Lacing spokes across plane of wheel
Bluto
wheelbuilding conventions I heard repeated time and again was that
spokes should always lace to the holes on the same side of the rim
centerline (assuming the holes are staggered).
Now I am building a 3-wheeled cargo sidecar. The rear wheels have a
scanty 50mm or so of flange separation, and their 20" rims have
dramatically staggered spoke holes which appear to be about 8mm to
either side of the rim centerline. Thus the bracing angle on the
spokes is pretty darn shallow.
This is of some concern to me since I am aiming for a GVW of about 900
lbs. for this vehicle, and it won't lean in corners. Side loads on
the wheels will be pretty serious. (Design target payload is two
adult riders and two 16-gallon kegs of beer.)
Looking at the rims, I can't see any evidence that the spoke holes are
canted. I assume that if I chose to lace the spokes to the opposite
side of the rim, across the plane of the wheel, I could obtain a much
higher bracing angle to support side loading of the wheels. I'd like
to hear a technical reason that this should not be done, because it
seems like an obvious solution to a potential structural problem. The
fact that it's contrary to wheelbuilding convention is not sufficient
reason for me to avoid trying this fix.
The rims are Araya RB-J1 Himiko freestyle rims in 48 hole drilling.
The hubs are XS BMX hubs with 110mm over locknut spacing. They are
obviously completely satisfactory for single bike use laced the way
they are. But I am concerned that the increase in spoke tension under
heavy side loads will break spokes or worse.
Is lacing across the plane of the wheel likely to help? My impression
is that it will.
Thanks for any input,
Chalo Colina
DirtRoadie
>This is of some concern to me since I am aiming for a GVW of about 900
>lbs. for this vehicle, and it won't lean in corners. Side loads on
>the wheels will be pretty serious. (Design target payload is two
>adult riders and two 16-gallon kegs of beer.)
>Is lacing across the plane of the wheel likely to help? My impression
>is that it will.
If you look at a wheel like a Shimano you will notice that they use this
concept with spokes which run from a hub flange to the sidewall on the
*opposite* side of the rim. I think your analysis makes complete sense, but I
would also be concerned that if the spoke holes are completely uncanted that
increasing the bracing angle might create more problems at the nipple/rim
interface from any increased misalignment (poor seating) at that point and may
offset any benefit which might be derived from the better bracing angle of the
spokes themselves.
Shouldn't be a problem if you stick to "light beer" ;-)
DR
9sDura-Ace
Using conventional components, I laced across the plane of the wheel
as you describe years ago. I built a rear cyclocross wheel using 36
spokes laced to the "wrong" side of the rim holes on a Rigida 13-19
rim. The wheel dies due to other causes (practicing cross with one
huge hit each lap bent the rim), but the other problem was the nipple
binding in the rim as spoke tension increased.
Not having learned my lesson, I tried again. Ironically, another
Rigida rim, this time a 30mm deep one. It had 24 spoke holes, I used
12, which made half the nipples bind. The contrast with the nipples in
the correct holes was what made me finally understand the problem.
If you can live with or overcome that, I think you'll be fine. I don't
think you'll break spokes from side loads, because spokes mostly
loosen when the wheel is loaded.
chump...@hotmail.com (Bluto) wrote in message news:<8b4b7de4.02092...@posting.google.com>...
Bluto
> I don't think you'll break spokes from side loads, because spokes mostly
> loosen when the wheel is loaded.
That's under radial loads (weight bearing loads). Under torsion and
especially under axial (side) loading, half the spokes lose tension
and the other half gain tension.
Side loads are a major wheel killer for this reason.
Chalo Colina
9sDura-Ace
side loaded. Spoke have always been fine. Usually I use the same
spokes and just do a rim swap.
chump...@hotmail.com (Bluto) wrote in message news:<8b4b7de4.02092...@posting.google.com>...
Paul Hays
(in message <8b4b7de4.02092...@posting.google.com>):
Might the rim not be more succeptible to torsional loads? I could see the
rim, in cross section, twisting around a virtual pivot {like a jacob's
ladder childrens toy, with the rim and hub being the wood slats, and the
spokes acting like the cloth straps... }
http://www.Wundersamessammelsurium.de/Mechanisches/AbwaertsNo/index.html
I'm not saying this would neccesarily be a problem in the real world, mind
you. Lacing across the plane is such an obvious solution to the problem of
uneven dish that there must be some inherent problem in it...
p
A Muzi
news:8b4b7de4.02092...@posting.google.com...
mmmm Himiko. Nice rim.
I don't see any reason not to bring a spoke from the left flange to a hole
the right side of the rim*. I agree with you that this would give better
triangulation. In the usual application that's nearly irrelevant but with
your high anticipated sideload it seems very sensible to me.
* Rims with angled spoke sockets would of course obviate swapping sides but
this isn't one of those.
