Rim Cracks
John Carrier
cleaning up the rim I discovered cracks radiating from a couple spoke holes
on the rear rim. Both are from drive side (highest tension) spokes. 1800
miles on the rim.
Rims are Mavic Reflex Tubular. I recall reading about similar problems with
the Reflex Clinchers (now replaced with the Open Pro). Has anyone had a
similar experience with the tubular rim?
Obviously, I'll have to replace the rim ... it's going to fail. Is the
failure mode catastrophic (One moment you're riding, the next you're sliding
down the pavement)?
Thanks, John
Don Lesco
This happened to me over the summer while I was on a tour. My
experience was that the wheel became more and more out of true.
Eventually, it got so bad that the wheel would rub the chainstays.
I had undone the cantilever brakes so that they would not rub there.
After fixing this a few times the spoke socket pulled out of the rim.
So, to answer your original question, I do not believe that the failure
is catastrophic.
Regards,
Don Lesco
Tim McNamara
"John Carrier" <j...@netdoor.com> wrote:
> Just finished a major tune-up on my bike and while installing a new
> tire and cleaning up the rim I discovered cracks radiating from a
> couple spoke holes on the rear rim. Both are from drive side
> (highest tension) spokes. 1800 miles on the rim.
>
> Rims are Mavic Reflex Tubular. I recall reading about similar
> problems with the Reflex Clinchers (now replaced with the Open Pro).
> Has anyone had a similar experience with the tubular rim?
It has been my experience with every Mavic rim other than the MA-2:
Open Pro, X-222, Cosmic Expert. I have gotten anywhere from 500 to
1500 miles before the rims fail. OTOH some of my MA-2s have 6000 miles
so far and showing no sign of problems.
The difference is anodizing. Anodized rims fail from cracking around
the spoke holes. Good luck finding any that aren't anodized! There is
one I know of, the Torelli Master.
> Obviously, I'll have to replace the rim ... it's going to fail. Is
> the failure mode catastrophic (One moment you're riding, the next
> you're sliding down the pavement)?
Well, it's catstrophic in that there's a sharp bang and suddenly the
wheel's well out of true because pieces of the rim have ripped away. If
you have a close tolerance frame it may get jammed and lock up.
Although I'd say the rim has *already* failed. It's broken.
kwalters
Tim McNamara wrote:
> In article <F3Ep8.167220$Gf.15...@bin2.nnrp.aus1.giganews.com>,
> "John Carrier" <j...@netdoor.com> wrote:
>
> > Just finished a major tune-up on my bike and while installing a new
> > tire and cleaning up the rim I discovered cracks radiating from a
> > couple spoke holes on the rear rim. Both are from drive side
> > (highest tension) spokes. 1800 miles on the rim.
> >
> It has been my experience with every Mavic rim other than the MA-2:
> Open Pro, X-222, Cosmic Expert. I have gotten anywhere from 500 to
> 1500 miles before the rims fail. OTOH some of my MA-2s have 6000 miles
> so far and showing no sign of problems.
>
I have a 36h MA-2 with cracks radiating from 6 eyelets. Maybe 5000 miles on
it.
Ken
jobst....@stanfordalumni.org
> Just finished a major tune-up on my bike and while installing a new
> tire and cleaning up the rim I discovered cracks radiating from a
> couple spoke holes on the rear rim. Both are from drive side
> (highest tension) spokes. 1800 miles on the rim.
Anodizing puts a ceramic crust on the aluminum and because it is so
much harder than aluminum takes all the load of any stress on the rim
before cracking. These cracks are visible on a new wheel when
inspected under grazing light sand magnification. That anodizing
causes structural failure is well understood in the aircraft industry
but, as usual, the bicycle industry is immune to cross contamination
from sources outside their own shop.
Early on, I had a used Mavic MA-40 and an MA-2 sectioned, polished and
photographed in the metallurgy lap at Alcan Aluminum that showed
anodizing cracks propagating into the aluminum while the MA-2 had no
cracks.
> Rims are Mavic Reflex Tubular. I recall reading about similar problems with
> the Reflex Clinchers (now replaced with the Open Pro). Has anyone had a
> similar experience with the tubular rim?
Unless there is a major revolt (and even then with minimal
probability) there will be no improvement in this department. There
is NO reason to anodize, weld or machine rims, all price increasing
features that do the rider no good. Machining absolves the bicycle
shop from squealing brakes on a show room bicycle, a feature that
wears of in the first few brake application in wet weather.
Fashion being what it is to most bicyclists, we won't even hear an
audible response to this situation, just as we haven't since I first
wrote on this subject years ago. In fact, after I wrote about it, I
got the impression that Mavic stopped making the MA-2 (their best all
around rim) that I touted, in retribution for my negative comments.
