Any disadvantages of asymmetric rims?

Discussion in 'Cycling Equipment' started by Konstantin Shem, May 29, 2003.

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  1. An asymmetric rim on the rear allows for a smaller dish, or even no dish at all.

    Why are they not used very widely? Is an asymmetric rim in some respect weaker by itself, than a
    symmetric rim of comparable weight and quality?

    Or, put it this way. Imagine a |_| -shaped rim and two options. First, drill holes in the middle and
    build a strongly dished wheel. Second, drill holes offset to the left and build it less-dished. Will
    the second option be superior to the first one in any aspect, or (as I guess) the rim itself will
    get noticeably weaker?

    Thanks in advance.
    --
    Konstantin Shemyak

    Remove the 2 parts from the "reply-to"
     
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  2. Jobst Brandt

    Jobst Brandt Guest

    Konstantin Shemyak writes:

    > An asymmetric rim on the rear allows for a smaller dish, or even no dish at all.

    > Why are they not used very widely? Is an asymmetric rim in some respect weaker by itself, than a
    > symmetric rim of comparable weight and quality?

    > Or, put it this way. Imagine a |_| -shaped rim and two options. First, drill holes in the middle
    > and build a strongly dished wheel. Second, drill holes offset to the left and build it
    > less-dished. Will the second option be superior to the first one in any aspect, or (as I guess)
    > the rim itself will get noticeably weaker?

    It means you need to stock two kinds of rims for a bicycle with the "same" rim front and rear. Spoke
    pull-out from a rim is dependent on two factors, maximum spoke tension (when wheel is unloaded) and
    varying spoke tension (the cyclic untensioning of spokes with each wheel rotation due to rider
    weight). You can't do much about the dynamic load but lowering spoke preload reduces incidence of
    rim cracking around spokes, something that happens around right side rear spokes more often.

    Therefore, reducing dish, or spoke tension disparity from left to right is the main bonus, and it is
    worth doing in some of the more severe cases of asymmetric rear wheels. As long as I can get away
    with it, I am going to use symmetric rims, but then I run 120mm dropout spacing and fewer gears than
    are considered necessary these days.

    Jobst Brandt [email protected] Palo Alto CA
     
  3. konstantin-<< An asymmetric rim on the rear allows for a smaller dish, or even no dish at all.

    Why are they not used very widely?

    More expensive to make, tough to use eyelets.

    Great idea but more expensive to drill off center...

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

    Matt O'Toole Guest

    "Qui si parla Campagnolo" <[email protected]> wrote in message
    news:[email protected]...

    > konstantin-<< An asymmetric rim on the rear allows for a
    smaller dish, or
    > even no dish at all.
    >
    > Why are they not used very widely?
    >
    > More expensive to make, tough to use eyelets.
    >
    > Great idea but more expensive to drill off center...

    That may be true, but note that current asymmetric models (Bontrager, Ritchey) are the same price or
    cheaper than popular non-asymmetric ones (Mavic).

    Matt O.
     
  5. In article <[email protected]>, Matt O'Toole <[email protected]> wrote:
    >
    >"Qui si parla Campagnolo" <[email protected]> wrote in message
    >news:[email protected]...
    >
    >> konstantin-<< An asymmetric rim on the rear allows for a
    >smaller dish, or
    >> even no dish at all.
    >>
    >> Why are they not used very widely?
    >>
    >> More expensive to make, tough to use eyelets.
    >>
    >> Great idea but more expensive to drill off center...
    >
    >That may be true, but note that current asymmetric models (Bontrager, Ritchey) are the same price
    >or cheaper than popular non-asymmetric ones (Mavic).

    I haven't seen an OCR rim for a road bike that has eyelets. Does such a thing exist?

    --Paul
     
  6. David Ornee

    David Ornee Guest

    "Paul Southworth" <[email protected]> wrote in message
    news:eek:tNBa.35535$A%[email protected]...
    > In article <[email protected]>, Matt O'Toole <[email protected]> wrote:
    > >
    > >"Qui si parla Campagnolo" <[email protected]> wrote in message
    > >news:[email protected]...
    > >
    > >> konstantin-<< An asymmetric rim on the rear allows for a
    > >smaller dish, or
    > >> even no dish at all.
    > >>
    > >> Why are they not used very widely?
    > >>
    > >> More expensive to make, tough to use eyelets.
    > >>
    > >> Great idea but more expensive to drill off center...
    > >
    > >That may be true, but note that current asymmetric models (Bontrager, Ritchey) are the same price
    > >or cheaper than popular non-asymmetric ones (Mavic).
    >
    > I haven't seen an OCR rim for a road bike that has eyelets. Does such a thing exist?
    >
    > --Paul

    Yes. Check out the Bontrager Fairlane OSB at URL:
    http://www.bontrager.com/rims/detail.asp?id=109&pt=6 22 mm wide and 560 g... it's not light and
    skinny, but it is 700C with eyelets.

