Re: Durable Rims for Road Wheels - Recommendations?

[Steve Sr.]

On Tue, 15 Aug 2006 21:49:04 -0700, jim beam <[email protected]>
wrote:

>Steve Sr. wrote:
>> I am looking to build a set of road wheels and am looking for
>> suggestions for suitable rims. Of course, I would like them to be as
>> light as possible without sacrificing the durability.
>>
>> While we all appreciate a litle nostalgia please limit your
>> suggestions to rims that are still available. Previously I think I
>> remember hearing about Mavic rims being a good choice but not any
>> more. Apparently their quality has suffered in the race for "stupid
>> light" and marketing fad of the day. What would you build up a pair of
>> wheels with today?
>>
>> BTW, I weigh about 160 pounds and the roads in this area are somewhat
>> rough but not too many potholes to hit.
>>
>>
>> Thanks,
>>
>> Steve
>>
>how much do you want to spend? you asked earlier about well sealed hubs
>- if you want them + good rims + a good build, get a mavic cosmos
>wheelset. open-pro type rims, straight pull spokes to resist fatigue,
>and very very well sealed hubs. you'll easily spend the same money on
>hand built wheels with inferior hubs. they cope with my weight just
>fine - your measly #160 is no problem.

Jim,

So you are saying that it is possible to find good, durable, and well
sealed pre-built wheels?

After all of the talk and answers I have been hearing was that if you
wanted wheels that met these criteria you pretty much had to have
them custom made out of select components.

The pre-built wheels seemed to be pretty much like the Real Design
Supersphere "boutique" wheels I currently have. Low spoke count and
inferior components at rip-off pricing. The only thing I have found
good about these wheels is the sealed bearings. The freehub isn't
sealed hardly at all and now at 4000 miles the rear rim has cracked.

I would definitely be interested in looking at complete pre-built
wheels if they meet the well sealed and durable 32 or 36 spoke
criteria. You specifically mentioned the Mavic Cosmos are there others
as well that I should be considering?

It looks like my other option would be to go with Phil hubs and work
up from there since no one has much regard for the sealing on
Shimano's road hubs and I don't think you can put a 10 speed road
cassette on an MTB freehub.

Thanks,

Steve

 

[jim beam]

Steve Sr. wrote:
> On Tue, 15 Aug 2006 21:49:04 -0700, jim beam <[email protected]>
> wrote:
>
>> Steve Sr. wrote:
>>> I am looking to build a set of road wheels and am looking for
>>> suggestions for suitable rims. Of course, I would like them to be as
>>> light as possible without sacrificing the durability.
>>>
>>> While we all appreciate a litle nostalgia please limit your
>>> suggestions to rims that are still available. Previously I think I
>>> remember hearing about Mavic rims being a good choice but not any
>>> more. Apparently their quality has suffered in the race for "stupid
>>> light" and marketing fad of the day. What would you build up a pair of
>>> wheels with today?
>>>
>>> BTW, I weigh about 160 pounds and the roads in this area are somewhat
>>> rough but not too many potholes to hit.
>>>
>>>
>>> Thanks,
>>>
>>> Steve
>>>
>> how much do you want to spend? you asked earlier about well sealed hubs
>> - if you want them + good rims + a good build, get a mavic cosmos
>> wheelset. open-pro type rims, straight pull spokes to resist fatigue,
>> and very very well sealed hubs. you'll easily spend the same money on
>> hand built wheels with inferior hubs. they cope with my weight just
>> fine - your measly #160 is no problem.
>
> Jim,
>
> So you are saying that it is possible to find good, durable, and well
> sealed pre-built wheels?

that's been my experience, yes. i only bought some to see if all the
negative hoopla here on r.b.t was accurate, and have found my
pre-built's to be perfectly reliable. [with the exception of trashing
rims on a giant pothole at least - but that's not the wheel's fault.]

>
> After all of the talk and answers I have been hearing was that if you
> wanted wheels that met these criteria you pretty much had to have
> them custom made out of select components.

sure. a good quality hand built wheel can be a joy, but two factors
stand against them:

1. it's /very/ hard to find a good builder. i've tried about 6
different highly reputable builders here in the san francisco bay area
and only one has proven to me that he can build a wheel that stays true
under my weight. that's len at the bike nook in sf.

2. i was also surprised to discover that low spoke count wheels can be a
substantial benefit when riding in strong cross winds. i proved that to
myself again the other weekend. had a flat so quickly grabbed a spare
32 spoke wheel and used that on my commute across the golden gate
bridge. it was startling how much difference the extra spoke count made
to cross-wind handling. next day, back to normal, 24 count front on the
mavic cosmos, much less wrestling required. try that for yourself some
time.

