Rim failure

Quoted message said:

http://www.btinternet.com/~john.tomo/KIF_2154.JPG

Similar to what happened to an MA3 rim I used to have. On mine the cracking
extended along the inner surface of the rim

Cheers, helen s

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John Tomlinson composed the following ...

Quoted message said:

I have had rims fail on me before but not like this:

http://www.btinternet.com/~john.tomo/KIF_2154.JPG

Previously I have always worn through the side of the rim. This
failure, however, looks like the spokes are too tight - which is odd.

For about a year the wheel has been breaking spokes on a regular
basis; about one spoke every month or so and always on the none drive
side [1]. Until now I have blamed these breakages on the spokes being
too loose. But, I did not tighten the spokes, even though I wanted to
because the spoke nipples are at the end of their threads and cannot
be tightened any more. So how come the rim failed in this way with the
eyelet pulling out? Were the spokes too tight or too loose? I would
value to combined expertise of urc.

Too loose spokes will tend to move in the sockets and Al rims don't take
kindly to brass nipples / eyelets being rubbed on them, no matter how small
the movements. This would normally lead to an elongation of the hole before
pulling through though ..

Your description above, though, suggests that the spokes may actually be the
wrong size for the hub / rim combination, or simply laced differently to how
the wheel was designed.

What does the inside of the rim look like, could there be any fluid in there
that has attacked the Al locally to this spoke and weakened it, something
like a drop of battery acid maybe ...

--
Paul ...
http://www.4x4prejudice.org/index.php
(8(!) Homer Rules ... 😉
"A [censored] is a [censored], no matter what mode of transport they're using."

John Tomlinson said:

I have had rims fail on me before but not like this:

http://www.btinternet.com/~john.tomo/KIF_2154.JPG

Previously I have always worn through the side of the rim. This
failure, however, looks like the spokes are too tight - which is odd.

For about a year the wheel has been breaking spokes on a regular
basis; about one spoke every month or so and always on the none drive
side [1]. Until now I have blamed these breakages on the spokes being
too loose. But, I did not tighten the spokes, even though I wanted to
because the spoke nipples are at the end of their threads and cannot
be tightened any more. So how come the rim failed in this way with the
eyelet pulling out? Were the spokes too tight or too loose? I would
value to combined expertise of urc.

I should say that the eyelet has pulled out of a drive side spoke and
the wheel is on a Dawes Super Galaxy (new in 2000 - new to me in 2003)
so I would say the wheels are machine built.

Unless I can find a new rim and spokes tomorrow I shall be without a
bike over Christmas :-( I think Santa needs to bring me a second bike.

John T.

[1] - There are not many of the original non drive side spokes left.
Remove the singers of Spam before replying

Possibly too thick spokes and/or uneven tension between them due to
frequent replacements. The former results in less load sharing between
spokes and therefore more force on an individual eyelet and the latter
just exacerbates the problem. rec.bicycles.tech is the place to ask
although be prepared for the odd grouch in there. The following is in
their FAQ:

Quoted message said:

- Choose spokes according to the type of wheel failure. If spoke or
rim eyelet durability is a problem, use lighter spokes. It may seem
odd to solve breaking problems by going to a lighter spoke; but
spokes are run at 1/2 their yield strength or less, so do not break
from overload. Instead, they fail from gradual degradation caused by
repeated stretching and relaxing of the metal. Lighter spokes cause
the wheel load to be shared among more spokes, reducing the loads on
each spoke and thus improving spoke lifetime. A similar mechanism
can damage rims at the eylet, and lighter spokes can therefore also
help reduce rim damage. Note that using more spokes and a rim with
greater radial stiffness also helps spoke and rim bed durability.

Tony

John Tomlinson said:

I have had rims fail on me before but not like this:

http://www.btinternet.com/~john.tomo/KIF_2154.JPG

You've got an extreme example but it's common to see some deformation and
cracking around eyelets. I last saw it on a Vuelta Tempest. I think it's
simply caused by excessive spoke tension for the rim.

Rims such as Open Pro, A719* (aka T520), X618 have sockets at the spoke
holes to distribute load more evenly between upper & lower walls to enable
the rim to take high tension, the kind of tension needed for strong rear
dished wheels. Too many rims (eg. MA3) don't have this feature.

* http://tinyurl.com/2xypb (diagram to bottom-right of pic is wrong and
illustrates another model with an alternative double-wall design without
sockets that's not as good IMO; these models tend to use weaker alloys as
well).

Quoted message said:

Previously I have always worn through the side of the rim. This
failure, however, looks like the spokes are too tight - which is odd.

For about a year the wheel has been breaking spokes on a regular
basis; about one spoke every month or so and always on the none drive
side [1]. Until now I have blamed these breakages on the spokes being
too loose.

Tight spokes can break too. Whatever, they probably weren't
stress-relieved.

Quoted message said:

But, I did not tighten the spokes, even though I wanted to
because the spoke nipples are at the end of their threads and cannot
be tightened any more. So how come the rim failed in this way with the
eyelet pulling out? Were the spokes too tight or too loose?