    David Ornee, Western Springs, IL
     
  7. David Ornee

    David Ornee Guest

    "David Ornee" <[email protected]> wrote in message
    news:[email protected]...
    >
    > "Paul Southworth" <[email protected]> wrote in message
    > news:eek:tNBa.35535$A%[email protected]...
    > > In article <[email protected]>, Matt O'Toole <[email protected]>
    > > wrote:
    > > >
    > > >"Qui si parla Campagnolo" <[email protected]> wrote in message
    > > >news:[email protected]...
    > > >
    > > >> konstantin-<< An asymmetric rim on the rear allows for a
    > > >smaller dish, or
    > > >> even no dish at all.
    > > >>
    > > >> Why are they not used very widely?
    > > >>
    > > >> More expensive to make, tough to use eyelets.
    > > >>
    > > >> Great idea but more expensive to drill off center...
    > > >
    > > >That may be true, but note that current asymmetric models (Bontrager, Ritchey) are the same
    > > >price or cheaper than popular non-asymmetric ones (Mavic).
    > >
    > > I haven't seen an OCR rim for a road bike that has eyelets. Does such a thing exist?
    > >
    > > --Paul
    >
    > Yes. Check out the Bontrager Fairlane OSB at URL:
    > http://www.bontrager.com/rims/detail.asp?id=109&pt=6 22 mm wide and 560 g... it's not light and
    > skinny, but it is 700C with eyelets.
    >
    > David Ornee, Western Springs, IL
    Also 700C Ritchey PRO Trekking OCR @ 23 mm wide and 480 g. There are versions without eyelets as
    well. See URL: http://www.ritcheylogic.com/trpdfcharts/rims.pdf near the bottom of the chart.

    David Ornee
     
  8. Matt O'Toole

    Matt O'Toole Guest

    "Qui si parla Campagnolo" <[email protected]> wrote in message
    news:[email protected]...

    > Matt-<< That may be true, but note that current asymmetric
    models
    > (Bontrager, Ritchey) are the same price or cheaper than popular non-asymmetric ones (Mavic).
    >
    > I'm guessing it has something to do with country of
    manufacture...Asia vs
    > France and/or Australia
    >
    > There is no doubt having front and back rim models are
    more expensive than just
    > having one. The reason for threadeless, afterall...to save
    money.

    All true, but what I'm getting at is that manufacturing cost has little to do with selling price.
    Price is set by the market, or perhaps in this case, the market's response to advertising. Mavic are
    more expensive because they've built their brand name with glammy ads, cute store displays, etc.

    Aren't Velocity rims (Australia) generally a bit cheaper than the others? Also, until recently, Sun
    rims (USA) were cheap too.

    Matt O.
     
  9. Precious Pup

    Precious Pup Guest

    Matt O'Toole wrote:
    >
    > "Qui si parla Campagnolo" <[email protected]> wrote in message
    > news:[email protected]...
    >
    > > Matt-<< That may be true, but note that current asymmetric
    > models
    > > (Bontrager, Ritchey) are the same price or cheaper than popular non-asymmetric ones (Mavic).
    > >
    > > I'm guessing it has something to do with country of
    > manufacture...Asia vs
    > > France and/or Australia
    > >
    > > There is no doubt having front and back rim models are
    > more expensive than just
    > > having one. The reason for threadeless, afterall...to save
    > money.
    >
    > All true, but what I'm getting at is that manufacturing cost has little to do with selling price.

    Assuming there isn't much competition, that will be true to some extent. There is some competition
    -- multiple manufacturers want your business. It may not be "perfect competition," but it isn't
    quite an oligarchy either. If you only see what a few of the more famous MO houses have to order,
    you might think the rim marketplace is an oligarchy.

    > Price is set by the market, ...

    Well, yeah. It ain't like government cheese.

    > ... or perhaps in this case, the market's response to advertising.

