Spoke Tension of Radial/3x rear wheel



B

Bestest Handsan

Guest
I'm trying to learn to build my own wheels, but I'm having a
hard time with my rear wheel. I tried doing a 3x 32 hole
rear wheel, but it came undone on me during the first ride
ruining the rim ($65 bucks chalked up to experience). I'm
pretty sure I just didn't have the spokes tight enough. I
bought a Wheelsmith Tensiometer a new rim and tried again.
After reading L. Zinn's thoughts on heavy riders on rear
wheels, I decided to do a radial lace on the left side and a
3x lace of the right (drive side).

My question involves spoke tension (what seems to be my main
problem). I understand radial laced spokes need to be
tighter to prevent them from coming loose under load, but on
a rear wheel it seems the drive side spokes must be under
more tension to keep the wheel dished properly.

Right now my rear wheel seems true, but the drive side 3x
spokes are at cir. 120 kgf and the left radial side spokes
are between 83 and 98. Is this going to be okay? Do I need
to get either side tighter? I'd hate to ruin another rim on
trial and error. This little educational experience is
costing me twice what a new set of wheels would have! :)

FWIW... Ultegra FH-6500, 14 gauge DT spokes, Open pro rim.

I've order both wheel building books, but neither have
arrived yet.

Any advice would be appreciated.
 
On Mon, 26 Apr 2004 02:52:29 -0600, "Bestest Handsander" <[email protected]>
wrote:

>I'm trying to learn to build my own wheels, but I'm having
>a hard time with my rear wheel. I tried doing a 3x 32 hole
>rear wheel, but it came undone on me during the first ride
>ruining the rim ($65 bucks chalked up to experience). I'm
>pretty sure I just didn't have the spokes tight enough.

Yep, this is very likely.

> I bought a Wheelsmith Tensiometer a new rim and
> tried again.

Good decision.

>My question involves spoke tension (what seems to be my
>main problem). I understand radial laced spokes need to be
>tighter to prevent them from coming loose under load,

Any spoke (radial or not) needs to be tight enough to
prevent loosening.

> but on a rear wheel it seems the drive side spokes must be
> under more tension to keep the wheel dished properly.

Correct.

>Right now my rear wheel seems true, but the drive side 3x
>spokes are at cir. 120 kgf and the left radial side spokes
>are between 83 and 98.

Those are good numbers. For Open Pros Mavic recommends
100~110 kgf. so you're pretty close. I'd leave it alone.

> Is this going to be okay?

Time will tell! :)

> Do I need to get either side tighter?

Not in my experience. Tighter spokes lead to earlier fatigue
cracking in the rim.
 
none-<< I'm pretty sure I just didn't have the spokes tight
enough. I bought a Wheelsmith Tensiometer a new rim and
tried again. After reading L. Zinn's thoughts on heavy
riders on rear wheels, I decided to do a radial lace on the
left side and a 3x lace of the right (drive side).
>><BR><BR>

This does nothing if the right side tension is proper.
Whether radial, 1, 2 or 3 cross, the tension will be the
same on the left if the tension is the same on the right.

none<< My question involves spoke tension (what seems to be
my main problem). I understand radial laced spokes need to
be tighter to prevent them from coming loose under load, but
on a rear wheel it seems the drive side spokes
>><BR><BR>

If the rim is new, and round and the right side are proper
tension(120 kgf is a little high, BTW. 100 kgf is more like
it), then the left side will take care of itself and will
always be less than the right.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St.
Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali
costruite eccezionalmente bene"
 
Originally posted by Bestest Handsan
I'm trying to learn to build my own wheels, but I'm having a
hard time with my rear wheel. I tried doing a 3x 32 hole
rear wheel, but it came undone on me during the first ride
ruining the rim ($65 bucks chalked up to experience). I'm
pretty sure I just didn't have the spokes tight enough. I
bought a Wheelsmith Tensiometer a new rim and tried again.
After reading L. Zinn's thoughts on heavy riders on rear
wheels, I decided to do a radial lace on the left side and a
3x lace of the right (drive side).

