Snapped forks

John Miller said:

Out on Sunday for my usual ride and my forks snapped without warning while I
was climbing a small hill out of the saddle. The aluminium steerer tube on
my ITM Big One carbon forks sheered about an inch above the fork crown. End
result was that I pitched forward, landed on my face and ended up calling an
ambulance and then spent 6 hours in A&E while they stitched my nose and lips
back together as best they could. I've lost one tooth, damaged a couple more
and I'm very sore around the ribs and back, but they tell me nothing is
broken.

Count yourself less unlucky than you could have been. Given that this
failure was going to occur, going relatively slowly uphill is probably
the least unpleasant time it could have happened.

Hope you recover quickly!

--
Mark.
http://tranchant.plus.com/

in message <[email hidden]>, John Miller

(') said:

So far as I can see at the moment, the Look carbon frame is undamaged
but I'll have to get it checked, one Ergo lever is smashed and front
wheel is a write-off. However, what really bothers me is the sudden
failure of the steerer. I seem to remember a report about the glue
failing on one of these forks last year,

Google says:

"In earlier correspondence on carbon forks, it was opined that any
problems were unlikely to arise in the carbon fibre itself, but where
it’s bonded to metal components. The experience of CTC member Dave
Goodall bears that out, when his less than two years old ITM Big One
carbon fork failed mid-ride. The carbon steerer tube came loose from
the aluminium fork crown, allowing the handlebars to turn
independently of the fork.

He discovered this whilst stationary, just after a 40mph descent."

Source: <URL:http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3519>

Further down the same page it says:

"Fractures are more likely where this is bonded onto metal inserts due
to different stiffness and thermal expansion of the two materials.
Where forks have an alloy steerer tube, this – rather than any failing
of carbon fibre – is likely to result in a shorter life expectancy
than a good steel fork, since alloy has inferior fatigue properties."

From my own knowledge of working with composites (which is strictly
amateur) I know that bonding to Aluminium is tricky (much trickier than
bonding to other composite components or to wood).

A google search for [carbon fork break OR broke OR snapped OR fail]
brought up the following further first-hand reports of actual failures:

<URL:http://dbclist.org/pipermail/goldrushriders/2005-July/000318.html>
<URL:http://www.roadbikereview.com/cat/frames-and-forks/forks/easton/PRD_326183_2492crx.aspx>

Yup, only two. Or, counting your own report and the other cited above,
four, of which two are ITMs. So it would look to me like an ITM design
or quality control problem rather than a more general carbon fork
problem.

This, though not reporting a failure, is interesting:
<URL:http://www.velonews.com/tech/report/articles/3270.0.html>
because it says how long manufacturers think their forks should last.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; First they came for the asylum seekers,
;; and I did not speak out because I was not an asylum seeker.
;; Then they came for the gypsies,
;; and I did not speak out because I was not a gypsy...
;; Pastor Martin Niemöller, translated by Michael Howard.

John Miller said:

Out on Sunday for my usual ride and my forks snapped without warning while I
was climbing a small hill out of the saddle. The aluminium steerer tube on
my ITM Big One carbon forks sheered about an inch above the fork crown. End
result was that I pitched forward, landed on my face and ended up calling an
ambulance and then spent 6 hours in A&E while they stitched my nose and lips
back together as best they could. I've lost one tooth, damaged a couple more
and I'm very sore around the ribs and back, but they tell me nothing is
broken. I have to return to hospital tomorrow to see if anything else needs
doing once the swelling subsides. Last week it was the bee-sting, now this.
I'm beginning to think that somebody up there doesn't like me!

So far as I can see at the moment, the Look carbon frame is undamaged but
I'll have to get it checked, one Ergo lever is smashed and front wheel is a
write-off. However, what really bothers me is the sudden failure of the
steerer. I seem to remember a report about the glue failing on one of these
forks last year, but I wonder if anyone else knows about any other failures.
The forks came with the bike which I bought new 3 years ago. I also feel
that I should report this to somebody, but I'm not sure who. I'm a CTC
member so perhaps I'll try them if there are no better suggestions.

John Miller

Sympathies for your prang. Get well soon.

It's always the unexplained or unexpected prangs that are unnerving.
Knowing that it might happen again and that you can't really take any
precautions causes lost sleep.

CTC's engineering bod is Chris Judens. It is probably worth dropping
him a line or calling him for a chat.

Simon Brooke said:

A google search for [carbon fork break OR broke OR snapped OR fail]
brought up the following further first-hand reports of actual
failures:

<URL:http://dbclist.org/pipermail/goldrushriders/2005-July/000318.html>

<URL:http://www.roadbikereview.com/cat/frames-and-forks/forks/easton/PRD_3
26183_2492crx.aspx>

Quoted message said:

Yup, only two. Or, counting your own report and the other cited above,
four, of which two are ITMs. So it would look to me like an ITM design
or quality control problem rather than a more general carbon fork
problem.

