Near-Catastrophic Rim Failure
Ray
get home in time to catch the 49er game at the end of 1st quarter. I
didn't make it. My rear rim blew out as I took a slow (translated:
continuous braking down 18% descent to hold speed at 10(-)mph.)
descent down back side of Conzumel Road toward the lighthouse.
Because I crashed on the same section of this road in January and
broke my collarbone, I have been taking this descent extra carefully
and slowly now that I am back on the bike. Just as I was in the last
tight turn before the road levels out to a reasonable grade, my rear
tire popped and blew out.
I managed to stay upright and bring it to a stop against a bank.
There, I discovered that my rear rim blew out and a 18" section of the
sidewall bead just blew out and tangled up in the spokes and
chainstay. The wheel rims are Araya. Just prior to leaving home, I
pumped up the rear Pasella x32 to 85 pounds. The wheels are about
three years old. No prior wheel trauma.
Could this failure resulted from the long braking over-heating the rim
and the pressure blowing it out? Seems strange, but, can that happen?
Here are the pix:
http://www.flickr.com/photos/8581354@N03/sets/72157628281638979/with/6455986331/
Steve Palincsar
You didn't happen to touch the rim to see if it was actually hot, did
you?
Just to cast a glance over the usual suspects -- is this by any chance a
non-hook bead rim? Is 85 psi a usual pressure for you, that you've used
successfully with this particular tire/tube/rim combination before? Was
the tire recently installed, or has it been in service in this
configuration for some time?
And by the way, I'm very glad you are unhurt.
EricP
rim. On the other hand, had a similar rim failure early this year on
my LHT (which is also a winter commuter). My LBS concluded that a
small stone (or something similar) got stuck in a brake pad and
quickly cut a deep groove in the wall of the rim. Which then failed.
Might want to check your pads and make sure nothing is embedded and
waiting to chew another rim apart.
Eric Platt
St. Paul, MN
> http://www.flickr.com/photos/8581354@N03/sets/72157628281638979/with/...
Ray Shine
I checked the brake pads and the sidewalls of both wheels like Eric suggested, and see nothing out of the ordinary.
From: Steve Palincsar <pali...@his.com>
To: rbw-owne...@googlegroups.com
Sent: Sun, December 4, 2011 4:43:48 PM
Subject: Re: [RBW] Near-Catastrophic Rim Failure
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Ray Shine
Yes, and thanks to all for the best wishes. I'm fine, but can't help thinking that mountain does not want be on it for some reason…
From: cyclotourist <cyclot...@gmail.com>
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Sent: Sun, December 4, 2011 5:29:51 PM
grant
caused by rock-wear, as Eric suggested. That's not to say nothing else
can cause it, but that is (in my experience) the most common (100
percent) reason for it. Rim makers and tire makers build more wiggle-
room into their stuffs than...an extra five psi. Close inspection
would tell the story---whether the chunk-o-rim just blew out suddenly
("catastrophically" means suddenly and complete, in this context), or
whether the rim had been scored deep by Foreign Object for a while,
and just couldn't take it anymore.
Conzelman (note spelling) is a beautiful road, as neat as any in
California (maybe the world). Too short, one way, and what a
dropoff.Glad you're OK, Ray.
> http://www.flickr.com/photos/8581354@N03/sets/72157628281638979/with/...
Tim McNamara
> Could this failure resulted from the long braking over-heating the rim
> and the pressure blowing it out? Seems strange, but, can that happen?
I've seen this before. Usually it is from braking wear thinning the sidewall over time, more prevalent for people who ride in hilly or mountainous terrain and/or in rainy weather a lot. The road grit and slurry that gets on the rims forms a nice grinding pace. Sometimes the sidewall is scored by a small pebble or bit of metal that gets caught in the brake pad. And once in great a while the cause of the failure is an extrusion flaw.
Glad you weren't hurt! It might be that your long braking heated the rim and caused the blowout, which took the weakened rim with it. When the rim gets really hot, the rubber of the sidewall along the bead gets hot and slippery and can lift over the rim.
James Black
> Could this failure resulted from the long braking over-heating the rim
> and the pressure blowing it out? Seems strange, but, can that happen?
