Rim Failure

"Noel" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

1. Is this normal?! If this had happened an hour earlier I would have
been heading down Titsey Hill at 35mph with oncoming traffic...

Yup, worn out rim.

Quoted message said:

2. If this is normal, how do you check for 'rim wear'?

Ask Chris Juden of the CTC - quite a few mentions of it a couple of years
back :-)

You need to measure the thickness of the rim, but the hook gets in the way.
One way is to stick a bit of spoke on the inside (known thickness) and
measure rim + spoke thickness.

Quoted message said:

3. If this is not normal, do you think Mavic would be interested in
hearing about 18 month old rims which do about 60 miles/week doing this?

Depends what sort of use. If any MTBing (ie muck wearing the rims out when
braking), it's expected. If shimano brake pads, it's expected. I wore
through most of a rim in about 6 months once (touring bike). Changed the
pads and it lasted ages afterwards.
Ceramic rims are expensive, but do appear to work. I'd not bother for a road
bike, but for an MTB maybe.

Quoted message said:

Since I will have to get a new wheel tomorrow anyway, any recommendations
for 26" wheels (maybe other than Mavic...)?

I'd be getting a new rim, probably the same make as before to make swapping
nice and easy. For new I'd be looking at eg chain reaction or merlin for a
handbuilt wheel.

cheers,
clive

On 23/07/2007 19:28, Noel said,

Quoted message said:

2. If this is normal, how do you check for 'rim wear'?

For rim brakes, it is at some point, I guess. I discovered one of my
rims (a 10 year old Mavic used for all-weather commuting for the last
five years) was worn when I realised that the braking surface was
concave instead of flat. Panic order from SJSC a couple of weeks ago
ensued (so where is it????)

Quoted message said:

3. If this is not normal, do you think Mavic would be interested in
hearing about 18 month old rims which do about 60 miles/week doing this?

....but not for that short a time. I wonder if you got a stone or
something wedged into the brake block?

Quoted message said:

Since I will have to get a new wheel tomorrow anyway, any recommendations
for 26" wheels (maybe other than Mavic...)?

I've bought a pair of 26" wheels from Chain Reaction, and they are
brilliant - very well built. I don't think there's anything
fundamentally wrong with Mavic rims - your problem is the cutting discs
you're using instead of brake blocks :-) From personal experience, I
wouldn't recommend wheels from Merlin Cycles. I did have a pair, but
they weren't particularly tight or true. The price is good though, so
if you're handy with a spoke nipple they might still be an option.

--
Paul Boyd
http://www.paul-boyd.co.uk/

This happened to me a few years back. Pumped up my tyres, ready for my
commute to work. Went into the living room and there was this almighty bang,
rear rim had split and inner tube exploded. Glad it happened before I was
riding the bike.

Spa cycles do a good range of wheels for touring/commuting.

John

in message <[email hidden]>, Noel

(') said:

Hi All,

Out for a Sunday morning ride on my trusty Claude Butler Cape Wrath with
Mavic X-117 rims, tyres inflated to 40-50psi. Did 25 miles of road and
off-road. Just 5mins from home along a bridlepath with some bricks buried
in the path (giving almost a cobbly effect) when suddenly my back wheel
locked and i skidded to a halt.

Thinking I must have picked up a stone or something I got off to find the
entire wheel (both tyre and rim) had become horribly enlarged and had
locked into the brake arms.

It all looked rather weird so I yanked the wheel backwards to free it and
get a better look but when I did that the top half of the rim itself
started peeling and curling away! I fumbled for the valve but before I
could get to it the tyre had opened enough to let the entire tube escape
and which then proceeded to explode like a gunshot! The whole thing took
about 10secs from when I freed it from the brake arms.

The wheel/spokes all look fine to me and it has never been buckled or
involved in any accidents.

Some pics here:

http://www.flickr.com/photos/drnoelkelly/sets/72157600964454774/

Couple of questions:

1. Is this normal?! If this had happened an hour earlier I would have
been heading down Titsey Hill at 35mph with oncoming traffic...

