Why high-flange hubs on low-spoke count wheels?

Thomas David Kehoe <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

My new Roval wheels (700C, 20 spokes front, 24 rear) have high-flange
hubs. A friend and I were arguing why.

He said that you'd break fewer spokes with high-flange hubs because
the spokes are shorter, hence a shorter lever arm working to snap the
spokes.

I said that higher flanges are equivalent to wider hubs, so the wheel
has more strength side to side. E.g., you can hit a rock while leaned
over and the wheel will flop around less.

We bet lunch so tell me I'm right! :-)

Betcha one JB says you're both wrong, then the other JB says all three of
you are wrong.

Oh, the merriment!

-HW

From: [email hidden] (Thomas David Kehoe)

Quoted message said:

My new Roval wheels (700C, 20 spokes
front, 24 rear) have high-flange hubs. A
friend and I were arguing why.

Quoted message said:

He said that you'd break fewer spokes
with high-flange hubs because the
spokes are shorter, hence a shorter lever
arm working to snap the spokes.

Quoted message said:

I said that higher flanges are equivalent
to wider hubs, so the wheel has more
strength side to side. E.g., you can hit a
rock while leaned over and the wheel will
flop around less.

Quoted message said:

We bet lunch so tell me I'm right! :-)

I suggest you go Dutch. Both arguements have their basis in truth. The
shorther spokes would be stronger, resulting in less breakage. And the
greater angles (as viewed from the edge) caused by the shorter spoke
length would result in the wheel being somewhat stronger laterally as
well.
--
Electronic Anti-Stuttering Devices      
http://www.casafuturatech.com Thomas David Kehoe       Casa Futura
Technologies       (303) 417-9752

- -
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Your Friendly Neighborhood Wheelman

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To E-mail me:
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Thomas David Kehoe said:

My new Roval wheels (700C, 20 spokes front, 24 rear) have
high-flange hubs. A friend and I were arguing why.

Quoted message said:

He said that you'd break fewer spokes with high-flange hubs because
the spokes are shorter, hence a shorter lever arm working to snap
the spokes.

You ought to ask him what forces act on the "lever" he perceives.
Spokes are so flexible that they can be bent effortlessly in hand for
large excursions without exceeding them taking a set (exceeding their
elastic limit). Besides, spokes are loaded only in tension and do not
articulate to any measurable angle with respect to the hub.

Quoted message said:

I said that higher flanges are equivalent to wider hubs, so the
wheel has more strength side to side. E.g., you can hit a rock while
leaned over and the wheel will flop around less.

The widening effect of higher flanges is insignificantly small, being
a cosine effect of small angles near perpendicular. This concept is
brought up now and then on this forum as is the idea that a larger
flange causes less tension changes in spokes from drive torque. Drive
torque is not a significant load until the spoke count gets below
about 20 spokes and even then radial loading is a far greater cyclic
stress that the highest torque induces tension change.

This is a fashion matter that even the manufacturer won't answer get
you to a free lunch. It is much like my quest to find a manufacturer
of sic brakes who could tell me why bicycle discs are full of holes.
They weren't ready for the question and the answers I got seemed to be
constructed on the fly.

Quoted message said:

We bet lunch so tell me I'm right! :-)

Don't wait too long or you'll starve.

Jobst Brandt

"Thomas David Kehoe" wrote: (clip) I said that higher flanges are
equivalent to wider hubs, so the wheel has more strength side to side. E.g.,
you can hit a rock while leaned over and the wheel will flop around less.
(clip)
^^^^^^^^^^^^^^^^
There is another factor that makes the wheel less "floppy" with higher
flanges. Since the spokes are shorter, a given amount of stress will
produce less elongation--hence a stiffer wheel. However, without doing the
math, I'm estimating that the difference will be only a couple (or a few)
percent.

Thomas David Kehoe said:

My new Roval wheels (700C, 20 spokes front, 24 rear) have
high-flange hubs. A friend and I were arguing why.

Quoted message said:

He said that you'd break fewer spokes with high-flange hubs because
the spokes are shorter, hence a shorter lever arm working to snap
the spokes.

