> >>So the next time I had the arms off, I greased the tapers and
>>> >>torqued the bolts once to 300 inch pounds. I was surprised how
>>> >>much farther the arms slid up the taper on installation with
>>> >>grease.
>>> It's possible you applied more than 300 in/lbs to the bolts. I
>>> read a
>>> BMW tech bulletin that said that applying anti-sieze to spark plug
>>> threads was a bad idea, because it could lead to over-torquing and
>>> stripping the threads in the (aluminum) head. Not sure if that's
>>> directly applicable, but it's food for thought.
I doubt that BMW recommended this, but who knows. Why not simply
specify a lower torque value? The reason you use anti-seize compound
is so that you can get the steel spark plug out of the aluminum
cylinder head a year or so down the road. It's a hell of a lot of
trouble to remove a cylinder head and have the broken spark plug body
removed by a head rebuilder.
>Um, no. If he had a torque wrench and it read 300 in-lbs then
>that's what the torque was. What you (probably) meant to say was that if
>lubricated, 300 might have been too much for the material to
>withstand (which is extremely unlikely).
I agree that it's unlikely. Many times, when torque figures are
given, it is for clean, dry threads. That should not be interpreted
that the fasteners be put together dry. It's just a bit tricky to
specify the torque figure not knowing what kind of lubricant will be
used.
And, yes, 300 in-lbs is 300 in-lbs. So what? When dealing with
fasteners, the thing you are seeking is the correct "stretch" of the
fastener, so it will deliver a desired amount of gripping force. In
some fairly high-end racing applications, the mechanic will rig up a
measuring gauge and tighten the fastener till it stretches the desired
amount. On some water-cooled VW engines, the head-bolt tightening
procedure was to tighten the bolt to a specific torque -- then tighten
it an additional 1/4 turn. These "stretch" bolts were not supposed to
be reised. But, for 99% of applications, measuring the torque on the
fastener head is more than adequate.
>>> > Sheesh. Sometimes I wonder why I even read this group.
Entertainment value.
>Shimano recommends 305-465 lbs/sqin on the new Dura Ace BB. It does
>have the new splined design but I don't think 300lbs/sqin is too much.
If they recommend 305-465 in-lbs of torque, then 300 in-lbs is not too
much. But look at the _range_ they recommend. What better evidence
that you are not likely to "overtorque" the crank? BTW, I doubt that
they specified torque in pounds per square inch.
..........dh
John Getsoian
On Sat, 13 Sep 1997 21:06:37 -0700, Vincent Huang wrote:
>
>Shimano recommends 305-465 lbs/sqin on the new Dura Ace BB. It does
>have the new splined design but I don't think 300lbs/sqin is too much.
>
I hope Shimano really means "in*lbs" 'cause it sure will be awkward
trying to turn my torque wrench with a two-stage air compressor. ;-)
Stella Hackell
> Smallpox has been eradicated worldwide several times in my lifetime. I
> wonder if we will ever be able to say the same about the "Don't grease
> the cranks" myth?
We can say that right now. The myth of steel frames getting soft
(for example) has also been eradicated several times on this newsgroup.
Hmm, let me look up "eradicated" again.
Personally, I find that greasing the cranks liberally has made my pedaling
style much smoother, extending the pre-softening life of my frame
for several thousand miles. I can't wait to try waxing them.
--
Stella Hackell ste...@apple.com
Richard Strayer
I assume, from your pretentious bluster, that you've already done this;
so put up or shut up - lets see your data. This has all been examined
and discussed and documented long before, I'd wager, you ever got around
to even thinking about it. The onus of proof is on those who claim that
a bicycle crank mysteriously transcends everything that is already known
about press fits and tapers, not the other way around.
RES
Jobst Brandt
Vincent Huang writes:
> Shimano recommends 305-465 lbs/sqin on the new Dura Ace BB. It does
> have the new splined design but I don't think 300lbs/sqin is too much.
Don't get torque confused with stress or pressure. It's 300 in-lb.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Sam Bond writes:
> Are you an expert then? What evidence can you produce to say it is
> "nonsense"? Spend some time with a micrometer and torque gauge -
> produce the numbers and with your extensive knowledge of
> lubrication. the strength of materials, their metalurgy and the
> design of taper fitted cranks show whow it is "nonsense" .
whow, I didn't even know how to spell metallurgist and now I are one.
How about 30 years of installing cranks with grease and nary a split
crank, just cranks that broke off at the pedal eye, the neck, and the
spider.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Dave H(who?) writes:
> I agree that it's unlikely. Many times, when torque figures are
> given, it is for clean, dry threads. That should not be interpreted
> that the fasteners be put together dry. It's just a bit tricky to
> specify the torque figure not knowing what kind of lubricant will be
> used.
I think you have that backwards. It is difficult to specify torque
for an unlubricated assembly because the cleanliness of the parts is
ill defined, there often being traces of oil on most parts. By
lubricating all sliding interfaces with whatever oil you choose is far
more predictable than no lubrication.
> And, yes, 300 in-lbs is 300 in-lbs. So what? When dealing with
> fasteners, the thing you are seeking is the correct "stretch" of the
> fastener, so it will deliver a desired amount of gripping force.
It is the press fit of the component that is controlled by the torque
specification, there being no perceptible stretch in a crank bolt.
> In some fairly high-end racing applications, the mechanic will rig
> up a measuring gauge and tighten the fastener till it stretches the
> desired amount. On some water-cooled VW engines, the head-bolt
> tightening procedure was to tighten the bolt to a specific torque --
> then tighten it an additional 1/4 turn. These "stretch" bolts were
> not supposed to be reised. But, for 99% of applications, measuring
> the torque on the fastener head is more than adequate.
All this applies to strain bolts that have a swaged area like a spoke
to take some elongating preload. This is not the case with a short
uniform cross section screw as we have on crank bolts.
Jobst Brandt <jbr...@hpl.hp.com>
Chris Phillipo
In message <5vju8l$c...@hplms2.hpl.hp.com> - jbr...@hpl.hp.com (Jobst
Brandt)15 Sep 1997 18:20:05 GMT writes:
:>
:>Dave H(who?) writes:
:>
:>> I agree that it's unlikely. Many times, when torque figures are
:>> given, it is for clean, dry threads. That should not be interpreted
:>> that the fasteners be put together dry. It's just a bit tricky to
:>> specify the torque figure not knowing what kind of lubricant will be
:>> used.
:>
:>I think you have that backwards. It is difficult to specify torque
:>for an unlubricated assembly because the cleanliness of the parts is
:>ill defined, there often being traces of oil on most parts. By
:>lubricating all sliding interfaces with whatever oil you choose is far
:>more predictable than no lubrication.
I'm enjoying reading this discussion, I just want to interrupt for a moment to
ask if any of you know where to get an affordable torque wrench that can be
used on the 8mm hexbolt? I've been just doing it by feel up until now.
___________________________________________
Chris Phillipo - webm...@tread.pair.com
TREAD Publications - TREAD Online! Cycle Magazine. <09-08-97>
Rinards
There is much debate about whether one should grease the fit between the
crank spindle and the square tapered hole in the crank or not. I recently
found a cracked crank on my bike and became curious about the effects of
greasing the tapers. So I made some measurements of how far a crank slips
up the taper on a bottom bracket spindle when the tapers are greased
compared to when the grease is wiped off.
TEST METHOD
I measured seven cranks: the left and right arms of three crank sets, and
one loose right hand arm I had lying around. The cranks were a pair of
old, used Nuovo Record cranks, a new pair of Dura-Ace FC-7402 cranks, a new
pair of Ofmega Super Competitzione arms, and an NOS Sugino “2 GC” melt
forged arm.
During the course of my test I mounted all the cranks dry, then mounted
them greased, then wiped them off and mounted them all dry again. I
measured the cranks’ position before tightening them and after.
I used the same spindle and bolt for all cranks. I mounted the cranks the
same orientation on the spindle each time. I used a cheap torque wrench to
determine when I got to 300 in*lb. I greased the bolt’s threads and washer.
EFFECT ON HOW FAR THE CRANK SLIPS UP THE TAPER
On average, cranks mounted on a dry spindle slide about 2.2 mm up the
taper. That’s starting from finger tight and ending at 300 inch pounds.
However, the same cranks, when mounted on greased tapers, slide 3.1 mm up
the taper on average. That’s about 40% farther up the taper when greased
than dry. Since the crank slips farther up the taper, it must be straining
more after installation on a greased spindle.
It appears greasing the tapers of your bottom bracket spindle increases
the stress on your crank’s square tapered hole.
EFFECT ON PREDICTING CHAINLINE
Reducing the stress on the square tapered hole is one apparent benefit of
mounting the cranks dry. Another benefit is more accuracy predicting
chainline, too. As I said above, cranks mounted dry slip 2.2mm up the
taper on average. Of the seven cranks I measured, some slipped farther and
some slipped less. During the first dry mounting, the most any crank
slipped up the taper was 2.7mm, and the least any crank slipped was 1.8mm.
