Rebuilding hubs



C

Chuck Huffstetl

Guest
Is it ok to change the lacing from a 3x to radial or 2x? I
bought a used Dura Ace hubset and I would like to change
from the original 3x. It is a 28 hole hubset. Thanks Chuck
Huffstetler
 
Q

Qui Si Parla Ca

Guest
chuck-<< Is it ok to change the lacing from a 3x to radial
or 2x? I bought a used Dura Ace hubset and I would like to
change from the original 3x. It is a 28 hole hubset.
>><BR><BR>

No problem from 3x to 2x but ya 'may' have problems if you
make it radial(hub flange failure).

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St.
Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali
costruite eccezionalmente bene"
 
S

Song

Guest
I'm not sure if it's generally a good idea to decrease the
'cross count' - especially when it sounds like you already
have a rim and spokes of a specific length?

Weight savings are negligible, the improvement in
aerodynamics even more so (according to things I've read on
this NG and elsewhere), only thing I can think of is
aesthetics. Mostly you just increase stresses as Peter said.
When I have the extra time / cash, I'd want to relace my
front radial at least 2x.

just my $0.02 song
 
J

Jobst Brandt

Guest
Chuck Huffstetler writes:

> Is it ok to change the lacing from a 3x to radial or 2x? I
> bought a used Dura Ace hubset and I would like to change
> from the original 3x. It is a 28 hole hubset.

You'll notice that spoke holes in the flanges have dents
made from each spoke. These were made by steel bearing on
softer aluminum. Changing the spoke pattern will make a new
set of dents that will weaken the flanges. This practice can
lead to flange failure. I have a couple of Campagnolo Record
hubs with a section of three and four spokes that ripped
out, lying in my collection. Yielding spoke holes in a hub
more than once is not a reliable way of building a wheel.

Why do you want to make this change?

Jobst Brandt [email protected]
 
A

A Muzi

Guest
Chuck Huffstetler wrote:
> Is it ok to change the lacing from a 3x to radial or 2x? I
> bought a used Dura Ace hubset and I would like to change
> from the original 3x. It is a 28 hole hubset.

What will be stronger? What will be better?

For showing off, a fit body goes a lot farther than a loopy
spoke pattern for attracting attention from girls.

--
Andrew Muzi www.yellowjersey.org Open every day since 1
April, 1971
 
J

Jim Beam

Guest
if a hub flange is fatigue loaded, and cracks are initiated
perpendicular to the direction of the stress, why would
loading in a different direction cause premature failure? it
is /certain/ that continued loading in the same orientation
will continue to grow the same fatigue cracks.

[email protected] wrote:
> Chuck Huffstetler writes:
>
>
>>Is it ok to change the lacing from a 3x to radial or 2x? I
>>bought a used Dura Ace hubset and I would like to change
>>from the original 3x. It is a 28 hole hubset.
>
>
> You'll notice that spoke holes in the flanges have dents
> made from each spoke. These were made by steel bearing on
> softer aluminum. Changing the spoke pattern will make a
> new set of dents that will weaken the flanges. This
> practice can lead to flange failure. I have a couple of
> Campagnolo Record hubs with a section of three and four
> spokes that ripped out, lying in my collection. Yielding
> spoke holes in a hub more than once is not a reliable way
> of building a wheel.
>
> Why do you want to make this change?
>
> Jobst Brandt [email protected]
 
J

Jobst Brandt

Guest
jim beam who? writes:

>>> Is it OK to change the lacing from a 3x to radial or 2x?
>>> I bought a used Dura Ace hubset and I would like to
>>> change from the original 3x. It is a 28 hole hubset.

>> You'll notice that spoke holes in the flanges have dents
>> made from each spoke. These were made by steel bearing on
>> softer aluminum. Changing the spoke pattern will make a
>> new set of dents that will weaken the flanges. This
>> practice can lead to flange failure. I have a couple of
>> Campagnolo Record hubs with a section of three and four
>> spokes that ripped out, lying in my collection. Yielding
>> spoke holes in a hub more than once is not a reliable way
>> of building a wheel.

>> Why do you want to make this change?

> if a hub flange is fatigue loaded, and cracks are
> initiated perpendicular to the direction of the stress,
> why would loading in a different direction cause premature
> failure?

Major hub manufacturers I know of from people with returns
for flange failure, turned them down when it was evident
that the hub had been re-spoked with different angles. I
find it logical to assume that an additional yielded groove
in the flange at each spoke causes weakening. On the other
hand, if the spoke pattern is purely tangential, as it is
with 36 x 4 then there is less probability of such a
failure. In any case, as I said, I saved two Campagnolo
Record rear 36 x 3 hubs with torn out flanges of several
that I have seen.

> it is /certain/ that continued loading in the same
> orientation will continue to grow the same fatigue cracks.

As certain as that the moon is made of green cheese. THe
flanges only yiels on initial tightening and stress
relieving. Otherwise they would fail in the first 100 miles
or less. My similar Campagnolo hubs have withstood failure
for much more than 200,000 miles, probably 300,000, I lost
count, but at about 10,000 per year close to 30 years is a
good reliability test considering I ride all sorts of roads
and terrain with them and have worn out many rims... all on
the same hubs and spokes.