>
> The pre-built wheels seemed to be pretty much like the Real Design
> Supersphere "boutique" wheels I currently have. Low spoke count and
> inferior components at rip-off pricing. The only thing I have found
> good about these wheels is the sealed bearings. The freehub isn't
> sealed hardly at all and now at 4000 miles the rear rim has cracked.

stick to major brands and make sure they haven't been "helped".

>
> I would definitely be interested in looking at complete pre-built
> wheels if they meet the well sealed and durable 32 or 36 spoke
> criteria. You specifically mentioned the Mavic Cosmos are there others
> as well that I should be considering?

i only mention the cosmos because i have direct personal experience of
them and their hub seal proficiency. i weigh #205 and have found them
to remain perfectly true straight out of the box. they do have the
lower spoke count, but if they work with my weight, they'll /definitely/
work with yours. i've also got a pair of shimano r540's which i've
found reliable, but i wouldn't' recommend them for wet stuff because
they just have standard shimano seals.

>
> It looks like my other option would be to go with Phil hubs

sure. while they'll be just dandy, you'll still be using j-bend spokes
and be dependent on finding a competent wheel builder.

> and work
> up from there since no one has much regard for the sealing on
> Shimano's road hubs and I don't think you can put a 10 speed road
> cassette on an MTB freehub.

i'm pretty sure that if they're both shimano, you can. the freehub
bodies are identical afaik. it's only the 10-speed d/a that can't take
the 9-speed cassette. check sheldon's web site - i think he's got a
cross-compatibility chart.

>
> Thanks,
>
> Steve

 

[Dave Mayer]

"Steve Sr." <[email protected]> wrote in message
news:[email protected]...
> On Tue, 15 Aug 2006 21:49:04 -0700, jim beam <[email protected]>
> wrote:
>
> So you are saying that it is possible to find good, durable, and well
> sealed pre-built wheels?
>

I doubt it. Possible exception: Campagnolo wheels. Big $$ though.

Modern rims are generally poor, as anodizing, machining, seam welding and
the lack of nipple sockets are all major problems. Oh, and the current
generation rims weigh a ton.

I find older rims such as MA2s, Sun M14s and Ambrosio Elites to be clearly
superior.

I get my rims from the basements of older bike shops. I've never paid more
than $35 for a rim. Actually, I rarely pay this for an entire wheel.

Mate the older rims with Shimano cassette hubs, double-butted stainless
spokes, and most importantly a good wheelbuilder, and you have the parts for
a perfect set of wheels.

 

[[email protected]]

On Wed, 16 Aug 2006 21:20:15 -0700, jim beam <[email protected]>
wrote:

[snip]

>2. i was also surprised to discover that low spoke count wheels can be a
>substantial benefit when riding in strong cross winds. i proved that to
>myself again the other weekend. had a flat so quickly grabbed a spare
>32 spoke wheel and used that on my commute across the golden gate
>bridge. it was startling how much difference the extra spoke count made
>to cross-wind handling. next day, back to normal, 24 count front on the
>mavic cosmos, much less wrestling required. try that for yourself some
>time.

[snip]

Dear Jim,

My almost flat, non-aero front rim (not even box section) and 700c x
26 front tire and rim are about 38mm thick.

Most posters would have thicker tire and rim combinations.

At a circumference of about 2100mm, that's 38 x 2100 = 79,800 mm^2 of
tire and rim, as viewed by a side wind.

With about 290mm of my 36 straight 2mm spokes exposed, that's 36 x 290
x 2 = 20,880 mm^2.

Some crude theoretical calculations:

290mm 2mm 38mm 36 32 28 24
spoke spoke rim+tire total spoke spoke spoke spoke
count mm^2 mm^2 mm^2 change change change change
----- ------ -------- ------- ------ ------ ------ ------
36 20,880 79,800 100,680 100.0% 102.4% 104.8% 107.4%
32 18,560 79,800 98,360 97.7% 100.0% 102.4% 105.0%
28 16,240 79,800 96,040 95.4% 97.6% 100.0% 102.5%
24 13,920 79,800 93,720 93.1% 95.3% 97.6% 100.0%

So on my front wheel, it looks as if the simple sideways area changes
only about 5% between 32 and 24 spokes.

My wheel, of course, maximizes this difference with thick 2.0mm
straight spokes and thin rim+tire combination.

With thinner spokes and a thicker box-section or even aero rim, the
effect on area of a spoke count reduction from 32 to 24 would be even
smaller.

With straight 1.8mm spokes (a rough approximation of the kind of thin,
butted spokes often mentioned) and a rim+tire thickness of about 45mm
for a modest box-section with mild aero profile, reducing the exposed
spoke-length to 283mm (like a wheel hanging in my garage) . . .