This range is only 0.9mm. During the second dry mounting, the range was
even less: 0.7mm.
In contrast, when mounted on a greased spindle, there was a wider range of
how far the crank would slip up the taper. The farthest any crank slipped
was 3.6mm, and the least a crank slipped was 2.4mm, for a range of 1.1mm.
That’s 20 to 57% more spread than when the cranks were mounted dry. I
admit that's a pretty small difference, but one that bothers the
perfectionist in me when I am trying to choose a spindle to give a desired
chainline. It is harder to predict what chainline you’ll get if you mount
your cranks with grease on the tapers.
EFFECT ON “STRETCHING” THE CRANK’S SQUARE HOLE
Repeatedly mounting and removing these cranks during my test caused them
to fit farther onto the spindle each time. They did not go back to where
they were the first time, even when the grease was wiped off and the cranks
were mounted dry again.
I recorded the position of each crank after mounting it the first time
(dry). Then I recorded the position of each crank after mounting it the
second time (greased). On average, the final resting place was 1.1mm
farther on the spindle when mounted the second time (with grease) compared
to the first time (dry). After wiping off the grease and re-mounting the
cranks a third time (dry), they still ended up 0.6mm farther up the taper
than they did the first time, though they did recover somewhat from the
greased position.
I do not know why the cranks ended up farther on the spindle after each
time. I don’t know if the cranks were stretched once by mounting them with
grease, or if the fit gets looser even from mounting them dry. Someday I
may get around to measuring the cranks’ position after repeated dry
mountings to find out. But probably I won’t.
HOW I PLAN TO MOUNT MY CRANKS IN THE FUTURE
I will wipe off the spindle and the square tapered hole in the crank with
a rag, and mount the cranks dry. I will carefully wipe off the threads of
the bolt, grease them, the bolt’s shoulder and the washer. I will torque
the bolt to 300 in*lb. I will take my cranks off as seldom as possible.
Damon Rinard
da...@erinet.com
>> And, yes, 300 in-lbs is 300 in-lbs. So what? When dealing with
>> fasteners, the thing you are seeking is the correct "stretch" of the
>> fastener, so it will deliver a desired amount of gripping force.
>
>It is the press fit of the component that is controlled by the torque
>specification
No, torque is twisting. What you want is pre-load.
> there being no perceptible stretch in a crank bolt.
It may not be perceptible but it's still there. If it wasn't there,
you wouldn't have any pre-load on the connecttion. The problem is that
you can't readily measure pre-load, and, in most situations, you can't
conveniently measure the stretch, so you use torque on the fastener,
which is an acceptable proxy.
>> In some fairly high-end racing applications, the mechanic will rig
>> up a measuring gauge and tighten the fastener till it stretches the
>> desired amount.
I've seen this done several places. One automotive example was a
fairly long (6" or so) fastener in the front suspension. Both ends
were accessible, so it was a fairly straight forward matter to measure
the stretch with a dial gauge.
On a few critical aircraft component fasteners, they measured the
stretch of the fastener, (or at least they did back in the late 60's
at LTV Aerospace). Maybe it was just a way to soak the government on
a cost-plus contract.
In both of the above cases, I don't recall that the fastener was a
"stretch bolt" or anything other than an extremely high quality
fastener. They did not have a swaged area as I recall. On very short
fasteners or blind fasteners (the crank bolt example is both) this
isn't practical. In the vast majority of cases, it's not necessary.
>> On some water-cooled VW engines, the head-bolt
>> tightening procedure was to tighten the bolt to a specific torque --
>> then tighten it an additional 1/4 turn. These "stretch" bolts were
>> not supposed to be reised. But, for 99% of applications, measuring
>> the torque on the fastener head is more than adequate.
>
>All this applies to strain bolts that have a swaged area like a spoke
>to take some elongating preload.
I've looked carefully at the VW head bolts, and there's no swaging.
You might want to check that.
> This is not the case with a short
> uniform cross section screw as we have on crank bolts.
See above.
.........dh
>Jobst Brandt <jbr...@hpl.hp.com>
Chris Phillipo
:>
:>HOW I PLAN TO MOUNT MY CRANKS IN THE FUTURE
:>I will wipe off the spindle and the square tapered hole in the crank with
:>a rag, and mount the cranks dry. I will carefully wipe off the threads of
:>the bolt, grease them, the bolt’s shoulder and the washer. I will torque
:>the bolt to 300 in*lb. I will take my cranks off as seldom as possible.
:>
:>Damon Rinard
I was just wondering if you tried riding any of these, perhaps after riding
the dry crank, it would slip as far as the greased one?
I never grease the tapers, not for any particular reason other than I didn't
know it was done until I hit the net. I figured since you arn't supposed to
grease the wedge in the head set, nothing meant to stay put should be greased.
Richard Strayer
>I'm enjoying reading this discussion, I just want to interrupt for a moment to
>ask if any of you know where to get an affordable torque wrench that can be
>used on the 8mm hexbolt? I've been just doing it by feel up until now.
>
Most any torque wrench you can find at an auto-parts or hardware store
will accept either a standard 1/4" (usually found on the in-lbs.
wrenches) or 1/2" (usually found on the ft-lbs. wrenches) metric
socket (which can be purchased separately, if you don't need an entire
set.) Cheapie torque-wrenches retail for under $20.
RES
bog
Rinards wrote:
> HOW I PLAN TO MOUNT MY CRANKS IN THE FUTURE
> I will wipe off the spindle and the square tapered hole in the crank with
> a rag, and mount the cranks dry. I will carefully wipe off the threads of
> the bolt, grease them, the bolt’s shoulder and the washer. I will torque
> the bolt to 300 in*lb. I will take my cranks off as seldom as possible.
>
> Damon Rinard
This is the method that I use and any of the bike shops that I've been
in use. I've had best results with your method over 15 years on
installing and removing crankarms. Good experiment.
Ken Bognar
Vancouver, B.C.
Bognar Engineering
Rick Denney
Just by an 8mm Allen-head socket for a conventional square-drive
torque wrench. Sears can help you for a few dollars. The
deflection-beam wrenches are much cheaper than the automatic
click-when-you-get-there wrenches, and are just as accurate if a
little less convenient (especially for those old of eyes, as I am).
They also don't ever need to be recalibrated (although the calibration
has never gone out on my 20-year-old Craftsman automatic-as compared
to my beam wrench anyway).
On 15 Sep 1997 21:01:50 GMT, webm...@tread.pair.com (Chris Phillipo)
wrote:
>In message <5vju8l$c...@hplms2.hpl.hp.com> - jbr...@hpl.hp.com (Jobst
>Brandt)15 Sep 1997 18:20:05 GMT writes:
>:>
>:>Dave H(who?) writes:
>:>
>:>> I agree that it's unlikely. Many times, when torque figures are
>:>> given, it is for clean, dry threads. That should not be interpreted
>:>> that the fasteners be put together dry. It's just a bit tricky to
>:>> specify the torque figure not knowing what kind of lubricant will be
>:>> used.
>:>
>:>I think you have that backwards. It is difficult to specify torque
>:>for an unlubricated assembly because the cleanliness of the parts is
>:>ill defined, there often being traces of oil on most parts. By
>:>lubricating all sliding interfaces with whatever oil you choose is far
>:>more predictable than no lubrication.
>:>
>
>I'm enjoying reading this discussion, I just want to interrupt for a moment to
>ask if any of you know where to get an affordable torque wrench that can be
>used on the 8mm hexbolt? I've been just doing it by feel up until now.
>
>___________________________________________
>Chris Phillipo - webm...@tread.pair.com
>TREAD Publications - TREAD Online! Cycle Magazine. <09-08-97>
>http://www.tread.pair.com/ - http://www.tread.pair.com/bikemag/
Rick Denney
Mark McMaster
Rinards wrote:
>
> There is much debate about whether one should grease the fit between the
> crank spindle and the square tapered hole in the crank or not. I recently
> found a cracked crank on my bike and became curious about the effects of
> greasing the tapers. So I made some measurements of how far a crank slips
> up the taper on a bottom bracket spindle when the tapers are greased
> compared to when the grease is wiped off.
<much information on procedures, results, and analysis deleted>
There seems to be a very important part of the test procedure missing.
When a is crank loaded in use, it is subjected to a twisting torque
along its longitudinal axis as a result of the of the pedal offset.