My question involves spoke tension (what seems to be my main
problem). I understand radial laced spokes need to be
tighter to prevent them from coming loose under load, but on
a rear wheel it seems the drive side spokes must be under
more tension to keep the wheel dished properly.

Right now my rear wheel seems true, but the drive side 3x
spokes are at cir. 120 kgf and the left radial side spokes
are between 83 and 98. Is this going to be okay? Do I need
to get either side tighter? I'd hate to ruin another rim on
trial and error. This little educational experience is
costing me twice what a new set of wheels would have! :)

FWIW... Ultegra FH-6500, 14 gauge DT spokes, Open pro rim.

I've order both wheel building books, but neither have
arrived yet.

Any advice would be appreciated.

1. Tension balance.
2. Spoke align at hub and nipples. When you get "the Bicycle Wheel" book you will see what this looks like. The issue is the shortest distance between two points is a straight line.
3. Stress relieve. Check tension again and true again.
Stress relieve again... check tension again, true again... you get the idea.
4. Double butted spokes help make the wheel more durable.
5. Radial spokes aren't the best idea in any position... you will read more on this subject when you get "the book". I am suprised that you left side tensions are that high in a properly centered rear wheel.
6. Remove all wind up. Check tension, true, and stress relieve again.


Wheel building takes time to learn. You are making the correct investments... don't give up.
One of the most telling statements in "the book":
"It may be futile to suggest the ordinary but let me try to persuade you that just to build a conventional standard 36 spoke wheel is not a trivial task if a durable wheel is your goal... <SNIP>
Your true contribution is to build conventional wheels exceptionally well."
 
Bestest Handsander <[email protected]> wrote:

> Right now my rear wheel seems true, but the drive side 3x
> spokes are at cir. 120 kgf and the left radial side spokes
> are between 83 and 98. Is this going to be okay? Do I need
> to get either side tighter? I'd hate to ruin another rim
> on trial and error. This little educational experience is
> costing me twice what a new set of wheels would have! :)

> FWIW... Ultegra FH-6500, 14 gauge DT spokes, Open pro rim.

If you replace the left side spokes with 15 gauge (or
even 15-16-15) they'd be less likely to go slack. I'd
also lace them 3x.

Art Harris
 
Bestest Handsander wrote:

> I'm trying to learn to build my own wheels, but I'm having
> a hard time with my rear wheel. I tried doing a 3x 32 hole
> rear wheel, but it came undone on me during the first ride
> ruining the rim ($65 bucks chalked up to experience). I'm
> pretty sure I just didn't have the spokes tight enough. I
> bought a Wheelsmith Tensiometer a new rim and tried again.
> After reading L. Zinn's thoughts on heavy riders on rear
> wheels, I decided to do a radial lace on the left side and
> a 3x lace of the right (drive side).
>
> My question involves spoke tension (what seems to be my
> main problem). I understand radial laced spokes need to be
> tighter to prevent them from coming loose under load, but
> on a rear wheel it seems the drive side spokes must be
> under more tension to keep the wheel dished properly.
>
> Right now my rear wheel seems true, but the drive side 3x
> spokes are at cir. 120 kgf and the left radial side spokes
> are between 83 and 98. Is this going to be okay? Do I need
> to get either side tighter? I'd hate to ruin another rim
> on trial and error. This little educational experience is
> costing me twice what a new set of wheels would have! :)

Having the drive side tangentially spoked and the non-drive
side radially spoked exacerbates the difference in tension
between each side, as you've found. It's possible to do it
the other way round, which looks wrong but gives more even
spoke tension. Most hubs will happily transmit the torque
from one side to the other without appreciably twisting, but
I'd be wary of three-piece hubs with a separate centre
sleeve. Tony Oliver recommends this type of spoking in his
semi-classic book "Touring Bikes" and Mavic have just
"rediscovered" it and called it Isopulse. Disclaimer: I've
never tried it myself, but I have too many wheels as it is.
 
