Handlebar Failure

The last club ride I went on was about three months ago. I was worried about
wether I'd be on form to keep up but fortunately I did alright. That is,
until on our way back *this* happened:

http://www.btinternet.com/~asqui/pub/Bars/

The worst part (given that I didn't fall off or get run over) is that I
spent £7 and an hour or two changing the bar tape... *yesterday*

The handlebar tubing sheared off as I went over the bumpy side-line on a
main road. I moved back to the right of it, then through the next couple of
seconds had the following train of thought:
"Why am I swerving into the middle of the road?"
"Why is my bike handling weirdly?"
"Hmmm, my left hand feels awfully low."
"...and the end of my handlebar about to touch my rim."
"This can't be good."

Fortunately it came apart gently, and not completely -- I can't imagine the
spectacular crash that would have taken place if my left hand instantly lost
all support (especially if I was sprinting or something). As I slowed I
transferred my left hand to the stem, and tried to brake and negotiate said
bumpy lane marking without crashing (I suck when it comes to one-handed
braking/maneuvering).

My colleagues suggested that it was probably scratched (maybe when being put
into the stem -- which I understand can be a fairly forceful procedure with
that style of stem) and I think I can make out a scratch at the top of the
tubing where it presumably started shearing off. They also recommended I go
for an open-ended racing-style stem, which is gentler on the bars.

I've had the bike since June and have done just over 2700mi on it. I've
dropped it a couple of times on each side and had one proper crash (the bike
came down on the right side though, so that couldn't have been influential).

Do you think they'll do it as a warranty replacement?

If not, should I change to an open-ended stem?


Thanks in advance,
Dani

asqui wrote:

The last club ride I went on was about three months ago. I was worried about
wether I'd be on form to keep up but fortunately I did alright. That is,
until on our way back *this* happened:

http://www.btinternet.com/~asqui/pub/Bars/

The worst part (given that I didn't fall off or get run over) is that I
spent £7 and an hour or two changing the bar tape... *yesterday*

The handlebar tubing sheared off as I went over the bumpy side-line on a
main road. I moved back to the right of it, then through the next couple of
seconds had the following train of thought:
"Why am I swerving into the middle of the road?"
"Why is my bike handling weirdly?"
"Hmmm, my left hand feels awfully low."
"...and the end of my handlebar about to touch my rim."
"This can't be good."

Fortunately it came apart gently, and not completely -- I can't imagine the
spectacular crash that would have taken place if my left hand instantly lost
all support (especially if I was sprinting or something). As I slowed I
transferred my left hand to the stem, and tried to brake and negotiate said
bumpy lane marking without crashing (I suck when it comes to one-handed
braking/maneuvering).

My colleagues suggested that it was probably scratched (maybe when being put
into the stem -- which I understand can be a fairly forceful procedure with
that style of stem) and I think I can make out a scratch at the top of the
tubing where it presumably started shearing off. They also recommended I go
for an open-ended racing-style stem, which is gentler on the bars.

I've had the bike since June and have done just over 2700mi on it. I've
dropped it a couple of times on each side and had one proper crash (the bike
came down on the right side though, so that couldn't have been influential).

Do you think they'll do it as a warranty replacement?

If not, should I change to an open-ended stem?

Alloy bars need to be replaced periodically - 3TTT give recommendations
based on mileage and/or age, whichever comes sooner. However, 2700
miles is well within even the recommendations for professional racing.

Onto the failu firstly, longitudinal scratches caused when sliding
the bars in wouldn't have caused this failure. However, when fitting new
bars it's a good idea to chamfer the edges of the clamp on the stem with
a file, as sharp edges at the bar/stem interface can notch the bar
during normal riding and lead to this kind of failure. This hasn't been
done on your stem.

I also use grease between the bars and the stem, but this is mainly to
prevent any creaking.

BTW, what make and model of bars and stem are they?