You ought to ask him what forces act on the "lever" he perceives.
Spokes are flexible enough that they can be bent effortlessly in hand
for large excursions without exceeding their elastic limit. Besides,
spokes are loaded only in tension and do not articulate to any
measurable angle at the hub.

Quoted message said:

I said that higher flanges are equivalent to wider hubs, so the
wheel has more strength side to side. E.g., you can hit a rock while
leaned over and the wheel will flop around less.

The widening effect of higher flanges is insignificantly small, being
a cosine effect of small angles near perpendicular. This concept is
brought up now and then on this forum as is the idea that a larger
flange causes less drive torque induced tension changes. Drive torque
is not a significant spoke load until the spoke count falls below
about 20 spokes or the spokes are not suitably cross laced. Even with
extra low number of spokes radial loading is a far greater cyclic
stress than the highest torque induces.

This is a fashion matter that even the manufacturer's answer won't get
you to a free lunch. It is much like my quest to find a manufacturer
brakes who could tell me why their bicycle discs are full of holes.
They weren't ready for the question and the answers I got seemed to be
constructed on the fly.

Quoted message said:

We bet lunch so tell me I'm right! :-)

Don't wait too long or you'll starve.

Jobst Brandt

Leo Lichtman said:

Quoted message said:

I said that higher flanges are equivalent to wider hubs, so the
wheel has more strength side to side. E.g., you can hit a rock
while leaned over and the wheel will flop around less...

Quoted message said:

There is another factor that makes the wheel less "floppy" with
higher flanges. Since the spokes are shorter, a given amount of
stress will produce less elongation--hence a stiffer wheel.
However, without doing the math, I'm estimating that the difference
will be only a couple (or a few) percent.

You must wonder how people with 1.8-1.6mm spokes survive on their
floppy spokes. I've done it for years. A 2mm diameter straight gauge
spoke is more than 1.5 times as stiff as a 1.8-1.6mm diameter spoke
and yet the work. Even 1.5mm diameter Revolution DT spokes work well.
I don't think you are aware of the minuscule radial spoke elongation
occurs under the load of a rider. For example, you would have to be
able to feel riding over a sheet of copier paper lying on the road to
feel the difference, that is if you could in succession do that
rapidly with the two kinds of spokes.

Maybe you could explain where this floppiness is perceptible.

Jobst Brandt

Thomas David Kehoe said:

My new Roval wheels (700C, 20 spokes front, 24 rear) have high-flange hubs.
A friend and I were arguing why.

He said that you'd break fewer spokes with high-flange hubs because the
spokes are shorter, hence a shorter lever arm working to snap the spokes.

I said that higher flanges are equivalent to wider hubs, so the wheel has
more strength side to side. E.g., you can hit a rock while leaned over and
the wheel will flop around less.

We bet lunch so tell me I'm right! :-)

spoke leverage between the two lengths is effectively zero - it's not
really a function of spoke length, it's the length of the shank between
the head and the elbow. a small difference there makes a big difference
to the flex loading the elbow experiences. to mitigate breakage, use
decent spokes and make sure the spokes are bedded in correctly or shift
to wheels with straight pull spokes - that way there is no elbow to flex.

if you want to argue difference in effective flange spacing, again, it's
trivial unless you're radial spoking, and even than it's minor. and the
larger flange will be more flexible, so again, advantage is arguable.

personally, i think you two need to go dutch.

Quoted message said:

Leo Lichtman said:

Quoted message said:

I said that higher flanges are equivalent to wider hubs, so the
wheel has more strength side to side. E.g., you can hit a rock
while leaned over and the wheel will flop around less...

Quoted message said:

There is another factor that makes the wheel less "floppy" with
higher flanges. Since the spokes are shorter, a given amount of
stress will produce less elongation--hence a stiffer wheel.
However, without doing the math, I'm estimating that the difference
will be only a couple (or a few) percent.