2100 x 45 = 94,500 mm^2 rim+tire side-view area

36 x 1.8 x 283 = 18,338 mm^2 spoke area

283mm 1.8mm 45mm 36 32 28 24
spoke spoke rim+tire total spoke spoke spoke spoke
count mm^2 mm^2 mm^2 change change change change
----- ------ -------- ------- ------ ------ ------ ------
36 18,338 94,500 112,838 100.0% 101.8% 103.7% 105.7%
32 16,301 94,500 110,801 98.2% 100.0% 101.9% 103.8%
28 14,263 94,500 108,763 96.4% 98.2% 100.0% 101.9%
24 12,226 94,500 106,726 94.6% 96.3% 98.1% 100.0%

This suggests that most posters would see a 3.7% drop in side-view
front wheel+rim+spoke area if they dropped from 32 to 24 spokes (or
gain 3.8% if they added 8 spokes to a 24-spoke wheel).

Aerodynamics is a tricky matter, so raw side area may somehow be
deceptive

But the 8-spoke count reduction sounds like less than a 3% change.

Moving from one kind of rim to another in my poorly stocked garage can
reduce side area from 94,500 mm^2 to 79,800 mm^2, which is 8.4%.
almost three times as much.

The winds on the Golden Gate vary more than that much every day. They
also blow sideways against the handlebars, fork legs, levers, hands,
and arms of the rider.

So I'm curious what the spoke thicknesses and exposed lengths are on
the two wheels that you rode, as well as how thick the tire plus rim
is on each wheel.

The weight would be interesting, too. At speed, a heavier tire and
wheel have more angular momentum and should be more stable in gusting
winds.

Maybe someone will have a link to wind tunnel tests, or an explanation
of how the spokes have a much greater effect than would be expected.

Cheers,

Carl Fogel

 

[Smokey]

Steve Sr. wrote:
> On Tue, 15 Aug 2006 21:49:04 -0700, jim beam <[email protected]>
> wrote:
>
> >Steve Sr. wrote:
> >> I am looking to build a set of road wheels and am looking for
> >> suggestions for suitable rims. Of course, I would like them to be as
> >> light as possible without sacrificing the durability.
> >>
> >> While we all appreciate a litle nostalgia please limit your
> >> suggestions to rims that are still available. Previously I think I
> >> remember hearing about Mavic rims being a good choice but not any
> >> more. Apparently their quality has suffered in the race for "stupid
> >> light" and marketing fad of the day. What would you build up a pair of
> >> wheels with today?
> >>
> >> BTW, I weigh about 160 pounds and the roads in this area are somewhat
> >> rough but not too many potholes to hit.
> >>
> >>
> >> Thanks,
> >>
> >> Steve
> >>
> >how much do you want to spend? you asked earlier about well sealed hubs
> >- if you want them + good rims + a good build, get a mavic cosmos
> >wheelset. open-pro type rims, straight pull spokes to resist fatigue,
> >and very very well sealed hubs. you'll easily spend the same money on
> >hand built wheels with inferior hubs. they cope with my weight just
> >fine - your measly #160 is no problem.
>
> Jim,
>
> So you are saying that it is possible to find good, durable, and well
> sealed pre-built wheels?
>
> After all of the talk and answers I have been hearing was that if you
> wanted wheels that met these criteria you pretty much had to have
> them custom made out of select components.
>
> The pre-built wheels seemed to be pretty much like the Real Design
> Supersphere "boutique" wheels I currently have. Low spoke count and
> inferior components at rip-off pricing. The only thing I have found
> good about these wheels is the sealed bearings. The freehub isn't
> sealed hardly at all and now at 4000 miles the rear rim has cracked.
>
> I would definitely be interested in looking at complete pre-built
> wheels if they meet the well sealed and durable 32 or 36 spoke
> criteria. You specifically mentioned the Mavic Cosmos are there others
> as well that I should be considering?
>
> It looks like my other option would be to go with Phil hubs and work
> up from there since no one has much regard for the sealing on
> Shimano's road hubs and I don't think you can put a 10 speed road
> cassette on an MTB freehub.
>
> Thanks,
>
> Steve

I've had good luck with my custom wheels that were built by Colorado
Cyclist. They've got Ultegra hubs, 36 14ga spokes laced in a cross-3
pattern, and Mavic CXP-33 rims. I haven't had to lay a spoke wrench on
them in over three years, including some rough gravel road riding. I'm
not sure how well sealed they are, though. I haven't done much rain
riding with them.

Smokey

 

[jim beam]

Dave Mayer wrote:
> "Steve Sr." <[email protected]> wrote in message
> news:[email protected]...
>> On Tue, 15 Aug 2006 21:49:04 -0700, jim beam <[email protected]>
>> wrote:
>>
>> So you are saying that it is possible to find good, durable, and well
>> sealed pre-built wheels?
>>
>
> I doubt it. Possible exception: Campagnolo wheels. Big $$ though.
>
> Modern rims are generally poor, as anodizing, machining, seam welding and
> the lack of nipple sockets are all major problems. Oh, and the current
> generation rims weigh a ton.

anodizing protects, machining ensures consistency, welding ensures
strength, consistency and better weight distribution, and the eyelet
thing is a complete red herring. i'm surprised you didn't try to say
that machined rims are thinner:

http://www.flickr.com/photos/38636024@N00/121453841/

>
> I find older rims such as MA2s, Sun M14s and Ambrosio Elites to be clearly
> superior.

er, weight of the ma2 vs. open pro please?