This causes the crank to "squirm" on the taper (i.e. rotationally wiggle
on its longitudinal axis). A crank with less pre-load on the taper will
squirm more than one with more pre-load, and because the bolt keeps it
from squirming down the taper, it tends to squirm up the taper instead
(this is all well covered in the FAQ). To get a better measurement of
how far up the taper the cranks move when either dry or greased, you
should have put the cranks through some pedal loading cycles, until they
found their final resting place, and then measured their position. I
think you'll find that cranks that were installed dry will continue to
move up the taper more during use than those which were installed
lubricated.
Mark McMaster
MMc...@ix.netcom.com
da...@erinet.com
> I figured since you arn't supposed to
>grease the wedge in the head set, nothing meant to stay put should be greased.
Where did this bit of information come from?
.................dh
p.s. A lot of politicians are well greased and they certainly stay
put.
da...@erinet.com
>>I'm enjoying reading this discussion, I just want to interrupt for a moment to
>>ask if any of you know where to get an affordable torque wrench that can be
>>used on the 8mm hexbolt? I've been just doing it by feel up until now.
>
>Most any torque wrench you can find at an auto-parts or hardware store
>will accept either a standard 1/4" (usually found on the in-lbs.
>wrenches) or 1/2" (usually found on the ft-lbs. wrenches) metric
>socket (which can be purchased separately, if you don't need an entire
>set.) Cheapie torque-wrenches retail for under $20.
Look for a torque wrench with a deflecting-beam style of indicator.
Avoid wrenches which are "automatic" or in which you dial in the
desired torque. The latter are convenient for automotive use, but are
more expensive, tend to get out of adjustment and are expensive to
have recalibrated. The beam wrenches are simple and almost
indestructible.
Indestro makes some nice ones -- $25 or so for a 1-50 fl-lbs model
with 3/8" drive.
............dh
Matt O'Toole
Chris Phillipo <webm...@tread.pair.com> wrote in article
<5vk7nu$4p5$1...@news.istar.ca>...
> I'm enjoying reading this discussion, I just want to interrupt for a
moment to
> ask if any of you know where to get an affordable torque wrench that can
be
> used on the 8mm hexbolt? I've been just doing it by feel up until now.
Try Sears. If those are too expensive for you, borrow one from a neighbor,
or look for one at a garage sale or swap meet. I see a lot of good
Craftsman tools for sale at swap meets, for about half of what they cost
new. There are higher quality brands around, like SK or Snap-On, but
Craftsman are good quality at the lowest price.
Matt O.
VCopelan
Thankfully I missed most of this thread about greasing/not greasing
crankarms. I just have one observation based upon my limited personal
experience. I have tried on many occasions to use my cranks with dry
ungreased axle flats and each time the crankarms would creak after
extensive climbing even after the fixing bolts were taken to the proper
torque. I finally gave up and did the unthinkable (I oiled the axle flats
prior to installing the crankarms) and my crankarms are quiet. I used
locktight on the fixing bolts (again the horror).
Fasteners used in other applications spec different torques for dry,
oiled, or greased fasteners. How about oiling the axle flats? Finally,
how do you keep those dry crankarms quiet anyway?
Chris Phillipo
In message <3424cfb5...@nntp.erinet.com> - da...@erinet.com writes:
:>
:>> I figured since you arn't supposed to
If I remember correctly, it was in the owner's manual of my first 26" wheel
bike. A big blue CCM that I still have. Either that or it was on the
instructions with a stem. I remember seeing it in print in any case. It
could be wrong of course. I still remember the St. John's Ambulance and Red
Cross public messages on TV that used to tell you that putting the victim's
head back s the way to stop a nose bleed! Those were inaccurate times.
*gurgle*
Matt O'Toole
bog <kbo...@direct.ca> wrote in article <341E0A...@direct.ca>...
> Ken Bognar
> Vancouver, B.C.
> Bognar Engineering
Are you a PE, as might be implied by this sig?
Just curious,
Matt O.
Chris Phillipo
In message <19970916052...@ladder01.news.aol.com> - vcop...@aol.com
(VCopelan)16 Sep 1997 05:28:54 GMT writes:
:>
:>
:>Thankfully I missed most of this thread about greasing/not greasing
:>crankarms. I just have one observation based upon my limited personal
A couple of new questions for the mechanically inclinded. With all the talk
about preload and bolt stretch, the question arises, is the proper torque the
same for steel, titanium and aluminum crank bolts? The other is, what grease
to use with aluminum on steel? Lithium based or your basic petroleum jelly?
___________________________________________
Chris "keep the debate going Sheldon style" Phillipo -
Rinards
In article <5vkfbi$99d$1...@news.istar.ca>, webm...@tread.pair.com (Chris
Phillipo) writes:
>I was just wondering if you tried riding any of these,
Good question. No, I did not ride any of them.
>perhaps after riding
>the dry crank, it would slip as far as the greased one?
The difference in initial torqued position between a crank installed
dry and one installed with grease is 0.9mm on average, with the
greased one going on farther.
In order for the dry crank to "catch up with" the greased one as it
is ridden, not only would it have to squirm as much as the greased
one does (how far do cranks creep up the taper when ridden?),
but it would also have to make up the 0.9mm "advantage" the
greased crank started out with as well. Is there that much strain
in the bolt, or would the bolt become totally slack at some earlier
point?
Damon Rinard
Joshua_Putnam
In <341E0A...@direct.ca> bog <kbo...@direct.ca> writes:
>Rinards wrote:
>> HOW I PLAN TO MOUNT MY CRANKS IN THE FUTURE
>> I will wipe off the spindle and the square tapered hole in the crank with
>> a rag, and mount the cranks dry.
>This is the method that I use and any of the bike shops that I've been
>in use. I've had best results with your method over 15 years on
>installing and removing crankarms. Good experiment.
Of course, unless your rag is soaked in solvent, and you also
clean the inside of the socket with solvent, you aren't really
mounting the cranks dry. Wiping the spindle with a rag will
leave a thin film of grease that's more than enough to prevent
galling on installation -- it's such a tight fit, any more grease
than that thin film would be squeezed out anyway.
--
Jo...@WolfeNet.com is Joshua Putnam / P.O. Box 13220 / Burton, WA 98013
"My other bike is a car."
http://www.wolfenet.com/~josh/
Don Winston
On Tue, 16 Sep 1997 01:11:00 GMT, da...@erinet.com wrote:
>
>
>Look for a torque wrench with a deflecting-beam style of indicator.
>Avoid wrenches which are "automatic" or in which you dial in the
>desired torque. The latter are convenient for automotive use, but are
>more expensive, tend to get out of adjustment and are expensive to
>have recalibrated. The beam wrenches are simple and almost
>indestructible.
>
The problem with a deflecting beam torque wrench is that it is very
difficult to see when working on crank bolts, since you have to lean
your head around to the other side of the bike.
Don Winston<dwin...@erols.com>
Jeffrey Potoff
bog wrote:
>
> Rinards wrote:
>
> > HOW I PLAN TO MOUNT MY CRANKS IN THE FUTURE
> > I will wipe off the spindle and the square tapered hole in the crank with
> > the bolt, grease them, the bolt’s shoulder and the washer. I will torque
> > the bolt to 300 in*lb. I will take my cranks off as seldom as possible.
> >
> > Damon Rinard
>
> in use. I've had best results with your method over 15 years on
> installing and removing crankarms. Good experiment.
>
> Vancouver, B.C.
> Bognar Engineering
I disagree. No mention was made of exactly how the measurements were
made
(what instruments were used, what was the point of reference). In
addition,
we all know that the crank squirms up the spindle after you've ridden
it.
He should have measured all the crank arms after riding them. For all
we
know, all the cranks could have ended up in the exact same spot, grease
or
no grease. Furthermore, the use of the word 'stress' was not correct.
It
was never clear exactly what the original poster meant by 'putting
grease
on the tapers of the crank increases the stress on the square hole in
the
crank arm'. Huh ?! I'd like the original poster to define what he
means
by 'stress'. In the engineering world, words like 'stress' and 'strain'
have
very specific meanings and from the poster's comments I don't think he
understands
this.
Jeff
da...@erinet.com
>>Look for a torque wrench with a deflecting-beam style of indicator.
>>Avoid wrenches which are "automatic" or in which you dial in the
>>desired torque. The latter are convenient for automotive use, but are
>>more expensive, tend to get out of adjustment and are expensive to
>>have recalibrated. The beam wrenches are simple and almost
>>indestructible.
>>
>The problem with a deflecting beam torque wrench is that it is very
>difficult to see when working on crank bolts, since you have to lean
>your head around to the other side of the bike.
Don:
Ehhhh? One hand holds the crank, one hand honks the wrench. I
usually try to do this from the side of the bike where the crank (or
arm) is being attached.
I'll concede that deflecting beams may be less convenient to
use in certain cirmumstances -- flat on your back, under a car, down
in a pit, you name it. But on a bike? No big deal.
.................dh
Jobst Brandt
Damon Rinards writes:
> There is much debate about whether one should grease the fit between
> the crank spindle and the square tapered hole in the crank or not.