It's rare (and the most extreme one I've ever seen), but it the mode of
failure of rims used with rim brakes. Remember that the brakes operate by
abrading the rims, and so all rim braked wheels will ultimately fail this
way, if they don't fail in some other way first. Obviously, mountain bikes
ridden in the wet over abrasive soils will wear rims quicker than other
bikes, but this seems a surprisingly short life.

Quoted message said:

2. If this is normal, how do you check for 'rim wear'?

There are normally markers milled into the rim, which should show before
the point of failure.

Quoted message said:

3. If this is not normal, do you think Mavic would be interested in
hearing about 18 month old rims which do about 60 miles/week doing this?

I think Mavic probably would be interested in seeing this rim, given that
as I say it seems to have worn out quicker than one would expect.

Quoted message said:

Since I will have to get a new wheel tomorrow anyway, any recommendations
for 26" wheels (maybe other than Mavic...)?

They are one of the best rim makers; the other is DT Swiss.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/
Iraq war: it's time for regime change...
... go now, Tony, while you can still go with dignity.
[update three years after this .sig was written: it's still relevant]

Noel said:

Some pics here:

http://www.flickr.com/photos/drnoelkelly/sets/72157600964454774/

Same thing happened to me once, slowing down towards the bottom of a
30+ mph hill for a right turn, probably doing 20 mph. The main problem
was the loudness of the bang, I've never heard anything like it from a
bike. Completed the turn OK then stopped to examine the problem, back
wheel looked rather like yours, but over a shorter section.

LBS thought it was due to a bit of grit getting into the brake block
and scoring a groove. The wheel was fairly old.

Didn't cause a problem with a back wheel, I find the prospect of the
same thing happening with a front wheel rather scary.

Rob

Clive George said:

Quoted message said:

1. Is this normal?! If this had happened an hour earlier I would have
been heading down Titsey Hill at 35mph with oncoming traffic...

Yup, worn out rim.

Depends what sort of use. If any MTBing (ie muck wearing the rims out when
braking), it's expected. If shimano brake pads, it's expected. I wore

Hmmm I see your point. Makes me think I should invest in the hub-braking
kit for the Cape Wrath as I guess that is only way to be more confident it
does not happen again other than buying new wheels every year.

I guess the front wheel might be liable to go too although it probably gets
a little less use. Front wheel locking out at speed is probably less
attractive than the back wheel locking!

Cheers
Noel

leandr42 said:

Didn't cause a problem with a back wheel, I find the prospect of the
same thing happening with a front wheel rather scary.

Yes me too! Rapidly thinking I'll switch to some hub-brakes - or are
there scare stories about those locking out somehow?!

Cheers
Noel

Noel said:

Yes me too! Rapidly thinking I'll switch to some hub-brakes - or are

Sorry - meant to say 'disk-brakes'.

Noel

Noel said:

1. Is this normal?! If this had happened an hour earlier I would have
been heading down Titsey Hill at 35mph with oncoming traffic...

Yes. The action of the (rim) brakes causes a smidgeon of the rim
surface to wear away. The amount of wear varies with rim type, brake
block material and the kind of riding (off road is generally
dirtier,allowing more grit etc to be picked up and causemore wear)

Quoted message said:

2. If this is normal, how do you check for 'rim wear'?

Many rims have built in indicator. My Mavic A117 (?) have a small slot
machined on the inside of the rim. When the rim is worn such that the
slot becomes visible as a hole from the outside, it's time for a new
rim. Other rims have a groove machined on the braking surface. When
the ret of therim is worn such that the groove has gone, it's new rim
time.

looking at the Mavic website, I can only find an XM 117. This appears
to have a wear indicator groove in it. Is this the rim you have?

Quoted message said:

3. If this is not normal, do you think Mavic would be interested in
hearing about 18 month old rims which do about 60 miles/week doing this?

18 x 4 x 60 = 4320 miles. Depends how much braking you did.