>
> I get my rims from the basements of older bike shops. I've never paid more
> than $35 for a rim. Actually, I rarely pay this for an entire wheel.
>
> Mate the older rims with Shimano cassette hubs, double-butted stainless
> spokes, and most importantly a good wheelbuilder, and you have the parts for
> a perfect set of wheels.
>
>

 

[jim beam]

[email protected] wrote:
> On Wed, 16 Aug 2006 21:20:15 -0700, jim beam <[email protected]>
> wrote:
>
> [snip]
>
>> 2. i was also surprised to discover that low spoke count wheels can be a
>> substantial benefit when riding in strong cross winds. i proved that to
>> myself again the other weekend. had a flat so quickly grabbed a spare
>> 32 spoke wheel and used that on my commute across the golden gate
>> bridge. it was startling how much difference the extra spoke count made
>> to cross-wind handling. next day, back to normal, 24 count front on the
>> mavic cosmos, much less wrestling required. try that for yourself some
>> time.
>
> [snip]
>
> Dear Jim,
>
> My almost flat, non-aero front rim (not even box section) and 700c x
> 26 front tire and rim are about 38mm thick.
>
> Most posters would have thicker tire and rim combinations.
>
> At a circumference of about 2100mm, that's 38 x 2100 = 79,800 mm^2 of
> tire and rim, as viewed by a side wind.
>
> With about 290mm of my 36 straight 2mm spokes exposed, that's 36 x 290
> x 2 = 20,880 mm^2.
>
> Some crude theoretical calculations:
>
> 290mm 2mm 38mm 36 32 28 24
> spoke spoke rim+tire total spoke spoke spoke spoke
> count mm^2 mm^2 mm^2 change change change change
> ----- ------ -------- ------- ------ ------ ------ ------
> 36 20,880 79,800 100,680 100.0% 102.4% 104.8% 107.4%
> 32 18,560 79,800 98,360 97.7% 100.0% 102.4% 105.0%
> 28 16,240 79,800 96,040 95.4% 97.6% 100.0% 102.5%
> 24 13,920 79,800 93,720 93.1% 95.3% 97.6% 100.0%
>
> So on my front wheel, it looks as if the simple sideways area changes
> only about 5% between 32 and 24 spokes.
>
> My wheel, of course, maximizes this difference with thick 2.0mm
> straight spokes and thin rim+tire combination.
>
> With thinner spokes and a thicker box-section or even aero rim, the
> effect on area of a spoke count reduction from 32 to 24 would be even
> smaller.
>
> With straight 1.8mm spokes (a rough approximation of the kind of thin,
> butted spokes often mentioned) and a rim+tire thickness of about 45mm
> for a modest box-section with mild aero profile, reducing the exposed
> spoke-length to 283mm (like a wheel hanging in my garage) . . .
>
> 2100 x 45 = 94,500 mm^2 rim+tire side-view area
>
> 36 x 1.8 x 283 = 18,338 mm^2 spoke area
>
> 283mm 1.8mm 45mm 36 32 28 24
> spoke spoke rim+tire total spoke spoke spoke spoke
> count mm^2 mm^2 mm^2 change change change change
> ----- ------ -------- ------- ------ ------ ------ ------
> 36 18,338 94,500 112,838 100.0% 101.8% 103.7% 105.7%
> 32 16,301 94,500 110,801 98.2% 100.0% 101.9% 103.8%
> 28 14,263 94,500 108,763 96.4% 98.2% 100.0% 101.9%
> 24 12,226 94,500 106,726 94.6% 96.3% 98.1% 100.0%
>
> This suggests that most posters would see a 3.7% drop in side-view
> front wheel+rim+spoke area if they dropped from 32 to 24 spokes (or
> gain 3.8% if they added 8 spokes to a 24-spoke wheel).
>
> Aerodynamics is a tricky matter, so raw side area may somehow be
> deceptive
>
> But the 8-spoke count reduction sounds like less than a 3% change.
>
> Moving from one kind of rim to another in my poorly stocked garage can
> reduce side area from 94,500 mm^2 to 79,800 mm^2, which is 8.4%.
> almost three times as much.
>
> The winds on the Golden Gate vary more than that much every day. They
> also blow sideways against the handlebars, fork legs, levers, hands,
> and arms of the rider.
>
> So I'm curious what the spoke thicknesses and exposed lengths are on
> the two wheels that you rode, as well as how thick the tire plus rim
> is on each wheel.
>
> The weight would be interesting, too. At speed, a heavier tire and
> wheel have more angular momentum and should be more stable in gusting
> winds.
>
> Maybe someone will have a link to wind tunnel tests, or an explanation
> of how the spokes have a much greater effect than would be expected.
>
> Cheers,
>
> Carl Fogel

