i think we're talking at crossed purposes.

for good lateral stability, you want flanges further apart. at what point do you have zero lateral
stability? zero flange separation!

jb

Bruni wrote:
> Vector. The left spokes can only pull leftward to balance the rightward vector regardless of
> angle.Ex: at100kg tension a 10 deg spoke exerts 17.36 kg laterally, 98.5 radially. To balance this
> a 20 deg. spoke is tensioned at approx 51 kg. This nets 48kg. radially. Indeed the radial is
> affected. Tom
>
> --
> Bruni Bicycles "Where art meets science" brunibicycles.com
> 410.426.3420 jim beam <uce@ftc.gov> wrote in message
> news:JZ5ub.2304$Vi.1698@newssvr13.news.prodigy.com...
>
>>it sounds like you're confusing lateral with radial. lateral stability is a function of the angle
>>the spokes make with the hub. the closer the angle to 90 degrees, the less lateral stability. the
>>wider the hub spacing, the more lateral stability.
>>
>>as jobst says, radial is unaffected.
>>
>>jb
>>
>>Bruni wrote:
>>
>>>The statment "laterally softer " is suspect. Left spokes must develop a lateral vector equal to
>>>that on the right, which is the limiting factor
>
> due
>
>>>to space. How you acheive that vector is the only issue. AC does this
>
> with a
>
>>>higher static tension which makes for higher minimums under dynamic
>
> loads,
>
>>>thereby reducing fatigue. You could put the left flange at the dropout
>
> and
>
>>>allyou would have is loose spokes. Left-lateral vector would be the
>
> same-not
>
>>>softer, not stiffer, the same.
>>>
>>>--
>>>Bruni Bicycles "Where art meets science"
>>

On 17 Nov 2003 15:05:34 -0800, Chalo <chumpychump@hotmail.com> wrote:
> I find that minimizing dish, even at the expense of narrower overall flange spacing, makes for
> longer-lasting wheels that stay truer.

> By moving the left flange towards the center, the left side per-spoke tension can increase,
> therefore the total sum spoke tension can increase. A wheel with higher sum tension can bear a
> heavier load.

It seems to me that if you use the near-taco technique (ala "The Bicycle=
=

Wheel") to determine maximal spoke tension, you should reach the *same* =

sum tension regardless of dish. Did I miss something?

-- =

Dave dvt at psu dot edu

"Chalo" <chumpychump@hotmail.com> wrote in message
news:8b4b7de4.0311171505.750b2277@posting.google.com...
> "Phil, Squid-in-Training" <philMuNgEd_lee@hahtmail.com> wrote :
>
> > Quoted from a online dealer:
> >
> > "American Classic Hubs-a stronger wheel. American Classic rear hubs
are
> > different than our competitors hubs. Our flange spacing is narrower
than
> > ordinary hubs...The American Classic narrow flange spacing design
builds a
> > better, stronger rear wheel."
> >
> > Is this BS? Jobst?
>
> Jobst seems to have no serious trouble with dished rear wheels. I do, though. I find that
> minimizing dish, even at the expense of narrower overall flange spacing, makes for longer-lasting
> wheels that stay truer.
>
> When I machined my own hubs, I researched attributes of tandem-specific hubs. I found that many of
> them were symmetrical, even at ordinary over-locknut sizes. I also found that no tandem-specific
> hub of any kind was even close to as asymmetrical as today's road bike hubs. There may be reasons
> other than sound engineering practice that this is so, but tandem use is one of those bicycle
> "tests of truth" that exposes weaknesses in components.
>
> By moving the left flange towards the center, the left side per-spoke tension can increase,
> therefore the total sum spoke tension can increase. A wheel with higher sum tension can bear a
> heavier load.
>
> I chose to use 21mm/28mm c-f spacing, though I could easily have increased the left spacing to
> well over 40mm. Thus I was able to apply a high tension to both sides of the wheel, and I have not
> yet had to touch that wheel even to true it in many thousands of miles. The wheel may be more
> flexible laterally or more vulnerable to side loads than if it had wider left spacing, but so far
> I've seen no ill effects either from it or from a symmetrical Phil Wood tandem-hubbed wheel I have
> with 25mm/25mm flange spacing.