I'm wondering if the heat caused the tire to blow out, and it was the
force of the tire blowout that then destroyed the rim?
James Black
Los Angeles, CA
jimD
Me, I'd stay off of that road.
-JimD
Steve Palincsar
> I did touch the rim, and it was hot. However, I've touched other rims
> on the same descent and they seemed hotter. I never rolled faster than
> 10 mph when I started the descent. I scared. So, I was on the brakes
> for about 3/4 mile on an 18% descent. The tires, tubes and wheels
> have been mated for several months, and I have ridden the bike a lot,
> maybe 3 or 4 hundred miles. This was the second trip down this grade
> on this bike this week. I normally do inflate to about 80, but thought
> they seemed "squishy", so I added 5. The sidewall says 95.
>
> I checked the brake pads and the sidewalls of both wheels like Eric
> suggested, and see nothing out of the ordinary.
So you've eliminated installation issues and it sounds like you've
eliminated overheating as well. Rim wear is the prime suspect, in my
estimation.
Ray Shine
From: grant <gran...@gmail.com>
To: RBW Owners Bunch <rbw-owne...@googlegroups.com>
Sent: Sun, December 4, 2011 6:25:09 PM
Subject: [RBW] Re: Near-Catastrophic Rim Failure
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Ray Shine
From: Ray Shine <r.s...@sbcglobal.net>
To: rbw-owne...@googlegroups.com
Sent: Sun, December 4, 2011 7:16:48 PM
Subject: Re: [RBW] Re: Near-Catastrophic Rim Failure
Joe Bunik
>
> I've seen this before. Usually it is from braking wear thinning the
> sidewall over time, more prevalent for people who ride in hilly or
> mountainous terrain and/or in rainy weather a lot. The road grit and slurry
> that gets on the rims forms a nice grinding pace.
I've *had* this, as per Tim's description, happen before (Ritchey
Girder rim)... fortunately however, while on the stand! Was inflating
a Pasela x35 to a higher pressure than I now prefer, when kaboom! 50%
of the sidewall sheared/collapsed away...
The rims were *nowhere* as near pristine-appearing as Ray's though-
instead, exactly fit the above description on my Boston and Pittsburgh
winter commuter. Inspection afterward taught me concave rim wear is A
Very Bad Sign.
=- Joe Bunik
Walnut Creek, CA
Manuel Acosta
on a decent down.
On Dec 4, 4:35 pm, Ray <r.sh...@sbcglobal.net> wrote:
> http://www.flickr.com/photos/8581354@N03/sets/72157628281638979/with/...
Smitty-A-Go-Go
Jim Thill - Hiawatha Cyclery
Rims are definitely a wear item. I've read claims by old-timers like Jobst Brandt that suggest rims should last tens of thousands of miles. IME, that is generally not the case. Perhaps modern rim alloys are softer, or maybe brake pads are different, or perhaps there are more bike commuters out in foul weather nowadays?
Bill M.
need to brake.
Maybe I don't ride any particular set of wheels enough, or I'm spoiled
by riding relatively clean, dry NorCal pavement all year round, but
I've never had a rim that showed significant sidewall wear.
Bill
On Dec 5, 12:35 am, Jim Thill - Hiawatha Cyclery <thill....@gmail.com>
wrote:
Tim McNamara
On Dec 5, 2011, at 2:35 AM, Jim Thill - Hiawatha Cyclery wrote:
> We had a string of rim failures this summer, maybe 5-6 in just a few weeks (it seemed). All were cases of simple wear, except in Eric's case, where there was an obvious groove likely caused by a foreign object in an otherwise lightly worn rim. One guy had worn out and cracked both rims in a very short time, but he is well known at the shop for his rapid pace of brake pad wear (I suspect he brakes subconsciously at every intersection or any long-shot potential for danger).
>
> Rims are definitely a wear item. I've read claims by old-timers like Jobst Brandt that suggest rims should last tens of thousands of miles. IME, that is generally not the case. Perhaps modern rim alloys are softer, or maybe brake pads are different, or perhaps there are more bike commuters out in foul weather nowadays?