Quoted message said:

Since I will have to get a new wheel tomorrow anyway, any recommendations
for 26" wheels (maybe other than Mavic...)?

Stick with Mavic. Things wear out.

Tim

Noel said:

Hi All,

Out for a Sunday morning ride on my trusty Claude Butler Cape Wrath with
Mavic X-117 rims, tyres inflated to 40-50psi. Did 25 miles of road and
off-road. Just 5mins from home along a bridlepath with some bricks buried
in the path (giving almost a cobbly effect) when suddenly my back wheel
locked and i skidded to a halt.

Thinking I must have picked up a stone or something I got off to find the
entire wheel (both tyre and rim) had become horribly enlarged and had
locked into the brake arms.

It all looked rather weird so I yanked the wheel backwards to free it and
get a better look but when I did that the top half of the rim itself
started peeling and curling away! I fumbled for the valve but before I
could get to it the tyre had opened enough to let the entire tube escape
and which then proceeded to explode like a gunshot! The whole thing took
about 10secs from when I freed it from the brake arms.

It's fortunate that rear rims fail first (assuming the same age and rim
brakes on both wheels) - the rear wheel gets more grinding paste thrown
at it than the front one does. Change the front one too - a locked rear
wheel is (usually) an inconvenience, a locked front wheel can be fatal.

Clive George said:

"Noel" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

1. Is this normal?! If this had happened an hour earlier I would have
been heading down Titsey Hill at 35mph with oncoming traffic...

Yup, worn out rim.

Quoted message said:

2. If this is normal, how do you check for 'rim wear'?

Ask Chris Juden of the CTC - quite a few mentions of it a couple of years
back :-)

You need to measure the thickness of the rim, but the hook gets in the way.
One way is to stick a bit of spoke on the inside (known thickness) and
measure rim + spoke thickness.

Actually I think the Mavic XM117 rim which these are has a wear
indicator consisting of a groove in the middle of the brake track. When
the it's worn past the level of the groove then it's time for a new rim.

Can't see the groove on the OP's pictures. But then I don't know for
sure if all XM117s are like that.

Quoted message said:

Quoted message said:

3. If this is not normal, do you think Mavic would be interested in
hearing about 18 month old rims which do about 60 miles/week doing this?

Depends what sort of use. If any MTBing (ie muck wearing the rims out when
braking), it's expected. If shimano brake pads, it's expected. I wore
through most of a rim in about 6 months once (touring bike). Changed the
pads and it lasted ages afterwards.
Ceramic rims are expensive, but do appear to work. I'd not bother for a road
bike, but for an MTB maybe.

Or disk brakes if you're getting rim wear that bad.

in message <[email hidden]>, Noel

(') said:

Clive George said:

Quoted message said:

1. Is this normal?! If this had happened an hour earlier I would have
been heading down Titsey Hill at 35mph with oncoming traffic...

Yup, worn out rim.

Depends what sort of use. If any MTBing (ie muck wearing the rims out
when braking), it's expected. If shimano brake pads, it's expected. I
wore

Hmmm I see your point. Makes me think I should invest in the hub-braking
kit for the Cape Wrath as I guess that is only way to be more confident
it does not happen again other than buying new wheels every year.

I guess the front wheel might be liable to go too although it probably
gets
a little less use. Front wheel locking out at speed is probably less
attractive than the back wheel locking!

Front wheel should be /more/ worn, because you use your front brake more
(or if you don't you should). You could fit disk brakes, but it'll be
expensive. I would just replace the rim.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

' ' <------- this blank intentionally spaced left

Tim Hall said:

Quoted message said:

2. If this is normal, how do you check for 'rim wear'?

Many rims have built in indicator. My Mavic A117 (?) have a small slot
machined on the inside of the rim. When the rim is worn such that the
slot becomes visible as a hole from the outside, it's time for a new
rim. Other rims have a groove machined on the braking surface. When
the ret of therim is worn such that the groove has gone, it's new rim
time.

Just had a look for this groove but no sign of it on the broken rear wheel
or the front wheel but that might be because they are both worn away!
Worryingly the front rim has a rather concave feel to it so I think that
one has to go to.