What hub spacing are you running, Chalo? What about using a 140mm tandem hub and having the best of
both worlds -- assuming you have heel clearance and can bend the frame that far. -- Jay Beattie.

dvt <dvt spam@psu.edu> wrote:

> Chalo <chumpychump@hotmail.com> wrote:
>
> > By moving the left flange towards the center, the left side per-spoke tension can increase,
> > therefore the total sum spoke tension can increase. A wheel with higher sum tension can bear a
> > heavier load.
>
> It seems to me that if you use the near-taco technique (ala "The Bicycle Wheel") to determine
> maximal spoke tension, you should reach the *same* sum tension regardless of dish. Did I miss
> something?

Yes. The rim is the limiting factor in spoke tension only when the rim is relatively light or
slender or soft *and* the rim diameter is large. A high spoke count helps buckle the rim too.

However, if a rim is sturdy and the spoke count normal, or especially if the rim diameter is small,
it is entirely possible to apply enough tension to cause spoke breakage, cracking at eyelets, galled
nipples, rounded wrench flats, etc., before causing any buckling of the rim.

Since I don't mess around with feeble rims, I can use the buckling point to set spoke tension if I
am building a 48 spoke road bike wheel, and usually not otherwise. The last wheelset I built this
last weekend used a 700c Alex Adventurer front rim with 36 15ga spokes, and a 24" Alex DX38 rear rim
with 36 14ga spokes. I put 1250N per-spoke tension on the front, and over 1500N on the right side
rear spokes without encountering any signs of imminent rim collapse.

Chalo Colina

"Jay Beattie" <jbeattie@lindsayhart.com> wrote:

> "Chalo" <chumpychump@hotmail.com> wrote:

> > I chose to use 21mm/28mm c-f spacing, though I could easily have increased the left spacing to
> > well over 40mm.
>
> What hub spacing are you running, Chalo? What about using a 140mm tandem hub and having the best
> of both worlds -- assuming you have heel clearance and can bend the frame that far.

Heel clearance isn't an issue with that bike, since it has 18" chainstays. But it's an older
Cannondale with huge thick stays, and cold setting the dropouts to a wider spacing would probably
require a hydraulic jack.

I measured 128mm between relaxed dropout faces, so that's how wide I made my hub.

That old Phil tandem hub I mentioned is 130mm, and I put it in an old Nishiki frame that had to be
bent open from 120mm spacing.

140mm or even 160mm spacing would be fine with me, but I've not had occasion to use it. I would only
require it in order to use a cassette hub, and I would only require a cassette hub in order to run 8
or more speeds, which seems like a bad idea given my chain loads.

Chalo Colina

"Bruni" <brunibik@bcpl.net> writes:

> <jobst.brandt@stanfordalumni.org> wrote in message news:s29ub.6915$Wy2.107427@typhoon.sonic.net...
> >
> > Bruni <brunibik@bcpl.net> writes:
> >
> > > The statement "laterally softer " is suspect. Left spokes must develop a lateral vector equal
> > > to that on the right, which is the limiting factor due to space. How you achieve that vector
> > > is the only issue. AC does this with a higher static tension which makes for higher minimums
> > > under dynamic loads, thereby reducing fatigue.

All spokes must achieve a radial vector, or the wheel will collapse under load. The bracing angle of
the right spokes in a highly dished wheel is almost nonexistant, so there is very little lateral
force vector in that direction. Hence the left side spokes have little to compensate to center the
rim in the dropouts, and because of the much larger bracing angle they cannot achieve much by way of
the radial vector.