Maybe they were too tight (for the rim) in the first place.

Quoted message said:

I should say that the eyelet has pulled out of a drive side spoke

That's where the highest trension is.

Quoted message said:

and
the wheel is on a Dawes Super Galaxy (new in 2000 - new to me in 2003)
so I would say the wheels are machine built.

Machine built wheels don't have particularly high spoke tension but maybe
they were retensioned by hand.

However, I agree it's all a bit odd IF the left spokes were quite slack
(right spokes would then not be extremely tight if wheel is dished
correctly).

Anyway, wheels were never Dawes's strong point. T221 rims? Super Galaxy
deserves better. An A719 would be better for the rear at least, together
with some really good spokes, eg. DT Alpine III drive-side, DT Competition
or Sapim Laser left.

~PB

John Tomlinson said:

I have had rims fail on me before but not like this:

http://www.btinternet.com/~john.tomo/KIF_2154.JPG

you've been lucky, it is the 'prefered' mode of failure currently
--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

On Wed, 22 Dec 2004 22:46:06 +0000 (UTC), John Tomlinson
<[email hidden]> wrote in message
<[email hidden]>:

Quoted message said:

http://www.btinternet.com/~john.tomo/KIF_2154.JPG

Looks like uneven / insufficient tension. Almost certainly fatigue,
I'd say. What was the mileage?

Guy
--
"then came ye chavves, theyre cartes girded wyth candels
blue, and theyre beastes wyth straynge horn-lyke thyngs
onn theyre arses that theyre fartes be herde from myles
around." Chaucer, the Sheppey Tales

Just zis Guy said:

Quoted message said:

http://www.btinternet.com/~john.tomo/KIF_2154.JPG

Looks like uneven / insufficient tension. Almost certainly fatigue,
I'd say.

I would have thought too much tension, since it happened to John's on the
rear drive-side, and rims of mine after tightening spokes.

~PB

On Thu, 23 Dec 2004 12:04:31 -0000, "Pete Biggs"
<[email hidden]> wrote in message
<[email hidden]>:

Quoted message said:

Quoted message said:

Looks like uneven / insufficient tension. Almost certainly fatigue,
I'd say.

Quoted message said:

I would have thought too much tension, since it happened to John's on the
rear drive-side, and rims of mine after tightening spokes.

Maybe. I was thinking about the repeated load/unload cycles in the
bottom quadrant of the wheel as the it turns (note careful avoidance
of hang/stand argument), and considering that the rim may be less
likely to fail if the tension is maintained, than if it is dropped to
zero and re-applied repeatedly. But it's a guess. Fatigue is less of
a guess...

Guy
--
"then came ye chavves, theyre cartes girded wyth candels
blue, and theyre beastes wyth straynge horn-lyke thyngs
onn theyre arses that theyre fartes be herde from myles
around." Chaucer, the Sheppey Tales

John Tomlinson said:

I have had rims fail on me before but not like this:
http://www.btinternet.com/~john.tomo/KIF_2154.JPG

What make of rim ?

I had a Mavic 217 go like this, long before reasonable wear should
have got to it. Popular opinion blamed Mavics and some cracking
problem related to their poor anodising. Under the microscope the tame
metallurgist reckoned there was considerable chemical corrosion,
although couldn't tell if this was cause or a resultant effect of
leaving cracks out in the rain.

One thing that did cross my mind was my bike cleaner. I use "Muc-Off",
which feels like it has a fair portion of potassium hydroxide in it,
which would certainly be a corrosion hazard on aluminium if it wasn't
washed off completely. Now I'm aware of this, so rinse carefully, but
around a nipple socket there's always going to be a trace left.

Andy Dingley said:

John Tomlinson said:

I have had rims fail on me before but not like this:
http://www.btinternet.com/~john.tomo/KIF_2154.JPG

Quoted message said:

One thing that did cross my mind was my bike cleaner.

I've had wheels returned before they got dirty! Single eyeletted FiRs
going in 200 km's. Some bikeparts are terrible, period
--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

Andy Dingley said:

metallurgist reckoned there was considerable chemical corrosion,
although couldn't tell if this was cause or a resultant effect of
leaving cracks out in the rain.

If you haven't got the space to bring your bike indoors, at least bring
in the cracks.

--
Dave...

"m-gineering" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I've had wheels returned before they got dirty! Single eyeletted FiRs
going in 200 km's. Some bikeparts are terrible, period
--

I agree entirely - rims are an example of cycle components having got
significantly poorer in quality over the past 20 years IMO.

As has been pointed out, fewer quality rims now have double eyelets, whilst
some manufacturers have tried to save too much weight (even on touring
rims). These factors have made them much more prone to the type of problem
experienced.

The wheel probably *wasn't* well tensioned from what you've said, but it's
likely that it was headed for an early grave regardless of how it was
assembled. There are some rims which are just not worth buying (Helen has
mentioned the MA3 for one...)