thanks carl. believe me, the most surprised person on this subject is
me. when i first compared these wheels, i took them both [same rim
profile and tires] and swapped back and forth on the same day same test
route. no doubt about it - the 24-spoker is /much/ less of a wrestle.
the comparison is that when i ride the 32, i have to be alert to both
sudden steering changes as well as balance due to wind on my body,
particularly rounding the northern pylon, with steering being the
dominant concern. on the 24, the dominant issue is balance, not
steering. if you find yourself in sf, i'll loan you the two wheels so
you can try for yourself. oh, and it's also noticeable when riding with
others. two people same place, same wind gust, you can see one deviate
much more than the other.

 

[Matt]

Dave Mayer wrote:
> "Steve Sr." <[email protected]> wrote in message
> news:[email protected]...
> > On Tue, 15 Aug 2006 21:49:04 -0700, jim beam <[email protected]>
> > wrote:
> >
> > So you are saying that it is possible to find good, durable, and well
> > sealed pre-built wheels?
>
> I doubt it. Possible exception: Campagnolo wheels. Big $$ though.

I really like my Campy Protons, typically around $400/pair I think (I
got 'em as part of a kit). And my neighbor's got a pair of Ventos that
are heavy, but pretty inexpensive and durable.

 

[Mike DeMicco]

In article <[email protected]>,
jim beam <[email protected]> wrote:

> and the eyelet thing is a complete red herring.

Why? Eyelets/sockets distribute the load over a wider area and thus the
rims are less likely to crack. All the rims that I've had crack had no
eyelets/sockets.

--
Mike DeMicco <[email protected]>

 

[[email protected]]

On Thu, 17 Aug 2006 08:27:27 -0700, Mike DeMicco
<[email protected]> wrote:

>In article <[email protected]>,
> jim beam <[email protected]> wrote:
>
>> and the eyelet thing is a complete red herring.
>
>Why? Eyelets/sockets distribute the load over a wider area and thus the
>rims are less likely to crack. All the rims that I've had crack had no
>eyelets/sockets.

Dear Mike,

I have no objection to eyelets and sockets, and I expect that they do
exactly what you say.

But the plain 36-spoke rims (no-box-section, no sockets, no eyelets)
on my 1998 Schwinn LeTour lasted around 35,000 miles at a rough guess
with no cracks.

They spun at about 20 mph on daily 15-mile rides that involve about 6
miles of deteriorating bike path with cracked concrete slabs and
endless tree root cracks in the asphalt. (A "Caution Trail Damage"
sign is cheaper than repairs.)

Bike, bags, and rider are about 220 lbs. There's hardly any braking,
so the rims don't wear out.

Cheers,

Carl Fogel

 

[jim beam]

Mike DeMicco wrote:
> In article <[email protected]>,
> jim beam <[email protected]> wrote:
>
>> and the eyelet thing is a complete red herring.
>
> Why? Eyelets/sockets distribute the load over a wider area and thus the
> rims are less likely to crack. All the rims that I've had crack had no
> eyelets/sockets.
>
the herring is the [incorrect] assertion that modern rims are not
double-eyeleted.

 

[[email protected]]

[email protected] wrote:
> Some crude theoretical calculations:

Wires have a long and disreputable history in the field of
aerodynamics. Almost the first thing that airplane designers changed
with the advent of wind tunnel drag testing was to remove external guy
wires, cross braces, and antennas.

If you look at figure 2 here, you'll notice a vast increase in drag
coefficient as reynolds number (a scaling factor, like diameter) is
reduced:

http://www.princeton.edu/~asmits/Bicycle_web/blunt.html

For instance, going from 10^0 to 10^-1 creates 10x less frontal area
(and 100x less cross section), but the CD goes from 10 to over 60,
giving less than a 40% reduction in drag.

> The winds on the Golden Gate vary more than that much every day. They

An example here is that new safety barrier on the inner side. IIRC
there was a long period of calculations to make sure that any new
structure wouldn't drastically increase the drag of the bridge, or
create a Tacoma Narrows Bridge situation.

 

[[email protected]]

On 17 Aug 2006 20:55:14 -0700, [email protected] wrote:

>
>[email protected] wrote:
>> Some crude theoretical calculations:
>
>Wires have a long and disreputable history in the field of
>aerodynamics. Almost the first thing that airplane designers changed
>with the advent of wind tunnel drag testing was to remove external guy
>wires, cross braces, and antennas.
>
>If you look at figure 2 here, you'll notice a vast increase in drag
>coefficient as reynolds number (a scaling factor, like diameter) is
>reduced:
>
>http://www.princeton.edu/~asmits/Bicycle_web/blunt.html
>
>For instance, going from 10^0 to 10^-1 creates 10x less frontal area
>(and 100x less cross section), but the CD goes from 10 to over 60,
>giving less than a 40% reduction in drag.
>
>> The winds on the Golden Gate vary more than that much every day. They
>
>An example here is that new safety barrier on the inner side. IIRC
>there was a long period of calculations to make sure that any new
>structure wouldn't drastically increase the drag of the bridge, or
>create a Tacoma Narrows Bridge situation.

