Spoke Tension of Radial/3x rear wheel



B

Bestest Handsander

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"
 
Bestest Handsan 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! :)
> 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]
 
paul-<< 4. Double butted spokes help make the wheel more durable.

In what way will the wheel be more durable? >><BR><BR>

Both can make for a strong, durable wheel but dbl butted, with the inherit
'give' does make a more durable wheel, I agree with Dave on this one

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"
 
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"
 
On 27 Apr 2004 12:38:40 GMT, [email protected] (Qui si parla
Campagnolo ) wrote:

>paul-<< 4. Double butted spokes help make the wheel more durable.
>
>In what way will the wheel be more durable? >><BR><BR>
>
>Both can make for a strong, durable wheel but dbl butted, with the inherit
>'give' does make a more durable wheel, I agree with Dave on this one


I build with butted spokes. Lately, on 32 spoke wheels, 1.8/1.6.
I've used 2.0/1.8, 2.0, 1.8 and on a rear wheel, 2.0x1.8 DS and 1.8
NDS.

It takes me a long time to build a wheel but I build them using the
technique in "The Bicycle Wheel". I have not seen any difference in
the durability. My oldest wheel, a Wolber 59 rim x 36 hole XT hub and
2.0 guage spokes has been around since '92. At first a touring bike
wheel but years as a tandem rear wheel. It's still a good wheel.
 
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
> <[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
 
Zog-<< That must be the least subtle Campag sales pitch I've ever read ;-)
>><BR><BR>



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 what me peepers SAW...

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



--