> Obviously, I'll have to replace the rim... it's going to fail. Is
> the failure mode catastrophic (One moment you're riding, the next
> you're sliding down the pavement)?
Yes? And with what? There isn't much choice today although some rims
are silver anodized which is no better. Besides they are welded and
mostly machined.
Jobst Brandt <jobst....@stanfordalumni.org> Palo Alto CA
jobst....@stanfordalumni.org
>>> Just finished a major tune-up on my bike and while installing a
>>> new tire and cleaning up the rim I discovered cracks radiating
>>> from a couple spoke holes on the rear rim. Both are from drive
>>> side (highest tension) spokes. 1800 miles on the rim.
>> It has been my experience with every Mavic rim other than the MA-2:
>> Open Pro, X-222, Cosmic Expert. I have gotten anywhere from 500 to
>> 1500 miles before the rims fail. OTOH some of my MA-2s have 6000
>> miles so far and showing no sign of problems.
> I have a 36h MA-2 with cracks radiating from 6 eyelets. Maybe 5000
> miles on it.
I am no lightweight and have never had a crack on an MA-2 with as much
as 20000miles on many rims (when the sidewall wore out). Any rim
loaded heavily enough can crack but, for most riders, this is not a
problem. What is too bad is that if your durability of an MA-2 is so
poor, what will you do to improve the situation.
jobst....@stanfordalumni.org
> Just finished a major tune-up on my bike and while installing a new
> tire and cleaning up the rim I discovered cracks radiating from a
> couple spoke holes on the rear rim. Both are from drive side
> (highest tension) spokes. 1800 miles on the rim.
Anodizing puts a ceramic crust on the aluminum and because it is so
much harder than aluminum. It takes all the load of any stress on the
rim and cracks before the aluminum carries any load. These cracks are
visible on a new wheel when inspected under grazing light with
magnification. That anodizing causes structural failure is well
understood in the aircraft industry but, as usual, the bicycle
industry is immune to cross contamination from sources outside their
own shop.
Early on, I had a used Mavic MA-40 and an MA-2 sectioned, polished and
photographed in the metallurgy lap at Alcan Aluminum that showed
anodizing cracks propagating into the aluminum while the MA-2 had no
cracks.
> Rims are Mavic Reflex Tubular. I recall reading about similar
> problems with the Reflex Clinchers (now replaced with the Open Pro).
> Has anyone had a similar experience with the tubular rim?
Unless there is a major revolt (and even then with minimal
probability) there will be no improvement in this department. There
is NO reason to anodize, weld or machine rims, all price increasing
features, that do the rider no good. Machining absolves the bicycle
shop from squealing brakes on a show room bicycle, a feature that
wears of in the first few brake application in wet weather.
Fashion being what it is to most bicyclists, we won't even hear an
audible response to this situation, just as we haven't since I first
wrote on this subject years ago. In fact, after I wrote about it, I
got the impression that Mavic stopped making the MA-2 (their best all
around rim) that I touted, in retribution for my negative comments.
> Obviously, I'll have to replace the rim... it's going to fail. Is
> the failure mode catastrophic (One moment you're riding, the next
> you're sliding down the pavement)?
Yes? And with what? There isn't much choice today although some rims
are silver anodized which is no better. Besides they are welded and
mostly machined.
Jobst Brandt <jobst....@stanfordalumni.org> Palo Alto CA
RK
>
> Anodizing puts a ceramic crust on the aluminum and because it is so
> much harder than aluminum. It takes all the load of any stress on the
> rim and cracks before the aluminum carries any load. These cracks are
> visible on a new wheel when inspected under grazing light with
> magnification. That anodizing causes structural failure is well
> understood in the aircraft industry but, as usual, the bicycle
> industry is immune to cross contamination from sources outside their
> own shop.
Just wondering if sanding off the anodizing, before the cracks
propogated into thee Aluminum, would help.
30x26
scritto:
>never had a crack on an MA-2 with as much
>as 20000miles on many rims (when the sidewall wore out).
when do you consider a sidewall worn out?
is there any generic rule?
--
30x26
jobst....@stanfordalumni.org
>> I never had a crack on an MA-2 with as much as 20000 miles on many
>> rims (when the sidewall wore out).
> When do you consider a sidewall worn out? Is there any generic
> rule?
Since the wall thickness is about 1.5mm, when the braking surface is
about 0.8-1.0mm hollow, you are at he limit of bursting the sidewall
out. You decide what you feel is safe. I find 0.5mm side wall my
limit.
kwalters
jobst....@stanfordalumni.org wrote:
The cracks are hairline, and the wheel is on my townie/beater/commuter,
so
I won't replace it until the sidewall or an eyelet gives out, and then
probably
with an MA-3, which is what I used to replace a 32h MA40 last year when
an
eyelet did pull out. That rim had 6000-7000 miles on it. I did some light
loaded
touring on the MA-2, and for much of it's life I weighed in excess of
200lbs. I'm
now down to low 190s, so maybe I will get more mileage out of my wheels.