With the MA2 (non-anodized, spoke nipple sockets) and 36 spokes on a 5 speed/120 OLN or 6 speed 126 OLN wheel that was possible. With 8/9/10 speed wheels on 130 mm it ain't gonna happen, especially with the minimal spoking patterns now considered normal. Modern road frame designs aren't going to accommodate the 145 mm OLN that would be needed to sufficiently reduce dish.
Bike components are no longer durable goods in the eyes of the bike industry. They think it's just fine for you to spend $5000 every 2-4 years to replace your bike. What, a bike should last longer than that? Pah!
My All-Rounder has 135 mm OLN with a 7 speed Phil hub and freewheel (Jim's shop knows this wheel well, they spent about 4 hours trying to get a freewheel off of it, finally resorting to disassembling the freewheel and cutting it off with an angle grinder. I didn't ask for the details. But I digress). The original build was in 1996 with a Sun CR-16 rim (polished, no eyelets). The dish is only about 2 mm. That rim lasted for 14 years/30,000 miles until it finally developed a crack by one of the spoke holes. I've never broken a spoke on that wheel; now I can't remember if I used new spokes when I rebuilt that wheel or taped the new rim (CR-18) to the old and transferred the spokes to the new rim since the ERD is within a mm between the two.
I think the key points of rim longevity are (1) number of spokes, (2) less dish is much, much better and no dish is perfect, (3) minimizing braking wear. The last point is going to be dependent on a lot of factors- if you live in a mountainous rainy area you're going to wear through rims faster than a fair weather rider in Kansas who can go for a 50 mile ride without touching the brakes except at the very end of the ride. Many modern rims have some kind of wear indicator built into the braking surface.
Jan Heine
rim blowout is perhaps the worst mechanical failure.
If you use your rear brake for slowing, you'll wear out rear rims in
quick succession. Rear rims collect much more road grit than front
ones (spray from front wheel). The grit works like a very effective
abrasive, and will wear through your rim quickly.
It's easy to check whether this is the culprit: Take a hacksaw and cut
your rim in half in one of the places where it still is intact. Clean
off the burrs with a file. You will see how much material there was
initially by looking at the places where the brake blocks did not
touch. Compare that to the brake track. You also should be able to see
any gouges from sharp stones, as others have suggested.
For every rider, it is a good practice to check rim wear from time to
time. Some newer rims have built-in marks. Once these disappear, you
should replace the rim. Also, most rims start bulging outward when
they get seriously thin. You can see that with calipers. If the sides
of your rim no longer are parallel, then the rim is getting
dangerously thin.
Overheating rims doesn't appear to be a problem. You tire will melt
before you damage the rim, and blow off. (That is very dangerous, but
the tire being the weak link, the rim is unlikely to explode from
overheating.)
Jan Heine
Editor
Bicycle Quarterly
http://www.bikequarterly.com
Follow our blog at http://janheine.wordpress.com/
Jim Thill - Hiawatha Cyclery
The reason I say that wheels with fewer spokes and more dish are ok (within reason) is because of modern rim stiffness. I probably wouldn't suggest the MA2 with 24 or 28 spokes for most riders, but with some kind of stiff deep-v style rim, fewer spokes are ok.
Ray Shine
http://www.flickr.com/photos/8581354@N03/sets/72157628298441377/
EricP
than a week old), with less than 100 miles on it. 36 spokes. Just
happen to be a stone that cut really sharp and deep.
Will admit to having one bike with 32 hole rims. Otherwise,
everything is 36 hole. And even there I feel at 225 pounds am
probably pushing the envelope and 40 or 48 hole would be more
practical.
To the OP, sorry but the new photos don't change my mind, but the
middle photo is interesting. If you can, take the rim tape off.
Would not shock me if the inside of the rim was cracked. Had that
happen on a Synergy rim. Almost forgot about that rim failure.
Gee, makes me realize I'm harder than most on my rims. Guess that
what happens when one is a super heavyweight.