John Tomlinson said:

I have had rims fail on me before but not like this:

http://www.btinternet.com/~john.tomo/KIF_2154.JPG

Previously I have always worn through the side of the rim. This
failure, however, looks like the spokes are too tight - which is odd.

For about a year the wheel has been breaking spokes on a regular
basis; about one spoke every month or so and always on the none drive
side [1]. Until now I have blamed these breakages on the spokes being

I've had the same thing happen with MA3's. They wern't particulally tight,
just made of cheese with [censored] eyelets.

Nowhere near as good as the old MA2s

--
Andy Morris

AndyAtJinkasDotFreeserve.Co.UK

Love this:
Put an end to Outlook Express's messy quotes
http://home.in.tum.de/~jain/software/oe-quotefix/

you know? said:

Maybe. I was thinking about the repeated load/unload cycles in the
bottom quadrant of the wheel as the it turns (note careful avoidance
of hang/stand argument), and considering that the rim may be less
likely to fail if the tension is maintained, than if it is dropped to
zero and re-applied repeatedly.

This sounds more likely than an overstressed wheel. As I say the
spokes on the none drive side were loose and could be be tightened up
any more.

JT
Remove the singers of Spam before replying

motorhommer said:

Mileage ?

I have done about 6000ish miles in the last 18 months. What the bike
did before, I do not know but I think it was used at the weekends
only; rather than the every day pumishment I have been giving it.

Quoted message said:

Type of wheel ?

Mavic T221.

JT

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Pete Biggs said:

Anyway, wheels were never Dawes's strong point. T221 rims?

Right first time.

Quoted message said:

Super Galaxy deserves better

I have been coming round to this opinion over the last 18 months.

Quoted message said:

An A719 would be better for the rear at least, together
with some really good spokes, eg. DT Alpine III drive-side, DT Competition
or Sapim Laser left.

I never did understand why plain guage spokes were used - it just
seemed a little penny pinching on a so called Super Galaxy.

I am going to Madgetts (Diss) tomorrow to have a look at some decent
rims and to get a good set of spokes. I will then have a quiet time
wheel building on Boxing Day.

JT
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On Thu, 23 Dec 2004 01:23:15 -0000, "Pete Biggs"
<[email hidden]> wrote in message
<[email hidden]>:

Quoted message said:

wheels were never Dawes's strong point. T221 rims? Super Galaxy
deserves better.

I had T221s on my tourer for some years without problems, but they
were hand-built. What really lets a bike down is machine-built
wheels, IMO.

Guy
--
"then came ye chavves, theyre cartes girded wyth candels
blue, and theyre beastes wyth straynge horn-lyke thyngs
onn theyre arses that theyre fartes be herde from myles
around." Chaucer, the Sheppey Tales

John Tomlinson said:

I have had rims fail on me before but not like this:

http://www.btinternet.com/~john.tomo/KIF_2154.JPG

Previously I have always worn through the side of the rim. This
failure, however, looks like the spokes are too tight - which is odd.

For about a year the wheel has been breaking spokes on a regular
basis; about one spoke every month or so and always on the none drive
side [1]. Until now I have blamed these breakages on the spokes being
too loose. But, I did not tighten the spokes, even though I wanted to
because the spoke nipples are at the end of their threads and cannot
be tightened any more. So how come the rim failed in this way with the
eyelet pulling out? Were the spokes too tight or too loose? I would
value to combined expertise of urc.

I should say that the eyelet has pulled out of a drive side spoke and
the wheel is on a Dawes Super Galaxy (new in 2000 - new to me in 2003)
so I would say the wheels are machine built.

Unless I can find a new rim and spokes tomorrow I shall be without a
bike over Christmas :-( I think Santa needs to bring me a second bike.

John T.

[1] - There are not many of the original non drive side spokes left.
Remove the singers of Spam before replying

Jobst Brandt blames hard anodising (it's too brittle, and cracks can
propagate into the rim alloy) for most cases of rim cracking, but your
rims don't look hard anodised. Probably just excessive spoke tension
and age.

FWIW, a wheel with very tight spokes is no stronger than a wheel with
adequately tight spokes. The limit is where the spokes cannot become
loose (and potentially unscrew their nipples) at the bottom of the
wheel. When you have got this far there is no point in having the
spokes any tighter - it just increases the risk of cracking and "pringles".

Zog The Undeniable said:

Jobst Brandt blames hard anodising (it's too brittle, and cracks can
propagate into the rim alloy) for most cases of rim cracking, but your
rims don't look hard anodised. Probably just excessive spoke tension
and age.

Yes I have just read that bit in The Good Book. The rim was a Mavic
T221. I have just had a little surf and cannot find any details so I
do not know if it was anodised. I still have the rim leaning against
the dustbin, is there any way I can tell if it was anodised?

I still doubt that the spokes where too tight. Anyway I have now built
a new wheel on the old hub using new spokes. The new rim is a DRC one
and I have the set the spoke tension higher than it was for the Mavic
rim - in setting the spoke tension on the new rim I realised how low
the tension was on the old rim.

John T.

PS. My Conti 2000 tyres are very tight in the new DRC rim :-(

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