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Total wheel Failure

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Cycling Equipment
Published
6 June 2006
Last activity
13 June 2006
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  1. 41 said:


    Quoted message said:

    Not mine, but a friends.

    Your thoughts?

    Currently the server is slow, so it may take a bit to load.

    http://bikeforums.net/showthread.php?t=201510

    I have not used this rim, but from the pictures, the walls look
    extremely thin. As others have noted, 37mm tires at 85psi is
    unnecessarily, even strangely high, and exerts a lot of force. There
    may have been some contributory defect in the rim, perhaps some
    cracking.

    Advice: (1) avoid this rim; (2) what is the point of running 37mm at
    85psi? 32mm at that pressure is already ouch ouch ouch, try 50-60 at
    most, and use a more suitable rim width; (3) ensure spokes properly
    tensioned a la Jobst.

    The Velox rim tape held up well though.

    Dear 41,

    "Wilderness Trail Bikes"

    "WTB Slickasaurus 700x37 Hybrid Tire"

    "The Slickasaurus is well suited for city streets, gravel, DG, and
    hard pack dirt roads. Wire bead, inflate 50-80psi.700x37 Black 460g."

    http://www.nashbar.com/profile.cfm?category=&subcategory=&brand=1246&sku=13703&storetype=&estoreid=&pagename=

    So 85 psi on a 50-85 psi tire, but I can't see any mention of what
    specific Mavic rim was used on this "36-spoke, 3-cross, custom built,
    tensioned, and true" wheel with only 500 miles. Knowing what Mavic rim
    was used might show if 85 psi on a 700x37 tire was the culprit.

    Cheers,

    Carl Fogel

  2. Quoted message said:
    41 said:


    Quoted message said:

    Not mine, but a friends.

    Your thoughts?

    Currently the server is slow, so it may take a bit to load.

    http://bikeforums.net/showthread.php?t=201510

    I have not used this rim, but from the pictures, the walls look
    extremely thin. As others have noted, 37mm tires at 85psi is
    unnecessarily, even strangely high, and exerts a lot of force. There
    may have been some contributory defect in the rim, perhaps some
    cracking.

    Advice: (1) avoid this rim; (2) what is the point of running 37mm at
    85psi? 32mm at that pressure is already ouch ouch ouch, try 50-60 at
    most, and use a more suitable rim width; (3) ensure spokes properly
    tensioned a la Jobst.

    The Velox rim tape held up well though.

    Dear 41,

    "Wilderness Trail Bikes"

    "WTB Slickasaurus 700x37 Hybrid Tire"

    "The Slickasaurus is well suited for city streets, gravel, DG, and
    hard pack dirt roads. Wire bead, inflate 50-80psi.700x37 Black 460g."

    http://www.nashbar.com/profile.cfm?category=&subcategory=&brand=1246&sku=13703&storetype=&estoreid=&pagename=

    So 85 psi on a 50-85 psi tire,

    Make that 50-80. I have no doubt the tire can take that overload, and
    more, but the points are (1) that's more problematic for what appears
    to be a terribly thin walled rim destined presumably for 18-25mm,
    perhaps 28mm, tires; (2) unless the rider is *well* over 200lbs, or
    carrying huge amounts of gear, what is the point of running a 37mm tire
    at 85 psi? Machismo, or masochism?
    t

  3. 41 said:


    Quoted message said:
    41 said:


    [email hidden] wrote:
    > Not mine, but a friends.
    >
    > Your thoughts?
    >
    > Currently the server is slow, so it may take a bit to load.
    >
    > http://bikeforums.net/showthread.php?t=201510

    I have not used this rim, but from the pictures, the walls look
    extremely thin. As others have noted, 37mm tires at 85psi is
    unnecessarily, even strangely high, and exerts a lot of force. There
    may have been some contributory defect in the rim, perhaps some
    cracking.