> I recently found a cracked crank on my bike and became curious about
> the effects of greasing the tapers. So I made some measurements of
> how far a crank slips up the taper on a bottom bracket spindle when
> the tapers are greased compared to when the grease is wiped off.
> TEST METHOD...
I am curious about your test and how you accomplished several of the
procedures you described.
1. How did you make sure the crank, screw, and spindle were grease
free? How did you degrease the threads inside the spindle? Did
you use solvent and a brush to clean the parts and subsequently
rinse them in clean degreaser? If not, then I don't believe they
were unlubricated. Wiping with a rag does not constitute removing
grease.
2. How did you measure the depth of engagement? Did you use a depth
micrometer from the face of the crank to the end of the spindle?
By the face I mean the surface surrounding the bolt recess.
3. When you say "slipped on 1.8mm", from where and how was this
measured?
The only valid measure of position of the crank on the spindle is with
a depth micrometer from the outside face of the crank to the end of
the spindle. After tightening, the crank bolt must be removed to make
this measurement. The initial position of the crank before tightening
is an ill defined position so it has no value for this test. It is a
guess at best.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt <jbr...@hpl.hp.com>
Jeffrey Potoff
Chris Phillipo wrote:
>
> :>
> :>HOW I PLAN TO MOUNT MY CRANKS IN THE FUTURE
> :>I will wipe off the spindle and the square tapered hole in the crank with
> :>a rag, and mount the cranks dry. I will carefully wipe off the threads of
> :>the bolt, grease them, the bolt’s shoulder and the washer. I will torque
> :>the bolt to 300 in*lb. I will take my cranks off as seldom as possible.
> :>
> :>Damon Rinard
>
> I was just wondering if you tried riding any of these, perhaps after riding
> the dry crank, it would slip as far as the greased one?
>
> I never grease the tapers, not for any particular reason other than I didn't
> know it was done until I hit the net. I figured since you arn't supposed to
> grease the wedge in the head set, nothing meant to stay put should be greased.
>
This is not correct. You grease your seatpost (right ?) and it stays
put.
You should also grease the stem or you risk it rusting to the steerer
tube.
With cranks, grease has no effect on whether or not they stay put.
Think
about the forces involved.
Jeff
Joshua_Putnam
>A couple of new questions for the mechanically inclinded. With all the talk
>about preload and bolt stretch, the question arises, is the proper torque the
>same for steel, titanium and aluminum crank bolts?
Yes, sort of, but: with weaker bolts, install the crank using
plain old steel bolts, torque them to spec, then remove them and
install the stupid-light bolts to the proper torque. That way
the heads will pop off from fatigue while you're riding, instead
of breaking while you're installing the cranks.
>The other is, what grease
>to use with aluminum on steel? Lithium based or your basic petroleum jelly?
Just about anything will work -- the grease isn't going to
permanently lubricate the joint, it's just there to avoid
galling while the cranks are being installed, so they get a
predictable fit. I use the excess grease oozing out of the BB
seals after squirting in fresh grease. (Greaseguard BB.) I
imagine butter would work fine, too.
Chuck Fry
In article <5vlifp$p7i$2...@news.istar.ca>,
Chris Phillipo <webm...@tread.pair.com> wrote:
>A couple of new questions for the mechanically inclinded. With all the talk
>about preload and bolt stretch, the question arises, is the proper torque the
>same for steel, titanium and aluminum crank bolts? The other is, what grease
>to use with aluminum on steel? Lithium based or your basic petroleum jelly?
Torque varies with the yield strength of the material. I think the
general rule of thumb for highly stressed fasteners is that the preload
should be a significant fraction of the yield strength, say 70-80%.
But check with a REAL expert before taking my word for it.
I suspect any grease will work to keep aluminum from galling on steel,
but again ask someone who really knows.
-- Chuck
--
Chuck Fry -- Jack of all trades, master of none
chu...@chucko.com (text only please), chuc...@home.com (MIME enabled)
This space for rent... NOT.
Jeffrey L. Bell
In article <19970915213...@ladder02.news.aol.com>,
Rinards <rin...@aol.com> wrote:
>..
>I do not know why the cranks ended up farther on the spindle after each
>
>HOW I PLAN TO MOUNT MY CRANKS IN THE FUTURE
>I will wipe off the spindle and the square tapered hole in the crank with
>a rag, and mount the cranks dry. I will carefully wipe off the threads of
The reason is that wiping them with a rag still leaves grease on the
surfaces. To truly degrease them would take solvents.
-Jeff Bell
[posted&emailed]
Chris Phillipo
:>
:>In order for the dry crank to "catch up with" the greased one as it
:>one does (how far do cranks creep up the taper when ridden?),
:>but it would also have to make up the 0.9mm "advantage" the
:>greased crank started out with as well. Is there that much strain
:>in the bolt, or would the bolt become totally slack at some earlier
:>point?
:>
:>Damon Rinard
I don't know the answer, but I do know that I don't grease the tapers
currently and I tighten the bolts until they are quite tight in my opinion. I
ride for a few days and the bolts are loose enough to be backed off with one
hand, not to mention the creaking that's going on by then. I know they don't
unscrew at all because I marked the bolt and the crank with matching notches.
The bolts also have a rubber o-ring which probably plays a part in preventing
them backing off.
I would have started to grease them as soon as I noticed this occurring, the
creaking drives me crazy, but I wanted to wait until I found a torque wrench.
I think I'm being somewhat torque shy with these bolts since they are
aluminum. But better undertorqued than striped.
___________________________________________
Chris Phillipo - webm...@tread.pair.com
Sam Bond
I give in. You grease away should you wish, I shan't.
I got riled because some pratt got sarcastic when I voiced my opinion
(based on what I was taught at engineering school and experience).
Sam
da...@erinet.com
>3. When you say "slipped on 1.8mm", from where and how was this
> measured?
>
>The only valid measure of position of the crank on the spindle is with
>a depth micrometer from the outside face of the crank to the end of
>the spindle. After tightening, the crank bolt must be removed to make
>this measurement. The initial position of the crank before tightening
>is an ill defined position so it has no value for this test. It is a
>guess at best.
As a matter of curiousity, is the same crank likely to move further up
the taper for each installation/removal cycle? If so, by how much?
I assume that the tester to whom you were responding used the same
crank over (and over) again.
.........................................dh
David Casseres
In article <5vjtei$c...@hplms2.hpl.hp.com>, jbr...@hpl.hp.com (Jobst
Brandt) wrote:
> Vincent Huang writes:
>
> > Shimano recommends 305-465 lbs/sqin on the new Dura Ace BB. It does
> > have the new splined design but I don't think 300lbs/sqin is too much.
>
> Don't get torque confused with stress or pressure. It's 300 in-lb.
And incidentally, 300 in-lb is 25 ft-lb, which is actually on the low
side. The torque I have seen recommended is 30-35 ft-lb or 360-420 in-lb.
--
Cheers,
David
Mark Janeba
John Getsoian <jget...@nojunk.compuserve.com> wrote:
>>
>>Shimano recommends 305-465 lbs/sqin on the new Dura Ace BB. It does
>>have the new splined design but I don't think 300lbs/sqin is too much.
>>
>
>trying to turn my torque wrench with a two-stage air compressor. ;-)
You mean I wasn't supposed to mount my cranks with an impact wrench?
(giggle)
--
Mark Janeba (503)370-6123
Dept. of Mathematics e-mail: mja...@willamette.edu
Willamette University web page: http://www.willamette.edu/~mjaneba
Salem, Oregon 97301-3922 USA "Speaking for myself, not the university"
Jobst Brandt
Chris Phillipo writes:
> With all the talk about preload and bolt stretch, the question
> arises, is the proper torque the same for steel, titanium and
> aluminum crank bolts?
Torque can be converted to lineal force by the slope of the thread
and this to press fit by the slope of the taper. It is the press
that is important without regard to material because torque is
transmitted by differential pressure across the faces of the spindle.
The preload must be great enough to prevent lift-off of the unloading
half of the face.
> The other is, what grease to use with aluminum on steel? Lithium
> based or your basic petroleum jelly?
It makes little difference because this is not an endurance effect
that governs what sort of lubricant is to be used in a bearing. This
application is a one time slide, after which fretting displaces the
lubricant anyway. I am sure there are extremes that should not be
used but motor oil to wheel bearing grease is certainly adequate.
Jobst Brandt <jbr...@hpl.hp.com>
Joshua_Putnam
In <3419db85...@news.demon.co.uk> s...@mimosa.demon.co.uk (Sam Bond) writes:
>rin...@aol.com (Rinards) wrote:
>>
>>I never used to grease the tapers, but the FAQ convinced me otherwise.
>Then I would suggest the FAQ is wrong. They should be clean and dry or, at
>the most, a film of something like Copperease nearly wiped off.