Eric Platt
St. Paul, MN
On Dec 5, 10:10 am, Jim Thill - Hiawatha Cyclery <thill....@gmail.com>
wrote:
Tim McNamara
Here's a photo of a rim sectioned like Jan suggests which gives a very graphic demonstration of sidewall wear. The amount of wear can be quite surprising!
http://pardo.net/bike/pic/fail-026/000.html
Tim McNamara
On Dec 5, 2011, at 7:31 PM, Ray Shine wrote:
> Hey all -- I have added three more pix of the strange bulge found on the sidewall of the failed rim. I have appreciated all of your responses, and I hope I don't burn you all out if I ask that you weigh in on this new evidence, too. Looking forward to your responses. Here's the new link to the three pix. Sorry they are only iPhone quality:
>
> http://www.flickr.com/photos/8581354@N03/sets/72157628298441377/
Huh. The spoke eyelet appears detached from the rim bed. Is there a blue rim strip partially popped up? Can you pull the rim strip off and photograph the rim edge-on?
There looks to be quite a groove worn into the sidewall at about the midpoint. And that rim seems to have taken some pothole hits- your tire pressure may be too low for the tire width and load.
Ray Shine
From: Tim McNamara <tim...@bitstream.net>
To: rbw-owne...@googlegroups.com
Sent: Mon, December 5, 2011 6:20:36 PM
Subject: Re: [RBW] Re: Near-Catastrophic Rim Failure
Andrew Johnson
- Andrew, Berkeley
Grant Petersen
Bontrager's maxim from the late '80s:
Light Strong Inexpensive: Pick Two
It works to some extent with all bike parts, but even IT can't come to
the rescue when the thing is just too light.
Do you know the thickness of the braking surface on a typical road
rim? It's about 1.2mm. Some are 1.1. That's what fails when rims wear
out and blow out. Well...1.1 or 1.2mm looks like nothing, which you
consider the abrasion they're subject to and can't possibly avoid.
(Disc brakes have their own set of problems, so let's stay on track.)
It used to be common practice to inspect brake pads AND rims, but
raise you hand if you can remember the last time you did that.
How much should a non-racing 700c rim weigh? How thick should the
braking surface be, and how tall? How wide should it be?
Reasonable answers, kind of, could be: Weight: 500g. Thickness of
braking surface: 2.5mm. Height: 11mm. Width: 24mm.
But a rim with those specs would weigh about 800g. I believe this
because we're having a NOBS rim made to our specs, and it has 1.6mm
braking surface, 10.5mm brake surface height, is 25.4 (1) mm wide, and
weighs about 650g. It's wider than 24, but way thinner than 2.5, and
the 10.5<11. I think this is a totally reasonable rim, in every way. I
wanted 2mm of braking surface, but that would have meant zero buyers,
so we settled on the world-record 1.6, bringing the weight down to a
near world record 650g, and even though I think it's a perfectly
fantastic rim for general nonracing use---touring, trails, commuting,
all purpose riding when there's not a timer or a finish line with a
banner---I believe we'll end up selling it mostly to guys who weigh
300 pounds and are sick and tired of wheel problems...because most
riders like the idea of stout stuff, but don't really want the weight
that comes with it.
We'll continue to offer other rims....but this new rim will be the way
to go when you truly, really, want a durable rim and wheel.
(Anyway....the new stouty won't be available for many months).
charlie
duty rims sound fantastic.
cyclotourist
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dougP
Is it possible for you to measure the thickness of the failed area?
Even a rough idea such as "half of original; quarter; or thin as a
soda can" may be helpful when the rest of us check our rims. Given
the dimensions that Grant lists, I should pay a lot more attention to
rim wear. My replacement cue has been when they're been banged up
enough they won't true up. The current Mavic A719s on my Atlantis
rarely need any attention but the braking surfaces have noticeable
wear (now that I'm looking).