    Advice: (1) avoid this rim; (2) what is the point of running 37mm at
    85psi? 32mm at that pressure is already ouch ouch ouch, try 50-60 at
    most, and use a more suitable rim width; (3) ensure spokes properly
    tensioned a la Jobst.

    The Velox rim tape held up well though.

    Dear 41,

    "Wilderness Trail Bikes"

    "WTB Slickasaurus 700x37 Hybrid Tire"

    "The Slickasaurus is well suited for city streets, gravel, DG, and
    hard pack dirt roads. Wire bead, inflate 50-80psi.700x37 Black 460g."

    http://www.nashbar.com/profile.cfm?category=&subcategory=&brand=1246&sku=13703&storetype=&estoreid=&pagename=

    So 85 psi on a 50-85 psi tire,

    Make that 50-80. I have no doubt the tire can take that overload, and
    more, but the points are (1) that's more problematic for what appears
    to be a terribly thin walled rim destined presumably for 18-25mm,
    perhaps 28mm, tires; (2) unless the rider is *well* over 200lbs, or
    carrying huge amounts of gear, what is the point of running a 37mm tire
    at 85 psi? Machismo, or masochism?
    t

    Dear 41,

    Aaargh! Too many typos today!

    Cheers,

    Carl Fogel

  4. Quoted message said:

    Not mine, but a friends.

    Your thoughts?

    Currently the server is slow, so it may take a bit to load.

    http://bikeforums.net/showthread.php?t=201510

    I'll weigh in with what I think.

    I believe that the first failure was the short break, and I suspect
    that an examination of the parting surfaces will reveal that the crack
    had started early and had migrated; I'm pretty sure that part of that
    surface will show work-polishing indicative of a fracture under
    varying stresses. When the crack finally went all the way through,
    the rim separated while rotating, one end jammed on a seat stay (I
    suspect that the location of the impact will not be hard to identify),
    and the sudden cessation of rotation of that end of the band caused
    the upward leap as traction and inertia pulled the gap open, wrinkling
    the rest of the rim and causing the secondary, larger tear in the
    process. The loud bang was the tube blowing out as the gap opened up
    between the ends of the failed rim hoop.

    The current clock position of the rim in the rear triangle is not
    indicative of much of anything; I'm sure it was rotated between the
    time of the failure and the time when the photos were taken.

    IMO, yes, Mavic owes the bike owner a new wheel.
    --
    Typoes are a feature, not a bug.
    Some gardening required to reply via email.
    Words processed in a facility that contains nuts.

  5. On Tue, 06 Jun 2006 22:13:32 -0600, [email hidden] quoted this
    from the Bikeforums site for our pleasure:

    Quoted message said:

    This wheel has failed as I would have expected it to if it had an
    explosive decompression near the valve.

    Look carefully. The wheel is in about the same position as when the
    accident occurred. Decompression near the valve (on the road at this
    time) causes a rapid destressing of the rim. The rim "springs out",
    and the elastic shock propogates (via the hub) to the top spokes (near
    the brake), pulling the rim down at the top. See how the top of the
    rim has been flattened, and at least one spoke head (near the label)
    is partially pulled out of the rim. The top spokes are already loaded
    at this time by the weight of the rider - remember, the bike hangs off
    the top spokes. The deformation (flattening) of the top half of the
    rim causes the rim to bulge out in the for/aft positions, ie. to make
    the rim elliptical. It is likely that at this time, the bottom half of
    the rim has elastically rebounded and is therefore contributing to the
    fore/aft elongation.

    The result of this is a classical shear failure at the fore/aft
    positions as shown in the photo. We would expect a shear failure would
    be at about 45 degrees, which is exactly what we see. The initiator
    for the shear failures is, as expected, spoke holes, which are the
    local stress raisers.

    I see no pre-existing contributor to this failure. It's just plain bad
    luck. You got an explosive blowout just at the point that the wheel
    contacted the ground and all the other dynamics were just not in your
    favour - saddle bouncing, slight road irregularities, pedal torque -
    it all came together at the wrong time.