Any explanation for that?
>>So the next time I had the arms off, I greased the tapers and torqued
>>the bolts once to 300 inch pounds. I was surprised how
>>much farther the arms slid up the taper on installation with grease.
>>
>>About 200 miles later the bike began making a creaking sound
>>when I pedalled. When I removed the left crank I saw two cracks, one
>>in each of two opposite corners of the taper.
>Because you over-tightened it started to split it - tapers are not designed
>to be tightened like that - they should fit well and be just tight enough
>to stop movement under load.
300 in-lb is on the *low* side of specified torque values for
crank arms -- it definitely is not overtightening. Sugino, for
example, specifies a settled tightening torque of 400 kgf/cm,
while SR/Sakae calls for 500-550 kgf/cm for nutted axles and
300-350 kgf/cm for bolt type axles.
Chuck Fry
In article <5vmjmi$7pq$1...@news.istar.ca>,
Chris Phillipo <webm...@tread.pair.com> wrote:
>I would have started to grease them as soon as I noticed this occurring, the
>creaking drives me crazy, but I wanted to wait until I found a torque wrench.
>I think I'm being somewhat torque shy with these bolts since they are
>aluminum. But better undertorqued than striped.
Amen.
Seems to me one way to make sure the cranks got the proper preload would
be to use an ordinary steel bolt to seat them, then remove it and
install the light-metal bolt at some appropriate torque setting. Any
opinions, O great MechEs of the Web?
Needless to say, this won't work with self-extracting steel bolts.
-- "Chain Suck" Chuck
Chris Phillipo
:>> I never grease the tapers, not for any particular reason other than I didn't
:>> know it was done until I hit the net. I figured since you arn't supposed to
:>> grease the wedge in the head set, nothing meant to stay put should be greased.
:>>
:>This is not correct. You grease your seatpost (right ?) and it stays
:>put.
Actually, I don't, because it wouldn't. Well, on my M@ I do, it has a good
seat clamp, but on my peugeot, I already have a pop can shim in there, it
bearly holds as it is, add grease and I can twist the thing around with the
bolt overtightened.
:>You should also grease the stem or you risk it rusting to the steerer
:>tube.
Well, neither stem nor steerer are steel, so that's not a problem. Putting
Lithium grease in there might cause it to bind however.
:>With cranks, grease has no effect on whether or not they stay put.
:>Think
:>about the forces involved.
No argument here.
bog
Chuck Fry wrote:
>
> In article <5vmjmi$7pq$1...@news.istar.ca>,
> Chris Phillipo <webm...@tread.pair.com> wrote:
> >I would have started to grease them as soon as I noticed this occurring, the
> >creaking drives me crazy, but I wanted to wait until I found a torque wrench.
> >I think I'm being somewhat torque shy with these bolts since they are
> >aluminum. But better undertorqued than striped.
>
> Amen.
>
> Seems to me one way to make sure the cranks got the proper preload would
> be to use an ordinary steel bolt to seat them, then remove it and
> install the light-metal bolt at some appropriate torque setting. Any
> opinions, O great MechEs of the Web?
>
> Needless to say, this won't work with self-extracting steel bolts.
I though all manufacturers recommend torquing the cranks with the
"regular" steel bolts and then installing the lighter bolts. This the
only way to do it if you want your lightweight bolts to last longer than
3 crankarm removals.
Ken Bognar
bog
Matt O'Toole wrote:
>
> bog <kbo...@direct.ca> wrote in article <341E0A...@direct.ca>...
>
> > Ken Bognar
> > Vancouver, B.C.
> > Bognar Engineering
>
> Are you a PE, as might be implied by this sig?
>
> Just curious,
>
> Matt O.
>
I am not yet a P.Eng. (its not PE in B.C.) but soon will be. Why did my
signature imply that. It is likely different in your area but I'd put
Ken Bognar, P.Eng in my signature if I had my Professional Engineering
certification.
Ken Bognar
Bognar Engineering
bog
Jeffrey Potoff wrote:
>
> bog wrote:
> >
> > Rinards wrote:
> >
> > > HOW I PLAN TO MOUNT MY CRANKS IN THE FUTURE
> > > I will wipe off the spindle and the square tapered hole in the crank with
> > > a rag, and mount the cranks dry. I will carefully wipe off the threads of
> > > the bolt, grease them, the bolt’s shoulder and the washer. I will torque
> > > the bolt to 300 in*lb. I will take my cranks off as seldom as possible.
> > >
> > > Damon Rinard
> >
> > This is the method that I use and any of the bike shops that I've been
> > in use. I've had best results with your method over 15 years on
> > installing and removing crankarms. Good experiment.
> >
> > Ken Bognar
> > Vancouver, B.C.
> > Bognar Engineering
>
> I disagree. No mention was made of exactly how the measurements were
> made
> (what instruments were used, what was the point of reference). In
> addition,
> we all know that the crank squirms up the spindle after you've ridden
> it.
> He should have measured all the crank arms after riding them. For all
> we
> know, all the cranks could have ended up in the exact same spot, grease
> or
> no grease. Furthermore, the use of the word 'stress' was not correct.
> It
> was never clear exactly what the original poster meant by 'putting
> grease
> on the tapers of the crank increases the stress on the square hole in
> the
> crank arm'. Huh ?! I'd like the original poster to define what he
> means
> by 'stress'. In the engineering world, words like 'stress' and 'strain'
> have
> very specific meanings and from the poster's comments I don't think he
> understands
> this.
>
> Jeff
Take it as a basic backyard maintenance type experiment as it was meant
to be. Hit the lab yourself if you want more than this. What the hell do
you think he used to measure this? A tape measure? I guess he just
eyeballed it right!
Ken Bognar
Jeffrey Potoff
Joshua_Putnam wrote:
>
> In <5vlifp$p7i$2...@news.istar.ca> webm...@tread.pair.com (Chris Phillipo) writes:
>
>
> >The other is, what grease
> >to use with aluminum on steel? Lithium based or your basic petroleum jelly?
>
<snip>
> I imagine butter would work fine, too.
Heh, heh, heh...good for crank installation and the leftovers can
be used on toast. What more could you want ?
Jeff
Jobst Brandt
Chris Phillipo writes:
> I would have started to grease them as soon as I noticed this
> occurring, the creaking drives me crazy, but I wanted to wait until
> I found a torque wrench. I think I'm being somewhat torque shy with
> these bolts since they are aluminum. But better undertorqued than
> striped.
You cannot get aluminum crank bolts to 35 in-lb without damage to the
thread or breaking the bolt. Your cranks are loose... and probably
ruined.
Jobst Brandt <jbr...@hpl.hp.com>
Trad...@rocketmail.com
In article <5vmjmi$7pq$1...@news.istar.ca>,
webm...@tread.pair.com wrote:
-Big snippage-
> I would have started to grease them as soon as I noticed this occurring, the
> creaking drives me crazy, but I wanted to wait until I found a torque wrench.
> I think I'm being somewhat torque shy with these bolts since they are
> aluminum. But better undertorqued than striped.
Back when Zeus's lightweight stuff was readily available,
(remember the "ergal" bolt sets?) the recommendation was
to install the cranks with steel bolts, then replace the
bolts with the aluminum bolts, because the aluminum bolts
couldn't withstand the forces needed to install the cranks.
I suggest you do it this way if you use aluminum bolts.
Mick.
-------------------==== Posted via Deja News ====-----------------------
http://www.dejanews.com/ Search, Read, Post to Usenet
hau...@mbi.org
In article <5vno9c$l...@hplms2.hpl.hp.com> jbr...@hpl.hp.com (Jobst Brandt) writes:
>From: jbr...@hpl.hp.com (Jobst Brandt)
>Subject: Re: greased cranks slip farther up the tapers
>Date: 17 Sep 1997 05:02:36 GMT
>Chris Phillipo writes:
>> I would have started to grease them as soon as I noticed this
>> occurring, the creaking drives me crazy, but I wanted to wait until
>> I found a torque wrench. I think I'm being somewhat torque shy with
>> these bolts since they are aluminum. But better undertorqued than
>> striped.
>You cannot get aluminum crank bolts to 35 in-lb without damage to the
>thread or breaking the bolt. Your cranks are loose... and probably
>ruined.
35 in lbs without damage, Jobst? Hmm, I'd have to disagree.
Rich
Just say I guess Jobst doesn't use aluminum bolts, since he recommends 300 in
lbs.
>Jobst Brandt <jbr...@hpl.hp.com>
Gene Tolli
Hypothetical question: If one has a Mavic road crank on a Phil Wood B/B
that is secured with Campagnolo crank bolts, and has run this setup for
one year with a torque setting of 270-280 in/lbs (checked with a torque
wrench), what are the chances the crank is damaged and how would one
tell? And in the future, would one run this at a higher torque setting?