Jobst Brandt [email protected]
 
C

Chris Zacho "Th

Guest
It shouldn't matter. You might want to take a file to the
flange if there is any deformation in the surface left by
the former pattern.

"May you have the wind at your back. And a really low gear
for the hills!"

Chris Zacho ~ "Your Friendly Neighborhood Wheelman"

Chris'Z Corner http://www.geocities.com/czcorner
 
J

Jim Beam

Guest
[email protected] wrote:
> jim beam who? writes:
>
>
>>>>Is it OK to change the lacing from a 3x to radial or 2x?
>>>>I bought a used Dura Ace hubset and I would like to
>>>>change from the original 3x. It is a 28 hole hubset.
>
>
>>>You'll notice that spoke holes in the flanges have dents
>>>made from each spoke. These were made by steel bearing on
>>>softer aluminum. Changing the spoke pattern will make a
>>>new set of dents that will weaken the flanges. This
>>>practice can lead to flange failure. I have a couple of
>>>Campagnolo Record hubs with a section of three and four
>>>spokes that ripped out, lying in my collection. Yielding
>>>spoke holes in a hub more than once is not a reliable way
>>>of building a wheel.
>
>
>>>Why do you want to make this change?
>
>
>>if a hub flange is fatigue loaded, and cracks are
>>initiated perpendicular to the direction of the stress,
>>why would loading in a different direction cause premature
>>failure?
>
>
> Major hub manufacturers I know of from people with returns
> for flange failure, turned them down when it was evident
> that the hub had been re-spoked with different angles. I
> find it logical to assume that an additional yielded
> groove in the flange at each spoke causes weakening.

what "kind" of weakening are you assuming? you'll find that
a microhardness test at that deformation point yields a
harder material than the region that's not yielded. a
manufacturer being squirrelly is no basis for a fatigue
crack growth hypothesis.

> On the other hand, if the spoke pattern is purely
> tangential, as it is with 36 x 4 then there is less
> probability of such a failure. In any case, as I said, I
> saved two Campagnolo Record rear 36 x 3 hubs with torn
> out flanges of several that I have seen.
>
>
>>it is /certain/ that continued loading in the same
>>orientation will continue to grow the same fatigue cracks.
>
>
> As certain as that the moon is made of green cheese.

come on jobst, i'm merely pointing out fact. if it's not
what you want to hear, that's /your/ problem. if a crack has
initiated in one orientation, perpendicular to applied
stress, and the hub is rebuilt using that same orientation,
that same crack is going to continue to grow. how can you
argue against that? if it's rebuilt at 90 degrees to the
original, i.e. those old cracks are now axial with newly
applied stress, those cracks are not oriented for growth, so
any fatigue process has to be newly initiated does it not?

> THe flanges only yiels on initial tightening and stress
> relieving. Otherwise they would fail in the first 100
> miles or less. My similar Campagnolo hubs have withstood
> failure for much more than 200,000 miles, probably
> 300,000, I lost count, but at about 10,000 per year close
> to 30 years is a good reliability test considering I ride
> all sorts of roads and terrain with them and have worn
> out many rims... all on the same hubs and spokes.
>
> Jobst Brandt [email protected]
 
J

Jeff Wills

Guest
A Muzi <[email protected]> wrote in message news:<[email protected]>...
> Chuck Huffstetler wrote:
> > Is it ok to change the lacing from a 3x to radial or 2x?
> > I bought a used Dura Ace hubset and I would like to
> > change from the original 3x. It is a 28 hole hubset.
>
> What will be stronger? What will be better?
>
> For showing off, a fit body goes a lot farther than a
> loopy spoke pattern for attracting attention from girls.

Geez, I've got to remember that one.

Jeff
 
D

Dianne_1234

Guest
On Sun, 14 Mar 2004 18:35:06 GMT, jim beam <[email protected]> replied to
Jobst Brandt thusly:

>you'll find that a microhardness test at that
>deformation point yields a harder material than the
>region that's not yielded.

Have you really done this? Can you actually get a hardness
tester in there? Is hardness a reliable measure of fatigue
strength in aluminum anyway?

> a manufacturer being squirrelly is no basis for a fatigue
> crack growth hypothesis.

Right.

But most rebuilds are in the direction of easier tear-out:
from, say, 3x to, say, radial. And this may orient any
damage from the original pattern at roughly right angles to
the new direction of load.

>if a crack has initiated in one orientation, perpendicular
>to applied stress,

Yes, usually a great textbook example for the case of pure
tensile fatigue.

But is this really a frequent load case in hub flange
failures? In my experience, most hub flange failures are
from one hole to the next, until a whole crescent piece of
the flange separates from the rest of the shell.

> and the hub is rebuilt using that same orientation, that
> same crack is going to continue to grow. how can you argue
> against that?

One counter argument might be that as the crack grows,
the new geometry of the remaining good material changes
the stress state because the features are different now
(what was once connected is no longer, so the load path
may change).