    I could be wrong and I only have the supplied photo to work from,
    however I am an engineer and have done this stuff before. Any other
    engineers care to comment on this failure - an ATSB accident
    investigator would be just dandy!!!

    I am interested in what other have to say about this failure. I ride
    on Mavic wheels (MA40's and M193's), weigh 95kg, and have no interest
    in a set of circumstances that may result in the seatpost comming out
    my nostrils!!!

    hope this helps,
    JohnF

    I agree with the final conclusion, but nothing else about how the
    conclusion was reached. I do not believe that any decompression,
    sudden or otherwise, could have had the result depicted; the
    decompression, IMO, *resulted from* the failure, not the other way
    around.
    --
    Typoes are a feature, not a bug.
    Some gardening required to reply via email.
    Words processed in a facility that contains nuts.

  6. Quoted message said:

    Not mine, but a friends.

    Your thoughts?

    Currently the server is slow, so it may take a bit to load.

    http://bikeforums.net/showthread.php?t=201510

    Dear D.,

    I have to hang this post somewhere . . .

    Aha! After swimming through tar to get the bikeforums server to
    register, I got in again and found that they've named the rim as a
    Mavic CXP33:

    TIRE SIZE MAXIMUM PRESSURE
    mm bars psi
    19 10.00 146.00
    23 9.50 138.00
    25 9.00 131.00
    28 8.00 117.00

    http://www.mavic.com/ewb_pages/p/produit_jante_cxp33.php?onglet=3&gamme=route

    So it doesn't look as if the rim was meant for 37mm tires. Perhaps
    someone can figure out what kind of force 85 psi on a 37mm tire would
    be exerting, compared to the widths and maximum pressures above.

    It's starting to look like the tire was just too big and the pressure
    too high.

    Cheers,

    Carl Fogel

  7. 41 said:


    Quoted message said:
    41 said:


    [email hidden] wrote:
    > Not mine, but a friends.
    >
    > Your thoughts?
    >
    > Currently the server is slow, so it may take a bit to load.
    >
    > http://bikeforums.net/showthread.php?t=201510

    I have not used this rim, but from the pictures, the walls look
    extremely thin. As others have noted, 37mm tires at 85psi is
    unnecessarily, even strangely high, and exerts a lot of force. There
    may have been some contributory defect in the rim, perhaps some
    cracking.

    Advice: (1) avoid this rim; (2) what is the point of running 37mm at
    85psi? 32mm at that pressure is already ouch ouch ouch, try 50-60 at
    most, and use a more suitable rim width; (3) ensure spokes properly
    tensioned a la Jobst.

    The Velox rim tape held up well though.

    Dear 41,

    "Wilderness Trail Bikes"

    "WTB Slickasaurus 700x37 Hybrid Tire"

    "The Slickasaurus is well suited for city streets, gravel, DG, and
    hard pack dirt roads. Wire bead, inflate 50-80psi.700x37 Black 460g."

    http://www.nashbar.com/profile.cfm?category=&subcategory=&brand=1246&sku=13703&storetype=&estoreid=&pagename=

    So 85 psi on a 50-85 psi tire,

    Make that 50-80. I have no doubt the tire can take that overload, and
    more, but the points are (1) that's more problematic for what appears
    to be a terribly thin walled rim destined presumably for 18-25mm,
    perhaps 28mm, tires; (2) unless the rider is *well* over 200lbs, or
    carrying huge amounts of gear, what is the point of running a 37mm tire
    at 85 psi? Machismo, or masochism?
    t

    Dear 41,

    I not only got in again, but became a member and posted--took a shower
    while waiting for the post to go through, to give you an idea of the
    slow-server problem.

    Anyway, it turns out to be a 275 lb rider on a CXP33 Mavic rim
    recommended only for 19-28mm, running a 37mm tire at 80-85 psi
    (estimated):

    TIRE SIZE MAXIMUM PRESSURE
    mm bars psi
    19 10.00 146.00
    23 9.50 138.00
    25 9.00 131.00
    28 8.00 117.00

    http://www.mavic.com/ewb_pages/p/produit_jante_cxp33.php?onglet=3&gamme=route

    Looks like a heavy rider who mounted too big a tire and then inflated
    it too much.