On Mon, 26 Apr 2004 13:46:07 GMT, daveornee
<[email protected]> wrote:

>4. Double butted spokes help make the wheel more durable.

In what way will the wheel be more durable? The braking
surfaces will wear the same. The true of the wheel will be
the same. The spoke tension for straight vs. butted is the
same. The rigidity of the rim is the same.
 
Paul Kopitg writes:

>> 4. Double butted spokes help make the wheel more durable.

> In what way will the wheel be more durable? The braking
> surfaces will wear the same. The true of the wheel will be
> the same. The spoke tension for straight vs. butted is the
> same. The rigidity of the rim is the same.

In a swaged spoke the thinnest cross section of spokes
(the root of the thread) is no longer many times smaller
than the shaft of the spoke. The rigidity of the spoke is
given by the thinner cross section. That is to say for the
same tension, the swaged spoke stretches more and therefor
its tension varies less with shock loads such as ripples
in the pavement.

It the spokes were twice as thick, 4.0mm for instance, they
would slacken with each bump in the road and the tension
change would be more localized to one or two spokes. This is
one of the problems with low spoke court wheels. To make up
for the low spoke population, their spokes are thicker and
more rigid and loosen more easily if not arrested by other
means. The whole idea of SpokePrep comes from insufficient
spoke elongation.

Jobst Brandt [email protected]
 
Zog-<< Having the drive side tangentially spoked and the non-
drive side radially spoked exacerbates the difference in
tension between each side, as you've found. It's possible to
do it the other way round, which looks wrong but gives more
even spoke tension. >><BR><BR>

I've seen two hubs laced with radial right side and both
twisted the hub so badly the holes on either flange lned up
with one another and the 'Dura Ace' in the middle was
distorted.

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

> I've seen two hubs laced with radial right side and both
> twisted the hub so badly the holes on either flange lned
> up with one another and the 'Dura Ace' in the middle was
> distorted.

That must be the least subtle Campag sales pitch I've
ever read ;-)
 
Paul Kopit wrote:
> On Mon, 26 Apr 2004 13:46:07 GMT, daveornee <usenet-
> [email protected]> wrote:
>
>
>>4. Double butted spokes help make the wheel more durable.
>
>
> In what way will the wheel be more durable? The braking
> surfaces will wear the same. The true of the wheel will be
> the same. The spoke tension for straight vs. butted is the
> same. The rigidity of the rim is the same.

Plain gauge spokes have one advantage - if one does break,
the wheel goes out of true by less because the remaining
spokes don't stretch much compared to d/b spokes. For this
reason some tourists prefer them, as you can continue to
your destination and put a new spoke in there. With
d/b you usually have to fix the wheel on the road or do a
bit of bodged truing with the remaining spokes, which
you'll have to reverse when you make a proper repair.
 
Paul Kopit <[email protected]> wrote:

> daveornee wrote:
>
> >4. Double butted spokes help make the wheel more
> > durable.
>
> In what way will the wheel be more durable? The braking
> surfaces will wear the same. The true of the wheel will be
> the same. The spoke tension for straight vs. butted is the
> same. The rigidity of the rim is the same.

Bike wheels carry load by deflecting inward at the rim, in
the vicinity of the contact patch of the tire.

Butted spokes stretch more at a given tension than straight
gauge spokes of the same end thickness, so they can retract
more (when the wheel is loaded) before they go slack.

Intermittent slackening under load is one of the chief
causes of spoke breakage and wheel reliability problems.

Chalo Colina
 
Chalo Colina writes:

>>> Double butted spokes help make the wheel more durable.

>> In what way will the wheel be more durable? The braking
>> surfaces will wear the same. The true of the wheel will
>> be the same. The spoke tension for straight vs. butted is
>> the same. The rigidity of the rim is the same.

> Bike wheels carry load by deflecting inward at the rim, in
> the vicinity of the contact patch of the tire.

> Butted spokes stretch more at a given tension than
> straight gauge spokes of the same end thickness, so they
> can retract more (when the wheel is loaded) before they
> go slack.