Dear 3T,

Yes, and rotating wires moving forward through side winds are probably
even more disreputable.

Treated as a propellor with 24 or 32 badly-designed blades, the front
wheel could see a 25% reduction in--well, in something-or-other.

And the spokes are going to be 33% further apart, which should have
some effect on their turbulence.

(But some impressive hand-waving may be needed here to remove the rim,
tire, fork, handlebars, rider, and trailing part of the bicycle.)

So it's possible that Jim is indeed feeling exactly what he thinks, a
dramatic difference in handling in cross-winds, the physical result of
removing 8 out of 32 spokes.

But the winds themselves probably vary that much during a typical ride
across the bridge, so I'd love to see some wind tunnel or other
practical demonstration of the side-wind effect.

Cheers,

Carl Fogel

 

[[email protected]]

On 18 Aug 2006 10:44:43 -0700, [email protected] wrote:

[snip]

>You, my friend, are like me. Relatively poor athletically, it is
>almost beyond our comprehension that others can feel some tiny amount
>of change of something which is so much smaller than the minimum change
>we can detect.

[snip]

Dear Doug,

Jim did not say that the change is "some tiny amount" that only he can
detect.

I repeated it, but you snipped it, so here again is what Jim said:

> substantial benefit when riding in strong cross winds. i proved that to
^^^^^^^^^^^^^^^^^^^
> myself again the other weekend. had a flat so quickly grabbed a spare
> 32 spoke wheel and used that on my commute across the golden gate
> bridge. it was startling how much difference the extra spoke count made
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> to cross-wind handling. next day, back to normal, 24 count front on the
> mavic cosmos, much less wrestling required.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
My point is that when we expect a difference, we often feel it quite
sincerely, even if it's not there or something else is affecting
things.

In this case, the side winds on the Golden Gate bridge are notoriously
strong and variable.

Unless you ride two bicycles across the bridge at the same time, a
good deal of the apparent difference is likely to be different
expectations and different wind speeds.

A controlled test could eliminate the psychological expectations and
the physical variation of the wind.

Jim could be substantially right--there could be a large physical
effect.

He could also be partly right--there could be a physical effect, but
rather smaller than he thinks.

And he could be substantially mistaken--there must be a physical
effect, but it could turn out to be so small in testing that even he
would change his mind.

One of the hallmarks of double-blind, controlled testing is that
otherwise sensible people argue that there's no need for it.

We routinely see posts here on RBT about how this or that [fill in the
blank] is so much lighter that the poster can feel the awesome
difference.

The posts are made in good faith.

When the weight differences are plugged into a variety of speed
calculators, the improvement usually amounts to a couple of feet per
mile, a few hundredths of an mph, a couple of seconds per hour, and so
forth.

I'm willing to believe that Jim is mostly right (or partly right, or
mostly mistaken). What's the physics?

Cheers,

Carl Fogel

 

[[email protected]]

[email protected] wrote:

>
> Jim could be substantially right--there could be a large physical
> effect.
....
>
> I'm willing to believe that Jim is mostly right (or partly right, or
> mostly mistaken). What's the physics?
>

Dear Carl,

My mistake, then. I thought you were disputing Jim's claim when you
wrote

>Maybe someone will have a link to wind tunnel tests, or an explanation
>of how the spokes have a much greater effect than would be expected.

But, I guess, the only mystery is how he could possibly have held
incorrect expectations to begin with.

For my own part, things surprise me all the time, so I'm not surprised
that he was surprised.

Cheers,
Doug

 

[Mike Jacoubowsky]

> Dear Mike,
>
> I have no objection to eyelets and sockets, and I expect that they do
> exactly what you say.
>
> But the plain 36-spoke rims (no-box-section, no sockets, no eyelets)
> on my 1998 Schwinn LeTour lasted around 35,000 miles at a rough guess
> with no cracks.
>
> They spun at about 20 mph on daily 15-mile rides that involve about 6
> miles of deteriorating bike path with cracked concrete slabs and
> endless tree root cracks in the asphalt. (A "Caution Trail Damage"
> sign is cheaper than repairs.)

We're talking about very heavy rims (approximately 550-600 grams?), combined
with wider tires (28c? 32?). Is it any wonder that they should last forever?
That option still exists today on some touring bikes and many hybrids.