After reading Grant's dimensions for the upcoming Stouty rim, I
checked Mavic's website for comparables on the A719. They only list
weight (565 grams for 700). tire width (28 to 47), but not rim width
or height. IIRC they used to have more detail. The next level down
for touring is the A319 @ 595 grams. So Grant's 650 gram is right on
target. Most of us are going to mount tires in the 600-900 gram range
so another 50-100 grams of rim is worth it for a stronger, longer
wearing rim.
dougP
On Dec 5, 11:08 pm, Grant Petersen <gep71...@gmail.com> wrote:
Ray Shine
Subject: [RBW] Re: Near-Catastrophic Rim Failure
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PATRICK MOORE
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Patrick Moore
Albuquerque, NM
For professional resumes, contact
Patrick Moore, ACRW
http://resumespecialties.com/index.html
Ray Shine
http://www.flickr.com/photos/8581354@N03/sets/72157628310179371/with/6467935809/
From: dougP <doug...@cox.net>
To: RBW Owners Bunch <rbw-owne...@googlegroups.com>
Sent: Tue, December 6, 2011 8:18:15 AM
Subject: [RBW] Re: Near-Catastrophic Rim Failure
Tim McNamara
On Dec 6, 2011, at 3:21 PM, Ray Shine wrote:
> This will be the last time I come to this well over this issue, but here are 3 more pix of the failed rim sawn in cross-section. Pretty alarming! Look here:
>
> http://www.flickr.com/photos/8581354@N03/sets/72157628310179371/with/6467935809/
Wow. The asymmetry of the rim wear is astonishing to me. One side is worn practically paper thin and the other side looks untouched. Strange. Do you have a brake pad that doesn't touch the wheel, or a brake pad that drags?
EricP
Yeah, that sidewall looks pretty thin. Oddly enough, on the photo
with the white paper back, the inside of the rim looks thin, not just
the outside. Especially below the bead on the section pointed up.
Patrick - am one that prefers bike stuff overbuilt, not under. Have
had to learn over many years that heavy duty for some is normal to
light for me. Always has worked that way. Not abusive, just fat.
And well outside the norms for the average bike designer. Will fess
up that my single speed is pushing the limits with 32h front and
rear. Am hopeful of reliability, but won't be surprised if it isn't.
Eric Platt
St. Paul, MN
On Dec 6, 3:21 pm, Ray Shine <r.sh...@sbcglobal.net> wrote:
> This will be the last time I come to this well over this issue, but here are 3
> more pix of the failed rim sawn in cross-section. Pretty alarming! Look here:
>
> http://www.flickr.com/photos/8581354@N03/sets/72157628310179371/with/...
>
Ray Shine
Subject: [RBW] Re: Near-Catastrophic Rim Failure
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Greg Walton
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Sean Whelan
I think this thread might jump start the Christmas Wheelset sales rush.
I, for one, am thinking about it rather seriously.
Thanks,
Sean
--- On Tue, 12/6/11, Grant Petersen <gep7...@gmail.com> wrote:
> From: Grant Petersen <gep7...@gmail.com>
> Subject: [RBW] Re: Near-Catastrophic Rim Failure
> To: "RBW Owners Bunch" <rbw-owne...@googlegroups.com>
Ray Shine
From: Sean Whelan <strumm...@yahoo.com>
To: rbw-owne...@googlegroups.com
Sent: Wed, December 7, 2011 10:35:17 AM
Subject: Re: [RBW] Re: Near-Catastrophic Rim Failure
> For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
>
>
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Angus
weaken the metal...it's going to more than feel hot on our
fingers...it's going to sear them. The rubber bits will melt first.
Angus
On Dec 7, 1:10 pm, Ray Shine <r.sh...@sbcglobal.net> wrote:
> I'm with you! Scary, especially since I ride soooo many hills and grades. Lots
> of braking.
>
> ________________________________
> Sent: Wed, December 7, 2011 10:35:17 AM
> Subject: Re: [RBW] Re: Near-Catastrophic Rim Failure
>
> All of this talk has me suddenly worrying about what my many-year old rims with
> thousands of miles on them would look like in profile when hack-sawed.
>
> I think this thread might jump start the Christmas Wheelset sales rush.
>
> I, for one, am thinking about it rather seriously.
>
> Thanks,
> Sean
>
> >http://groups.google.com/group/rbw-owners-bunch?hl=en.
>
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> - Show quoted text -
davidfrench
Pics of the rim are really scary. It makes me think that I'll have a
look at mine !
I sometimes ride this hill (living in SF) and man, it could have been
worst if you were speeding.
Take care !
David
Ray Shine
Subject: [RBW] Re: Near-Catastrophic Rim Failure
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