> Intermittent slackening under load is one of the chief
> causes of spoke breakage and wheel reliability problems.

It may be the cause of spokes unscrewing to affect trueness
and wheel collapse for lack of tension, but it does not
increase spoke failure. Spoke failure is caused by fatigue
cracking at high tensile stress locations, typically at
spoke threads and elbows.

Jobst Brandt [email protected]
 
[email protected] wrote:

> Chalo Colina writes:
>
> > Intermittent slackening under load is one of the chief
> > causes of spoke breakage and wheel reliability problems.
>
> It may be the cause of spokes unscrewing to affect
> trueness and wheel collapse for lack of tension, but it
> does not increase spoke failure.

In my observed experience as a former shop mechanic, tension
low enough to allow spokes to dislocate under load is
correlated with spoke breakage. On a coaster-braked bike
with grossly overbuilt steel wheels, that is often the
symptom that prompts a customer to bring in the bike for
service, because the wheel doesn't necessarily collapse from
loose spokes.

Chalo Colina
 
Chalo <[email protected]> writes:

>>> Intermittent slackening under load is one of the chief
>>> causes of spoke breakage and wheel reliability problems.

>> It may be the cause of spokes unscrewing to affect
>> trueness and wheel collapse for lack of tension, but it
>> does not increase spoke failure.

> In my observed experience as a former shop mechanic,
> tension low enough to allow spokes to dislocate under load
> is correlated with spoke breakage. On a coaster-braked
> bike with grossly overbuilt steel wheels, that is often
> the symptom that prompts a customer to bring in the bike
> for service, because the wheel doesn't necessarily
> collapse from loose spokes.

A wheel that is loose enough to do that probably was built
by someone not skilled enough to build a durable wheel and
one who does not stress relieve spokes. I think you are
right in your assessment but cause and effect are not shown
to be what you say.

What mechanism do you believe causes these fatigue failures?
The must be fatigue failures or they would have broken the
first time the wheel was loaded.

Jobst Brandt [email protected]
 
> Zog-<< That must be the least subtle Campag sales pitch
> I've ever read ;-)

Qui si parla Campagnolo wrote:
> Sorry Zoggy, but the hubs were DA, not Campagnolo...which
> I'm sure would have twisted the same way...not gonna lie
> to you about wh

I've seen classic Record 1034 and 1035 do the same thing.

--
Andrew Muzi www.yellowjersey.org Open every day since 1
April, 1971
 
Originally posted by daveornee

5. Radial spokes aren't the best idea in any position... you will read more on this subject when you get "the book". I am suprised that you left side tensions are that high in a properly centered rear wheel.



Hi all -- I'm new here, so I hope I'm doing this right!

I'm confused. Lennard Zinn in "Zinn and the Art of Road Bike Maintenance" (around pg. 214, if I remember correctly!) offers seemingly contrary advice to daveornee's advice above, when offering guidance about building rear wheels for bigger (>190 lbs.) riders (i.e., he recommends radial lacing on the nondrive side). Similarly, Sheldon Brown at http://www.sheldonbrown.com/wheelbuild.html states:

"More and more rear wheels now are built 'half-radial' with semi-tangent spoking on the right side and radial spoking on the left. Radial front wheels offer mainly esthetic benefits, but half radial rear wheels are substantially more durable than conventional ones. The high amount of dishing called for to make room for more and more sprockets has caused an increase in spoke breakage on the left side of rear wheels. This is caused by metal fatigue.

"A spoked wheel relies on having all of the spokes in constant tension. A highly dished rear wheel starts with very light tension on the left side spokes. The torque of hard pedaling can cause the left side 'leading' spokes to occasionally go completely slack momentarily. Repeated cycles of tension and slackness cause these spokes to fatigue at the bends, and ultimately break.

"With half-radial spoking, the amount of dish is slightly less to begin with if you run the radial spokes up along the inside of its flange. In addition, since there are no 'leading' spokes, no amount of torque on the hub can reduce the tension on any of the spokes. In fact, if you have a customer who has been breaking left side spokes, 'half rebuilding' the wheel into a half radial will solve the problem once and for all."