I think two new rims and a some disc brakes will make me feel happier
about fast descents...

Cheers
Noel

"Simon Brooke" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Front wheel should be /more/ worn, because you use your front brake more
(or if you don't you should).

For hardish braking, maybe, but for gentle braking, which is what I do more
of, I tend to use the rear brake - there's no particular reason to use the
front then. So the back wheel ends up more worn.

cheers,
clive

Clive George said:

"Simon Brooke" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Front wheel should be /more/ worn, because you use your front brake more
(or if you don't you should).

For hardish braking, maybe, but for gentle braking, which is what I do more
of, I tend to use the rear brake - there's no particular reason to use the
front then. So the back wheel ends up more worn.

cheers,
clive

mmm i've noticed that as well on the green paniered thing, has a more
upride postion etc, and tend to be going slower, and have noticed a
trend to use the rear more than i would on the other more sporty bikes.

roger
--
www.rogermerriman.com

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

Quoted message said:

Just had a look for this groove but no sign of it on the broken rear wheel
or the front wheel but that might be because they are both worn away!
Worryingly the front rim has a rather concave feel to it so I think that
one has to go to.

It depends how thick the rim is - obviously some wear to the braking
surface will reduce its resistance to impact, but spreading at the bead
due to tyre pressure is the real danger sign. As others have said, the
rim thickness is measurable. It has also been widely reported that
Shimano brake blocks cause more rim wear than other good brands - I
don't know if that's still the case.

Quoted message said:

I think two new rims and a some disc brakes will make me feel happier
about fast descents...

There's not really any need to worry about rim brakes as long as you're
aware that rims are consumable just like brake blocks, and keep an eye
on them. Don't forget that brake discs also wear out, and this can lead
to catastrophic failure too.

Rob Morley said the following on 24/07/2007 08:08:

Quoted message said:

As others have said, the
rim thickness is measurable. It has also been widely reported that
Shimano brake blocks cause more rim wear than other good brands - I
don't know if that's still the case.

The last set of Shimano brake blocks I had were so soft that they wore
out in just a couple of months or so of commuting. I kept thinking
"these brake cables seem to be stretching quite a lot" as I twiddled the
adjuster again, because it hadn't occurred to me that any blocks could
wear so fast. I don't think there was much danger of those blocks doing
much damage to the rim - I now have Koolstops and everything is again as
it should be. Other Shimano blocks I've had in the past seem to be made
of carborundum paste or something!

--
Paul Boyd
http://www.paul-boyd.co.uk/

Noel said:

It all looked rather weird so I yanked the wheel backwards to free it
and get a better look but when I did that the top half of the rim
itself started peeling and curling away! I fumbled for the valve but
before I could get to it the tyre had opened enough to let the entire
tube escape and which then proceeded to explode like a gunshot! The
whole thing took about 10secs from when I freed it from the brake
arms.

Exactly the same happened to me in January - I posted here about it -
fortunately at 1mph going over Kingston Bridge not 30mph going down
/Wimbledon hill on the way home! Your picture is remarkably similar to mine.

The gunshot effect is quite dramatic, isn't it!

The silver lining was that I had an excuse to buy a new bike as new wheels
and all the other stuff needed made the old on uneconomic. In my case too
much wet weather riding to the Towpath - river silt makes a great grinding
paste! I swapped the Specialized rockhopper for a Marin nail trail with
discs!

pk

In news:[email hidden],
Rob Morley <[email hidden]> tweaked the Babbage-Engine to tell us:

Quoted message said:

Don't forget that brake discs also wear out,
and this can lead to catastrophic failure too.

In my experience, a worn-out brake disc just goes from being flat to
lens-shaped, thereby preventing the wheel from turning. Inconvenient[1] but
not terribly dangerous.

1 - especially when one discovers it's happened at 22:30 on a Saturday
night, when one is in Aberystwyth and one's motorcar is in Stockport.

--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
My liver is evil, and must be punished.