I reckon ITM is by far the most popular make for carbon forks with alloy
steerers--sold in big numbers now at 'discount' prices. It is natural
that most of the failures would be with the most common make.

Could the problem also happen with forks with *carbon* steerers that have
alloy crowns? Is the carbon steerer bonded in the same way? Same
question for steel steerers, or are the crowns then steel too?

Would carbon steerers be safer on balance anyway, given that they can fail
in other ways as well?

I'm worried now as I use ITM Synper forks with alloy steerer, similiar
model I think to Big One.

ps. Get well soon John!

~PB

in message <[email hidden]>, Pete Biggs

(') said:

Simon Brooke said:

A google search for [carbon fork break OR broke OR snapped OR fail]
brought up the following further first-hand reports of actual
failures:

<URL:http://dbclist.org/pipermail/goldrushriders/2005-July/000318.html>

Quoted message said:

Quoted message said:

<URL:http://www.roadbikereview.com/cat/frames-and-forks/forks/easton/PRD_3

Quoted message said:

26183_2492crx.aspx>

Quoted message said:

Yup, only two. Or, counting your own report and the other cited above,
four, of which two are ITMs. So it would look to me like an ITM design
or quality control problem rather than a more general carbon fork
problem.

I reckon ITM is by far the most popular make for carbon forks with
alloy
steerers--sold in big numbers now at 'discount' prices. It is natural
that most of the failures would be with the most common make.

Could the problem also happen with forks with *carbon* steerers that
have
alloy crowns? Is the carbon steerer bonded in the same way? Same
question for steel steerers, or are the crowns then steel too?

The problem with bonding onto Aluminium is (IME) that it oxidises very
quickly, and this tends to muck up the bond. You have to clean off all
oxide and then bond immediately (although I suppose if you're doing this
in a production environment you may set up an inert gas chamber).
Bonding composite to composite is usually very good indeed, particularly
if you can do it before the first epoxy wetout is fully cured. Even if
you have to work on a fully cured surface, a slight roughening is all
you need to get a good bond.

Also I'd expect a decent carbon fork design to have at least some tows
(bundles of fibre) running continuously from the top of the head tube to
each dropout - I would /not/ expect the thing to be made up as discrete
components and then bonded together as a second operation. I may be
naive in this, of course...

Quoted message said:

Would carbon steerers be safer on balance anyway, given that they can
fail in other ways as well?

Having read what I've read this morning, I would guess they would.

Quoted message said:

I'm worried now as I use ITM Synper forks with alloy steerer, similiar
model I think to Big One.

Mine's an Alpina Wing TT - but it's also a carbon fork bonded to an
aluminium steerer.

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

The Conservative Party is now dead. The corpse may still be
twitching, but resurrection is not an option - unless Satan
chucks them out of Hell as too objectionable even for him.

I would have thought you could sue for damages as the forks were
clearly unfit for the purpose even if out of guarantee.
Steel better - my last bike heavily used and misused was nearly 40
years old with the original 531 forks.

cheers

Jacob

Simon Brooke said:

The problem with bonding onto Aluminium is (IME) that it oxidises very
quickly, and this tends to muck up the bond. You have to clean off all
oxide and then bond immediately (although I suppose if you're doing this
in a production environment you may set up an inert gas chamber).

The other issue with bonding CF to metal is that CF is conductive and
electrolytic corrosion can occur (OSIHBLTB) so an initial insulating
layer of glass or other non-conducting fibre is used first as an
insulating layer.

Still worth while hauling out the forks to check the steerer every
season or so to look for cracks.
Knowing how much my front forks flex on braking hard, I'd be worried
about testing to only 50k flex cycles.

...d

Quoted message said:

Steel better - my last bike heavily used and misused was nearly 40
years old with the original 531 forks.

Plenty of steel forks have snapped over the years. Google for that
and you'll find them as well. Given a large enough set, some of them
are going to fail.

--
Arthur Clune

Quoted message said:

Quoted message said:

Steel better - my last bike heavily used and misused was nearly 40
years old with the original 531 forks.

Plenty of steel forks have snapped over the years. Google for that
and you'll find them as well. Given a large enough set, some of them
are going to fail.

As suddenly and catastrophically?

~PB

in message <[email hidden]>, Pete Biggs

(') said:

Quoted message said:

Quoted message said:

Steel better - my last bike heavily used and misused was nearly 40
years old with the original 531 forks.

Plenty of steel forks have snapped over the years. Google for that
and you'll find them as well. Given a large enough set, some of them
are going to fail.

As suddenly and catastrophically?