    It is still the marketplace setting the price. To say that "perception" doesn't count in how prices
    are set in a market is meaningless. You deal with it as a market participant whether you think those
    perceptions are wrong or right.

    > Mavic are more expensive because they've built their brand name with glammy ads, cute store
    > displays, etc.

    I think they made good rims too; some would say this is past tense though. I think they cost too
    much and don't see myself buying or recommending them.

    > Aren't Velocity rims (Australia) generally a bit cheaper than the others? Also, until recently,
    > Sun rims (USA) were cheap too.

    Check Nashbar for blowouts. You can get whole wheelsets for under $100.
     
  10. Precious Pup

    Precious Pup Guest

    David Ornee wrote:
    >

    > Yes. Check out the Bontrager Fairlane OSB at URL:

    Yes, the Fairlane has eyelets, but they are only single. I like double eyelets the best. It seems
    like double eyelets would make a stronger-lighter rim since the tension could be distributed across
    two surfaces rather than one. Then again, I'm guessing.
     
  11. Snoopy

    Snoopy Guest

    On Fri, 30 May 2003 06:31:03 GMT, [email protected] wrote:

    >
    > Spoke pull-out from a rim is dependent on two factors, maximum spoke tension (when wheel is
    > unloaded) and varying spoke tension (the cyclic untensioning of spokes with each wheel rotation
    > due to rider weight). You can't do much about the dynamic load but lowering spoke preload reduces
    > incidence of rim cracking around spokes, something that happens around right side rear spokes
    > more often.
    >
    >

    Increasing the tension in the spoke means that the change in strain of the spoke is reduced under
    normal riding conditions. This is because the cyclic decrease in spoke tension as the wheel goes
    around for a given rider weight is relatively less if the static tension in the wheel is higher.

    Correspondingly the 'equal and opposite' (according to Newton's Third Law) change in tension in each
    of the associated spoke nipples and rim holes should also be reduced. Would this not reduce the
    fatigue load on the spoke holes, and so increase their durability?

    I do not understand how "lowering spoke preload reduces incidence of rim cracking around spokes."
    Can anyone explain that for me please?

    Furthermore, is spoke hole cracking really an issue on an unanodized rim and wheel that has been
    built in accordance with "the book"?

    >
    >
    >Therefore, reducing dish, or spoke tension disparity from left to right is the main bonus, and it
    >is worth doing in some of the more severe cases of asymmetric rear wheels. As long as I can get
    >away with it, I am going to use symmetric rims, but then I run 120mm dropout spacing and fewer
    >gears than are considered necessary these days.
    >
    >

    The more dish on a wheel, then potentially the weaker it is from a fatigue point of view. This I
    understand from the relative forces
    (DS/NDS) required to build the static wheel structure.

    I don't run a nine speed cluster either, but are you saying that a nine speed cluster makes a rear
    wheel so assymmetric that it cannot be built to an acceptable touring standard of durability. Even
    if all the instructions in "the Bicycle Wheel" are followed concisely?

    SNOOPY

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  12. David Kunz

    David Kunz Guest

    Snoopy wrote: ...
    > I do not understand how "lowering spoke preload reduces incidence of rim cracking around spokes."
    > Can anyone explain that for me please?
    >
    > Furthermore, is spoke hole cracking really an issue on an unanodized rim and wheel that has been
    > built in accordance with "the book"?
    ... IME, cracking at the spoke holes is a straight pull phenomena. It has only happened to me with
    tightly spoked rims.

    David
     
  13. Snoopy

    Snoopy Guest

    On Sat, 07 Jun 2003 10:32:52 GMT, David Kunz <[email protected]> wrote:

    >Snoopy wrote:
    >
    >... IME, cracking at the spoke holes is a straight pull phenomena. It has only happened to me with
    >tightly spoked rims.
    >

    If rim cracking was just a 'straight pull phenomena', then the maximum pull on the spoke is when
    the wheel was built in the first place. All subsequent loading on the wheel *reduces* the pull on
    the spoke.

    This means that if you built two identical wheels and put one on a courier bike that was used
    sixteen hours a day, and the other under your bed, the rim under your bed would fail first. Unless
    you fell through your bed slats directly onto the wheel under your bed, this seems very unlikely!

    I accept your experience but offer an alternative explanation. The rim that cracked was defective in
    the metallurgy of its construction. What sort of rim was it that failed on you?