    Cheers,

    Carl Fogel

  8. Quoted message said:
    Quoted message said:

    Not mine, but a friends.

    Your thoughts?

    Currently the server is slow, so it may take a bit to load.

    http://bikeforums.net/showthread.php?t=201510

    Dear D.,

    I have to hang this post somewhere . . .

    Aha! After swimming through tar to get the bikeforums server to
    register, I got in again and found that they've named the rim as a
    Mavic CXP33:

    TIRE SIZE MAXIMUM PRESSURE
    mm bars psi
    19 10.00 146.00
    23 9.50 138.00
    25 9.00 131.00
    28 8.00 117.00

    http://www.mavic.com/ewb_pages/p/produit_jante_cxp33.php?onglet=3&gamme=route

    So it doesn't look as if the rim was meant for 37mm tires. Perhaps
    someone can figure out what kind of force 85 psi on a 37mm tire would
    be exerting, compared to the widths and maximum pressures above.

    It's starting to look like the tire was just too big and the pressure
    too high.

    Cheers,

    Carl Fogel

    Yes, a quick graph of the 4 sizes and pressures shows a steepening
    downward curve for maximum pressure in psi versus width in mm.

    The last two points aim at about 65 psi, well below the 80-85 the
    rider estimated, and the curve may well drop below that.

    I almost went out to lower the rear tire pressure on my ancient Honda
    trials machine, since I replaced its original 4x18 tire with an
    illegal (for competition) 4.50 monster about 30 years ago, but since
    the pressure is only 4-6 psi, I'm going to bed instead.

    CF

  9. Quoted message said:

    On Tue, 06 Jun 2006 19:18:18 -0700, jim beam <[email hidden]>

    Quoted message said:


    judging by the way every spoke hole seems to bulged, i'd say wildly
    excessive spoke tension had a significant role in this.

    Dear Jim,

    Can you specify a spoke hole in a picture, say by numbering left to
    right or something like that?

    I've looked again, but I can't say that I see bulging at any intact
    spoke hole. No cracking, either.

    The curve of the rim's silhouette seems to run quite smoothly to the
    lip of the spoke holes that I see, and then resumes, all without any
    bulging that I notice.

    I see what appears to be somewhat diffuse reflections of the spokes on the
    rim in the third photo, which might be mistaken for bulging.

    --
    Benjamin Lewis

  10. Benjamin Lewis said:
    Quoted message said:

    On Tue, 06 Jun 2006 19:18:18 -0700, jim beam <[email hidden]>

    Quoted message said:


    judging by the way every spoke hole seems to bulged, i'd say wildly
    excessive spoke tension had a significant role in this.

    Dear Jim,

    Can you specify a spoke hole in a picture, say by numbering left to
    right or something like that?

    I've looked again, but I can't say that I see bulging at any intact
    spoke hole. No cracking, either.

    The curve of the rim's silhouette seems to run quite smoothly to the
    lip of the spoke holes that I see, and then resumes, all without any
    bulging that I notice.

    I see what appears to be somewhat diffuse reflections of the spokes on the
    rim in the third photo, which might be mistaken for bulging.

    Dear Benjamin,

    They're faint, but that could explain Jim's theory.

    I doubt that it matters any more, since a far more likely explanation
    has turned up.

    It turns out that the rim was a Mavic CXP33 recommended for up to 28mm
    tires running a grossly oversized 37mm tire.

    If you graph the maximum pressures against rim width, you'll get 4
    points that show a steepening downward curve:

    TIRE SIZE MAXIMUM PRESSURE
    mm bars psi
    19 10.00 146.00
    23 9.50 138.00
    25 9.00 131.00
    28 8.00 117.00

    http://www.mavic.com/ewb_pages/p/pro...=3&gamme=route

    The last two points, for 25mm/131psi and 28mm/117psi point straight
    toward a maximum pressure of about 65 psi at 37mm. (It's actually
    probably even lower, since the curve steepens.)