The need for eyelets & sockets doesn't exist until you get into lighter
designs, with the exception that it's far easier to true a wheel when you
have a brass nipple against an eyelet or socket (made of brass or whatever,
but certainly not aluminum).

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com


<[email protected]> wrote in message
news:[email protected]...
> On Thu, 17 Aug 2006 08:27:27 -0700, Mike DeMicco
> <[email protected]> wrote:
>
>>In article <[email protected]>,
>> jim beam <[email protected]> wrote:
>>
>>> and the eyelet thing is a complete red herring.
>>
>>Why? Eyelets/sockets distribute the load over a wider area and thus the
>>rims are less likely to crack. All the rims that I've had crack had no
>>eyelets/sockets.
>
> Dear Mike,
>
> I have no objection to eyelets and sockets, and I expect that they do
> exactly what you say.
>
> But the plain 36-spoke rims (no-box-section, no sockets, no eyelets)
> on my 1998 Schwinn LeTour lasted around 35,000 miles at a rough guess
> with no cracks.
>
> They spun at about 20 mph on daily 15-mile rides that involve about 6
> miles of deteriorating bike path with cracked concrete slabs and
> endless tree root cracks in the asphalt. (A "Caution Trail Damage"
> sign is cheaper than repairs.)
>
> Bike, bags, and rider are about 220 lbs. There's hardly any braking,
> so the rims don't wear out.
>
> Cheers,
>
> Carl Fogel
>

 

[[email protected]]

On Mon, 21 Aug 2006 07:08:42 GMT, "Mike Jacoubowsky"
<[email protected]> wrote:

>> Dear Mike,
>>
>> I have no objection to eyelets and sockets, and I expect that they do
>> exactly what you say.
>>
>> But the plain 36-spoke rims (no-box-section, no sockets, no eyelets)
>> on my 1998 Schwinn LeTour lasted around 35,000 miles at a rough guess
>> with no cracks.
>>
>> They spun at about 20 mph on daily 15-mile rides that involve about 6
>> miles of deteriorating bike path with cracked concrete slabs and
>> endless tree root cracks in the asphalt. (A "Caution Trail Damage"
>> sign is cheaper than repairs.)
>
>We're talking about very heavy rims (approximately 550-600 grams?), combined
>with wider tires (28c? 32?). Is it any wonder that they should last forever?
>That option still exists today on some touring bikes and many hybrids.
>
>The need for eyelets & sockets doesn't exist until you get into lighter
>designs, with the exception that it's far easier to true a wheel when you
>have a brass nipple against an eyelet or socket (made of brass or whatever,
>but certainly not aluminum).
>
>--Mike-- Chain Reaction Bicycles
>www.ChainReactionBicycles.com
>
>
><[email protected]> wrote in message
>news:[email protected]...
>> On Thu, 17 Aug 2006 08:27:27 -0700, Mike DeMicco
>> <[email protected]> wrote:
>>
>>>In article <[email protected]>,
>>> jim beam <[email protected]> wrote:
>>>
>>>> and the eyelet thing is a complete red herring.
>>>
>>>Why? Eyelets/sockets distribute the load over a wider area and thus the
>>>rims are less likely to crack. All the rims that I've had crack had no
>>>eyelets/sockets.
>>
>> Dear Mike,
>>
>> I have no objection to eyelets and sockets, and I expect that they do
>> exactly what you say.
>>
>> But the plain 36-spoke rims (no-box-section, no sockets, no eyelets)
>> on my 1998 Schwinn LeTour lasted around 35,000 miles at a rough guess
>> with no cracks.
>>
>> They spun at about 20 mph on daily 15-mile rides that involve about 6
>> miles of deteriorating bike path with cracked concrete slabs and
>> endless tree root cracks in the asphalt. (A "Caution Trail Damage"
>> sign is cheaper than repairs.)
>>
>> Bike, bags, and rider are about 220 lbs. There's hardly any braking,
>> so the rims don't wear out.
>>
>> Cheers,
>>
>> Carl Fogel

Dear Mike,

I'm far too lazy to unlace two rear wheels just to compare rim
weights, so instead . . .

dt swiss champion 2.0 straight spokes weigh 444g/64
http://www.dtswiss.com/index.asp?fuseaction=spokes.bikedetail&id=8

dt swiss competition 2.0x1.8x2.0 weigh 382g/64
http://www.dtswiss.com/index.asp?fuseaction=spokes.bikedetail&id=7

brass nipples weigh about ~1gram each

36-spoke straight 2mm Schwinn rear wheel
no box section, no eyelets or sockets
just a simple curved rim
24mm wide, 15mm deep
2lb 10.3 oz = 907.181 + 291.999 = 1199.180 grams

32-spoke 2.0x1.8x2.0 Performance Forte rear wheel
box section, eyelets, sockets
what I had handy
19mm wide, 20mm deep
2lb 7.4 oz = 907.181 +209.786 = 1116.967 grams

simple-rim 36-spoke wheel weighs 1199.180 grams
box-eyelet 32-spoke wheel weighs 1116.967 grams
--------
82.213 grams difference

roughly 294mm spokes on each wheel

294/264 x 444/64 = 7.726 grams / 2.0 straight spoke
294/264 x 382/64 = 6.647 grams / 2.0x1.8x2.0 spoke

So subtract ~4 grams for 32 versus 36 spokes

Subtract ~4 more grams for 32 versus 36 nipples

So if the hubs and freewheels are the same . . .