--
Andrew Muzi
http://www.yellowjersey.org
Open every day since 1 April 1971
jobst....@stanfordalumni.org
> I don't see any reason not to bring a spoke from the left flange to
> a hole the right side of the rim*. I agree with you that this would
> give better triangulation. In the usual application that's nearly
> irrelevant but with your high anticipated side load it seems very
> sensible to me.
Shimano does and it has merit, especially when spoke to rim connection
is one that facilitates that as thier's does. The lateral strength of
this wheel is greater than were it not cross spoked.
http://www.shimano-europe.com/cycling/index.phtml
http://www.shimano-europe.com/cycling/phpimages/product/exp_view/WH-7701-F.pdf
> * Rims with angled spoke sockets would of course obviate swapping
> sides but this isn't one of those.
Many rims have their sockets angled and off center. Spoking to the
opposite side on these usually puts a bend in the spoke where it
enters the nipple. This can be ameliorated by "improving the spoke
line" and subsequent stress relieving. This was a common problem in
the days of large flange hubs.
Jobst Brandt <jobst....@stanfordalumni.org> Palo Alto CA
Sheldon Brown
>>I don't see any reason not to bring a spoke from the left flange to
>>a hole the right side of the rim*. I agree with you that this would
>>give better triangulation. In the usual application that's nearly
>>irrelevant but with your high anticipated side load it seems very
>>sensible to me.
Jobst added:
> Shimano does and it has merit, especially when spoke to rim connection
> is one that facilitates that as thier's does. The lateral strength of
> this wheel is greater than were it not cross spoked.
>
> http://www.shimano-europe.com/cycling/index.phtml
> http://www.shimano-europe.com/cycling/phpimages/product/exp_view/WH-7701-F.pdf
>
>>* Rims with angled spoke sockets would of course obviate swapping
>>sides but this isn't one of those.
>
> Many rims have their sockets angled and off center. Spoking to the
> opposite side on these usually puts a bend in the spoke where it
> enters the nipple. This can be ameliorated by "improving the spoke
> line" and subsequent stress relieving. This was a common problem in
> the days of large flange hubs.
...and cross 4 lacing.
It is important that the spokes be plenty long if you do this. The bend
at the nipple needs to be in an un-threaded part of the spoke or the
thread will act as s stress riser.
This "X" lacing is nothing new. If you look at an old automobile with
wire wheels, you'll see that this idea was old before any of us was
born, even me!
It makes most sense for two- or more track vehicles, because they are
subject to much greater lateral stresses than are bicycles, since they
can't lean into corners.
The trendy "half-radial" pattern used on many rear wheels is also quite
old, standard equipment on Model "T" Fords.
Sheldon "What's New?" Brown
+------------------------------------------------+
| What was the real cause of the 1861-65 war? |
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+------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772, 617-244-1040 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com
A Muzi
I opined:
> > I don't see any reason not to bring a spoke from the left flange to
> > a hole the right side of the rim*. I agree with you that this would
> > give better triangulation. In the usual application that's nearly
> > irrelevant but with your high anticipated side load it seems very
> > sensible to me.
<jobst....@stanfordalumni.org> wrote in message
news:YlJl9.32301$Ik.6...@typhoon.sonic.net...
> Shimano does and it has merit, especially when spoke to rim connection
> is one that facilitates that as thier's does. The lateral strength of
> this wheel is greater than were it not cross spoked.
>
> http://www.shimano-europe.com/cycling/index.phtml
>
http://www.shimano-europe.com/cycling/phpimages/product/exp_view/WH-7701-F.p
df
>
> > * Rims with angled spoke sockets would of course obviate swapping
> > sides but this isn't one of those.
>And Jobst further:
> Many rims have their sockets angled and off center. Spoking to the
> opposite side on these usually puts a bend in the spoke where it
> enters the nipple. This can be ameliorated by "improving the spoke
> line" and subsequent stress relieving. This was a common problem in
> the days of large flange hubs.
Yes, we agree.
When I wrote "nearly irrelevant" I meant in the usual Hikima application.
It's a 48 spoke very deep square section rim, usually built into a twenty
inch wheel with large flange hubs. As you note, the effect is more
significant in a 700C clincher with low spoke count.
Mark McMaster
>
> Andrew Muzi writes:
>
> > I don't see any reason not to bring a spoke from the left flange to
> > a hole the right side of the rim*. I agree with you that this would
> > give better triangulation. In the usual application that's nearly
> > irrelevant but with your high anticipated side load it seems very
> > sensible to me.
>
> Shimano does and it has merit, especially when spoke to rim connection
> is one that facilitates that as thier's does. The lateral strength of
> this wheel is greater than were it not cross spoked.
This would be true if the torsional stiffness/strength of
the rim cross-section were adequate to support the new
torsional loads place on it by the widely offset spoke
attachments. Measurements of the lateral stiffness of these
wheels show that they have a relatively low lateral
stiffness (as compared to other wheel with similar rims and
spokes), so I question if the Shimano wheel is able to fully
utilize the greater spoke bracing angle.