    So it's likely that the rim was simply overwhelmed by the force of the
    rider's estimated 80-85 psi acting through a 37mm rim, which provides
    much more leverage than a narrower rim at the same pressure.

    The rider mentions that it had only 500 miles and that he weighs 275.

    Cheers,

    Carl Fogel

  11. I think this logic of too large a tire is wrong as the cause of failure. Logic
    dictates it would be an overpreassure situation and by previous threads from the
    Mavic website 85psi is no where near an overpreassure situation. Also the rim
    should be strong enough to have some safety factor even at +10% of maximum
    tire preassure specified. It does not make sense the 38c tire caused or even
    contributated. Many have spoken to a very unlikely chain of events causing
    this, but in the end even that unlikely chain of events should not have caused
    such a cataclysmic failure unless (1) the rim was basically flawed or (2) the
    wheel was not built properly. However in the case of (2) the wheel builder has
    come forward and I do not believe that the cause.

    My 2 cents and I think Mavic should step up and determine conclusively what
    happened. This was too catastrophic.

    In article <[email hidden]>,
    [email hidden] says...

    Quoted message said:
    Quoted message said:

    Not mine, but a friends.

    Your thoughts?

    Currently the server is slow, so it may take a bit to load.

    http://bikeforums.net/showthread.php?t=201510

    Dear D.,

    I have to hang this post somewhere . . .

    Aha! After swimming through tar to get the bikeforums server to
    register, I got in again and found that they've named the rim as a
    Mavic CXP33:

    TIRE SIZE MAXIMUM PRESSURE
    mm bars psi
    19 10.00 146.00
    23 9.50 138.00
    25 9.00 131.00
    28 8.00 117.00

    http://www.mavic.com/ewb_pages/p/produit_jante_cxp33.php?


    onglet=3&gamme=route

    Quoted message said:


    So it doesn't look as if the rim was meant for 37mm tires. Perhaps
    someone can figure out what kind of force 85 psi on a 37mm tire would
    be exerting, compared to the widths and maximum pressures above.

    It's starting to look like the tire was just too big and the pressure
    too high.

    Cheers,

    Carl Fogel

  12. However, to add to my previous post, if the rider is 275 lb then that could easily
    be well beyond Mavic's specifications for the rim.

    I would value Jobst's or Sheldon's thoughts on this wheel failure.

    In article <[email hidden]>,
    [email hidden] says...

    Quoted message said:

    I think this logic of too large a tire is wrong as the cause of failure. Logic
    dictates it would be an overpreassure situation and by previous threads from


    the

    Quoted message said:

    Mavic website 85psi is no where near an overpreassure situation. Also the rim
    should be strong enough to have some safety factor even at +10% of


    maximum

    Quoted message said:

    tire preassure specified. It does not make sense the 38c tire caused or even
    contributated. Many have spoken to a very unlikely chain of events causing
    this, but in the end even that unlikely chain of events should not have caused
    such a cataclysmic failure unless (1) the rim was basically flawed or (2) the
    wheel was not built properly. However in the case of (2) the wheel builder has
    come forward and I do not believe that the cause.

    My 2 cents and I think Mavic should step up and determine conclusively what
    happened. This was too catastrophic.

    In article <[email hidden]>,
    [email hidden] says...

    Quoted message said:
    Quoted message said:

    Not mine, but a friends.

    Your thoughts?

    Currently the server is slow, so it may take a bit to load.

    http://bikeforums.net/showthread.php?t=201510

    Dear D.,

    I have to hang this post somewhere . . .