Gene Tolli
sna...@binc.net
sch...@fnald.fnal.gov
>
> Back when Zeus's lightweight stuff was readily available,
> (remember the "ergal" bolt sets?) the recommendation was
> to install the cranks with steel bolts, then replace the
> bolts with the aluminum bolts, because the aluminum bolts
> couldn't withstand the forces needed to install the cranks.
> I suggest you do it this way if you use aluminum bolts.
> Mick.
>
I've heard this tecnique for titanium bolts but I've never
heard of aluminum crank bolts...
Mark Schmitz
schmitz@fnaldotgov
Sean Williams
I asked a mill wright what they use on tapers: Never-Seize.
John Getsoian
On 16 Sep 1997 09:11:21 GMT, Chris Phillipo wrote:
>A couple of new questions for the mechanically inclinded. With all the talk
>about preload and bolt stretch, the question arises, is the proper torque the
>same for steel, titanium and aluminum crank bolts?
In this case, "proper torque" is defined as the torque that produces
a the desired thrust load on the crank along the line of the axle.
The tension in the bolt is directly a function of the torque induced
stress, and is not _directly_ affected by any strain (stretch) that
may occur. In the case of a crank bolt, there is virtually no
overhanging bolt length to strain anyway, since the engaged thread
comprises most of the length of the bolt, i.e., the section of crank
bolt that sees the full tension from the torque is so short that any
strain on a scale relevant to the joint makeup would result in
failure.
The torque required to produce a given tension in a bolt is a
function of: the major and minor diameter, pitch, form and face angle
(for V threads) of the thread; the coefficient of friction between
the male and female thread surfaces, this last term in turn being a
factor of both the material of construction and the surface
characteristics (finish); plus the diameter of the head and its
coefficient of friction against the seat material. My recollection is
that crank bolts are ISO 8mm diam x 1mm pitch, and they have a
shoulder or 'built in' washer below the heads that pretty much fills
the cavity in the crank. Given an Al crank and steel BB axle, then
for a steel bolt, the head to socket interface is steel/Al, whereas
for an Al bolt, it may be Al/Al or Al/steel depending on whether a
steel thrust washer is used.
Mark's Handbook gives the equations necessary to solve these
relationships. It also gives estimates of dry sliding ffs of 0.47 for
Al/steel; 0.57 for steel/steel; and 1.04 for Al/Al (sorry, no data
for Ti, if anyone has the numbers, I can easily plug them in). I've
taken the bolt shoulder diameter as roughly 2x the bolt diam or 16mm,
which is 1mm beyond the points of the usual 14mm hex head - Campy
bolts are allen head and dished, which we'll ignore. The results of
the calculations is that the thrust load achieved by a torque of 30
ft*lbf with a steel bolt (w or w/o washer, since one mating surface
is Al/steel either way and that is the lower friction interface) will
be achieved with 27 ft*lbf with an Al bolt and steel thrust washer,
but will require nearly 48 ft*lbf with an Al bolt riding directly on
the Al crank. Thus, FWIW the equations predict that the Al/Al head
friction is actually a more important factor here than the Al/steel
thread friction so the answer to the question depends on the
presence (or lack) of a steel thrust washer.
OTOH, the equations also indicate that the tensile loading on the
steel bolt at 30 ft*lbf is about 28,000 psi. This means that to
install the average crank to its design thrust load with an alloy Al
crank bolt puts that bolt at >>50% of its yield strength (40,000psi
for 6061-T6) and thus is probably not a good application in the first
place for any Al alloy except fully hard 7075-T6. There is a lot of
variation in friction factors in practice and should the ffs
experienced in a particular case drop only as low as .35, a 6000
series Al crank bolt torqued to 30 ft*lbf would be stressed to its
yield point and a 7000 series would be past my idea of reasonable
design factor. Note that unless you are using a steel thrust washer,
an Al crank bolt will not draw up a crank to its design installation
thrust at 30 ft*lbf torque. In practice, this may help keep many of
them from failing.
Note also that I have used DRY friction coefficients. This is because
even for lubricated threads, the surface loadings involved are so far
beyond the film strength of the lubricant that it becomes irrelevant
at final loading, it affects only the initial draw and corrosion
resistance in the voids. In fact, a quick substitution of a
lubricated ff for steel vs steel (< 0.1)) into the the thread
torque/load relationship shows that the mechanical advantage of the
average screwthread is so high that if lubricated ff factors were
ever achieved in practice, a steel 8mm x 1mm bolt would pull to its
yield strength (60,000 psi) at a mere 10 ft*lbf torque.
regards,
j. getsoian
Mark Atanovich
In article <341ebed9...@news.demon.co.uk>
s...@mimosa.demon.co.uk (Sam Bond) writes:
What engineering school was that? Perhaps the class was "Engineering
Myths and Legends 101".
Jobst Brandt
Chuck Fry writes:
> Seems to me one way to make sure the cranks got the proper preload
> would be to use an ordinary steel bolt to seat them, then remove it
> and install the light-metal bolt at some appropriate torque setting.
This is much like the aluminum stem bolts that are inserted after
tightening with a steel one. What is overlooked, is that, when in
use, the crank squirms and puts large dynamic thrust loads on the
bolt. I suspect that an aluminum bolt would work fine riding around
in the flatland and then break off on a hill climb if any consistently
strong pedaling occurs.
On the other hand, some riders always use their lowest gears on any
slope and would have little concern, but why would such a person worry
about two or three extra grams of crank reliability?
Jobst Brandt <jbr...@hpl.hp.com>
Chris Phillipo
:>
:>You cannot get aluminum crank bolts to 35 in-lb without damage to the
:>thread or breaking the bolt. Your cranks are loose... and probably
:>ruined.
:>Jobst Brandt <jbr...@hpl.hp.com>
Well they're working pretty well for 3 year old ruined cranks I must say. So
what torque should the aluminum bolts be once the steel one is removed?
Mark McMaster
Rinards wrote:
>
> In article <341E19...@ix.netcom.com>, Mark McMaster
> <MMc...@ix.netcom.com> writes:
>
> >To get a better measurement of
> >how far up the taper the cranks move when either dry or greased, you
> >should have put the cranks through some pedal loading cycles, until they
> >found their final resting place,
>
> How many cycles and at what torque would you say is acceptable?
>
> I'm not sure how precisely I can load the pedal. I am looking for
> something like "stand on the pedal ten times with all your weight,
> then measure again."
I don't know if I can come up with exact numbers, but a good starting
point for the torque would be the weight of the average rider (say 165
lb) times the offset to the center of the pedal platform (probably any
typical pedal would do). The number of times to achieve their final
resting position is anybody's guess - perhaps just choose a number of
cycles that assures a good confidence level that it would have had to
reach steady state.
One quick and dirty, but not especially exact, approach would be to
mount up a set of crank arms, measure their position on the taper, and
then ride up a really steep hill out of the saddle a number of times,
and then re-measuring their position. If you rode up the hill a
sufficiently large number of times and the same amount for both the
greased and ungreased cases, you could probably get at least a decent
comparitive number. (This is based on the assumption that you don't
want to build a motorized fixture to rotate the spindle with a rider
sized weight on a pedal attached to the crank, to simulate loading
cycles.)
Mark McMaster
MMc...@ix.netcom.com
Trad...@rocketmail.com
Mick said:
> >
> > Back when Zeus's lightweight stuff was readily available,
> > (remember the "ergal" bolt sets?) the recommendation was
> > to install the cranks with steel bolts, then replace the
> > bolts with the aluminum bolts, because the aluminum bolts
> > couldn't withstand the forces needed to install the cranks.
> > I suggest you do it this way if you use aluminum bolts.
> > Mick.
> >
>
> I've heard this tecnique for titanium bolts but I've never
> heard of aluminum crank bolts...
Really? IMO, if a titanium alloy isn't substantially
stronger than 100,000 psi in tension, then they've got
no business making bolts out of it.
Mick.
Just say titanium is one of the strongest materials
available to us.
P.S. I've heard a lot of stuff said about weak titanium
parts over the years, including the above comment, and
always thought that if the manufacturer thought their
parts were that weak, then I didn't want them.
Trad...@rocketmail.com
In article <342027...@binc.net>,
Gene Tolli <sna...@binc.net> wrote:
>
> Hypothetical question: If one has a Mavic road crank on a Phil Wood B/B
> that is secured with Campagnolo crank bolts, and has run this setup for
> one year with a torque setting of 270-280 in/lbs (checked with a torque
> wrench), what are the chances the crank is damaged
I believe shimano used to say 18-22 ft-lbs, so I used 20.
Jobst seems to use more, but I can't find any instance in which he's
said what he uses. FAQ 8.45 mentions using a torque wrench, but not
the specification to torque with it.I've seen him reply to persons using
anywhere from 300 to 420in-lb without objecting to their specification,
you aren't far below this.