I'm 195-200 lbs., have a history of breaking spokes, and looking to have some new wheels (CXP33's around Ultegra hubs?) built, and the final question I'd like resolved before having them built is this "to spoke the rear half-radially or not" question. But as seen here, there are conflicting opinions on this! (I've not read Jobst Brandt's book on wheels ("the book" referred to above, I believe), and now I feel I may at a bit of a loss....)

I'd appreciate any guidance y'all can offer, to help resolve my confusion. Thanks!
 
Originally posted by Cleophus
Originally posted by daveornee

5. Radial spokes aren't the best idea in any position... you will read more on this subject when you get "the book". I am suprised that you left side tensions are that high in a properly centered rear wheel.



Hi all -- I'm new here, so I hope I'm doing this right!

I'm confused. Lennard Zinn in "Zinn and the Art of Road Bike Maintenance" (around pg. 214, if I remember correctly!) offers seemingly contrary advice to daveornee's advice above, when offering guidance about building rear wheels for bigger (>190 lbs.) riders (i.e., he recommends radial lacing on the nondrive side). Similarly, Sheldon Brown at http://www.sheldonbrown.com/wheelbuild.html states:

"More and more rear wheels now are built 'half-radial' with semi-tangent spoking on the right side and radial spoking on the left. Radial front wheels offer mainly esthetic benefits, but half radial rear wheels are substantially more durable than conventional ones. The high amount of dishing called for to make room for more and more sprockets has caused an increase in spoke breakage on the left side of rear wheels. This is caused by metal fatigue.

"A spoked wheel relies on having all of the spokes in constant tension. A highly dished rear wheel starts with very light tension on the left side spokes. The torque of hard pedaling can cause the left side 'leading' spokes to occasionally go completely slack momentarily. Repeated cycles of tension and slackness cause these spokes to fatigue at the bends, and ultimately break.

"With half-radial spoking, the amount of dish is slightly less to begin with if you run the radial spokes up along the inside of its flange. In addition, since there are no 'leading' spokes, no amount of torque on the hub can reduce the tension on any of the spokes. In fact, if you have a customer who has been breaking left side spokes, 'half rebuilding' the wheel into a half radial will solve the problem once and for all."

I'm 195-200 lbs., have a history of breaking spokes, and looking to have some new wheels (CXP33's around Ultegra hubs?) built, and the final question I'd like resolved before having them built is this "to spoke the rear half-radially or not" question. But as seen here, there are conflicting opinions on this! (I've not read Jobst Brandt's book on wheels ("the book" referred to above, I believe), and now I feel I may at a bit of a loss....)

I'd appreciate any guidance y'all can offer, to help resolve my confusion. Thanks!

I haven't read Zinn's book.
I have read Sheldon's article and I don't agree with his conclusion that radial spoking results in a more durable wheel.
Take a rear hub and lace one spoke through th hub in the way Sheldon's article suggests and see what support the spoke elbow has and what area of contact the spoke has with the hub.
Compare and contrast that to what a standard configuration looks like with 3 cross spokes with alternate head-in - head-out and spoke crossing.
Radial spokes have no torsional strength but they do move when pedaling torque is applied. This movement puts more stress on the spoke elbow and the small area of contact between the spoke and hub.
Crossing spokes will also move in response to pedaling torque, but the pulling spokes grow tighter and the "pushing" spokes grow looser. The crossing of a spoke that is tightening with a spoke that is loosening helps keep the "pushing" spokes from going slack. The amount of support for a semi-tangential spoke at the hub helps both spoke and hub durability. There is also a much larger area of contact of a properly built semi-tangential wheel between the spoke and hub surfaces. The larger area of contact helps spread the load.
I don't have the experience of either Zinn or Sheldon Brown, but my experience differs with both of them. My experience with radial lacing is that it wears spoke holes larger and results in the spokes slackening. It's easy to repeat the spoke tensioning cycle until the hub flange gives way or the spoke elbow fatigues and breaks.
I agree with Jobst Brandt. I hope you will read his book before making your final decision.