See the wheel deflection test at:
http://www.sheldonbrown.com/rinard/wheel/index.htm
Mark McMaster
MMc...@ix.netcom.com
John Schreiber
Much wiser and more experienced fingers have written above, but my
intuition leads me to question the idea of laterally crossed spokes.
When a side load is experienced, very significant in a three-wheeler
as above but far less significant for a bicycle, the stress goes from
the contact point on the road to the hub flange. I don't see how
crossing the spokes from side to side would decrease the stress on the
spoke. If somehow lateral triangulation were being achieved, I could
understand it, but I don't see that.
Similarly in an asymmetrical rear rim, the equalizing of spoke tension
is significant, but the stress from the road to the hub flange still
goes the same way. Since the force is not centered over the rim's
spoke holes, there is a bending force on the rim/nipple interface even
when there is no side force on the rim.
Please help me improve my intuition.
Thanks John Schreiber
jobst....@stanfordalumni.org
> My intuition leads me to question the idea of laterally crossed
> spokes.
> When a side load is experienced, very significant in a three-wheeler
> as above but far less significant for a bicycle, the stress goes
> from the contact point on the road to the hub flange. I don't see
> how crossing the spokes from side to side would decrease the stress
> on the spoke.
Let's take this problem to the limit, a method that often clarifies
what is not so apparent in small variations. With a narrow hub, not
much wider than the rim, and a rim like the Shimano 7700, spokes
attached to the outside walls, spoked un-crossed the hub, rim and
spokes make essentially a parallelogram with no lateral strength.
Laterally crossed the wheel will have significant lateral strength.
> If somehow lateral triangulation were being achieved, I could
> understand it, but I don't see that.
Let's assume paired spoking so that spokes can be tied at their
crossing. This crossing, like tied and soldered conventional spokes,
is functionally static, a node where two TRIANGLES meet. That more or
less explains in situ what is happening, however, actually moving hub
flanges apart together with their spokes until spoke ends met at the
rim at a common point, the actual triangulation would be apparent.
> Similarly in an asymmetrical rear rim, the equalizing of spoke
> tension is significant, but the stress from the road to the hub
> flange still goes the same way. Since the force is not centered
> over the rim's spoke holes, there is a bending force on the
> rim/nipple interface even when there is no side force on the rim.
I think the problem is ignoring the path of forces between endpoints.
The shape and makeup of the connecting structure a large effect as the
first example tries to show. Using the same components, the
configuration of the structure must be designed with ingenuity, to
achieve the desired effect.
Bruce Jackson
> This "X" lacing is nothing new. If you look at an old automobile with
> wire wheels, you'll see that this idea was old before any of us was
> born, even me!
Which reminds me of one of the mysteries I experienced back when I
worked in bike shops.
Was the Weinmann Concave rim a left-handed or right-handed rim?
If you lace the spokes to the closest hole it is an odd-ball
left-handed rim.
If you lace the spokes to the more perpendicular socket on the
other side of the rim it is a more common right-handed rim.
(warning: crude ASCII drawing)
SPOKES-> \ /
X
|\/ \/|
| \_/ |
| RIM |
All of the production bikes I saw that came with these rims had them
laced as left-handed rims without the 'X'. I followed that pattern
but always wondered if the wheels would be stronger crossing over the
spokes.
> Harris Cyclery, West Newton, Massachusetts
> Phone 617-244-9772, 617-244-1040 FAX 617-244-1041
> http://harriscyclery.com
> Hard-to-find parts shipped Worldwide
> http://captainbike.com http://sheldonbrown.com
Bruce Jackson - Sr. Systems Programmer - DMSP
Bluto
> Now I am building a 3-wheeled cargo sidecar. Side loads on
> the wheels will be pretty serious. (Design target payload is two
> adult riders and two 16-gallon kegs of beer.)
>
> Is lacing across the plane of the wheel likely to help? My impression
> is that it will.
< many helpful replies followed >
Thanks all for the valuable, and highly relevant, input. I'll go
ahead with lacing the aforementioned wheels with a lateral crossover,
just to be thorough. Because the beer _must_ get through!
On a related note, I'd like to hear any observations about DT's
"ProHead" spoke nipples. Though I've not tried them, I believe they
have a spherical load bearing surface and may be applicable to these
wheels (or any other wheels with a high deviation from
perpendicularity at the spoke nipple).
Chalo Colina
"riding a kegmobile eliminates the need for a water bottle"
9sDura-Ace
http://seetool.be/sites/sapim/index.php?st=products&sub=nipples
chump...@hotmail.com (Bluto) wrote in message news:<8b4b7de4.0210...@posting.google.com>...
jobst....@stanfordalumni.org
> On a related note, I'd like to hear any observations about DT's
> "ProHead" spoke nipples. Though I've not tried them, I believe they
> have a spherical load bearing surface and may be applicable to these
> wheels (or any other wheels with a high deviation from
> perpendicularity at the spoke nipple).
So I don't know why they make the conical seat spoke nipples at all.
I've always wondered about that. Even with a small angle to the
eyelet, contact (bearing area) is reduced.
They ought to stop making the old cone-heads and be done with it.