It's worth trying for a warranty replacement, but don't expect anything
if you mention you've dropped the bike. I doubt this has anything to do
with the failure - I think they're just overlight and substandard bars -
but a bad shop will use any excuse.

asqui wrote:

The last club ride I went on was about three months ago. I was worried about
wether I'd be on form to keep up but fortunately I did alright. That is,
until on our way back *this* happened:

http://www.btinternet.com/~asqui/pub/Bars/

The worst part (given that I didn't fall off or get run over) is that I
spent £7 and an hour or two changing the bar tape... *yesterday*

The handlebar tubing sheared off as I went over the bumpy side-line on a
main road. I moved back to the right of it, then through the next couple of
seconds had the following train of thought:
"Why am I swerving into the middle of the road?"
"Why is my bike handling weirdly?"
"Hmmm, my left hand feels awfully low."
"...and the end of my handlebar about to touch my rim."
"This can't be good."

Fortunately it came apart gently, and not completely -- I can't imagine the
spectacular crash that would have taken place if my left hand instantly lost
all support (especially if I was sprinting or something). As I slowed I
transferred my left hand to the stem, and tried to brake and negotiate said
bumpy lane marking without crashing (I suck when it comes to one-handed
braking/maneuvering).

My colleagues suggested that it was probably scratched (maybe when being put
into the stem -- which I understand can be a fairly forceful procedure with
that style of stem) and I think I can make out a scratch at the top of the
tubing where it presumably started shearing off. They also recommended I go
for an open-ended racing-style stem, which is gentler on the bars.

I've had the bike since June and have done just over 2700mi on it. I've
dropped it a couple of times on each side and had one proper crash (the bike
came down on the right side though, so that couldn't have been influential).

Do you think they'll do it as a warranty replacement?

If not, should I change to an open-ended stem?

Alloy bars need to be replaced periodically - 3TTT give recommendations
based on mileage and/or age, whichever comes sooner. However, 2700
miles is well within even the recommendations for professional racing.

Onto the failu firstly, longitudinal scratches caused when sliding
the bars in wouldn't have caused this failure. However, when fitting new
bars it's a good idea to chamfer the edges of the clamp on the stem with
a file, as sharp edges at the bar/stem interface can notch the bar
during normal riding and lead to this kind of failure. This hasn't been
done on your stem.

I also use grease between the bars and the stem, but this is mainly to
prevent any creaking.

BTW, what make and model of bars and stem are they?

It's worth trying for a warranty replacement, but don't expect anything
if you mention you've dropped the bike. I doubt this has anything to do
with the failure - I think they're just overlight and substandard bars -
but a bad shop will use any excuse.

Zog The Undeniable wrote:

asqui wrote:

The last club ride I went on was about three months ago. I was worried
about
wether I'd be on form to keep up but fortunately I did alright. That is,
until on our way back *this* happened:

Just another thought - when adjusting the bars, it's possible that the
mechanic twisted the bars repeatedly, without prising open the stem
first. This would have had a similar effect to a plumber's tube cutter.

Zog The Undeniable wrote:

asqui wrote:

The last club ride I went on was about three months ago. I was worried
about
wether I'd be on form to keep up but fortunately I did alright. That is,
until on our way back *this* happened:

Just another thought - when adjusting the bars, it's possible that the
mechanic twisted the bars repeatedly, without prising open the stem
first. This would have had a similar effect to a plumber's tube cutter.

"Zog The Undeniable" wrote in message
...
Zog The Undeniable wrote:
Just another thought - when adjusting the bars, it's possible that the
mechanic twisted the bars repeatedly, without prising open the stem
first. This would have had a similar effect to a plumber's tube cutter.


Yeah, you can kinda see scratches around the circumference near the stem,
conincidentally, right where it broke. I'm surprised it broke so soon
though. 2700 miles doesn't seem like that much even with scratches like
that. But I've rarely seen broken handlebars so I can't really say wity any
authority. I think you'll definitely get a warranty job on that if you
scream enough. I suspect, if you're a shop regular, they'll give you a
discount on a better set of bars, maybe cost.