I agree with Sheldon and Zinn (if he says it) about the bracing angle of heads out radial left spokes is less than the average of the heads-in/heads-out of a typical 3 cross lacing. That helps balance the side to side spoke tension and therefore helps the left spokes carry more of the wheel load.
I like to use rims that provide OSB, offset spoke beds, for rear wheels. The OSB rim helps accomplish the desired balancing of spoke tension and therefore load sharing, from side to side, without resorting to radial spoking.

I call for Chalo and Jobst to bring your thought to this discussion.
 
daveornee <[email protected]> wrote:

> I haven't read Zinn's book. I have read Sheldon's article
> and I don't agree with his conclusion that radial spoking
> results in a more durable wheel.

When the amount of dish places the limiting factor on wheel
strength, moderating this dish with heads-out radial lacing
on the non-drive side is of net benefit. the almost-slack
left spokes resulting from exaggerated dish to accomodate 9
or 10 speeds can contribute almost no structural integrity
to the wheel. Anything a wheelbuilder can do to add tension
to the left side will improve the wheel's ability to carry
load without failing.

> Take a rear hub and lace one spoke through th hub in the
> way Sheldon's article suggests and see what support the
> spoke elbow has and what area of contact the spoke has
> with the hub. Compare and contrast that to what a standard
> configuration looks like with 3 cross spokes with
> alternate head-in - head-out and spoke crossing.

Heads-out radially laced spokes typically show annular
contact between the hub flange and the spoke head. I don't
see how any other arrangement could be significantly better
supported than this.

> Radial spokes have no torsional strength but they do
> move when pedaling torque is applied. This movement puts
> more stress on the spoke elbow and the small area of
> contact between the spoke and hub. Crossing spokes will
> also move in response to pedaling torque, but the
> pulling spokes grow tighter and the "pushing" spokes
> grow looser. The crossing of a spoke that is tightening
> with a spoke that is loosening helps keep the "pushing"
> spokes from going slack.

Radial non-drive side lacing must be paired with highly
tangential drive side lacing if it is to hold up under drive
torques. To me that means x3 for 28 or 32 spokes, or x4 for
36 spokes. As an example, in a 36 spoke wheel, the effective
torque arm for x2 lacing is less than 70% of the effective
torque arm for x4 lacing.

High flanges help even more. Low flanges seem to work OK for
most people, but they just seem like a poor bargain to me,
given that spoke tension fluctuation under torque is
inversely proportional to flange diameter.

If the drive flange is laced adequately to provide
good torsional rigidity, then the left flange does not
need to be.

Note that although what you say about crossing spokes taking
up each other's slack is true, radial spokes don't ever
slacken under torsional windup-- they tighten slightly. If
the right flange spokes are doing their job, though, there
should be no significant windup on the left.

> The amount of support for a semi- tangential spoke at the
> hub helps both spoke and hub durability.

I have no problem with this, but I would disagree with the
implied corollary that a less conformal spoke fit causes
durability problems. Radial lacing is obviously hard on
hubs, as I've never seen tangentially laced spokes tear out
a section of hub flange, but I have seen this repeatedly
with radial and x1 wheels. But the stresses that cause this
sort of hub flange failure are unaffected by comformal
support at the spoke elbows. It's just net radial stress
working on the "perforation" of the hub flange. I have never
observed breakage in radially laced spokes that I could
attribute to insufficient support at the elbow.

> There is also a much larger area of contact of a properly
> built semi- tangential wheel between the spoke and hub
> surfaces. The larger area of contact helps spread the
> load. I don't have the experience of either Zinn or
> Sheldon Brown, but my experience differs with both of
> them. My experience with radial lacing is that it wears
> spoke holes larger and results in the spokes slackening.

To me, that sounds like the wheels in question were built
without enough tangency on the drive spokes, and the non-
drive spokes were required to bear an inappropriate amount
of torsional windup.