    Aha! After swimming through tar to get the bikeforums server to
    register, I got in again and found that they've named the rim as a
    Mavic CXP33:

    TIRE SIZE MAXIMUM PRESSURE
    mm bars psi
    19 10.00 146.00
    23 9.50 138.00
    25 9.00 131.00
    28 8.00 117.00

    http://www.mavic.com/ewb_pages/p/produit_jante_cxp33.php?


    onglet=3&gamme=route

    Quoted message said:


    So it doesn't look as if the rim was meant for 37mm tires. Perhaps
    someone can figure out what kind of force 85 psi on a 37mm tire would
    be exerting, compared to the widths and maximum pressures above.

    It's starting to look like the tire was just too big and the pressure
    too high.

    Cheers,

    Carl Fogel


  13. Quoted message said:
    Quoted message said:

    Not mine, but a friends.

    Your thoughts?

    Currently the server is slow, so it may take a bit to load.

    http://bikeforums.net/showthread.php?t=201510

    I forgot to mention that there are pics, and that this is a pretty
    unique wheel failure.

    Surely someone . . . .??

    To confuse things even more, there is now an additional thread on this
    at BFN

    http://69.16.211.161/showthread.php?t=201676

  14. Quoted message said:

    Aha! After swimming through tar to get the bikeforums server to
    register, I got in again and found that they've named the rim as a
    Mavic CXP33:

    TIRE SIZE MAXIMUM PRESSURE
    mm bars psi
    19 10.00 146.00
    23 9.50 138.00
    25 9.00 131.00
    28 8.00 117.00

    There is a more general document that completes data :
    19 10,0 146
    23 9,5 138
    25 9,0 131
    28 8,0 117
    32 7,0 103
    35 6,0 88
    http://www.tech-mavic.com/tech-mavic/uk/sources/Produits/Piste/GalRouePiste/Recommended_Tire_Pressure.pdf
    or http://minilien.com/?dlX45Auply
    So 85 psi in a 37mm tyre is on the high side but still within normal
    use (as would be 135psi in a 23mm tyre, and isn't that quite common for
    a 200lb+ rider?). I personnally sees that as a good compromise between
    rolling resistance and comfort, btw.

    Considering the original question, I would point out the fact that the
    fore failure (wheel3.jpg) has the eyelet pulled out, but have no
    particular idea of what caused it... Impressive!

  15. Quoted message said:
    Quoted message said:
    Quoted message said:

    Your thoughts?


    Surely someone . . . .??


    To confuse things even more, there is now an additional thread on this
    at BFN

    I am not pretending to say something new, since I have not gone through
    the whole lot of these posts, but let me voice it anyhow.

    I believe it was caused by failure of the side wall of the rim, alas
    too thin and fragile.
    I have myself seen some Ambrosio Excellence Extralight (or Superlight?)
    rim failing there with no sensible reason, other than it being
    underdimensioned.

    Sergio
    Pisa

  16. John Forrest Tomlinson said:

    What pressure is used in those Nokians?

    I'm guessing that 85psi is on the high side for 37mm tires. I have
    some 28s and 85 or 95psi is the max for them, and they hold a lot less
    air than 37s can.

    Maximum pressure recommended by the manufacturer is 4.5 bar (65 psi),
    but I think many people use pressures lower than that. It depends on the
    conditions.

    -as

  17. Quoted message said:

    There is a more general document that completes data :
    ?19 10,0 146
    23 9,5 138
    25 9,0 131
    28 8,0 117
    32 7,0 103
    35 6,0 88
    http://www.tech-mavic.com/tech-mavic/uk/sources/Produits/Piste/GalRouePiste/Recommended_Tire_Pressure.pdf
    or http://minilien.com/?dlX45Auply
    So 85 psi in a 37mm tyre is on the high side but still within normal
    use

    It is OK for a 275lb rider, but insane for e.g. a 150lb rider. The
    questions though are still (a) whether such a rim, as spec'd above, can
    take the next data point of 37mm/85psi with a 275lb rider; and (b)
    whether Mavic's specs as above are indeed realistic for the strength
    and durability of the rim, and the size of the rider. A bump may have
    been encountered earlier, causing a crack and leading to the
    catastrophic failure JRA.