My simple no-box section Schwinn rim weighs 74 grams more than my
Forte box-section rim with eyelets and sockets, but is also 25% wider
and 25% shallower. This doesn't sound like 550-600 gram rim.

Tires were 700x26 at ~125 psi, bike and rider were ~220 lbs. The
Schwinn rim seems fine after about 35,000 miles of daily 15 mile rides
with about 6 miles of badly deteriorated bicycle path

Cheers,

Carl Fogel

 

[[email protected]]

> Dear Doug,
>
> There's a nice graph on page 3.
>
> What happens at 30 mph to the drag force in pounds as the angle of the
> wind changes from 0 to 20 degrees?
>
> What happens after that, as the wind angle changes from 20 to 30
> degrees?
>
> Those two contradictory trends surprised me.

Dear Carl,

Well, if the wind was all coming from the front, then it would be
hindering the spokes moving forward, but helping the spokes which are
on the bottom half of the rotatation. So it will tend to slow down
the spokes in the top half of the wheel, but not speed up the spokes in
the bottom half, since they are not free to move backwards, being fixed
to the road. So it hinders more than it helps.

A wind coming from the side, however, cares not about the direction of
the movement of the spokes in the inline plane, and helps or hinders
all 36 the same. Apparently it hinders. Since more spokes are visible
from the side then from the front, there are more spokes affected by
wind from 90 than from 0 degrees.

As the angle of attack of the wind changes from 0 to 20 degrees, the
effect of hindrance on the spokes in the top half of the wheel drops
off, and the graph dips. As the angle of attack increases past 20, the
effect it has on all spokes increases, and the graph rises.

Cheers,
Doug

 

[[email protected]]

On 21 Aug 2006 22:35:28 -0700, [email protected] wrote:

>> Dear Doug,
>>
>> There's a nice graph on page 3.
>>
>> What happens at 30 mph to the drag force in pounds as the angle of the
>> wind changes from 0 to 20 degrees?
>>
>> What happens after that, as the wind angle changes from 20 to 30
>> degrees?
>>
>> Those two contradictory trends surprised me.
>
>Dear Carl,
>
>Well, if the wind was all coming from the front, then it would be
>hindering the spokes moving forward, but helping the spokes which are
>on the bottom half of the rotatation. So it will tend to slow down
>the spokes in the top half of the wheel, but not speed up the spokes in
>the bottom half, since they are not free to move backwards, being fixed
>to the road. So it hinders more than it helps.
>
>A wind coming from the side, however, cares not about the direction of
>the movement of the spokes in the inline plane, and helps or hinders
>all 36 the same. Apparently it hinders. Since more spokes are visible
>from the side then from the front, there are more spokes affected by
>wind from 90 than from 0 degrees.
>
>As the angle of attack of the wind changes from 0 to 20 degrees, the
>effect of hindrance on the spokes in the top half of the wheel drops
>off, and the graph dips. As the angle of attack increases past 20, the
>effect it has on all spokes increases, and the graph rises.
>
>Cheers,
>Doug

Dear Doug,

Could be.

But look at the next graph down for the same 30 mph wind at angles
increasing to 30 degrees.

The 404 deep aero rim wheel shows the dip with 16, 20, 24, 0r 28
spokes.

A non-aero rim with 28 shows what might be a faint dip.

The non-aero rim with 32 spokes shows no dip.

Beastly tricky and surprising, like lots of aerodynamics.

A deeper rim is associated with an odd dip in straight-back drag as
the wind angle increases at 30 mph. The dip disappears with more
spokes on shallower rims. I'm baffled as to what the side forces must
be, but it seems reasonable to deduce that they're present.

Cheers,

Carl Fogel

 

[Ron Ruff]

jim beam wrote:
> that may well be the case, but if i have two wheels, same rim profile,
> one high spoke count, the other low, the comparison for /spokes only/ is
> direct and easy.

I was just thinking... side force is one parameter, but wouldn't it be
more important to know where it is relative to the steering axis? Seems
like that is the thing that would upset your handling. If the side
force is equal fore and aft of the steering axis it wouldn't turn the
wheel, but if the center of pressure was towards the front it sure
would!

So the question is... what configuration is most likely to give you the
biggest *unbalanced* side force... or net moment on the steering axis?
I'm still thinking the spokes won't matter much... but it is much too
late to think...