>and how would one tell?
Is the crank loose on the spindle? Does it hold the pedal parallel
to the spindle?
>And in the future, would one run this at a higher torque setting?
I wouldn't, others would. What is Mavic's recommended torque?
If I rode like Jobst, I might have to use 25-35 ft-lbs. (actually, if
I rode like Jobst, my knees would fail long before the crank)
The point is, thousands of cranks fail due to undertorquing,
probably at much less than 250in-lbs, while few if any fail due to
overtorquing.
Mick.
Jeffrey Potoff
I would, but since he never posted his methodology for measuring
distance
each crank moved up the taper what's the point ? What distance was he
measuring ? What tools did he use to measure it ? What's the error in
the measurement ? Since we don't have this information we can never
hope
to be able to reproduce his measurements, and hence can neither confirm
nor
deny the data he presented in his post. I say that makes the
'experiment'
useless.
> What the hell do you think he used to measure this? A tape measure?
> I guess he just eyeballed it right!
From what I've seen posted on this newsgroup and what I've seen of
many 'professionals' it wouldn't suprise me.
Jeff
John Serafin
ste...@apple.com (Stella Hackell) writes:
>
>> Smallpox has been eradicated worldwide several times in my lifetime. I
>> wonder if we will ever be able to say the same about the "Don't grease
>> the cranks" myth?
>We can say that right now.
Well, um, maybe in the past, and maybe in the future, but "right now" the
number of postings in this thread and its progeny seem to be exploding.
What's really a hoot are the number of alleged FAQ readers claiming that
wiping with a rag makes for a grease free installation.
>The myth of steel frames getting soft
>(for example) has also been eradicated several times on this newsgroup.
>Hmm, let me look up "eradicated" again.
Couldn't wait for it to restart on its own, eh?
--
John P. Serafin | Operating a bicycle is more like driving than riding.
jps at pobox com | Operating an automobile is more like riding than driving.
Rinards
>To get a better measurement of
>how far up the taper the cranks move when either dry or greased, you
>should have put the cranks through some pedal loading cycles, until they
>found their final resting place,
How many cycles and at what torque would you say is acceptable?
I'm not sure how precisely I can load the pedal. I am looking for
something like "stand on the pedal ten times with all your weight,
then measure again."
Damon Rinard
Rinards
In article <19970916052...@ladder01.news.aol.com>,
vcop...@aol.com (VCopelan) writes:
>how do you keep those dry crankarms quiet anyway?
Mine have never creaked in 15 years of riding cotterless cranks. I
always installed the cranks after wiping off the spindle and the
square hole in the crank.
Damon Rinard
Rinards
In article <5vmckk$k...@hplms2.hpl.hp.com>, jbr...@hpl.hp.com (Jobst
Brandt) writes:
>I am curious about your test and how you accomplished several of the
>procedures you described.
>
>1. How did you make sure the crank, screw, and spindle were grease
> free?
I never wrote that the crank was grease free. From my original post:
"So I made some measurements of how far a crank slips up the taper
on a bottom bracket spindle when the tapers are greased compared
to when the grease is wiped off."
I just wiped them off, that's all. I have no intention of mounting
cranks only after "de-greasing" them with solvents; as my measurements
show, just a thorough wipe with a rag makes a measurable difference.
>screw,
I never said the screw was grease free. In fact, I specifically said I
greased it: "METHOD... I greased the bolt’s threads and washer."
>and spindle
I never said the spindle was grease free, either. As I originally wrote,
I just wiped it off.
I did not wish to compare a greased interface to an artificial
"surgically cleaned" one; I compared an ordinary, wiped off
interface to a greased one, and said so in my post. I don't
know of anyone who recommends solvents and degreasers
to be used before mounting cranks. My measurements show
that wiping off the grease is all it takes to make what appears
to me to be a significant difference in how far the crank slides
up the taper.
>How did you degrease the threads inside the spindle?
I never said I degreased anything. In fact, as noted above, I
explicitly wrote in my original post that I greased the threads
of the bolt. "METHOD... I greased the bolt’s threads and washer."
>Did
> you use solvent and a brush to clean the parts and subsequently
> rinse them in clean degreaser?
Of course not. As I wrote in my original post, I wiped them off.
>If not, then I don't believe they
> were unlubricated.
I never said the parts were supposed to be *un*lubricated, just
"wiped off" as is commonly done.
>Wiping with a rag does not constitute removing
> grease.
Wiping with a rag is all I did. I removed all the grease that wiping
with a rag removes, and recorded the results.
One wonders if you read my original post carefully or not.
>2. How did you measure the depth of engagement?
Dial calipers.
>3. When you say "slipped on 1.8mm", from where and how was this
> measured and how?
I machined a flat reference surface on the inner face of an old crank.
I mounted said crank in my bench vise.
I mounted a bottom bracket spindle to the arm.
I mounted each test crank one at a time to the other end of the spindle.
I measured the distance from the test arm to the reference arm, inside to
inside.
I measured this distance when the crank was finger tight.
I also measured this distance after tightening the bolt to 300 in*lb.
The "slipped on" distance is the first measurement minus the second.
>The only valid measure of position of the crank on the spindle is with
>a depth micrometer from the outside face of the crank to the end of
>the spindle.
I didn't know there was only one valid way to measure such things.
Have you measured many cranks this way? The distance I measured
is the distance the crank slips up the taper. The distance your
method yields is the same slip distance, minus any retraction the
crank makes back down the tapers since you must take the bolt out.
>After tightening, the crank bolt must be removed to make
>this measurement.
Removal of the crank bolt is not necessary using my method, and I
did not remove the bolt for measurement. Removing the bolt is a
bad idea if you wish to find out where the crank sits after the bolt
is torqued. Removing the bolt calls into question whether the crank
remains in the same place or not.
>The initial position of the crank before tightening
>is an ill defined position so it has no value for this test.
Though inherently unreliable, the finger tight specification is surprisingly
repeatable, especially when the same person does it carefully the
same way each time, as I did for all the cranks in my test. To find
out how repeatable "finger tight" is, I mounted one crank ten times.
The variation was 0.1mm, and the standard deviation was only 0.03mm.
In spite of this apparent repeatability, the inherent vagueness of
this finger tight position is why I measured the distance from the
inside of the test crank to the machined reference surface on the
inside of the opposite crank. As I wrote in my original post:
"I recorded the position of each crank after mounting it the first
time (dry). Then I recorded the position of each crank after mounting
it the second time (greased). On average, the final resting place
was 1.1mm farther on the spindle when mounted the second time
(with grease) compared to the first time (dry). After wiping off the
grease and re-mounting the cranks a third time (dry), they still ended
up 0.6mm farther up the taper than they did the first time, though
they did recover somewhat from the greased position."
This is absolute position relative to the stationary opposite crank,
not relative position starting from finger tight.
So greased or dry, regardless of whether the crank was at the same
place when finger tight, it came to rest (after torquing) farther up
the tapers when greased than not. The greased cranks sat closer
to the opposite crank than did the cranks I mounted dry.
There are two things I did not measure, about which I am curious.
One is how far the crank squirms up the taper when ridden. I
think this must depend on the crank's preload, with a tighter fit
(the greased crank) allowing less squirm.
The other thing I did not measure is the strain on the bolt at initial
installation, after torque, before the crank squirms. This must
depend on the bolt's material and design (does it have a street of
a flare at the base of the threads?). Does bolt strain also depend
on the unengaged length of the bolt?
Have you made any measurements?
Damon Rinard
Rinards
In article <5vlifp$p7i$2...@news.istar.ca>, webm...@tread.pair.com (Chris
Phillipo) writes:
> With all the talk
>about preload and bolt stretch, the question arises, is the proper torque the
>same for steel, titanium and aluminum crank bolts?
I have installed aluminum and titanium crank bolts by first using steel
bolts to mount the cranks. I torque the steel bolt to the full torque
recommended by the crank maker, then install the light bolts to the
torque recommended by the bolt maker.
For what it's worth, Ultimate Machine Co., in Precott, AZ recommends
this procedure, and says 25 ft*lb is okay for their 7075 bolts.
Damon Rinard
Chris Phillipo
In message <19970918011...@ladder01.news.aol.com> - rin...@aol.com
(Rinards)18 Sep 1997 01:16:09 GMT writes:
:>
:>In article <341E19...@ix.netcom.com>, Mark McMaster
Since there is no way you are going to be able to do a precise load on each
pedal with what's available to you, maybe just take it for a vigorous ride. I
would assume that at some point, if it was properly installed, the crank finds
it's home and doesn't squirm any farther, unless it's deformed.
Mike Iglesias
In article <874554...@dejanews.com>, <Trad...@rocketmail.com> wrote:
>Slim to none. I have always used 20ft-lbs without problems,
>I believe shimano used to say 18-22 ft-lbs, so I used 20.