    If we plot hoop force per unit length as caculated by a previous poster
    as P*R, versus tire size, the results are not a horizontal line. The
    figures (force in megaN) are:

    mm psi mN
    19 146 9.56 (spec)
    23 138 10.94 (spec)
    25 131 11.29 (spec)
    28 117 11.29 (spec)
    35 88 10.62 (spec)
    37 85 10.84 (catastrophic failure)

    and the plot is an assymetric inverted U, except for the last one which
    hooks up. Still within the overall band, but inconsistent with the
    trend. The variation in force per unit length for all of these is
    within a ±10% band around the average. Still, since Mavic pointedly
    chooses the specs so as NOT to have a constant force per unit length as
    calculated above, they must be looking at some other factor, and
    whatever that is, the 37mm/85psi is clearly off the trend. If it were
    on an inverted U trend, the max psi would be about 80 with the 35/88
    spec included, and about 75 psi if the 35/88 were not included, so as
    to make the U symmetric. Then there is that 275lb rider on a
    thin-walled racing rim.

    Solution: (a) don't use that rim with that tire at that pressure and
    that rider weight; (b) don't use that rim. I suggest the rider needs a
    500+ g rim, such as at minimum an Ambrosio Evolution (480g, 13.5mm
    ERTRO width, <http://www.ambrosiospa.com/cerchi_corsa.htm>😉, much
    better an Ambrosio Keba (610g, 18mm ERTRO width,
    <http://www.ambrosiospa.com/touring.htm>😉.

  18. Benjamin Lewis said:
    Quoted message said:

    On Tue, 06 Jun 2006 19:18:18 -0700, jim beam <[email hidden]>

    Quoted message said:

    judging by the way every spoke hole seems to bulged, i'd say wildly
    excessive spoke tension had a significant role in this.

    Dear Jim,

    Can you specify a spoke hole in a picture, say by numbering left to
    right or something like that?

    I've looked again, but I can't say that I see bulging at any intact
    spoke hole. No cracking, either.

    The curve of the rim's silhouette seems to run quite smoothly to the
    lip of the spoke holes that I see, and then resumes, all without any
    bulging that I notice.

    I see what appears to be somewhat diffuse reflections of the spokes on the
    rim in the third photo, which might be mistaken for bulging.


    no mistake. the anodizing clouds where the rim deforms, hence the
    "diffuse reflections".

  19. -----BEGIN PGP SIGNED MESSAGE-----

    In article <[email hidden]>,

    41 said:
    Quoted message said:


    Make that 50-80. I have no doubt the tire can take that overload, and
    more, but the points are (1) that's more problematic for what appears
    to be a terribly thin walled rim destined presumably for 18-25mm,
    perhaps 28mm, tires; (2) unless the rider is *well* over 200lbs, or
    carrying huge amounts of gear, what is the point of running a 37mm tire
    at 85 psi? Machismo, or masochism?
    t

    _ The rider is well over 200lbs, 275 per the original
    thread. There are some interesting comments in there from
    the wheel builder. He claims to have used a tensionmeter
    and the wheel was within Mavics spoke tension tolerances
    (ie. under 100kgs ). This paraphased comment I found puzzling.

    The cxp33 was the strongest rim we could find.

    My guess was he didn't look too hard.

    _ Booker C. Bense

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  20. Quoted message said:

    Considering the original question, I would point out the fact that the
    fore failure (wheel3.jpg) has the eyelet pulled out, but have no
    particular idea of what caused it... Impressive!

    The break in the rim at that point crosses the eyelet hole. This is
    part of the reason that I believe that this was the first failure
    point. If, as I suspect, the crack began at the hole and migrated
    outward and across the inner web before the final failure, the rest
    follows logically.
    --
    Typoes are a feature, not a bug.
    Some gardening required to reply via email.
    Words processed in a facility that contains nuts.

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