Total wheel Failure

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 . . . .??

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.,

Your friend's wheel failure is so lurid that I'm shamelessly posting
links to the pictures and copying your friend's text, since your
server is slow and there's some prejudice against bikeforums:

http://members.cox.net/younggg/Wheel1.jpg
http://members.cox.net/younggg/Wheel2.jpg
http://members.cox.net/younggg/Wheel3.jpg

****
Facts are as follows:

This wheel was 36-spoke, 3-cross, custom built, tensioned, and true.
The wheel had about 500 miles on it when it detonated.
The tire was a WTB Slickisaurus 700x37c inflated to (Mfg. recommended)
85 psig.
The tube showed about a 9-inch-long smooth split on the spoke-side of
the tube.
The rim tape was not punctured
The wheel detonated with a bang on smooth pavement at about 19 mph
The rim did NOT fail at the weld - the weld is still intact.
The wheel bead showed no signs of damage other than where it was
punctured by the broken rim
The LBS does NOT think this was caused by the bead coming loose from
the rim (their opinion)

Questions:

What caused this rim to fail?
What can I do to prevent this from happening again? (I'm lucky to be
alive)
Does Mavic owe me another wheel?
I have three other wheels with the same rims - am I at risk from them
too?
***

Cheers,

Carl Fogel

If you read the entire thread, there is additional information
including some statements from the actual wheel builder, who is very
involved in trying to figure out the cause of this "unique" failure.

[Nom] schreef:

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

- any hole in the ground?
- sewer cover?
- grating?
- tram rail?

Have a CXP 33 myself as well (4 pcs) lasted 6000 / 500 km yet and still
counting.

--
Posted by news://news.nb.nu

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

Wow, when the rim cracked it blew the seat off too!

-nate

Martin Borsje said:

[Nom] schreef:

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

- any hole in the ground?
- sewer cover?
- grating?
- tram rail?

Have a CXP 33 myself as well (4 pcs) lasted 6000 / 500 km yet and still
counting.

--

I would refer you to the thread, where all of this and more is
discussed in some detail. As I understand it, smooth pavement, 19 mph,
BLOOEY!

Quoted message said:

Posted by news://news.nb.nu

Quoted message said:

Martin Borsje said:

[Nom] schreef:

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

- any hole in the ground?
- sewer cover?
- grating?
- tram rail?

Have a CXP 33 myself as well (4 pcs) lasted 6000 / 500 km yet and still
counting.

--

I would refer you to the thread, where all of this and more is
discussed in some detail. As I understand it, smooth pavement, 19 mph,
BLOOEY!

Quoted message said:

Posted by news://news.nb.nu

I quote from the thread and the person to whom this happened:

"What were you doing when the wheel broke?

I was riding on smooth pavement at 19mph. I was about 40 minutes into
my daily ride. No potholes, no debris - smooth pavement.

What did you hit or what hit you?

No collision whatsoever. One moment everything was normal, the next, I
was sliding down the road on my butt. I believe when the wheel
detonated, I was thrown up. When I came down, the seatpost bolt broke
and dumped me off the back of the bike. Luckily, I didn't land on the
seatpost or the broken rim or I'd not be here now.

Why does the wheel appear to be too big for the bike?

Must be an artifact of the photo - the bike is a Klein Navigator
touring frame made for (and with clearance for) the 700x37c tires that
are on the bike."

Quoted message said:

No collision whatsoever. One moment everything was normal, the next, I
was sliding down the road on my butt. I believe when the wheel
detonated, I was thrown up. When I came down, the seatpost bolt broke
and dumped me off the back of the bike.

There is a possibilty that he struck something (unseen) with the rear
wheel.

Also note that the rim (CXP33) is designed for <28mm tires, but a 37mm
was mounted.

Ron Ruff said:

Also note that the rim (CXP33) is designed for <28mm tires, but a 37mm
was mounted.

A lot of people use 37 mm or wider tyres on road rims, especially on
cyclocross bikes. Perhaps the most common example seen here in the
winter is the Nokian W240 studded tyre, size 40-622. Usually the wider
the tyre the lower the pressure, so the rim should be fine.

-as

Llatikcuf 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

Wow, when the rim cracked it blew the seat off too!

Never underestimate the power of compressed air when freed from it's
bonds! ;-)

Antti Salonen said:

Ron Ruff said:

Also note that the rim (CXP33) is designed for <28mm tires, but a 37mm
was mounted.

A lot of people use 37 mm or wider tyres on road rims, especially on
cyclocross bikes. Perhaps the most common example seen here in the
winter is the Nokian W240 studded tyre, size 40-622. Usually the wider
the tyre the lower the pressure, so the rim should be fine.

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.

JT

****************************
Remove "remove" to reply
Visit http://www.jt10000.com
****************************

In article
<[email hidden]>,

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.

There's your problem. It's that little yellow patch at
10 o'clock.

Good pictures. Thanks for sharing. Hope the rider is well.