Cheers,

Scott..

"Zog The Undeniable" wrote in message
...
Zog The Undeniable wrote:
Just another thought - when adjusting the bars, it's possible that the
mechanic twisted the bars repeatedly, without prising open the stem
first. This would have had a similar effect to a plumber's tube cutter.


Yeah, you can kinda see scratches around the circumference near the stem,
conincidentally, right where it broke. I'm surprised it broke so soon
though. 2700 miles doesn't seem like that much even with scratches like
that. But I've rarely seen broken handlebars so I can't really say wity any
authority. I think you'll definitely get a warranty job on that if you
scream enough. I suspect, if you're a shop regular, they'll give you a
discount on a better set of bars, maybe cost.

Cheers,

Scott..

On Sun, 25 Jan 2004 18:05:21 +0000, Zog The Undeniable
wrote:

asqui wrote:

http://www.btinternet.com/~asqui/pub/Bars/

...when fitting new
bars it's a good idea to chamfer the edges of the clamp on the stem with
a file, as sharp edges at the bar/stem interface can notch the bar
during normal riding and lead to this kind of failure. This hasn't been
done on your stem.

I'm not sure; I think I can see a fairly smooth radius on this stem
edge. This looks like a 3TTT stem, and 3TTTs I've seen have had a
radius, presumably to reduce the effects on the bar's fatigue life.

On Sun, 25 Jan 2004 18:05:21 +0000, Zog The Undeniable
wrote:

asqui wrote:

http://www.btinternet.com/~asqui/pub/Bars/

...when fitting new
bars it's a good idea to chamfer the edges of the clamp on the stem with
a file, as sharp edges at the bar/stem interface can notch the bar
during normal riding and lead to this kind of failure. This hasn't been
done on your stem.

I'm not sure; I think I can see a fairly smooth radius on this stem
edge. This looks like a 3TTT stem, and 3TTTs I've seen have had a
radius, presumably to reduce the effects on the bar's fatigue life.

you've covered it, and personally, i'd say twisting is likely although
the camera angles emphasize the region where the bar has torn, not
fatigued - the top where the stem and bar interface appears to be
exactly where there is a smother fatigue crack surface and where such
scarring would have occurred if twisted.

to avoid in the future,

1. make sure the stem clamp is sufficiently open to allow the bar to be
inserted without any twisting & therefore scarring of the bar. /any/
scratch can be a fatigue nucleation point.

2. pay that little extra for a quality bar. ones that have been
shot-peened are available. this creates good fatigue resistance
characteristics.

apart from regular changes of bars, using only quality components and
god fitting practice, it may be worth considering alternatives: i'm
personally uncommitted at this stage, but if this failure really worries
anyone, and i know it did me when i had one, it may be worth considering
a carbon bar. i am not using a carbon road bar at this point, but a
well made carbon bar does have superior fatigue characteristics to
aluminum. i use a carbon mountain bar and having gotten over my initial
random breakage worries, far feel more secure with this bar now than the
aluminum bar i was using previously.

also, the old cinelli bars with the 26.6mm clamp were excellent. they
had an external shim at the mounting point. this is excellent design
because any defects or damage at the shim cannot immediately propagate
into cracks of the bar itself. a good condition, low mileage bar of
that style is something in which you can have a lot of confidence,
albeit not of the anatomical style.

jb


Zog The Undeniable wrote:
Zog The Undeniable wrote:

asqui wrote:

The last club ride I went on was about three months ago. I was
worried about
wether I'd be on form to keep up but fortunately I did alright. That is,
until on our way back *this* happened:


Just another thought - when adjusting the bars, it's possible that the
mechanic twisted the bars repeatedly, without prising open the stem
first. This would have had a similar effect to a plumber's tube cutter.