> I agree with Sheldon and Zinn (if he says it) about the
> bracing angle of heads out radial left spokes is less than
> the average of the heads-in/heads- out of a typical 3
> cross lacing. That helps balance the side to side spoke
> tension and therefore helps the left spokes carry more of
> the wheel load. I like to use rims that provide OSB,
> offset spoke beds, for rear wheels. The OSB rim helps
> accomplish the desired balancing of spoke tension and
> therefore load sharing, from side to side, without
> resorting to radial spoking.

That is better than any other remedy for a deeply dished
rear wheel. Even better yet is to avoid so much dish by
using a modest cluster and a hub with reasonably equal center-to-
flange dimensions.

Chalo Colina
 
Originally posted by Chalo
<SNIP>
When the amount of dish places the limiting factor on wheel
strength, moderating this dish with heads-out radial lacing
on the non-drive side is of net benefit. the almost-slack
left spokes resulting from exaggerated dish to accomodate 9
or 10 speeds can contribute almost no structural integrity
to the wheel. Anything a wheelbuilder can do to add tension
to the left side will improve the wheel's ability to carry
load without failing.

Heads-out radially laced spokes typically show annular
contact between the hub flange and the spoke head. I don't
see how any other arrangement could be significantly better
supported than this.

<SNIP>

Radial non-drive side lacing must be paired with highly
tangential drive side lacing if it is to hold up under drive
torques. To me that means x3 for 28 or 32 spokes, or x4 for
36 spokes. As an example, in a 36 spoke wheel, the effective
torque arm for x2 lacing is less than 70% of the effective
torque arm for x4 lacing.

High flanges help even more. Low flanges seem to work OK for
most people, but they just seem like a poor bargain to me,
given that spoke tension fluctuation under torque is
inversely proportional to flange diameter.

If the drive flange is laced adequately to provide
good torsional rigidity, then the left flange does not
need to be.

Note that although what you say about crossing spokes taking
up each other's slack is true, radial spokes don't ever
slacken under torsional windup-- they tighten slightly. If
the right flange spokes are doing their job, though, there
should be no significant windup on the left.

<SNIP>
I have no problem with this, but I would disagree with the
implied corollary that a less conformal spoke fit causes
durability problems. Radial lacing is obviously hard on
hubs, as I've never seen tangentially laced spokes tear out
a section of hub flange, but I have seen this repeatedly
with radial and x1 wheels. But the stresses that cause this
sort of hub flange failure are unaffected by comformal
support at the spoke elbows. It's just net radial stress
working on the "perforation" of the hub flange. I have never
observed breakage in radially laced spokes that I could
attribute to insufficient support at the elbow.

<SNIP>
To me, that sounds like the wheels in question were built
without enough tangency on the drive spokes, and the non-
drive spokes were required to bear an inappropriate amount
of torsional windup.

<SNIP>. I like to use rims that provide OSB,
> offset spoke beds, for rear wheels. The OSB rim helps
> accomplish the desired balancing of spoke tension and
> therefore load sharing, from side to side, without
> resorting to radial spoking.

That is better than any other remedy for a deeply dished
rear wheel. Even better yet is to avoid so much dish by
using a modest cluster and a hub with reasonably equal center-to-
flange dimensions.

Chalo Colina [/B]

OK, a few more lessons learned.

Would there be any durability benefit of having tangential spoking on the left side with all the heads pointing out?

The spoke support angle would be decreased a little more and the the tension would therfore be even higher. This would seem to make for even greater balance of sharing the load from right to left.

I have never built a rear wheel with left radial spoking, but I have seen quite a few of them with various spoke and hub problems. I don't have a statistical basis for saying that they aren't as durable except for the fact that I have never seen a broken left rear flange except for a half radial spoked rear wheel. I have also only seen spoke heads pulled through enlarged holes on half radial spoked rear wheels. Since I saw these wheels after they were built and ridden for a while I can't say what the quality of the right side build was. Some problems could have been masked by service at shops along the way, but the spoke hole damage and fatigue can't be undone.

Thanks again for your explanations and sharing your wisdom Chalo.

I wish Jobst would jump in here.