The only forks I've ever seen snap 'suddenly and catastrophically' were
steel. They were an old style pair with a separate crown and blades, and
were visibly corroded so it wasn't entirely out of the blue. But when
they snapped they just snapped - the right hand blade broke entirely
about half an inch below the crown, and the left hand blade then folded
outwards. Bike was being ridden downhill at the time; I don't remember
the rider being particularly badly hurt, just gravel rash, I think.

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

Morning had broken, and there was nothing we could do but wait
patiently for the RAC to arrive.

Quoted message said:

I would have thought you could sue for damages

Absolutely - you are definitely eligible for some compensation off that
one.

--
Peter Headland

Quoted message said:

Plenty of steel forks have snapped over the years

There were some stupidly designed crowns out there that created perfect
stress risers. Those were also defective products for which the
manufacturers should be held to account. Properly designed and
manufactured forks don't fail - by definition the OP's forks were
defective.

--
Peter Headland

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

Quoted message said:

in message <[email hidden]>, John Miller
([email hidden]'😉 wrote:

Snipped
However, what really bothers me is the sudden

Quoted message said:

Quoted message said:

failure of the steerer. I seem to remember a report about the glue
failing on one of these forks last year,

Google says:

"In earlier correspondence on carbon forks, it was opined that any
problems were unlikely to arise in the carbon fibre itself, but where
it's bonded to metal components. The experience of CTC member Dave
Goodall bears that out, when his less than two years old ITM Big One
carbon fork failed mid-ride. The carbon steerer tube came loose from
the aluminium fork crown, allowing the handlebars to turn
independently of the fork.

He discovered this whilst stationary, just after a 40mph descent."

Source: <URL:http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3519>

Further down the same page it says:

"Fractures are more likely where this is bonded onto metal inserts due
to different stiffness and thermal expansion of the two materials.
Where forks have an alloy steerer tube, this - rather than any failing
of carbon fibre - is likely to result in a shorter life expectancy
than a good steel fork, since alloy has inferior fatigue properties."

From my own knowledge of working with composites (which is strictly
amateur) I know that bonding to Aluminium is tricky (much trickier than
bonding to other composite components or to wood).

A google search for [carbon fork break OR broke OR snapped OR fail]
brought up the following further first-hand reports of actual failures:

<URL:http://dbclist.org/pipermail/goldrushriders/2005-July/000318.html>
<URL:http://www.roadbikereview.com/cat/frames-and-forks/forks/easton/PRD_326183_2492crx.aspx>

Yup, only two. Or, counting your own report and the other cited above,
four, of which two are ITMs. So it would look to me like an ITM design
or quality control problem rather than a more general carbon fork
problem.

This, though not reporting a failure, is interesting:
<URL:http://www.velonews.com/tech/report/articles/3270.0.html>
because it says how long manufacturers think their forks should last.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; First they came for the asylum seekers,
;; and I did not speak out because I was not an asylum seeker.
;; Then they came for the gypsies,
;; and I did not speak out because I was not a gypsy...
;; Pastor Martin Niemöller, translated by Michael Howard.

Simon

Thanks for that (and to all others who replied) - for some reason I hadn't
thought of google - probably not thinking straight yet. I may be wrong, but
I think that the fork crown is also aluminium, I'll have to scrape a bit of
paint off. My other worry is that my Ribble winter bike is equipped with ITM
Spyder forks!

John Miller

Simon Brooke said:

in message <[email hidden]>, Pete Biggs

(') said:

Quoted message said:

[email hidden] wrote:

> Steel better - my last bike heavily used and misused was nearly 40
> years old with the original 531 forks.

Plenty of steel forks have snapped over the years. Google for that
and you'll find them as well. Given a large enough set, some of them
are going to fail.

As suddenly and catastrophically?

The only forks I've ever seen snap 'suddenly and catastrophically'
were steel. They were an old style pair with a separate crown and
blades, and were visibly corroded so it wasn't entirely out of the
blue. But when they snapped they just snapped - the right hand blade
broke entirely about half an inch below the crown, and the left hand
blade then folded outwards. Bike was being ridden downhill at the
time; I don't remember the rider being particularly badly hurt, just
gravel rash, I think.

I was luckier with my old steel forks: just one blade broke with the other
still supporting. Especially after John's message, I'm worrying more
about my ITM carbon/alloy forks.

~PB

Simon Brooke wrote:
...............

Quoted message said:

Also I'd expect a decent carbon fork design to have at least some tows
(bundles of fibre) running continuously from the top of the head tube
to each dropout - I would /not/ expect the thing to be made up as
discrete components and then bonded together as a second operation. I
may be naive in this, of course...

I'll check for ITM Millenium (popular example) via r.b.t.

~PB