You must wonder how people with 1.8-1.6mm spokes survive on their
floppy spokes. I've done it for years. A 2mm diameter straight gauge
spoke is more than 1.5 times as stiff as a 1.8-1.6mm diameter spoke
and yet the work. Even 1.5mm diameter Revolution DT spokes work well.
I don't think you are aware of the minuscule radial spoke elongation
occurs under the load of a rider. For example, you would have to be
able to feel riding over a sheet of copier paper lying on the road to
feel the difference

that's one of your favorite bogus examples. you deliberately use it so
the casual reader assumes this is a trivial amount as it is
insignificant compared to road surface roughness, tire flex, etc. in
reality, the magnitude of elasticity you cite is /at the rim/, not the
road surface so this flex is not masked by the tire as you would have
the casual reader believe.

and a 1.5mm revo spoke is 50% more flexible in elongation than a 2.0mm
straight gauge spoke. if you can't feel the difference between two
wheels built with those two different spokes, there's something wrong
with you. and yes jobst, i have two otherwise identical wheels i've
tested with these spokes. they can easily be differentiated [and
differentiated blind according to the friends on which i've tested
them]. oh, and that's ignoring the difference spoke gauge [and hence
elasticity] makes to lateral flexibility which is so helpfully
documented in damon rinard's testing.

Quoted message said:

, that is if you could in succession do that
rapidly with the two kinds of spokes.

Maybe you could explain where this floppiness is perceptible.

Jobst Brandt

In article <[email hidden]>,

Thomas David Kehoe said:

My new Roval wheels (700C, 20 spokes front, 24 rear) have high-flange hubs.
A friend and I were arguing why.

He said that you'd break fewer spokes with high-flange hubs because the
spokes are shorter, hence a shorter lever arm working to snap the spokes.

I said that higher flanges are equivalent to wider hubs, so the wheel has
more strength side to side. E.g., you can hit a rock while leaned over and
the wheel will flop around less.

We bet lunch so tell me I'm right! :-)

You each should do the calculations for your own and the
other's theses. Compare results. I predict that you will
find the differences negligible.

The one true purpose for large hub flanges is high spoke
count wheels where you need the room to keep enough flange
material to support the spokes, and the room to keep
spokes clear from one another in 3x and 4x spoke lacing.

It is said that a high flange on a rear track hub allows
you to lace in a new drive side spoke without removing the
cogwheel.

--
Michael Press

jim beam said:

and a 1.5mm revo spoke is 50% more flexible in elongation than a 2.0mm
straight gauge spoke. if you can't feel the difference between two
wheels built with those two different spokes, there's something wrong
with you.

I do hope you are talking about lateral flexibility here. Otherwise
this is a very silly assertion.

Chalo Colina

Thomas David Kehoe said:

My new Roval wheels (700C, 20 spokes front, 24 rear) have high-flange hubs.
A friend and I were arguing why.

As do my 35-year-old wheels. Everything old is new again.

Quoted message said:

He said that you'd break fewer spokes with high-flange hubs because the
spokes are shorter, hence a shorter lever arm working to snap the spokes.

Nonsense. Spokes break from fatigue. Shorter spokes are less elastic,
thus probably more subject to fatigue. But the differences are not
significant. With 4x 36-spoke wheels, there is no difference in length,
anyway. The spokes are essentially tangential at the hub, so it does not
matter how high the flange, you use the same size spokes. I recently
verified this by swapping out one hub for another. Different flange
heights (high, and higher, actually; I replaced a Shimano Nexus hub with
an old Campy high-flange road hub), same spokes.

Quoted message said:

I said that higher flanges are equivalent to wider hubs, so the wheel
has more strength side to side. E.g., you can hit a rock while leaned
over and the wheel will flop around less.

No. High flanges follow the angle of the spokes (at least my Campy hubs
do), so the bracing angle is the same. But anyway, with the difference
in flange height being basically an inch, it isn't enough to matter.

I always thought high-flange hubs looked cool. And, there is more meat
for the spokes to hang onto. OTOH, they are heavier.

--

David L. Johnson

__o | A mathematician is a machine for turning coffee into theorems.
_`\(,_ | -- Paul Erdos
(_)/ (_) |

Thomas David Kehoe said:

My new Roval wheels (700C, 20 spokes front, 24 rear) have high-flange hubs.
A friend and I were arguing why.