Ken
Craig Brozefsky
> > I am no lightweight and have never had a crack on an MA-2 with as
> > much as 20000miles on many rims (when the sidewall wore out). Any
> > rim loaded heavily enough can crack but, for most riders, this is
> > not a problem. What is too bad is that if your durability of an
> > MA-2 is so poor, what will you do to improve the situation.
> >
> > Jobst Brandt <jobst....@stanfordalumni.org> Palo Alto CA
>
> The cracks are hairline, and the wheel is on my
> townie/beater/commuter, so I won't replace it until the sidewall or
> an eyelet gives out, and then probably with an MA-3, which is what I
> used to replace a 32h MA40 last year when an eyelet did pull
> out. That rim had 6000-7000 miles on it. I did some light loaded
> touring on the MA-2, and for much of it's life I weighed in excess
> of 200lbs. I'm now down to low 190s, so maybe I will get more
> mileage out of my wheels.
I have some MA-3s with hairline cracks around one or two eyelets. The
rear has two eyelets with hairline cracks and is 36H and slightly out
of true (haven't trued it up since it's just barely off). The front
is 32h and has one one crack I could see. I was using bright overhead
lights at an angle, not direct beams like a flashlight so perhaps
there is a better detection method. On that note, any tips on
detecting and guaging metal fatique in various materials with common
household items would be welcome, books included. I could use some
tips or pointers on evaluating and dealing with steel frames too. Is
there perhaps a "Metallurgy for the Home Wrench" text? Jobst, does
your book cover this topic or have pointers to materials on it?
I am not planning on replacing these until there is a more definite
failure, barring some evidence that there is a likely chance of a
disasterous failure mode (front wheel collapsing) indicated by cracks
in the anodizing. Is there a way to guage the cracks? It seems like
this bit of triage will be more neccesarry when we can't buy
non-anodized rims anymore.
This is on my fixed city bike and I am quite dependent upon it and
spend a good deal of time on it each day.
--
Craig Brozefsky <cr...@red-bean.com>
Free Software Sociopath(tm) http://www.red-bean.com/~craig
Ask me about Common Lisp Enterprise Eggplants at Red Bean!
jobst....@stanfordalumni.org
>> The cracks are hairline, and the wheel is on my
>> townie/beater/commuter, so I won't replace it until the sidewall or
>> an eyelet gives out, and then probably with an MA-3, which is what
>> I used to replace a 32h MA40 last year when an eyelet did pull out.
>> That rim had 6000-7000 miles on it. I did some light loaded
>> touring on the MA-2, and for much of it's life I weighed in excess
>> of 200lbs. I'm now down to low 190s, so maybe I will get more
>> mileage out of my wheels.
All cracks are "hairline" until separation, so that is no consolation.
My pedal cranks that broke also had hairline cracks until they failed.
That is why I inspected them for (hairline) cracks under sunlight at
various angles.
> I have some MA-3s with hairline cracks around one or two eyelets.
> The rear has two eyelets with hairline cracks and is 36H and
> slightly out of true (haven't trued it up since it's just barely
> off). The front is 32h and has one one crack I could see. I was
> using bright overhead lights at an angle, not direct beams like a
> flashlight so perhaps there is a better detection method. On that
> note, any tips on detecting and gauging metal fatigue in various
> materials with common household items would be welcome, books
> included. I could use some tips or pointers on evaluating and
> dealing with steel frames too. Is there perhaps a "Metallurgy for
> the Home Wrench" text? Jobst, does your book cover this topic or
> have pointers to materials on it?
We rarely had rim failures before the low spoke count/anodized craze
began. Therefore, no one worried about these things. There were rims
with eyelets only and no socket to distribute load to the other wall
of the rim, but then no one who rode much used them. The MA-3 is such
a turkey but to underscore that, it is anodized.
> I am not planning on replacing these until there is a more definite
> failure, barring some evidence that there is a likely chance of a
> disastrous failure mode (front wheel collapsing) indicated by cracks
> in the anodizing. Is there a way to gauge the cracks? It seems
> like this bit of triage will be more necessary when we can't buy
> non-anodized rims anymore.
I don't know what users can do to motivate rim companies to produce a
reasonable and useful product. I have given up.
> This is on my fixed city bike and I am quite dependent upon it and
> spend a good deal of time on it each day.
I bought a small cache of MA-2's when it was almost too late. I would
have bought more had I known how fast they would vanish. It was the
most popular rim here and in Europe where nearly every bicycle shop
had them in stock. In Linz Austria, my friend had a wheel failure and
we just went into the bicycle shop, bought a new MA-2 and on our way
again. I saw these rims everywhere I went.