>Jobst seems to use more, but I can't find any instance in which he's
>said what he uses. FAQ 8.45 mentions using a torque wrench, but not
>the specification to torque with it.I've seen him reply to persons using
>anywhere from 300 to 420in-lb without objecting to their specification,
>you aren't far below this.
You must have missed section 8.49 of the FAQ, which lists common torque
values for various bolts 'n stuff. It says 250-300 in-lbs (~20-25 ft-lbs).
--
Mike Iglesias Internet: igle...@draco.acs.uci.edu
University of California, Irvine phone: (714) 824-6926
Office of Academic Computing FAX: (714) 824-2069
Rinards
In article <5vm75c$23k$1...@sparky.wolfe.net>, jo...@WOLFENET.COM
(Joshua_Putnam) writes:
>Of course, unless your rag is soaked in solvent, and you also
>clean the inside of the socket with solvent, you aren't really
>mounting the cranks dry. Wiping the spindle with a rag will
>leave a thin film of grease that's more than enough to prevent
>galling on installation -- it's such a tight fit, any more grease
>than that thin film would be squeezed out anyway.
When I wiped off the grease, I used no solvent. I just wiped off the
taper and the square hole in the crank as is commonly done.
And yet the difference between this dry mount and the
greased installation is clearly measurable, repeatable, and to me
at least, looks significant.
On average, cranks mounted on a dry spindle slide about 2.2 mm up the
taper. That’s starting from finger tight and ending at 300 inch pounds.
However, the same cranks, when mounted on greased tapers, slide 3.1 mm up
the taper on average. That’s about 40% farther up the taper when greased
than dry.
Damon Rinard
Rinards
In article <5vphhn$n...@hplms2.hpl.hp.com>, jbr...@hpl.hp.com (Jobst
Brandt) writes:
>I suspect that an aluminum bolt would work fine riding around
>in the flatland and then break off on a hill climb if any consistently
>strong pedaling occurs.
You need no longer suspect. Quite large pedalling forces are
applied when heavy mountain bike riders climb at low cadences.
Many of the riders I know who use aluminum bb bolts ride this way.
Others break aluminum crank bolts, but usually on (incorrect)
installation. I know of no one who has broken an aluminum bb
bolt while riding.
Damon Rinard
Rinards
In article <3423b65b...@nntp.erinet.com>, da...@erinet.com writes:
>As a matter of curiousity, is the same crank likely to move further up
>the taper for each installation/removal cycle? If so, by how much?
>
>I assume that the tester to whom you were responding used the same
>crank over (and over) again.
During the course of my test I mounted all the cranks dry, then mounted
them greased, then wiped them off and mounted them all dry again.
Repeatedly mounting and removing these cranks during my test caused them
to fit farther onto the spindle each time. They did not go back to where
they were the first time, even when the grease was wiped off and the cranks
were mounted dry again.
I recorded the position of each crank after mounting it the first time
(dry). Then I recorded the position of each crank after mounting it the
second time (greased). On average, the final resting place was 1.1mm
farther on the spindle when mounted the second time (with grease) compared
to the first time (dry).
After wiping off the grease and mounting the
cranks a third time (dry), they still ended up 0.6mm farther up the taper
than they did the first time, though they did recover somewhat from the
greased position.
I do not know why the cranks ended up farther on the spindle after each
time. I don’t know if the cranks were stretched once by mounting them with
grease, or if the fit gets looser even from mounting them dry.
Damon Rinard
Rinards
In article <5vmsig$b8b$1...@sparky.wolfe.net>, jo...@WOLFENET.COM
(Joshua_Putnam) writes:
> Sugino, for
>example, specifies a settled tightening torque of 400 kgf/cm,
>while SR/Sakae calls for 500-550 kgf/cm for nutted axles and
>300-350 kgf/cm for bolt type axles.
Thanks for the numbers, Joshua.
Damon Rinard
Rinards
In article <341E8E...@atlas.cheme.cornell.edu>, Jeffrey Potoff
<jpo...@atlas.cheme.cornell.edu> writes:
>No mention was made of exactly how the measurements were
>made
>(what instruments were used, what was the point of reference).
I address these questions in another post in this thread.
>In
>addition,
>we all know that the crank squirms up the spindle after you've ridden
>it.
>He should have measured all the crank arms after riding them. For all
>we
>know, all the cranks could have ended up in the exact same spot, grease
>or
>no grease.
The greased and dry cranks may indeed end up at the same spot after
riding. How many revolutions is enough before I stop and measure again?
I did not make any claims about where they end up after riding, only that
the greased cranks slip farther up the tapers after torquing the bolt.
During the course of my test I mounted all the cranks dry, then mounted
them greased, then wiped them off and mounted them all dry again. I
measured the cranks’ position before tightening them and after.
>Furthermore, the use of the word 'stress' was not correct.
>It
>was never clear exactly what the original poster meant by 'putting
>grease
>on the tapers of the crank increases the stress on the square hole in
>the
>crank arm'. Huh ?! I'd like the original poster to define what he
>means
>by 'stress'. In the engineering world, words like 'stress' and 'strain'
>have
>very specific meanings and from the poster's comments I don't think he
>understands
>this.
This is what I mean by strain: the change in the dimensions of the
square hole in the crank.
I assume mounting a crank deforms the aluminum elastically.
This deformation is strain. The farther up the taper you force it,
the more it must be deformed. Thus the farther up the taper the
crank goes, the more strain the hole sees.
This is what I mean by stress: the force per unit area on the walls
of the square hole in the crank.
In order to get the crank to fit farther up the taper, the hole in the
crank must deform more. This is accomplished by forcing the
square hole to strain to the larger dimensions needed to make it
fit on the larger part of the taper. You need increased force to
increase the strain this way. The more you increase the force,
the larger you can make the hole, and the farther up thet taper
the crank will go. Stress increases more and more the farther
the crank is forced up the spindle.
Damon Rinard
Rinards
In article <5vmjmi$7pq$1...@news.istar.ca>, webm...@tread.pair.com (Chris
Phillipo) writes:
>ride for a few days and the bolts are loose enough to be backed off with one
>hand, not to mention the creaking that's going on by then. I know they don't
>unscrew at all because I marked the bolt and the crank with matching notches.
Marking the bolt's position relative to the crank is an excellent idea! So
if the bolt is not turning, the decrease in its tightness is in fact due
to the
crank squirming up the taper.
Now, if only we knew the difference in the crank's position before and
after squirm.
It should be easy to measure the torque on the bolt after squirm. Just
put a torque wrench on the bolt and note at what torque it begins turning.
Can we then use the measured torque after squirm to find out how
much the bolt's tension has relaxed? If so, maybe this information
could be used to calculate the distance the crank has squirmed
away from the bolt...
Damon Rinard
Jeffrey L. Bell
>...
>After wiping off the grease and mounting the
>cranks a third time (dry), they still ended up 0.6mm farther up the taper
>than they did the first time, though they did recover somewhat from the
>greased position.
>
>I do not know why the cranks ended up farther on the spindle after each
>time. I don't know if the cranks were stretched once by mounting them with
>grease, or if the fit gets looser even from mounting them dry.
Or maybe there was more residual grease on the surface the third time
after greasing and wiping than there was the first time.
BTW Thanks for doing the measurments.
-Jeff Bell
Sam Bond
Oh, just go and grease your cranks.
Sam
Jobst Brandt
Damon Rinard writes:
> I'm not sure how precisely I can load the pedal. I am looking for
> something like "stand on the pedal ten times with all your weight,
> then measure again."
I suspect it's more like a thousand times, as in climbing a three mile
long hill standing. With about a 60 inch gear, that's about a
thousand revolutions. I'm only guessing, because I haven't checked
how soon a crank finds its favorite spot on the spindle. I've only
noticed that it has done so when removing it after substantial use.
Jobst Brandt <jbr...@hpl.hp.com>
Chris Phillipo
:>
:>>I suspect that an aluminum bolt would work fine riding around
:>>in the flatland and then break off on a hill climb if any consistently
:>>strong pedaling occurs.
:>
:>You need no longer suspect. Quite large pedalling forces are
:>applied when heavy mountain bike riders climb at low cadences.
:>Many of the riders I know who use aluminum bb bolts ride this way.
:>
:>Others break aluminum crank bolts, but usually on (incorrect)
:>installation. I know of no one who has broken an aluminum bb
:>bolt while riding.
:>
:>Damon Rinard
I finally got ahold of the shop's torque wrench and found that I've had my
aluminum bolts at around 30 all along, I torqued them to 35 and took them out
to look for damage, the blue ano isn't even scratched off the threads yet. I
put grease on the tapers this time, I haven't ridden it yet though. Mine were
never really dry anyway, just wiped off with a rag.