--
Michael Press

In article
<[email hidden]>,

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

Only one wildly improbable scenario for a JRA failure. The
7 o'clock fracture looks like the spoke pulled the eyelet
through the rim, and then the rim collapsed around the
hole.

--
Michael Press

Antti Salonen wrote:

<snip>

Quoted message said:

Usually the wider
the tyre the lower the pressure, so the rim should be fine.

-as

Hi Antti,

Don't forget that the force exerted by the tire on the rim scales with
the radius of the tire section (that is, with the surface area of the
casing). A wide tire at lowish pressure can exert more force at the
bead/rim interface than a 700x18 tire at 150 psi.

Hoop stress in a cylindrical pressure vessel is PR/T where P is
pressure, R is the cylinder radius and T is the thickness of the
material. Since we're concerned about force and not stress (which is
force/area), we can dispense with the denominator. This leaves us with
PR.

For an 18mm (0.009 m radius) tire pumped to 150 psi (1.03 megaPascals)
we get a force of 9270N per unit length*,

For a 37 mm (0.0185 m radius) tire pumped to 85 psi (0.59 MPa) we get a
force of 10,915N per unit length--obviously, a larger force.

When one considers a 23mm tire pumped to 115 psi (perhaps the most
common numbers), we get a result of 9118N per unit length.

This calculation incorporates a number of assumptions. I've assumed
that nominal tire width is actual width and that toroidal pressure
vessels (i.e., tires) operate exactly like cylindrical pressure
vessels. However, the forces I've listed should be pretty accurate on a
relative scale.

The point is that low-pressure fat tires can and do exert higher forces
on rims at the bead interface than do high-pressure skinny tires.

This is a very strange failure to me. I'll be interested to hear what
the cause was.

Cheers,

Jason

* N.B.: A Pascal is a unit of pressure, specifically, a force of one
Newton per square meter. Since P*R is (N/m^2)*m, the unit of radius
cancels with one of the units of area, yielding force (Newtons) per
meter.

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.,

Your friend's wheel failure is so lurid that I'm shamelessly posting
links to the pictures and copying your friend's text, since your
server is slow and there's some prejudice against bikeforums:

http://members.cox.net/younggg/Wheel1.jpg
http://members.cox.net/younggg/Wheel2.jpg
http://members.cox.net/younggg/Wheel3.jpg

****
Facts are as follows:

This wheel was 36-spoke, 3-cross, custom built, tensioned, and true.
The wheel had about 500 miles on it when it detonated.
The tire was a WTB Slickisaurus 700x37c inflated to (Mfg. recommended)
85 psig.
The tube showed about a 9-inch-long smooth split on the spoke-side of
the tube.
The rim tape was not punctured
The wheel detonated with a bang on smooth pavement at about 19 mph
The rim did NOT fail at the weld - the weld is still intact.
The wheel bead showed no signs of damage other than where it was
punctured by the broken rim
The LBS does NOT think this was caused by the bead coming loose from
the rim (their opinion)

Questions:

What caused this rim to fail?
What can I do to prevent this from happening again? (I'm lucky to be
alive)
Does Mavic owe me another wheel?
I have three other wheels with the same rims - am I at risk from them
too?
***

Cheers,

Carl Fogel

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

[[email hidden]

... and there's some prejudice against bikeforums...

Cheers,

Carl Fogel[/QUOTE]

Just curious, why is there a predjudice against bikeforums?

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

Quoted message said:

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.,

Your friend's wheel failure is so lurid that I'm shamelessly posting
links to the pictures and copying your friend's text, since your
server is slow and there's some prejudice against bikeforums:

http://members.cox.net/younggg/Wheel1.jpg
http://members.cox.net/younggg/Wheel2.jpg
http://members.cox.net/younggg/Wheel3.jpg

****
Facts are as follows:

This wheel was 36-spoke, 3-cross, custom built, tensioned, and true.
The wheel had about 500 miles on it when it detonated.
The tire was a WTB Slickisaurus 700x37c inflated to (Mfg. recommended)
85 psig.
The tube showed about a 9-inch-long smooth split on the spoke-side of
the tube.
The rim tape was not punctured
The wheel detonated with a bang on smooth pavement at about 19 mph
The rim did NOT fail at the weld - the weld is still intact.
The wheel bead showed no signs of damage other than where it was
punctured by the broken rim
The LBS does NOT think this was caused by the bead coming loose from
the rim (their opinion)

Questions:

What caused this rim to fail?
What can I do to prevent this from happening again? (I'm lucky to be
alive)
Does Mavic owe me another wheel?
I have three other wheels with the same rims - am I at risk from them
too?
***

Cheers,

Carl Fogel

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.

Cheers,

Carl Fogel

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.

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.,

Bikeforums seems to be working more quickly now, so I got in and saw
one theory (post#21) that might interest RBT posters, particularly the
part about the bike hanging off its top spokes.

Cheers,

Carl Fogel

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

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