>if it's rebuilt at 90 degrees to the original, i.e. those
>old cracks are now axial with newly applied stress, those
>cracks are not oriented for growth, so any fatigue process
>has to be newly initiated does it not?

Seems so, but I wonder if an existing crack has enough
stress in shear to grow even with the new orientation of
the tension?
 
J

Jim Beam

Guest
dianne_1234 wrote:
> On Sun, 14 Mar 2004 18:35:06 GMT, jim beam <[email protected]>
> replied to Jobst Brandt thusly:
>
>
>>you'll find that a microhardness test at that deformation
>>point yields a harder material than the region that's not
>>yielded.
>
>
> Have you really done this? Can you actually get a hardness
> tester in there? Is hardness a reliable measure of fatigue
> strength in aluminum anyway?

no, you wouldn't typically do a hardness test on a curved
surface. what i'm trying to say is that if you yield a
material like this, it does not automatically make it
weaker. hardness /is/ related to strength.

in ascii

S ~
| ~ ~ / 2 ~ / / 1 / / / / / / /
______________________ s

if the material starts yielding at point 1 and plastically
yields to point 2, any reapplication of stress at that
location will proceed immediately up to point 2, it does not
go through point 1 again.

no, hardness is not a measure of fatigue strength - but it
is a measure of work hardening and therefore "strength",
which can then affect fatigue.

>
>
>>a manufacturer being squirrelly is no basis for a fatigue
>>crack growth hypothesis.
>
>
> Right.
>
> But most rebuilds are in the direction of easier tear-out:
> from, say, 3x to, say, radial. And this may orient any
> damage from the original pattern at roughly right angles
> to the new direction of load.

i should have been more specific - i'm talking about a
rebuild with the same cross pattern, not radial. radial is
always much more stressful for a hub, whether it be new or
a rebuild.

>
>
>>if a crack has initiated in one orientation, perpendicular
>>to applied stress,
>
>
> Yes, usually a great textbook example for the case of pure
> tensile fatigue.
>
> But is this really a frequent load case in hub flange
> failures? In my experience, most hub flange failures are
> from one hole to the next, until a whole crescent piece of
> the flange separates from the rest of the shell.

like this: http://technology.open.ac.uk/materials/mem/mem-
ccf1.html

they go in pairs, but if you re-orient to the next flange
pair along, [if you see what i mean] you should be able to
dodge the fatigue bullet longer than you would rebuilding
exactly as before.

>
>
>>and the hub is rebuilt using that same orientation, that
>>same crack is going to continue to grow. how can you argue
>>against that?
>
>
> One counter argument might be that as the crack grows, the
> new geometry of the remaining good material changes the
> stress state because the features are different now (what
> was once connected is no longer, so the load path may
> change).

if you went from 3x to radial, yes, you'd still get
cracking because the load paths will share every other
flange pair and continue cracking, but from one 3x to
another 3x oriented perpendicular to how it was before,
pretty unlikely.

>
>
>>if it's rebuilt at 90 degrees to the original, i.e. those
>>old cracks are now axial with newly applied stress, those
>>cracks are not oriented for growth, so any fatigue process
>>has to be newly initiated does it not?
>
>
> Seems so, but I wonder if an existing crack has enough
> stress in shear to grow even with the new orientation of
> the tension?
>
>
you really don't see fatigue cracking in a true shear mode.
something like a coil spring has shear loads, but cracks
open perpendicular to stress, not along a shear axis.
 
T

Tim McNamara

Guest
David Reuteler <[email protected]> writes:

> Jeff Wills <[email protected]> wrote:
>>
>> A Muzi <[email protected]> wrote:

>>> For showing off, a fit body goes a lot farther than a
>>> loopy spoke pattern for attracting attention from girls.
>>
>> Geez, I've got to remember that one.
>
> it's a bit of an epiphany isn't it?

Danged depressing, if you ask me.
 
J

Jeff Wills

Guest
David Reuteler <[email protected]> wrote in message news:<[email protected]>...
> Jeff Wills <[email protected]> wrote:
> >
> > A Muzi <[email protected]> wrote in message
> > news:<[email protected] ws.com>...
> >> For showing off, a fit body goes a lot farther than a
> >> loopy spoke pattern for attracting attention from
> >> girls.
> >
> > Geez, I've got to remember that one.
>
> it's a bit of an epiphany isn't it?

Yup. Although it leaves me in a veritable quandary: should I
rebuild my wife's front wheel to change it from radial to
2-cross (it's a 20" wheel on her recumbent) or should I
resign myself to defending her from drooling technophilic
bike mechanics?

Jeff
 
D

David Reuteler

Guest
Jeff Wills <[email protected]> wrote:
> Yup. Although it leaves me in a veritable quandary: should
> I rebuild my wife's front wheel to change it from radial
> to 2-cross (it's a 20" wheel on her recumbent) or should I
> resign myself to defending her from drooling technophilic
> bike mechanics?

that might not work. a lot of the bike mechanics i know
would be more enamoured by the 2-cross. my 36 spoke
campag/velocity wheelset usually gets a positive remark.

it's sure to work on the sales drones who drank the
kool-aid, tho.
--
david reuteler [email protected]