Because the horizontal dimension is so much smaller than the radial dimension, the wheel is much
weaker laterally than vertically (radially if you prefer). As Bontrager, Brandt and others have
pointed out, however, bracing angle of the spokes is in fact a significant factor because, unlike
vertical loading, side loads result in a tension increase on one side and a tension decrease on
the other. Reducing the bracing angle by moving the spoke flanges in board will have the result of
increasing the radial tension vector; since it is the left flange that's moved in, the right
flange already being nearly in the centerline, left side spoke tension increases. There are
benefits to this. The downside is that the bracing angel is reduced and the wheel loses lateral
strength as a result.

> > I think you miss the significance of "laterally softer" which means wheel collapse is more
> > likely. Besides, when standing and leaning the bicycle from side to side, the top of the wheel
> > moves to the same side as the bottom, in a classic taco initiation move. That is why rear brakes
> > drag on climbs and why the close spacing of a dual pivot brake made racers open the QR (and fail
> > to close
> > it) on climbs.

<snip>

> > Besides all that, rear wheel lateral collapse is more of a threat with such narrow hubs. I'm
> > sure you've seen riders skid the rear wheel in a tight spot in a race and get crossed up. That's
> > when the wheel can and has collapsed.
> >
> > > You could put the left flange at the dropout and all you would have is loose spokes.
> > > Left-lateral vector would be the same-not softer, not stiffer, the same.
> >
> > You choose an extreme to make you point but it is invalid because no practical person would
> > choose to build a 4:1 (right-left) tensioned wheel. Just the same, until the left spokes go
> > slack, they are part of the lateral stiffness to either side. It's another "standing on the
> > spokes" example. They are part of the elastic equation until slack.
>
> Why would a practical person choose to build a2:1 wheel when they could build a nearly 1:1 wheel
> (Ritchey). The claim that these wheels are more prone to collapse is conjecture.

The conjecture of a person who has done extensive FEA analysis of bicycle wheels, that is. Hmm,
didn't Damon Rinard do some measurements of deflection under lateral loads? (Rhetorical question).
He did and his page on this is instructive, including his discussion of left flange placement.

http://www.sheldonbrown.com/rinard/wheel/index.htm

> Bruni Bicycles "Where art meets science"

And top posting flourishes.

dvt <dvt spam@psu.edu> wrote:
>> It seems to me that if you use the near-taco technique (ala "The Bicy=
cle
>> Wheel") to determine maximal spoke tension, you should reach the *sam=
e*
>> sum tension regardless of dish. Did I miss something?

Chalo <chumpychump@hotmail.com> wrote:
> Yes. The rim is the limiting factor in spoke tension only when the rim is relatively light or
> slender or soft *and* the rim diameter is large. A high spoke count helps buckle the rim too.
>
> However, if a rim is sturdy and the spoke count normal, or especially if the rim diameter is
> small, it is entirely possible to apply enough tension to cause spoke breakage, cracking at
> eyelets, galled nipples, rounded wrench flats, etc., before causing any buckling of the rim.

Yes, we have different assumptions. My assumption is that the rim is =

beefy enough to avoid cracking at eyelets (let's not start that whole =

anodized rim thread again). But the rim is "soft" enough that it begins=
=

to buckle before the spokes and nipples start to fail. I can see where = my =

assumptions may be invalid when it comes to the downhill-specific MTB =

rims. I have no experience with such creatures. And I generally use 32=
=

spokes, although I have used 28 on one front wheel and 36 on a few =

others. So my rims (MA2, Open Pro and the like) are generally "softer" =

than the spokes.

I'm considering building a set of aero wheels. The deep section rim =

combined with a lower spoke count might put me in the regime of spoke =

failure before rim buckling. I'll keep that in mind if I decide to fork=
=

out the cash for the wheels.

-- =

Dave dvt at psu dot edu

<snip>

I'm considering building a set of aero wheels. The deep section rim combined with a lower spoke
count might put me in the regime of spoke failure before rim buckling. I'll keep that in mind if I
decide to fork out the cash for the wheels.

--
Dave dvt at psu dot edu

You can usually tell when enough is enough. If you're building a DeepV wheelset, the spokes don't
need to be tensioned too much higher than normal. (if any).

Mike