    SNOOPY

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  14. David Kunz

    David Kunz Guest

    Snoopy wrote:
    > On Sat, 07 Jun 2003 10:32:52 GMT, David Kunz <[email protected]> wrote:
    >
    >
    >>Snoopy wrote:
    >>
    >>... IME, cracking at the spoke holes is a straight pull phenomena. It has only happened to me with
    >>tightly spoked rims.
    >>
    >
    >
    > If rim cracking was just a 'straight pull phenomena', then the maximum pull on the spoke is when
    > the wheel was built in the first place. All subsequent loading on the wheel *reduces* the pull on
    > the spoke.
    >
    > This means that if you built two identical wheels and put one on a courier bike that was used
    > sixteen hours a day, and the other under your bed, the rim under your bed would fail first. Unless
    > you fell through your bed slats directly onto the wheel under your bed, this seems very unlikely!
    >
    > I accept your experience but offer an alternative explanation. The rim that cracked was defective
    > in the metallurgy of its construction. What sort of rim was it that failed on you?
    >
    > SNOOPY
    >

    Good point about the bed thing :). All I know is that tighter rims do it for me. I've had problems
    with rims: either the tight ones break at the spoke holes or the slightly looser ones break under
    the rim tape between spoke holes. This is on mountain bikes riden about 80% on the road 20% on
    trails (some of which get pretty rough :)). I build my own wheels and use a tensiomenter to check
    final tension; they're evenly tensioned, stress relieved, and I've started running them through the
    wheel builder at my LBS for a final check because of the problems <sigh>.

    BUT, a Mavic 225 (Cannondale OEM) and a Mavic 219 are the ones that cracked at the spoke holes; a
    223, 225 (the warranty replacement of the one that split at the spoke holes), 519 and a Bontranger
    Mustang split under the rim tape. It's been rumored here that Mavic has problems with it's hard
    anodizing.

    David
     
  15. Snoopy

    Snoopy Guest

    On Sun, 08 Jun 2003 09:35:42 GMT, David Kunz <[email protected]> wrote:

    >
    > I've had problems with rims: either the tight ones break at the spoke holes or the slightly looser
    > ones break under the rim tape between spoke holes. This is on mountain bikes riden about 80% on
    > the road 20% on trails (some of which get pretty rough :)). I build my own wheels and use a
    > tensiomenter to check final tension; they're evenly tensioned, stress relieved, and I've started
    > running them through the wheel builder at my LBS for a final check because of the problems <sigh>.
    >
    >BUT, a Mavic 225 (Cannondale OEM) and a Mavic 219 are the ones that cracked at the spoke holes; a
    >223, 225 (the warranty replacement of the one that split at the spoke holes), 519 and a Bontranger
    >Mustang split under the rim tape. It's been rumored here that Mavic has problems with it's hard
    >anodizing.
    >

    In the absence of the real thing, I will call upon the 1998 version of Jobst and what he wrote about
    hard anodizing of rims in the FAQ

    http://draco.acs.uci.edu/rbfaq/FAQ/8c.2.html

    Given Jobst's silence on this thread since he made the claim that

    "lowering spoke preload reduces incidence of rim cracking around spokes"

    I am wondering if he had a 'senior moment' and forgot what he wrote in the rec.bike FAQ in 1998 on
    the subject of rim failure.

    I think you can take it from the FAQ reference that the main problem with Mavic's 'hard anodizing'
    is that they decided to do it in the first place!

    It sounds like you David, know what you are doing regarding the nuts and bolts of building wheels.
    Perhaps if, next time, you tried a plain vanilla rim with a simple brushed alloy finish and eyelets,
    your rim cracking problems would disappear?

    SNOOPY

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  16. In article <[email protected]>, (Snoopy)
    [email protected]*et.*z.*is'n' wrote:

    > Perhaps if, next time, you tried a plain vanilla rim with a simple brushed alloy finish and
    > eyelets, your rim cracking problems would disappear?

    I had two Mavic X-517 silver rims - purchased about two years apart from different shops - crack at
    the drive-side spoke nipples. (Yes, they are anodized, but not "hard anodized".) I am now using the
    slightly heavier Mavic X-618 with double eyelets, and these have held up so far.

    The X-618s were the only rims with double eyelets I could find, otherwise I wouldn't have chosen a
    Mavic product again.
    --
    Lambert Dickmeis <[email protected]
     
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