He said that you'd break fewer spokes with high-flange hubs because the
spokes are shorter, hence a shorter lever arm working to snap the spokes.

I said that higher flanges are equivalent to wider hubs, so the wheel has
more strength side to side. E.g., you can hit a rock while leaned over and
the wheel will flop around less.

We bet lunch so tell me I'm right! :-)

There is more metal between the spoke holes with fewer spokes. The
usual failure mode is for part of the flange to rip off.

Why? Because they just look so right! I really like the look of the
little spoked wheel inside the big spoked wheel, and I also like the
way the hub looks like a great big spool. I've got the same wheels on
my new bike.

The wheels make a statement. How something looks is just as important
as how it works. That's especially important on something as personal
as a bicycle.

Thomas David Kehoe said:

My new Roval wheels (700C, 20 spokes front, 24 rear) have high-flange hubs.
A friend and I were arguing why.

He said that you'd break fewer spokes with high-flange hubs because the
spokes are shorter, hence a shorter lever arm working to snap the spokes.

I said that higher flanges are equivalent to wider hubs, so the wheel has
more strength side to side. E.g., you can hit a rock while leaned over and
the wheel will flop around less.

We bet lunch so tell me I'm right! :-)

Fashion. My 1999 Campagnolo Vento deep dish wheels, 14 spokes front,
16 spokes rear, have very low flange hubs.

Zog The Undeniable said:

Thomas David Kehoe said:

My new Roval wheels (700C, 20 spokes front, 24 rear) have
high-flange hubs. A friend and I were arguing why.

He said that you'd break fewer spokes with high-flange hubs because
the spokes are shorter, hence a shorter lever arm working to snap
the spokes. I said that higher flanges are equivalent to wider hubs, so
the
wheel has more strength side to side. E.g., you can hit a rock while
leaned over and the wheel will flop around less.

We bet lunch so tell me I'm right! :-)

There is more metal between the spoke holes with fewer spokes. The
usual failure mode is for part of the flange to rip off.

I was going to say this, but then I realized that the OP was about spokes
breaking.
--
Phil, Squid-in-Training

In article <[email hidden]>,

Quoted post said:

Why? Because they just look so right! I really like the look of the
little spoked wheel inside the big spoked wheel, and I also like the
way the hub looks like a great big spool.

But you've just described our ancient family heirloom, a foot actuated
Necchi sewing machine. Agreed, it's quite attractive.

Quoted message said:

I've got the same wheels on
my new bike. The wheels make a statement.

I thought a wheel should be spun and not heard. But if a wheel makes a
statement and nobody hears it, does it still make a sound? And if the
wheel is spinning, does the declaration emanate from a spirit of
revolution? In the era of the Patriot Act this is a real concern - know
there's a price to pay for babbling Bontragers!

Quoted message said:

How something looks is just as important
as how it works. That's especially important on something as personal
as a bicycle.

Form *just* as important as function?! Only where it concerns the
fairer sex.

Luke

last week, i began lacing a first 700c 36h-forced to as the HD 27"
touring tires are gone-and was amazed by the extra strength (excuse)
immediate apparent from the 27" - for more than spoke length off
course. I wondered if the 32h 700c would approach a 36h 27" capacities?

Quoted message said:

last week, i began lacing a first 700c 36h-forced to as the HD 27"
touring tires are gone-and was amazed by the extra strength (excuse)
immediate apparent from the 27" - for more than spoke length off
course. I wondered if the 32h 700c would approach a 36h 27" capacities?

27 inch tires are easily available, so you didn't really need to rebuild
your wheels for that reason. Also, since there is only a 4mm difference
in radius between the two sizes, the strength difference is tiny. How
are you judging the comparative strenghts of those sizes?

As for your last question, given equal spokes and rims, the 27" wheel
with 36 spokes will be stronger, or at least longer-lasting, than the
32h 700c. Either could easily be strong enough, depending on use.

--
Ted Bennett